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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2016	Mar. 14, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
Trading Symbol	HSGX
Entity Registrant Name	Histogenics Corporation
Entity Central Index Key	0001372299
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		22,168,090
Entity Public Float			$ 14.9

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 31,908	$ 30,915
Prepaid expenses and other current assets	173	321
Total current assets	32,081	31,236
Property and equipment, net	3,860	5,213
Intangible asset, net		200
Restricted cash	137	137
Total assets	36,078	36,786
Current liabilities:
Accounts payable	1,588	2,024
Accounts payable due to Intrexon Corporation	360	229
Accrued expenses	2,097	1,444
Accrued expenses due to Intrexon Corporation		1,546
Current portion of deferred rent	136	126
Current portion of deferred lease incentive	407	407
Current portion of equipment loan	583	583
Total current liabilities	5,171	6,359
Accrued expenses due to Intrexon Corporation	3,040
Deferred rent, long-term	315	451
Deferred lease incentive, long-term	610	1,017
Equipment loan, long-term	178	761
Warrant liability	13,197
Total liabilities	22,511	8,588
Commitments and contingencies (Note 7)
Convertible preferred stock and stockholders' equity:
Convertible preferred stock, $0.01 par value; 30,000,000 shares authorized, 13,416.4734 and 0 shares issued and outstanding at December 31, 2016 and 2015, respectively
Common stock, $0.01 par value; 100,000,000 shares authorized, 20,647,612 and 13,273,470 shares issued and outstanding at December 31, 2016 and 2015, respectively	159	132
Additional paid-in capital	195,181	193,631
Accumulated deficit	(181,773)	(165,565)
Total stockholders' equity	13,567	28,198
Total liabilities and stockholders' equity	$ 36,078	$ 36,786

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Convertible preferred stock, shares authorized	30,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	20,647,612	13,273,470
Common stock, shares outstanding	20,647,612	13,273,470
Series A Convertible Preferred Stock [Member]
Convertible preferred stock, par value	$ 0.01	$ 0.01
Convertible preferred stock, shares authorized	30,000,000	30,000,000
Convertible preferred stock, shares issued	13,416.4734	0.0000
Convertible preferred stock, shares outstanding	13,416.4734	0.0000

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue	$ 0	$ 0
Operating expenses:
Research and development	21,577	23,243
General and administrative	8,530	8,266
Impairment of intangible asset	200	310
Total operating expenses	30,307	31,819
Loss from operations	(30,307)	(31,819)
Other income (expense):
Interest expense, net	(60)	(133)
Other expense, net	(248)	(72)
Warrant expense	(3,100)	(11)
Change in fair value of warrant liability	17,507
Total other income (expense), net	14,099	(205)
Net loss	(16,208)	(32,024)
Loss attributable to common stockholders-basic	(13,863)	(32,024)
Loss attributable to common stockholders-diluted	$ (31,370)	$ (32,024)
Loss per common share-basic	$ (0.97)	$ (2.42)
Loss per common share-diluted	$ (2.18)	$ (2.42)
Weighted-average shares used to compute loss per common share-basic	14,256,954	13,231,126
Weighted-average shares used to compute loss per common share-diluted	14,389,192	13,231,126

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Restricted Stock [Member]
Ending Balance at Dec. 31, 2015		$ 0
Beginning Balance at Dec. 31, 2014	$ 54,206		$ 127	$ 187,620	$ (133,541)
Beginning Balance, Shares at Dec. 31, 2014			12,746,519			8,493
Issuance of common stock from overallotment, net of underwriting fees and issuance costs of $377	4,738		$ 5	4,733
Issuance of common stock from overallotment, net of underwriting fees and issuance costs of $377, Shares			465,000
Issuance of warrant as part of the consideration for the consulting related to financial support services in March 2015	11			11
Vesting of restricted stock	0		$ 0	0	0	$ 0
Vesting of restricted stock, Shares			3,303			(3,303)
Stock-based compensation expense	1,228			1,228
Exercise of common stock options	39			39
Exercise of common stock options, Shares			53,458
Net loss	(32,024)				(32,024)
Ending Balance at Dec. 31, 2015	28,198		$ 132	193,631	(165,565)
Ending Balance, Shares at Dec. 31, 2015			13,268,280			5,190
Issuance of common stock related to private placement	26		$ 26
Issuance of common stock related to private placement, Shares			2,596,059
Issuance of Series A convertible preferred stock	0	$ 0	$ 0	0	0	$ 0
Issuance of Series A convertible preferred stock, Shares		24,159
Conversion of Series A convertible preferred stock	0	$ 0	$ 0	0	0	0
Conversion of Series A convertible preferred stock, Shares		(10,743)	4,774,398
Ending Balance at Dec. 31, 2016		$ 0
Ending Balance, Shares at Dec. 31, 2016		13,416
Vesting of restricted stock	0		$ 0	0	0	$ 0
Vesting of restricted stock, Shares			3,301			(3,301)
Stock-based compensation expense	1,548			1,548
Exercise of common stock options	$ 3		$ 1	2
Exercise of common stock options, Shares	3,685		3,685
Net loss	$ (16,208)				(16,208)
Ending Balance at Dec. 31, 2016	$ 13,567		$ 159	$ 195,181	$ (181,773)
Ending Balance, Shares at Dec. 31, 2016			20,645,723			1,889

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016
Common stock, par value	$ 0.01	$ 0.01
Issuance of common stock, net issuance costs	$ 377
Common Stock [Member]
Common stock, par value	$ 0.01	0.01
Series A Convertible Preferred Stock [Member]
Temporary equity, par value	0.01	0.01
Restricted Stock [Member]
Common stock, par value	$ 0.01	$ 0.01

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (16,208)	$ (32,024)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,673	1,614
Deferred rent and lease incentive	(533)	(322)
Impairment of intangible asset	200	310
Stock-based compensation	1,548	1,228
Change in fair value of warrant	(17,507)
Warrant expense in connection with private placement	3,100	11
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	148	475
Accrued expenses due to Intrexon Corporation	1,494	1,539
Accounts payable	(435)	(2,844)
Accounts payable due to Intrexon Corporation	131	211
Accrued expenses	653	(232)
Net cash used in operating activities	(25,736)	(30,034)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(320)	(1,949)
Net cash used in investing activities	(320)	(1,949)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock, preferred stock, and warrants in connection with private placement, net of issuance costs	27,630
Proceeds from overallotment, net of issuance costs of $377		4,738
Repayments on equipment term loan	(583)	(406)
Proceeds from exercise of stock options	2	39
Net cash provided by financing activities	27,049	4,371
Net increase (decrease) in cash and cash equivalents	993	(27,612)
Cash and cash equivalents-Beginning of period	30,915	58,527
Cash and cash equivalents-End of period	31,908	30,915
Supplemental Disclosure of Non-Cash Items:
Fair market value of private placement warrants at issuance	30,704
Supplemental Disclosure of Cash Flow information:
Cash paid for taxes	257	79
Cash paid for interest	$ 66	$ 94

Consolidated Statements of Cash Flows (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Statement of Cash Flows [Abstract]
Issuance costs	$ 377

Nature of Business

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Business

1.	NATURE OF BUSINESS

Organization

Histogenics Corporation (the “Company”) was incorporated under the laws of the Commonwealth of Massachusetts on June 28, 2000 and has its principal operations in Waltham, Massachusetts. In 2006, the Company’s board of directors approved a corporate reorganization pursuant to which the Company incorporated as a Delaware corporation. The Company is a regenerative medicine company engaged in developing and commercializing products in the musculoskeletal segment of the marketplace. The Company combines cell therapy and tissue engineering technologies to develop products for tissue repair and regeneration and is initially focused on patients suffering from cartilage-derived pain and immobility. The Company’s most advanced product, NeoCart, is currently in a Phase 3 clinical trial in the United States (the “U.S.”) under a special protocol assessment with the U.S. Food and Drug Administration (“FDA”) for the treatment of knee cartilage damage.

On May 13, 2011, the Company completed the acquisition of ProChon Biotech Ltd. (“ProChon”), a privately-held biotechnology company focused on modulating the fibroblast growth factor system for consideration of $2.2 million to enable it to create more effective solutions for tissue regeneration. ProChon’s products combine cell regeneration technologies with proprietary growth factors and biocompatible scaffolds to restore injured or chronically damaged tissues. The acquisition of ProChon provided the Company with access to a significant portfolio of intellectual property, including proprietary cell growth factors, in addition to furthering opportunities for the use of biomaterials to create more effective solutions for regenerating human tissue. The acquisition led to the initial recognition of goodwill, which was subsequently written off in 2011, and intangible assets including IPR&D and a licensing agreement which have been impaired as discussed in Note 2.

On December 18, 2014, the Company formed a wholly owned subsidiary, Histogenics Securities Corporation, under the laws of the Commonwealth of Massachusetts.

On September 29, 2016, the Company closed a private placement of common stock, preferred stock and warrants, contemplated by a securities purchase agreement dated September 15, 2016, with certain institutional and accredited investors. The net proceeds after deducting placement agent fees and other transaction-related expenses was $27.6 million. See Note 8, Capital Stock, for further discussion of the private placement.

Since its inception, the Company has devoted substantially all of its efforts to product development, recruiting management and technical staff, raising capital, starting up production and building infrastructure and has not yet generated revenues from its planned principal operations. Expenses have primarily been for research and development and related administrative costs.

The Company is subject to a number of risks. The developmental nature of its activities is such that significant inherent risks exist in the Company’s operations. Principal among these risks are the successful development of therapeutics, successfully enrolling patients in its clinical trials in a timely manner, obtaining regulatory approval for any of its product candidates in any jurisdiction, compliance with government regulations, ability to obtain adequate financing, protection of proprietary therapeutics, fluctuations in operating results, dependence on key personnel and collaborative partners, adoption of the Company’s products by the physician community, rapid technological changes inherent in the markets targeted, and substitute products and competition from larger companies.

The consolidated financial statements have been prepared on a going-concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. As shown in the accompanying consolidated financial statements, the Company has incurred losses and cash flow deficits from operations for the years ended December 31, 2016 and 2015. The Company has financed operations to date primarily through private placements of equity securities, including the sale of common stock and preferred stock, and the related issuance of warrants in September 2016, the issuance of common stock in the initial public offering completed in December 2014, and borrowings under debt agreements. The Company has incurred losses and negative cash flows from operations since inception resulting in an accumulated deficit at December 31, 2016 of $181.8 million. The Company anticipates that it will continue to incur net losses for the next several years. The Company believes that its existing cash and cash equivalents will be sufficient to fund its projected cash needs into the middle of 2018, and it has the ability to reduce or defer operating expenses as may be needed to fund its operations into the middle of the third quarter of 2018. The Company will require additional capital to complete the filing of a biologics license application with the FDA and commercialize NeoCart, if approved, and for the future development of its existing product candidates. However, the terms of such financing may not be on favorable terms or available to the Company.

Initial public offering

On December 3, 2014, the Company completed its initial public offering (“IPO”) whereby the Company sold 5,909,091 shares of common stock at a price of $11.00 per share. The shares began trading on the Nasdaq Global Market on December 3, 2014. Gross proceeds from the offering were $65 million. In January 2015, the underwriters exercised a portion of their overallotment option and purchased an additional 465,000 shares of the Company’s common stock at $11.00 per share, resulting in an additional $5.1 million in gross proceeds. After giving effect to underwriting discounts and commissions and offering expenses payable by the Company, net proceeds were $61.3 million.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Accounting

The consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The consolidated financial statements include the accounts of Histogenics Corporation and its wholly-owned subsidiaries, ProChon and Histogenics Securities Corporation. All significant intercompany accounts and transactions are eliminated in consolidation.

Reclassifications

The Company has reclassified certain prior period amounts to conform to the current period presentation. The amounts reclassified impact Accounts Payable and Accounts Payable due to Intrexon Corporation (“Intrexon”) for the year ended December 31, 2015.

Use of Estimates

The preparation of the Company’s consolidated financial statements requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company’s consolidated financial statements and accompanying notes. The most significant estimates in the Company’s consolidated financial statements relate to the valuation of equity awards, warrant liability, recoverability of deferred tax assets, estimated useful lives of fixed assets and intangible assets. The Company bases estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. The Company evaluates its estimates and assumptions on an ongoing basis. The Company’s actual results may differ from these estimates under different assumptions or conditions.

Foreign Currency Translation

The Company’s consolidated financial statements are prepared in U.S. dollars. The Company’s foreign subsidiary uses the U.S. dollar as its functional and reporting currency, as management determined that the U.S. dollar is the primary currency of the economic environment in which the subsidiary operates. When transactions are required to be paid in the local currency of the foreign subsidiary, any resulting foreign currency transaction gain or loss is recorded as a component of “Other income (expense), net” in the consolidated statements of operations.

Segment and Geographic Information

Operating segments are defined as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker (“CODM”) or decision-making group in making decisions regarding resource allocation and assessing performance. The Company operates in two geographic regions: the United States (Massachusetts) and Israel (Tel Aviv) and views its operations as two operating segments: Histogenics Corporation (United States) and ProChon (Israel) as the CODM reviews separate discrete financial information in making decisions regarding resource allocations and assessing performance. Operating segments that have similar economic characteristics can be aggregated. As the nature of the products, customers, and methods to distribute products are the same and the nature of the regulatory environment, the production processes and historical and estimated future margins are similar, the two operating segments have been aggregated into one reporting segment as they have similar economic characteristics.

Information about the Company’s operations in different geographic regions is presented in the tables below:


	December 31, 2016		December 31, 2015
	(in thousands)
Long-lived assets:
United States	$	3,860	$	5,204
Israel		—		9

Total long-lived assets	$	3,860	$	5,213

Fair Value Measurements

The carrying amounts reported in the Company’s consolidated financial statements for cash and cash equivalents, accounts payable, equipment loan, and accrued liabilities approximate their respective fair values because of the short-term nature of these accounts.

Fair value is defined as the price that would be received if selling an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date.

Fair value should be based on the assumptions that market participants would use when pricing an asset or liability and is based on a fair value hierarchy that prioritizes the information used to develop those assumptions. The fair value hierarchy gives the highest priority to quoted prices in active markets (observable inputs) and the lowest priority to the Company’s assumptions (unobservable inputs). Fair value measurements should be disclosed separately by level within the fair value hierarchy. For assets and liabilities recorded at fair value, it is the Company’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements, in accordance with established fair value hierarchy.

Fair value measurements for assets and liabilities where there exists limited or no observable market data are based primarily upon estimates, and often are calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, the results cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any valuation technique, and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the results of current or future values.

Additionally, from time to time, the Company may be required to record at fair value other assets on a nonrecurring basis, such as assets held for sale and certain other assets. These nonrecurring fair value adjustments typically involve application of lower-of-cost-or-market accounting or write-downs of individual assets.

The fair value hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets (Level 1), and the lowest priority to unobservable inputs (Level 3). The Company’s financial assets are classified within the fair value hierarchy based on the lowest level of inputs that is significant to the fair value measurement. The three levels of the fair value hierarchy, and its applicability to the Company’s financial assets, are described below.

Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date of identical, unrestricted assets.

Level 2: Quoted prices for similar assets, or inputs that are observable, either directly or indirectly, for substantially the full term through corroboration with observable market data. Level 2 includes investments valued at quoted prices adjusted for legal or contractual restrictions specific to the security.

Level 3: Pricing inputs are unobservable for the assets, that is, inputs that reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the assets. Level 3 includes private investments that are supported by little or no market activity.

Level 3 valuations are for instruments that are not traded in active markets or are subject to transfer restrictions and may be adjusted to reflect illiquidity and/or non-transferability, with such adjustment generally based on available market evidence. In the absence of such evidence, management’s best estimate is used.

An adjustment to the pricing method used within either Level 1 or Level 2 inputs could generate a fair value measurement that effectively falls in a lower level in the hierarchy. The Company had no assets or liabilities classified as Level 1 or Level 2 as of December 31, 2016 and 2015 other than the money market fund described in the “Cash and Cash Equivalents” section below and there were no material re-measurements of fair value with respect to financial assets and liabilities, during the periods presented, other than those assets and liabilities that are measured at fair value on a recurring basis. Other than the warrants issued in connection with the private placement transaction which closed on September 29, 2016, the Company had no assets or liabilities classified as Level 3 as of December 31, 2016 and 2015. Transfers are calculated on values as of the transfer date. There were no transfers between Levels 1, 2 and 3 during the twelve months ended December 31, 2016 and 2015.

The fair value of the warrants was determined using a Monte Carlo simulation model. This model incorporated several assumptions at each valuation date including: the price of the Company’s common stock on the date of valuation, the historical volatility of the price of the Company’s common stock, the remaining contractual term of the warrant and estimates of the probability of a fundamental transaction occurring. See Note 8, Capital Stock, for further discussion of the private placement.


Description	Total		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)
December 31, 2016
Assets:
Money market funds	$	30,318	$	30,318	$	—	$	—
Liabilities:
Warrant liability		13,197		—		—		13,197
December 31, 2015
Money market funds		25,764		25,764		—		—

The following table provides a reconciliation of all liabilities measured at fair value using Level 3 significant unobservable inputs:


	As of December 31, 2016
	(in thousands)
Beginning balance, January 1, 2016	$	—
Issuance of warrants,		30,704
Change in fair value of warrant liability		(17,507	)

Ending balance	$	13,197

Cash and Cash Equivalents

Cash and cash equivalents include cash in readily available checking and savings accounts and money market funds. The Company considers all highly liquid investments with an original maturity of three months or less from the date of purchase to be cash equivalents.

The Company’s cash equivalents, which consist of money market funds, are measured at fair value on a recurring basis. As of December 31, 2016 and 2015, the carrying amount of cash and cash equivalents was $31.9 million and $30.9 million, respectively, which approximates fair value and was determined based upon Level 1 inputs. Money market funds are valued using quoted market prices with no valuation adjustments applied. Accordingly, these securities are categorized as Level 1 and had a balance of $30.3 million and $25.8 million as of December 31, 2016 and 2015, respectively, shown in the table above.

Concentration of Credit Risk

Financial instruments, which potentially subject the Company to significant concentration of credit risk, consist primarily of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company has no financial instruments with off-balance sheet risk of loss.

Property and Equipment

Property and equipment are recorded at historical cost. Costs for capital assets not yet placed into service are capitalized as construction in progress, and will be depreciated in accordance with the below guidelines once placed into service. Maintenance and repair costs are expensed as incurred. Costs which materially improve or extend the lives of existing assets are capitalized. The Company provides for depreciation and amortization using the straight-line method over the estimated useful lives of the assets, which are as follows:


Asset Category		Estimated Useful Lives
Office equipment		3 to 5 years
Laboratory equipment		3 to 5 years
Leasehold improvements		Shorter of the remaining lease term or useful life

Upon retirement or sale, the cost of assets disposed and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is recorded in the consolidated statements of operations.

Impairment of Long-Lived Assets

Long-lived assets consist primarily of property and equipment and identifiable intangible assets. When impairment indicators exist, the Company’s management evaluates long-lived assets for potential impairment. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. While the Company’s current and historical operating losses and negative cash flows are indicators of impairment, management believes that future cash flows to be received support the carrying value of its long-lived assets.

Impairments, if any, are recognized in earnings. An impairment loss would be recognized in an amount equal to the excess of the carrying amount over the undiscounted expected future cash flows.

Intangible Asset

The Company’s intangible asset consists of acquired in-process research and development (“IPR&D”) obtained through the acquisition of ProChon. IPR&D represents the fair value assigned to research and development assets that have not been completed at the date of acquisition. The value assigned to acquired IPR&D is determined by estimating the costs to develop the acquired technology into commercially viable products, estimating the resulting revenue from the projects, and discounting the net cash flows to present value. The revenue and costs projections used to value acquired IPR&D were adjusted based on the probability of success of developing a new product. Additionally, the projections considered the relevant market sizes and growth factors, expected trends in technology and the nature and expected timing of new product introductions by the Company and its competitors. The rates utilized to discount the net cash flows to their present value were commensurate with the stage of development of the projects and uncertainties in the economic estimates used in the projections described above.

IPR&D is considered an indefinite-lived intangible asset and is assessed for impairment annually or more frequently if impairment indicators exist. When performing the impairment assessment, the Company first assesses qualitative factors to determine whether it is necessary to recalculate the fair value of its acquired IPR&D. If the Company believes, as a result of the qualitative assessment, that it is more likely than not that the fair value of acquired IPR&D is less than its carrying amount, it calculates the fair value using the same methodology as described above. If the carrying value of the Company’s acquired IPR&D exceeds its fair value, then an impairment charge is taken and the intangible asset is written-down to its fair value. During the fourth quarter the Company deemed the value of the IPR&D to be zero for the year ended December 31, 2016 as it has no plans to advance the technology or use it in any future clinical development activities. The result was a write-off of $0.2 million. For the year ended December 31, 2015, the Company determined that there was impairment of its IPR&D of $0.3 million. The Company performed its annual impairment test of its IPR&D as of December 31, 2015 using an income approach, including a discount rate of 13%, applied to probability-adjusted after-tax cash flows. The Company believes that the assumptions are representative of those a market participant would use in estimating the fair value of the IPR&D.

Intangible asset, net of accumulated impairment charges, are summarized as follows:


	As of December 31, 2016							As of December 31, 2015
	Cost		Accumulated Impairment			Net Book Value		Cost		Accumulated Impairment			Net Book Value
	(in thousands)							(in thousands)
IPR&D	$	630	$	(630	)	$	—	$	630	$	(430	)	$	200

	$	630	$	(630	)	$	—	$	630	$	(430	)	$	200

Initial Public Offering Costs

The Company deferred direct incremental costs attributable with the IPO of its common stock prior to the closing of the IPO. These costs represent legal, accounting and other direct costs related to the Company’s efforts to raise capital through a public sale of its common stock. Upon completion of the IPO, $3.9 million of IPO costs were reclassified to additional paid-in capital as a reduction of the IPO proceeds. As of December 31, 2014, the Company had paid $2.9 million with the remaining $1.0 million included in accounts payable in the consolidated balance sheet. This amount was subsequently paid in 2015.

Restricted Cash

Restricted cash represents cash held in a depository account at a financial institution to collateralize a conditional stand-by letter of credit related to the Company’s Lexington, Massachusetts facility lease agreement. Restricted cash is reported as non-current unless the restrictions are expected to be released in the next twelve months.

Deferred Rent

Deferred rent consists of the difference between cash payments and the recognition of rent expense on a straight-line basis for the facilities the Company occupies. The Company’s leases for its Waltham, Massachusetts facility and its Lexington, Massachusetts facility provide for fixed increases in minimum annual rental payments. The total amount of rental payments due over each lease term is being charged to rent expense ratably over the life of each lease, respectively.

Financial Instruments Indexed to and Potentially Settled in the Company’s Common Stock

The Company evaluates all financial instruments issued in connection with its equity offerings when determining the proper accounting treatment for such instruments in the Company’s financial statements. The Company considers a number of generally accepted accounting principles under U.S. GAAP to determine such treatment and evaluates the features of the instrument to determine the appropriate accounting treatment. The Company utilizes the Probability Weighted Expected Return Method (“PWERM”), Option Pricing Model (“OM”) or other appropriate methods to determine the fair value of its derivative financial instruments. For financial instruments indexed to and potentially settled in the Company’s common stock that are determined to be classified as liabilities on the consolidated balance sheet, changes in fair value are recorded as a gain or loss in the Company’s consolidated statement of operations with the corresponding amount recorded as an adjustment to the liability on its consolidated balance sheet.

Revenue Recognition

In the future, if we generate revenue, it may be through license agreements, collaborations and product sales. The Company recognizes revenue when all four of the following criteria are met: (1) persuasive evidence that an agreement exists; (2) delivery of the products and/or services has occurred; (3) the selling price is fixed or determinable; and (4) collectability is reasonably assured. The Company did not recognize any revenue for the years ended December 31, 2016 and 2015.

Research and Development Costs

Research and development costs are charged to expense as incurred. These costs include, but are not limited to: license fees related to the acquisition of in-licensed products; employee-related expenses, including salaries, benefits and travel; expenses incurred under agreements with contract research organizations and investigative sites that conduct clinical trials and preclinical studies; the cost of acquiring, developing and manufacturing clinical trial materials; facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities; insurance and other supplies; and costs associated with preclinical activities and regulatory operations.

Costs for certain development activities, such as clinical trials, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the consolidated financial statements as prepaid or accrued research and development expense.

Collaboration Arrangements

Costs reimbursed to a collaborator for work that it performs are recorded as research and development expenses. These reimbursements can include payments for work performed, or a milestone for which a payment is due, the reimbursements or development milestone achievement are recorded as research and development expense.

In September 2014, the Company entered into a collaboration agreement with Intrexon Corporation (“Intrexon”) for the development and commercialization of allogeneic cell therapeutics for the treatment or repair of damaged articular hyaline cartilage in humans, utilizing Intrexon’s proprietary technology (the “Collaboration Agreement”). Under the terms of the Collaboration Agreement, the Company is responsible for the costs of development and commercialization, with some exceptions. Refer to Note 14, Related Parties for further details on all terms, conditions and exceptions of this collaboration.

License Agreements

Costs associated with licenses of technology are expensed as incurred and are included in research and development expenses.

Patent Costs

Costs related to filing and pursuing patent applications are recorded as general and administrative expense as incurred since the recoverability of such expenditures is uncertain.

Stock-Based Compensation

The Company accounts for grants of stock options and restricted stock based on their grant date fair value and recognizes compensation expense over their vesting period. The Company estimates the fair value of stock options as of the date of grant using the Black-Scholes option pricing model and restricted stock based on the fair value of the underlying common stock as determined by management or the value of the services provided, whichever is more readily determinable.

Stock-based compensation expense represents the cost of the grant date fair value of employee stock option grants recognized over the requisite service period of the awards (usually the vesting period) on a straight-line basis, net of estimated forfeitures. The expense is adjusted for actual forfeitures at year end. Stock-based compensation expense recognized in the consolidated financial statements is based on awards that are ultimately expected to vest.

For stock option grants with performance-based milestones, the expense is recorded over the remaining service period after the point when the achievement of the milestone is probable or the performance condition has been achieved. For stock option grants with both performance-based milestones and market conditions, expense is recorded over the derived service period after the point when the achievement of the performance-based milestone is probable or the performance condition has been achieved. The Company issued performance-based awards in 2015, but not in 2016.

The Company accounts for stock options and restricted stock awards to non-employees using the fair value approach. Stock options and restricted stock awards to non-employees are subject to periodic revaluation over their vesting terms.

Income Taxes

The Company accounts for income taxes under the liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date.

The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future, in excess of its net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.

The Company records uncertain tax positions on the basis of a two-step process whereby (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more likely than not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability.

Earnings (Loss) per Common Share

Earnings (loss) per common share is calculated using the two-class method, which is an earnings allocation formula that determines earnings (loss) per share for the holders of the Company’s common shares and participating securities. All series of preferred stock contain participation rights in any dividend paid by the Company and are deemed to be participating securities. Earnings available to common stockholders and participating convertible redeemable preferred shares are allocated to each share on an as-converted basis as if all of the earnings for the period had been distributed. The participating securities include a contractual obligation to share in losses of the Company and are included in the calculation of net loss per share in the periods that have a net loss.

Diluted earnings per share is computed using the more dilutive of (a) the two-class method, or (b) the if-converted method. The Company allocates earnings first to preferred stockholders based on dividend rights and then to common and preferred stockholders based on ownership interests. The weighted-average number of common shares included in the computation of diluted earnings (loss) gives effect to all potentially dilutive common equivalent shares, including outstanding stock options, warrants, convertible redeemable preferred stock and the potential issuance of stock upon the conversion of the Company’s convertible notes. Common stock equivalent shares are excluded from the computation of diluted earnings (loss) per share if their effect is antidilutive.

Warrant Accounting

As noted in Note 9, the Company classifies warrants to purchase shares of its common stock as a liability on its consolidated balance sheet if the warrant is a free-standing financial instrument that may require the Company to transfer consideration upon exercise. Each warrant of this type is initially recorded at fair value on date of grant using the Monte Carlo simulation model and net of issuance costs, and is subsequently re-measured to fair value at each subsequent balance sheet date. Changes in fair value of the warrants are recognized as a component of other income (expense), net in the consolidated statement of operations. The Company will continue to adjust the liability for changes in fair value until the earlier of the exercise or expiration of the warrants.

Recently Adopted Accounting Pronouncements

In November 2015, Financial Accounting Standards Board (“the FASB”) issued Accounting Standard Update (“ASU”) No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. The new standard requires that deferred tax assets and liabilities be classified as noncurrent in a classified statement of financial position. The Company prospectively adopted this guidance in the fourth quarter of 2015, which resulted in the removal of gross deferred tax assets and liabilities from the Company’s consolidated balance sheet. The net impact was zero and the prior period was not retrospectively adjusted.

In November 2014, the FASB issued ASU No. 2014-16, Derivatives and Hedging (Topic 815): Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity. This standard provides guidance to eliminate the existing diversity in practice in accounting for hybrid financial instruments issued in the form of a share. A hybrid financial instrument consists of a “host contract” into which one or more derivative terms have been embedded. This guidance requires an entity to consider the terms and features of the entire financial instrument, including the embedded derivative features, in order to determine whether the nature of the host contract is more akin to debt or to equity. This guidance is effective for fiscal years and interim periods beginning after December 15, 2015, with early adoption permitted. A reporting entity should apply this guidance using a modified retrospective approach by recording a cumulative-effect adjustment to equity as of the beginning of the annual period of adoption. Retrospective application is permitted to all relevant prior periods. The Company has concluded that this guidance has no impact on the presentation of its results of operations, financial position and disclosures.

In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 2015-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. This guidance addresses management’s responsibility in evaluating whether there is substantial doubt about a company’s ability to continue as a going concern and to provide related footnote disclosures. The guidance is effective for fiscal years ending after December 15, 2016 and for interim periods within those fiscal years. The adoption of this standard did not have a material impact on our consolidated financial statements and related disclosures.

In June 2014, the FASB issued ASU No. 2014-12, Compensation-Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could be Achieved after the Requisite Service Period. This standard provides guidance requiring when there is a performance target that affects vesting of equity awards granted and could be achieved after the requisite service period to be treated as a performance condition. A reporting entity should apply existing guidance on stock-based compensation, as it relates to such awards. This guidance is effective for annual periods and interim periods within those annual periods beginning after December 15, 2015 with early adoption permitted using either of two methods: (i) prospective to all awards granted or modified after the effective date; or (ii) retrospective to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter, with the cumulative effect of applying this guidance as an adjustment to the opening retained earnings balance as of the beginning of the earliest annual period presented in the financial statements. The Company issued performance-based awards during the year ended December 31, 2015. The Company adopted this guidance on a prospective basis and there have not been any performance-based awards since the effective date of the guidance.

Recently Issued Accounting Pronouncements

In November 2016, the FASB issued guidance that requires restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the total beginning and ending amounts for the periods shown on the statement of cash flows. The new standard is effective for us on January 1, 2018 using a retrospective transition method to each period presented. Early adoption is permitted. We are currently evaluating the timing of our adoption and the expected impact that this standard could have on our consolidated financial statements and related disclosures.

In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Shared-Based Payment Accounting. This standard provides guidance on accounting for employee share-based payments. This guidance addresses several aspects of the accounting for share-based payment award transactions, including: (a) income tax consequences; (b) classification of awards as either equity or liabilities; and (c) classification on the statement of cash flows. This standard will be effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. The Company is evaluating the impact of this guidance on the presentation of its results of operations, financial position and disclosures.

In February 2016, the FASB, issued ASU No. 2016-02, Leases (Topic 842). The ASU requires companies to recognize on the balance sheet the assets and liabilities for the rights and obligations created by leased assets. ASU 2016-02 will be effective for the Company in the first quarter of 2019, with early adoption permitted. The Company is currently evaluating the impact that the adoption of ASU 2016-02 will have on the Company’s consolidated financial statements or related disclosures.

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014-09 will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. In July 2015, the FASB issued a one-year deferral of the effective date of the new revenue recognition standard. The new guidance will be effective for the Company’s first quarter of fiscal year 2018 and early application for fiscal year 2017 would be permitted. The Company is evaluating the impact of this guidance on the presentation of its results of operations, financial position and disclosures.

Loss Per Common Share

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Loss Per Common Share

3.	LOSS PER COMMON SHARE

Basic and diluted loss per common share are calculated as follows:


	For the Year Ended
	2016			2015
	(In thousands, except share and per share data
Numerator:
Net loss	$	(16,208	)	$	(32,024	)
Net Loss attributable to Series A Preferred Stock (a)		(2,345	)		—

Numerator for basic EPS—Earnings (loss) attributable to common stockholders		(13,863	)		(32,024	)

Effect of dilutive securities:
Deduct change in fair value of warrant liability		(17,507	)		—

Numerator for diluted EPS—Earnings (loss) attributable to common stockholders after assumed conversions	$	(31,370	)	$	(32,024	)

Denominator:
Weighted-average number of common shares used in earnings (loss) per share—basic		14,256,954			13,231,126
Effect of dilutive securities:
Nonparticipating warrants		132,238			—

Denominator for diluted EPS—adjusted weighted average shares		14,389,192			13,231,126

Earnings (loss) per share—basic	$	(0.97	)	$	(2.42	)

Earnings (loss) per share—diluted	$	(2.18	)	$	(2.42	)

(a)	The Series A Preferred Stock participates in income and losses

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares outstanding, as they would be anti-dilutive (in common stock equivalent shares):


	As of December 31,
	2016		2015
Unvested restricted stock and options to purchase common stock		1,578,905		1,227,957
Series A preferred stock unconverted		5,962,817		—
Warrants exercisable into common stock		166,403		166,403

Prepaid Expenses and Other Current Assets

12 Months Ended

Dec. 31, 2016

Text Block [Abstract]

Prepaid Expenses and Other Current Assets

4. PREPAID EXPENSES AND OTHER CURRENT ASSETS

Prepaid expenses and other current assets consisted of the following:


	As of December 31,
	2016		2015
	(in thousands)
Deposits	$	10	$	67
Undelivered laboratory and office equipment		—		17
Insurance		95		42
Other current assets		68		195

Prepaid expenses and other current assets	$	173	$	321

Property and Equipment

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property and Equipment

5. PROPERTY AND EQUIPMENT

Property and equipment consisted of the following:


	December 31, 2016			December 31, 2015
	(in thousands)
Office equipment	$	266		$	539
Laboratory equipment		4,443			4,337
Leasehold improvements		7,683			7,683
Construction in progress		759			547
Software		96			96

Total property and equipment		13,247			13,202
Less: accumulated depreciation		(9,387	)		(7,989	)

Property and equipment, net	$	3,860		$	5,213

Depreciation expense related to property and equipment amounted to $1.7 million and $1.6 million for the years ended December 31, 2016 and 2015, respectively.

Accrued Expenses

12 Months Ended

Dec. 31, 2016

Payables and Accruals [Abstract]

Accrued Expenses

6.	ACCRUED EXPENSES

Accrued expenses consisted of the following:


	As of December 31,
	2016		2015
	(in thousands)
Accrued compensation	$	1,402	$	758
Accrued clinical expenses		187		138
Accrued other		508		548

Total accrued expenses	$	2,097	$	1,444

Commitments and Contingencies

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

7.	COMMITMENTS AND CONTINGENCIES

Operating Leases

The Company leases office and research facilities in Waltham, Massachusetts under a non-cancellable operating lease, which expires in December 2017, with two additional five-year renewal options. Terms of the agreement provide for an initial rent-free period and future rent escalation, and provide that in addition to minimum lease rental payments, the Company is responsible for a pro-rata share of common area operating expenses. In June 2014, the Company entered into a lease agreement to rent a facility in Lexington, Massachusetts. The commencement date of the lease was July 9, 2014 with a term that extends through June 1, 2023, with one additional five-year renewal option. Terms of the lease agreement provide for an initial rent-free period and future rent escalation, and provide that in addition to minimum lease rental payments, the Company is responsible for a pro-rata share of operating expenses. The Company’s wholly-owned subsidiary, ProChon, leased a facility in Woburn, Massachusetts which expired in 2016 and was not renewed.

Aggregate minimum annual lease commitments of the Company under its non-cancellable operating leases as of December 31, 2016, are as follows:


For the Year Ended December 31,
	(in thousands)
2017	$	2,266
2018		754
2019		586
2020		596
2021		605
Thereafter		926

Total minimum lease payments	$	5,733

Rent expense under operating lease agreements amounted to $1.0 million and $1.1 million for the years ended December 31, 2016 and 2015, respectively.

As an inducement to enter into its Waltham facility lease, the lessor agreed to provide the Company with a construction allowance of up to $3.2 million towards the total cost of tenant improvements. As an inducement to enter into its Lexington facility lease, the lessor agreed to provide the Company with a construction allowance of up to $1.0 million towards the total cost of tenant improvements. The Company has recorded these costs in the consolidated balance sheet as leasehold improvements, with the corresponding liability as deferred lease incentive. These liabilities are amortized on a straight-line basis over the term of the lease as a reduction of rent expense.

License Agreements

From time to time, the Company enters into various licensing agreements whereby the Company may use certain technologies in conjunction with its product research and development.

Licensing agreements and the Company’s commitments under the agreements are as follows:

Hydrogel License

In May 2005, the Company entered into an exclusive license agreement with Angiotech Pharmaceuticals (US), Inc. for the use of certain patents, patent applications, and knowledge related to the manufacture and use of a hydrogel material in conjunction with NeoCart and certain other products (“Hydrogel License Agreement”). As of December 31, 2016, the Company has paid an aggregate $3.2 million in commercialization milestones under the terms of the Hydrogel License Agreement, which has been expensed to research and development.

Under the terms of the Hydrogel License Agreement, the Company’s future commitments include:

•

A one-time $3.0 million payment upon approval of an eligible product by the FDA; and

•

Single digit royalties on the net sales of NeoCart and certain other future products.

Tissue Regeneration License

In April 2001, the Company entered into an exclusive license agreement with The Board of Trustees of the Leland Stanford Junior University (“Stanford University”) for the use of certain technology to develop, manufacture and sell licensed products in the field of growth and regeneration of cartilage (“Tissue Regeneration License Agreement”). The term of the Tissue Regeneration License Agreement extends to the expiration date of Stanford University’s last to expire domestic or foreign patents. As of December 31, 2016, the Company has paid an aggregate $0.7 million in patent reimbursement costs, royalty fees, and commercialization milestone payments under the terms of the Tissue Regeneration License Agreement, which have been recorded to research and development expense.

Under the terms of the Tissue Regeneration License Agreement, the Company’s future commitments include:

•

A one-time $0.3 million payment upon approval of an eligible product by the FDA;

•

An annual minimum non-refundable royalty fee of $10 thousand for the life of the license that may be used to offset up to 50% of each earned royalty described below; and

•

Low single digit royalties on net sales.

Honeycomb License

In March 2013, the Company entered into a license agreement with Koken Co., Ltd. (“Koken”) and paid a fee for a non-exclusive, non-transferable and non-sublicensable right to use its know-how related to the process for manufacturing atelocollagen honeycomb sponge materials, which is used in scaffolds (the “Honeycomb License Agreement”). Under the terms of the Honeycomb License Agreement, future commitments will be based on the amount of materials supplied to the Company and may vary from period to period over the term of the agreement.

Tissue Processor Sub-License

In December 2005, the Company entered into an exclusive agreement to sub-license certain technology from Purpose, Co. (“Purpose”), which is owned by a stockholder of the Company (“Sub-License Agreement”). Purpose entered into the original license agreement (“Original Agreement”) with Brigham and Women’s Hospital, Inc. (“Brigham and Women’s”) in August 2001. The Original Agreement shall remain in effect for the licensed patents owned by Brigham and Women’s unless extended or terminated as provided for in the agreement. The technology is to be used to develop, manufacture, use and sell licensed products that cultivate cell or tissue development. The Sub-License Agreement extends to the expiration date of the last to expire domestic or foreign patents covered by the agreement. As of December 31, 2016, the Company has paid an aggregate $1.0 million in royalty and sub-license payments under the terms of the Sub-License Agreement.

The Sub-License Agreement was amended and restated in June 2012. Under the amended and restated agreement, the Company made Purpose the sole supplier of equipment the Company uses in its manufacturing processes, and granted Purpose distribution rights of the Company’s products for certain territories. In exchange, Purpose allowed for the use of its technology (owned or licensed) and manufactured and serviced exogenous tissue processors used by the Company. Under the terms of the agreement, as amended, Purpose granted the Company: (a) exclusive rights to all of Purpose’s technology (owned or licensed) related to the exogenous tissue processors, (b) continued supply of exogenous tissue processors during the Company’s clinical trials, and (c) rights to manufacture the exogenous tissue processors at any location the Company chooses. In exchange for such consideration, the Company granted Purpose an exclusive license in Japan for the use of all of the Company’s technology and made a payment of $0.3 million to reimburse Purpose for development costs on a next generation tissue processor.

In May 2016, the Original Agreement was amended whereby the Company acquired the development and commercialization rights to NeoCart for the Japanese market from Purpose. Under the terms of the amended agreement, the Company assumes sole responsibility for and rights to the development and commercialization of NeoCart in Japan. In exchange for the transfer of development and commercialization rights, the Company will pay a success-based milestone to Purpose upon conditional approval of NeoCart in Japan, as well as commercial milestones and a low single digit royalty on Japanese sales of NeoCart, upon full approval, if any, in Japan

In addition to the above, the Company’s future commitments under the terms of the Original Agreement and Sub-License Agreement include:

•

A minimum non-refundable annual royalty fee of $20 thousand, for the life of the license;

•

An additional, non-refundable annual royalty fee of $30 thousand from 2016 through 2019;

•

$10.2 million in potential milestone payments; and

•

Low single digit royalties on net sales of a licensed product.

The OCS Agreement

In connection with its research and development, the Company received grants from the Office of Chief Scientist of the Ministry of Industry and Trade in Israel (“OCS”) in the aggregate of $1.1 million for funding the fibroblast growth factor (“FGF”) program. In consideration for this grant, the Company is committed to pay royalties at a rate of 3% to 5% of the sales of sponsored products developed using the grant money, up to the amount of the participation payments received. The Company committed to pay up to 100% of grants received plus interest according to the LIBOR interest rate if the sponsored product is produced in Israel. If the manufacturing of the sponsored product takes place outside of Israel, the royalties can increase up to, but no more than, 300% of grants received plus interest based on the LIBOR interest rate, depending on the percentage of the manufacturing of sponsored product that takes place outside of Israel.

Engineering Agreement

The Company entered into an agreement with a development corporation to purchase a multi-unit bioreactor system. Pursuant to the agreement, as of December 31, 2016, the Company made total payments in an aggregate amount of $0.6 million of which $0.2 million was made in 2016 after acceptance of the final product. There are no additional payments due under this agreement.

Collagen Supply Agreement

In September 2015, the Company entered into an agreement with Collagen Solutions (UK) Limited (the “Supplier”) to purchase soluble collagen that meets specifications provided by the Company. The initial term of the agreement is three years and will automatically renew from year to year thereafter unless otherwise terminated with at least 180 days’ notice by either party. Pursuant to the agreement, starting 12 months after entering into the agreement, the Company will be required to order a minimum amount of material and/or services totaling $0.2 million from the Supplier in each calendar year until the expiration of the initial term of the agreement. The Company also committed to pay a non-refundable payment totaling $0.1 million by the end of 2015. This expense was recorded to research and development expense as of December 31, 2015.

Capital Stock

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Capital Stock

8.	CAPITAL STOCK

On September 29, 2016, the Company closed the private placement contemplated by the securities purchase agreement (the “Purchase Agreement”), dated September 15, 2016, between the Company and certain institutional and accredited investors in which the Company received gross proceeds of $30.0 million (the “Private Placement”). The net proceeds after deducting placement agent fees and other transaction-related expenses was $27.6 million. At the closing, the Company issued 2,596,059 shares of the Company’s common stock at a per share price of $2.25 and 24,158.8693 shares of the Company’s newly-created Series A Convertible Preferred Stock (“Series A Preferred Stock”), which are convertible into approximately 10,737,275 shares of common stock. As part of the Private Placement, the investors received warrants to purchase up to 13,333,334 shares of the Company’s common stock at an exercise price of $2.25 per share. The placement agent for the Private Placement, H.C. Wainwright & Co. LLC (“HCW”), and certain of its affiliates were also granted warrants to purchase 133,333 shares of the Company’s common stock at an exercise price of $2.25 per share in exchange for the services provided by HCW. The placement agent warrants were considered a financing cost of the Company and included in warrant expense within the consolidated statements of operations.

The warrants include a cashless-exercise feature that may be exercised solely in the event there is no effective registration statement, or no current prospectus available for, the resale of the shares of common stock underlying the warrants as of the six-month anniversary of the closing of the Private Placement. Upon a fundamental transaction, the holders of the warrant may require the Company to purchase any unexercised warrants in an amount equal to the Black-Scholes value of the option. A fundamental transaction is defined as a merger, sale of assets, sale of the Company, recapitalization of stock and a sale of stock whereby any owner after the transaction would own greater than 50% of the outstanding common stock in the Company. The warrants became exercisable following approval of the Private Placement by our stockholders in the fourth quarter of 2016 and expire five years after the date of such stockholder approval. The Company determined the warrants are classified as a liability on the consolidated balance sheet because they contain a provision whereby in a fundamental transaction (as described above), the holder can elect to receive either the amount they are entitled to on an as-if-exercised basis or an amount based on the Black-Scholes value of the warrants at the time of the fundamental transaction. At the issuance date, the warrants were recorded at the fair value of $30.7 million and approximately $0.4 million excess of the fair value of the liability recorded for these warrants over the proceeds received was recorded as a charge to earnings in the third quarter of 2016 and is included in warrant expense within the consolidated statement of operations. In connection with the Private Placement, the Company incurred expenses of $3.1 million in warrant expense within the consolidated statements of operations.

Concurrent with the closing of the Private Placement, the Company’s Certificate of Incorporation was amended by the filing of a Certificate of Designation to create the Series A Preferred Stock. The Series A Preferred Stock has a par value of $0.01 and each share is convertible into 444.44 shares of common stock, at a conversion price of $2.25 per share, at the option of the holder. The Series A Preferred Stock has no voting rights and is only entitled to dividends as declared on an as-converted basis. The Series A Preferred Stock contains no liquidation preferences or redemption rights and shares in distributions of the Company on an as-converted basis with the common stock.

As part of the Private Placement, affiliates of certain members of the Company’s Board of Directors purchased an aggregate of 283,046 shares of common stock, an aggregate of 2,563.1439 shares of Series A Preferred Stock and received warrants to purchase up to 1,422,221 shares of common stock at an exercise price of $2.25 per share in the Private Placement. These amounts are included in the amounts noted above.

Common Stock-100,000,000 shares authorized

The holders of shares of common stock are entitled to one vote per share. The holders of shares of common stock are not entitled to receive dividends, unless declared by the Company’s board of directors out of legally available funds, if ever.

Reserved for future issuance

The Company has reserved for future issuance the following number of shares of common stock:


	As of December 31,
	2016		2015
Vesting of restricted stock		1,889		5,190
Options to purchase common stock		1,577,016		1,222,767
Common stock warrants		13,633,070		166,403

Total		15,211,975		1,394,360

Preferred Stock-30,000,000 shares authorized

Series A Convertible Preferred Stock

On September 29, 2016, the Company issued 24,158.8693 shares of newly-created Series A Convertible Preferred Stock, which were convertible into approximately 10,737,275 shares of common stock at an initial conversion price of $2.25. The Series A Preferred Stock has a par value of $0.01 and each share is convertible into 444.44 shares of common stock at the option of the holder. The holders of Series A Preferred Stock have no voting rights, share in both income and losses and are only entitled to dividends as declared on an as-converted basis. The Series A Preferred Stock contains no liquidation preferences or redemption rights and shares in the distribution of the Company on an as-converted basis with the common stock. The Series A Preferred Stock shall not be converted if, after giving effect to the conversion, the holder and its affiliated persons would own beneficially more than 4.99% of our common stock (subject to adjustment up to 9.99% solely at the holder’s discretion upon 61 days’ prior notice to us or, solely as to a holder, if such limitation is waived by such holder upon execution of the private placement agreement).

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(31))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

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+ Details

Warrants

12 Months Ended

Dec. 31, 2016

Text Block [Abstract]

Warrants

9.	WARRANTS

Investor Warrants

In September 2016, in connection with the Private Placement, the Company issued common stock warrants to the investors to purchase up to 13,333,334 shares of our common stock at an exercise price of $2.25 per share. The warrants include a cashless-exercise feature that may be exercised solely in the event there is no effective registration statement registering, or no current prospectus available for, the resale of the shares of common stock underlying the warrants as of the six-month anniversary of the closing of the Private Placement. The warrants became exercisable following approval of the Private Placement by our stockholders in the fourth quarter of 2016 and expire five years after the date of such stockholder approval. The warrants were valued at $2.28 per share using a Monte Carlo simulation and are marked-to-market on a quarterly basis with the change in value recorded as warrant expense or income on the consolidated statements of operations.

Placement Agent Warrants

In September 2016, in connection with the Private Placement, the Company issued HCW and certain of its affiliates warrants for the purchase of 133,333 shares of common stock at an exercise price of $2.25 per share. The HCW warrants became exercisable following approval of the Private Placement by our stockholders in the fourth quarter of 2016 and expire five years after the date of such stockholder approval. The warrants were valued at $2.28 per share using a Monte Carlo simulation and are marked-to-market on a quarterly basis with the change in value recorded as warrant expense or income on the consolidated statements of operations.

Affiliates of an Advisor Warrant

On July 20, 2012, the Company issued a warrant to purchase its common stock to affiliates of an advisor. The warrant provides the holders with the right to purchase an aggregate of 161,977 shares of the Company’s common stock at a per share exercise price of $0.01. The warrants are exercisable, in whole or in part, immediately upon issuance and may be exercised on a cashless basis. The warrants expire on the tenth anniversary of issuance. The fair value of the warrants as of July 20, 2012 was estimated using the OM with the following inputs: (a) risk-free interest rate of 0.22%; (b) implied volatility of the Company’s common stock of 99%; and (c) the expected term to a liquidity event of 1.7 years. On December 3, 2014, the Company completed its IPO and warrants for 5,839 shares of common stock were surrendered and common stock was issued by the Company to Purpose, Co. for the warrant shares surrendered. As of December 31, 2016 and 2015, warrants to purchase an aggregate of 156,138 shares of the Company’s common stock at an exercise price of $0.01 are outstanding.

Consulting Agreement Warrant

In March 2015, in connection with a consulting agreement entered into for an interim chief financial officer, the Company issued a common stock warrant as compensation to the consulting firm. The warrant provides the holder with the right to purchase an aggregate of 7,398 shares of the Company’s common stock at a per share exercise price of $9.75, the closing price of the Company’s common stock on the date of issuance. The warrant vested and became exercisable in monthly installments over 24 months beginning September 30, 2015 and expires on the tenth anniversary of issuance. The warrant is equity classified and accounted for using the fair value approach. The fair value of the warrant is estimated using the Black-Scholes option pricing model and is subject to re-measurement at each reporting period until the measurement date is reached. On December 21, 2015, the Company terminated the consulting agreement resulting in the forfeiture of 50% (3,699) of the shares eligible for exercise under the warrant. The remaining 3,699 shares were vested and exercisable on December 31, 2016 and December 31, 2015.

Equipment Loan Payable

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Equipment Loan Payable

10.

EQUIPMENT LOAN PAYABLE

As of December 31, 2016 and 2015, the Company had the following outstanding borrowing obligations:


	December 31, 2016			December 31, 2015
	(in thousands)
Silicon Valley Bank Equipment Loan Payable	$	761		$	1,344

Less: current portion		(583	)		(583	)

Long-term debt, net	$	178		$	761

In July 2014, the Company entered into a loan and security agreement with Silicon Valley Bank, which provides for a line of credit to finance certain equipment purchases up to an aggregate of $1.8 million through March 31, 2015. The line has been fully drawn and is payable in 36 monthly installments of principal and interest, with an annual interest rate of 2.75% plus the greater of 3.25% and the prime rate in effect at the time of each draw, as published in the Wall Street Journal. The outstanding balance on the line of credit is secured by a first priority lien over all equipment purchased using the line of credit.

In accordance with the terms of the equipment line of credit, the Company issued a warrant to Silicon Valley Bank in July 2014 to purchase 6,566 shares of our common stock at an exercise price per share of $7.99.

The equipment line of credit includes customary operating but non-financial covenants, including limitations on the Company’s ability to incur additional indebtedness, issue dividends, sell assets, engage in any business other than its current business, merge or consolidate with other entities, create liens on our assets, make investments, repurchase stock in certain instances, enter into transactions with affiliates, make payments on subordinated indebtedness and transfer or encumber any collateral securing the debt.

As of December 31, 2016 and 2015, $0.8 and $1.3 million respectively, of borrowings were outstanding under the line of credit and the Company was in compliance with all required covenants.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

11.

STOCK-BASED COMPENSATION

Restricted Stock Awards and Stock Options

The Company adopted the 2012 Equity Incentive Plan, as amended (“2012 Plan”) in July 2012 pursuant to which 609,389 shares of common stock were authorized for issuance to employees, officers, directors, consultants and advisors of the Company as of December 31, 2014. Upon the closing of the IPO on December 3, 2014, no further grants will be made under the 2012 Plan as the 2013 Equity Incentive Plan (“2013 Plan”) replaced the 2012 Plan on this date. The 2012 Plan provided for the grant of incentive stock options, non-statutory stock options, rights to purchase restricted stock, stock appreciation rights, phantom stock awards and stock units. In connection with the issuance of restricted common stock, the Company maintains a repurchase right and shares of restricted common stock are released from such repurchase right over a period of time of continued service by the recipient. Recipients of incentive stock options shall be eligible to purchase shares of the Company’s common stock at an exercise price equal to no less than the estimated fair value of such stock on the date of grant. Stock options generally vest 25% on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years, unless they contain specific performance and/or market-based vesting provisions. The maximum term of stock options granted under the 2012 Plan is ten years.

In determining the exercise prices for options granted, the board of directors considered the fair value of the common stock as of the measurement date. The fair value of the common stock was determined by the board of directors based on a variety of different factors, including valuations prepared by third party valuation specialists, Company’s financial position, the status of development efforts within the Company, the composition and ability of the current scientific and management teams, the current climate in the marketplace, the illiquid nature of the Company’s common stock, arm’s length sale of the Company’s preferred stock, the effect of the rights and preferences of the preferred stockholders, and the prospects of a liquidity event, among others.

2013 Equity Incentive Plan

The Company’s board of directors adopted the 2013 Plan in November 2013 which the stockholders approved in October 2014. The 2013 Plan provides for the grant of incentive stock options, non-statutory stock options, rights to purchase restricted stock, stock appreciation rights and stock units. In connection with the issuance of restricted common stock, the Company maintains a repurchase right and shares of restricted common stock are released from such repurchase right over a period of time of continued service by the recipient. Recipients of stock options shall be eligible to purchase shares of the Company’s common stock at an exercise price equal to no less than the estimated fair value of such stock on the date of grant. Stock options generally vest 25% on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years, unless they contain specific performance and/or market-based vesting provisions. The maximum term of stock options granted under the 2013 Plan is ten years. In June 2016, the Company’s stockholders approved an amendment to the EIP to increase the number of shares of common stock available for issuance under the 2013 Plan by 300,000 shares and increase the number of shares of common stock automatically added to the 2013 Plan on January 1 of each year during the term of the 2013 Plan, starting with January 1, 2017 (the “EIP Amendment”). Following adoption of the EIP Amendment, the number of shares of common stock available for issuance under the 2013 Plan is subject to an automatic annual increase on the first day of the Company’s calendar year beginning in 2017 equal to the lesser of (a) 4.0% of the total number of shares of common stock outstanding on December 31 of the prior year or, (b) the number determined by the Company’s Board of Directors Accordingly, the number of shares of common stock available for issuance under the EIP was increased by 825,904 shares effective January 1, 2017. To the extent any awards under the 2013 Plan are forfeited, terminate, expire, lapse without the issuance of shares, or if the Company repurchases shares subject to awards under the 2013 Plan, those shares will again become available for issuance under the 2013 Plan.

2013 Employee Stock Purchase Plan

The Company’s board of directors adopted the 2013 Employee Stock Purchase Plan (“2013 ESPP”) in November 2013 which the stockholders approved in October 2014. The 2013 ESPP became effective upon the closing of the IPO on December 3, 2014. The Company’s 2013 ESPP qualifies under Section 423 of the Internal Revenue Code of 1986, as amended (the “Code”). Under the 2013 ESPP, 103,665 shares of the Company’s common stock are authorized for issuance to eligible employees. The number of shares reserved for issuance under the 2013 ESPP is automatically increased on the first business day of each of the Company’s fiscal years, commencing in 2015, by a number equal to the lowest of (a) 51,832 shares of common stock,(b) 1% of the shares of common stock outstanding on the last business day of the prior fiscal year; or (c) the number of shares determined by the Company’s Board of Directors. Accordingly, the number of authorized shares of the Company’s common stock authorized for issuance to eligible employees under the 2013 ESPP was increased by 206,476 shares effective January 1, 2017. The number of shares reserved under the 2013 ESPP will automatically be adjusted in the event of a stock split, stock dividend or a reverse stock split (including an adjustment to the per-purchase period share limit). The Company’s 2013 ESPP permits each eligible employee to purchase common stock through payroll deductions. There was no activity under the Plan in 2016 and 2015.

Stock option activity under the 2012 and 2013 plans is summarized as follows:


	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2015		1,229,339		$	7.32		9.0	$	(4,679	)
Granted		464,240			2.02
Exercised		(3,685	)		0.76
Cancelled		(112,878	)		4.97

Outstanding at December 31, 2016		1,577,016		$	5.95		8.4	$	71

Vested and expected to vest at December 31, 2016		1,492,341		$	5.97		8.4	$	69

Exercisable at December 31, 2016		561,693		$	6.79		7.8	$	52

As of December 31, 2016 and 2015, the unrecognized compensation cost related to outstanding options was $2.6 million and $3.9 million, respectively, and is expected to be recognized as expense over approximately 2.01 years and 2.68 years, respectively. The intrinsic value of options exercised during the years ended December 31, 2016 and 2015 was $10 thousand and $0.3 million, respectively.

As of December 31, 2016, the weighted average grant date fair value of vested options was $4.71 and the weighted average grant date fair value of options outstanding was $3.67.

Additional information about the Company’s stock option activity is as follows:


	Year Ended December 31,
	2016		2015
Weighted-average grant date fair value per share of employee option grants within the year	$	1.26	$	4.08
Cash received upon exercise of options		3		39

Restricted stock awards under the 2012 and 2013 plans are summarized as follows:


	Number of Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2015		5,190		$	1.07
Vesting of restricted stock		(3,301	)

Unvested at December 31, 2016		1,889		$	0.83

As of December 31, 2016 and 2015, the unrecognized compensation cost related to restricted stock awards was $1 thousand and $4 thousand respectively, and is expected to be recognized as expense over approximately 0.3 years and 1.2 years, respectively.

Stock-Based Compensation Expense

The Company granted stock options to employees for the years ended December 31, 2016 and 2015. The Company estimates the fair value of stock options as of the date of grant using the Black-Scholes option pricing model and restricted stock based on the fair value of the award. Stock options and restricted stock issued to non-board member, non-employees are accounted for using the fair value approach and are subject to periodic revaluation over their vesting terms.

For all periods from inception to date, stock-based compensation for all options granted and restricted stock awards are classified as research and development expense and general and administrative expense. Stock compensation expense amounted to approximately $1.5 million and $1.2 million for the years ended December 31, 2016 and 2015, respectively. Included in the table below is restricted stock-based compensation expense of $2 thousand and $4 thousand, respectively, recorded in general and administrative expense during the years ended December 31, 2016 and 2015.

Stock-based compensation is as follows:


	Year Ended
	2016		2015
	(in thousands)
Research and development	$	491	$	451
General and administrative		1,057		777

Total stock-based compensation expense	$	1,548	$	1,228

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows:


	Year Ended
	2016			2015
Risk-free interest rate		1.73	%		1.68	%
Expected volatility		72.5	%		62.6	%
Expected term (in years)		6.08			6.04
Expected dividend yield		0.0	%		0.0	%

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the non-employee stock option grants were as follows:


	Year Ended
	2016			2015
Risk-free interest rate		1.57	%		1.79	%
Expected volatility		63.5	%		63.2	%
Expected term (in years)		7.00			6.16
Expected dividend yield		0.0	%		0.0	%

Risk-free Interest Rate. The risk-free interest rate assumption is based on observed interest rates appropriate for the expected term of the stock option grants.

Expected Volatility. Due to the Company’s limited operating history and lack of company-specific historical or implied volatility, the expected volatility assumption is based on historical volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the biotechnology and medical device industries.

Expected Term. The expected term represents the period of time that options are expected to be outstanding. Because the Company does not have historical exercise behavior, through December 31, 2016 it determined the expected life assumption using the simplified method, which is an average of the contractual term of the option and its vesting period.

Expected Dividend Yield. The expected dividend yield assumption is based on the fact that the Company has never paid cash dividends and has no present intention to pay cash dividends.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Income Taxes

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

12.

INCOME TAXES

For the years ended December 31, 2016 and 2015, the Company did not record a current or deferred income tax expense or benefit due to current and historical losses incurred by the Company.

The components of loss before income taxes were as follows:


	As of December 31,
	2016			2015
	(in thousands)
U.S.	$	(15,838	)	$	(31,382	)
Foreign		(369	)		(691	)

Total	$	(16,208	)	$	(32,073	)

A reconciliation of income tax expense (benefit) computed at the statutory federal income tax rate to income taxes as reflected in the financial statements is as follows:


	As of December 31,
	2016			2015
Federal income tax (benefit) at statutory rate		34.0	%		34.0	%
(Increase) decrease income tax benefit resulting from:
Permanent differences		29.0			(1.2	)
Net Operating Loss Limitation		(111.1	)		—
R&D Credit Limitation		(1.5	)		—
Change in valuation allowance		48.7			(31.7	)
Other		0.9			(1.2	)

Income tax expense (benefit)		0.0	%		0.0	%

Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. The significant components of the Company’s deferred tax assets and liabilities are comprised of the following:


	As of December 31,
	2016			2015
Deferred tax assets:
Net operating loss carryforwards	$	16,146		$	28,200
Depreciation and amortization		6,229			6,688
Accrued expenses		2,082			1,183
Capitalized start-up costs		10,037			8,531
Other		75			259

Deferred tax assets before valuation allowance		34,569			44,861
Valuation allowance		(34,569	)		(43,751	)

		—			1,110
Deferred tax liabilities
IPR&D		—			(36	)
Change in accounting method		—			(1,074	)

		—			(1,110	)

Net deferred tax assets	$	—		$	—

The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets. As of December 31, 2016 and 2015, based on the Company’s history of operating losses, the Company has concluded that it is not more likely than not that the benefit of its deferred tax assets will be realized. Accordingly, the Company has provided a full valuation allowance for deferred tax assets as of December 31, 2016 and 2015. The valuation allowance decreased $9.2 million during the year ended December 31, 2016, due primarily to a reduction of net operating losses generated. The valuation allowance increased by $11.8 million during the year ended December 31, 2015, due primarily to net operating losses generated and capitalized expenses. In addition, the reduction in net operating losses were related to Section 382 limits as a result in a change in ownership.

During November 2015, the FASB issued ASU 2015-17, “Balance Sheet Classification of Deferred Taxes”, which simplifies the presentation of deferred income taxes. This ASU requires that deferred tax assets and liabilities be classified as non-current in a statement of financial position. We early adopted ASU 2015-17 effective December 31, 2015 on a prospective basis. Adoption of this ASU resulted in the removal of gross deferred tax assets and liabilities from the Company’s Consolidated Balance Sheet at December 31, 2015. The impact was zero. No prior periods were retrospectively adjusted. As of December 31, 2016 and 2015, the Company had U.S. federal NOL carryforwards of $24.5 million, and $55.5 million, respectively, which may be available to offset future income tax liabilities and expire at various dates through 2036. As of December 31, 2016 and 2015, the Company also had U.S. state NOL carryforwards of $24.3 million and $55.4 million, respectively, which may be available to offset future income tax liabilities and expire at various dates through 2036. At December 31, 2016 and 2015, the Company also had $26.1 million and $25.6 million, respectively, of foreign NOL carryforwards which may be available to offset future income tax liabilities, which carryforwards do not expire.

Utilization of the NOL and research and development credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that have occurred or that could occur in the future, as required by Section 382 and Section 383 of the Code, as well as similar state and foreign provisions. These ownership changes may limit the amount of NOL and research and development credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. In general, an “ownership change” as defined by Section 382 of the Code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percentage points of the outstanding stock of a company by certain stockholders. The Company has completed a study to assess whether an ownership change has occurred or whether there have been multiple ownership changes since its formation. The results of this study indicated we experienced ownership changes, as defined by Section 382 of the Code, in each of 2006, 2011, 2012, 2013, and 2016. The Company has not recorded NOLs that, as a result of these restrictions, will expire unused. The limitations were approximately $47.1 million in 2015 and $100.1 million in 2016.

The changes in the Company’s unrecognized tax benefits are summarized as follows:


	As of December 31,
	2016			2015
	(in thousands)
Unrecognized tax benefit, beginning of year	$	687		$	811
Increase (decrease) related to current year positions		(125	)		(124	)
Settlements		—			—

Unrecognized tax benefit, end of year	$	562		$	687

As of December 31, 2016 and 2015, the total amount of unrecognized tax benefits was $0.6 million and $0.7 million, respectively which, if recognized, would favorably affect the effective income tax rate in future periods. Note that liabilities for unrecognized tax benefits have been recorded to the extent that they do not exceed the Company’s available losses that are not limited as a result of ownership changes that have occurred under Section 382 of the Code. Reductions to unrecognized tax benefits for limitations on the utilization of net operating losses due to ownership changes occurring during the year has been reflected in the table as reductions based on tax positions related to the current year. Histogenics accrues interest and penalties related to unrecognized tax benefits as a component of its provision for income taxes. No accrued interest and penalties related to the Company’s unrecognized tax benefits has been accrued as of December 31, 2016 and 2015. The Company believes that it is reasonably possible that none of its unrecognized tax benefits, may be recognized at the end of 2016. The Company or one of its subsidiaries files income tax returns in the United States and various states and Israel. The Company is subject to U.S. federal, state and local income tax examinations by tax authorities for years 2001 through present. Carryforward attributes that were generated in earlier periods remain subject to examination to the extent the year in which they were used or will be used remains open for examination. The tax years which remain subject to examination by tax authorities in Israel, as of December 31, 2016, include years 2013 through the present.

Employee Benefits

12 Months Ended

Dec. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Employee Benefits

13.

EMPLOYEE BENEFITS

The Company has a defined contribution 401(k) plan for employees who are at least 21 years of age. Employees are eligible to participate in the plan beginning on the first day of the calendar quarter following their date of hire. Under the terms of the plan, employees may make voluntary contributions as a percent of compensation. No matching contributions have been made by the Company since the adoption of the 401(k) plan.

Related Parties

12 Months Ended

Dec. 31, 2016

Related Parties

14.

RELATED PARTIES

Intrexon Corporation

In September 2014, the Company entered into an Exclusive Channel Collaboration agreement with Intrexon (the “Collaboration Agreement”) to use Intrexon’s proprietary technology for the development and commercialization of allogeneic cell therapeutics (the “Collaboration Products”) to treat or repair damaged articular hyaline cartilage in humans. The term of the Collaboration Agreement commenced upon the effective date, September 30, 2014, and continues until either written notice of termination is given by the Company within ninety days, or if either party creates a material breach that cannot be remedied within sixty days.

Under the terms of the Collaboration Agreement, the Company is solely responsible for the costs to develop and commercialize any Collaboration Products with the following exceptions: (i) the establishment of certain manufacturing capabilities and facilities; (ii) the cost of basic research related to Intrexon’s proprietary technology outside of costs related to the Collaboration Products; (iii) payments related to certain in-licensed third party IP; (iv) the costs of filing, prosecution and maintenance of Intrexon patents; and (v) any other costs mutually agreed upon as being the responsibility of Intrexon. As partial consideration, the Company will pay commercialization milestones totaling $12 million, if and when achieved, and sales milestones totaling $22.5 million, if and when achieved. The milestone payments are payable in cash or shares of the Company’s common stock at the option of the Company. In the event the Company is sold prior to making any of these milestone payments and the Collaboration Agreement is transferred in the sale, the milestone payments would be payable in cash. The Company is also required to make low double digit royalty payments to Intrexon on any gross profit arising from the sale of Collaboration Products and to pay an intermediate double digit percentage of any sublicensing revenue it receives.

Under the terms of the Collaboration Agreement, the Company reimburses Intrexon for 50% of the product research and development costs with the remaining 50% due after acceptance by the FDA or equivalent regulatory authority of an Investigational New Drug Application or equivalent regulatory filing of a collaboration product or upon 90 day written notice of cancellation by the Company. Total incurred expenses were $3.0 million and $3.1 million for the year ended December 31, 2016 and 2015, respectively. The total accrued expenses due Intrexon at December 31, 2016 and December 31, 2015 was $3.0 million and $1.5 million, respectively. Amounts are reflected as current liabilities in the consolidated balance sheet as of December 31, 2015. Amounts have been reclassified to long term liabilities in the consolidated balance sheet as of December 31, 2016, as a result of a change in circumstances, including the plans for products that we are developing as a part of the Exclusive Channel Collaboration with Intrexon. These expenses were included in research and development in the consolidated statement of operations.

Purpose, Co.

In June 2012, the Company entered into an agreement with Purpose, Co. to amend its previous agreements. In the previous agreements, Purpose, Co. granted the Company a perpetual license to its patents related to its exogenous tissue processor which is used in the development of the Company’s products. In exchange, the Company granted Purpose, Co. a perpetual license to all of the Company’s biotechnology and biomaterial for use in Japan. The agreement provides for Purpose, Co. to manufacture and sell machinery to the Company for cost until the Company’s products become commercially viable. The Company has also agreed to pay royalties on any third-party revenue generated using Purpose, Co.’s licensed technology.

Under the June 2012 amendment, the Company received exclusive rights to all of Purpose, Co.’s technology related to the exogenous tissue processor, continued supply of exogenous tissue processors during the Company’s clinical trials, and rights to manufacture the exogenous tissue processors at any location the Company chooses. In exchange for such consideration, the Company named Purpose, Co. the sole manufacturer of equipment and also clarified the geographic territories of the exclusive license that Purpose Co. was granted for use of the Company’s technology. Also, the Company agreed to reimburse Purpose, Co. for $0.3 million of development costs on a next generation tissue processer. Refer to the discussion under Note 7, Tissue Processor Sub-License.

In May 2016, the Company acquired the development and commercialization rights to NeoCart for the Japanese market from Purpose, Co. Under the terms of the amended agreement, the Company assumes sole responsibility for and rights to the development and commercialization of NeoCart in Japan. In exchange for the transfer of development and commercialization rights, the Company will pay a success-based milestone to Purpose upon conditional approval of NeoCart in Japan, as well as commercial milestones and a low single digit royalty on Japanese sales of NeoCart, upon full approval, if any, in Japan.

The amounts that have been paid to Purpose, Co. under this agreement were $0.1 and $0.2 million for the years ended December 31, 2016 and 2015, respectively.

Board of Director Affiliates

Affiliates of certain members of the Company’s Board of Directors participated in the Private Placement as described in Note 8.

Subsequent Events

12 Months Ended

Dec. 31, 2016

Subsequent Events [Abstract]

Subsequent Events

15.

SUBSEQUENT EVENTS

On February 22, 2017, the Company entered into an amendment with Collagen Solutions (UK) LTD (the “Supplier”). The original agreement was entered into on September 15, 2015. Pursuant to the amendment, the Company agrees to pay the Supplier approximately $0.1 million in exchange for eliminating the minimum annual order of material and/or services and any other amounts due Supplier. The payment of $0.1 million will be made over the 18 months following the date of the amendment.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Basis of Accounting

Basis of Accounting

Reclassifications

Reclassifications

Use of Estimates

Use of Estimates

Foreign Currency Translation

Foreign Currency Translation

Segment and Geographic Information

Segment and Geographic Information

Information about the Company’s operations in different geographic regions is presented in the tables below:


	December 31, 2016		December 31, 2015
	(in thousands)
Long-lived assets:
United States	$	3,860	$	5,204
Israel		—		9

Total long-lived assets	$	3,860	$	5,213

Fair Value Measurements

Fair Value Measurements

Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date of identical, unrestricted assets.


Description	Total		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)
December 31, 2016
Assets:
Money market funds	$	30,318	$	30,318	$	—	$	—
Liabilities:
Warrant liability		13,197		—		—		13,197
December 31, 2015
Money market funds		25,764		25,764		—		—

The following table provides a reconciliation of all liabilities measured at fair value using Level 3 significant unobservable inputs:


	As of December 31, 2016
	(in thousands)
Beginning balance, January 1, 2016	$	—
Issuance of warrants,		30,704
Change in fair value of warrant liability		(17,507	)

Ending balance	$	13,197

Cash and Cash Equivalents

Cash and Cash Equivalents

Concentration of Credit Risk

Concentration of Credit Risk

Property and Equipment

Property and Equipment


Asset Category		Estimated Useful Lives
Office equipment		3 to 5 years
Laboratory equipment		3 to 5 years
Leasehold improvements		Shorter of the remaining lease term or useful life

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets

Impairments, if any, are recognized in earnings. An impairment loss would be recognized in an amount equal to the excess of the carrying amount over the undiscounted expected future cash flows.

Intangible Asset

Intangible Asset

Intangible asset, net of accumulated impairment charges, are summarized as follows:


	As of December 31, 2016							As of December 31, 2015
	Cost		Accumulated Impairment			Net Book Value		Cost		Accumulated Impairment			Net Book Value
	(in thousands)							(in thousands)
IPR&D	$	630	$	(630	)	$	—	$	630	$	(430	)	$	200

	$	630	$	(630	)	$	—	$	630	$	(430	)	$	200

Initial Public Offering Costs

Initial Public Offering Costs

Restricted Cash

Restricted Cash

Deferred Rent

Deferred Rent

Financial Instruments Indexed to and Potentially Settled in the Company's Common Stock

Financial Instruments Indexed to and Potentially Settled in the Company’s Common Stock

Revenue Recognition

Revenue Recognition

Research and Development Costs

Research and Development Costs

Collaboration Arrangements

License Agreements

License Agreements

Costs associated with licenses of technology are expensed as incurred and are included in research and development expenses.

Patent Costs

Patent Costs

Costs related to filing and pursuing patent applications are recorded as general and administrative expense as incurred since the recoverability of such expenditures is uncertain.

Stock-Based Compensation

Stock-Based Compensation

Income Taxes

Income Taxes

Earnings (Loss) per Common Share

Earnings (Loss) per Common Share

Warrant Accounting

Warrant Accounting

Recently Adopted Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

In February 2016, the FASB, issued ASU No. 2016-02, Leases (Topic 842). The ASU requires companies to recognize on the balance sheet the assets and liabilities for the rights and obligations created by leased assets. ASU 2016-02 will be effective for the Company in the first quarter of 2019, with early adoption permitted. The Company is currently evaluating the impact that the adoption of ASU 2016-02 will have on the Company’s consolidated financial statements or related disclosures.

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014- 09 will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. In July 2015, the FASB issued a one-year deferral of the effective date of the new revenue recognition standard. The new guidance will be effective for the Company’s first quarter of fiscal year 2018 and early application for fiscal year 2017 would be permitted. The Company is evaluating the impact of this guidance on the presentation of its results of operations, financial position and disclosures.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Summary of Operations in Different Geographic Regions

Information about the Company’s operations in different geographic regions is presented in the tables below:


	December 31, 2016		December 31, 2015
	(in thousands)
Long-lived assets:
United States	$	3,860	$	5,204
Israel		—		9

Total long-lived assets	$	3,860	$	5,213

Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis


Description	Total		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)
December 31, 2016
Assets:
Money market funds	$	30,318	$	30,318	$	—	$	—
Liabilities:
Warrant liability		13,197		—		—		13,197
December 31, 2015
Money market funds		25,764		25,764		—		—

Schedule of Reconciliation of Liabilities Measured at Fair Value

The following table provides a reconciliation of all liabilities measured at fair value using Level 3 significant unobservable inputs:


	As of December 31, 2016
	(in thousands)
Beginning balance, January 1, 2016	$	—
Issuance of warrants,		30,704
Change in fair value of warrant liability		(17,507	)

Ending balance	$	13,197

Schedule of Depreciation and Amortization using Straight-line Method over Estimated Useful Lives of Assets

The Company provides for depreciation and amortization using the straight-line method over the estimated useful lives of the assets, which are as follows:


Asset Category		Estimated Useful Lives
Office equipment		3 to 5 years
Laboratory equipment		3 to 5 years
Leasehold improvements		Shorter of the remaining lease term or useful life

Summary of Intangible Assets, Net of Accumulated Impairment Charges

Intangible asset, net of accumulated impairment charges, are summarized as follows:


	As of December 31, 2016							As of December 31, 2015
	Cost		Accumulated Impairment			Net Book Value		Cost		Accumulated Impairment			Net Book Value
	(in thousands)							(in thousands)
IPR&D	$	630	$	(630	)	$	—	$	630	$	(430	)	$	200

	$	630	$	(630	)	$	—	$	630	$	(430	)	$	200

Loss Per Common Share (Tables)

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Loss Per Common Share

Basic and diluted loss per common share are calculated as follows:


	For the Year Ended
	2016			2015
	(In thousands, except share and per share data
Numerator:
Net loss	$	(16,208	)	$	(32,024	)
Net Loss attributable to Series A Preferred Stock (a)		(2,345	)		—

Numerator for basic EPS—Earnings (loss) attributable to common stockholders		(13,863	)		(32,024	)

Effect of dilutive securities:
Deduct change in fair value of warrant liability		(17,507	)		—

Numerator for diluted EPS—Earnings (loss) attributable to common stockholders after assumed conversions	$	(31,370	)	$	(32,024	)

Denominator:
Weighted-average number of common shares used in earnings (loss) per share—basic		14,256,954			13,231,126
Effect of dilutive securities:
Nonparticipating warrants		132,238			—

Denominator for diluted EPS—adjusted weighted average shares		14,389,192			13,231,126

Earnings (loss) per share—basic	$	(0.97	)	$	(2.42	)

Earnings (loss) per share—diluted	$	(2.18	)	$	(2.42	)

(a)	The Series A Preferred Stock participates in income and losses

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share


	As of December 31,
	2016		2015
Unvested restricted stock and options to purchase common stock		1,578,905		1,227,957
Series A preferred stock unconverted		5,962,817		—
Warrants exercisable into common stock		166,403		166,403

Prepaid Expenses and Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2016

Text Block [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following:


	As of December 31,
	2016		2015
	(in thousands)
Deposits	$	10	$	67
Undelivered laboratory and office equipment		—		17
Insurance		95		42
Other current assets		68		195

Prepaid expenses and other current assets	$	173	$	321

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment consisted of the following:


	December 31, 2016			December 31, 2015
	(in thousands)
Office equipment	$	266		$	539
Laboratory equipment		4,443			4,337
Leasehold improvements		7,683			7,683
Construction in progress		759			547
Software		96			96

Total property and equipment		13,247			13,202
Less: accumulated depreciation		(9,387	)		(7,989	)

Property and equipment, net	$	3,860		$	5,213

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2016

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following:


	As of December 31,
	2016		2015
	(in thousands)
Accrued compensation	$	1,402	$	758
Accrued clinical expenses		187		138
Accrued other		508		548

Total accrued expenses	$	2,097	$	1,444

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Schedule of Minimum Annual Lease Commitments Under Non-Cancellable Operating Leases

Aggregate minimum annual lease commitments of the Company under its non-cancellable operating leases as of December 31, 2016, are as follows:


For the Year Ended December 31,
	(in thousands)
2017	$	2,266
2018		754
2019		586
2020		596
2021		605
Thereafter		926

Total minimum lease payments	$	5,733

Capital Stock (Tables)

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Schedule of Common Stock Reserved for Future Issuance

The Company has reserved for future issuance the following number of shares of common stock:


	As of December 31,
	2016		2015
Vesting of restricted stock		1,889		5,190
Options to purchase common stock		1,577,016		1,222,767
Common stock warrants		13,633,070		166,403

Total		15,211,975		1,394,360

Equipment Loan Payable (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Schedule of Outstanding Borrowing Obligations

As of December 31, 2016 and 2015, the Company had the following outstanding borrowing obligations:


	December 31, 2016			December 31, 2015
	(in thousands)
Silicon Valley Bank Equipment Loan Payable	$	761		$	1,344

Less: current portion		(583	)		(583	)

Long-term debt, net	$	178		$	761

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock Option Activity Under the 2012 and 2013 Plans

Stock option activity under the 2012 and 2013 plans is summarized as follows:


	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2015		1,229,339		$	7.32		9.0	$	(4,679	)
Granted		464,240			2.02
Exercised		(3,685	)		0.76
Cancelled		(112,878	)		4.97

Outstanding at December 31, 2016		1,577,016		$	5.95		8.4	$	71

Vested and expected to vest at December 31, 2016		1,492,341		$	5.97		8.4	$	69

Exercisable at December 31, 2016		561,693		$	6.79		7.8	$	52

Additional Information about Stock Option Activity

Additional information about the Company’s stock option activity is as follows:


	Year Ended December 31,
	2016		2015
Weighted-average grant date fair value per share of employee option grants within the year	$	1.26	$	4.08
Cash received upon exercise of options		3		39

Schedule of Restricted Stock Awards Under the 2012 and 2013 Plans

Restricted stock awards under the 2012 and 2013 plans are summarized as follows:


	Number of Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2015		5,190		$	1.07
Vesting of restricted stock		(3,301	)

Unvested at December 31, 2016		1,889		$	0.83

Summary of Stock-Based Compensation

Stock-based compensation is as follows:


	Year Ended
	2016		2015
	(in thousands)
Research and development	$	491	$	451
General and administrative		1,057		777

Total stock-based compensation expense	$	1,548	$	1,228

Summary of Weighted-Average Assumptions Used in the Black-Scholes Option Pricing Model to Determine the Fair Value of the Employee Stock Option Grants

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows:


	Year Ended
	2016			2015
Risk-free interest rate		1.73	%		1.68	%
Expected volatility		72.5	%		62.6	%
Expected term (in years)		6.08			6.04
Expected dividend yield		0.0	%		0.0	%

Summary of Weighted-Average Assumptions Used in the Black-Scholes Option Pricing Model to Determine the Fair Value of the Non-Employee Stock Option Grants

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the non-employee stock option grants were as follows:


	Year Ended
	2016			2015
Risk-free interest rate		1.57	%		1.79	%
Expected volatility		63.5	%		63.2	%
Expected term (in years)		7.00			6.16
Expected dividend yield		0.0	%		0.0	%

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Components of Loss Before Income Taxes

he components of loss before income taxes were as follows:


	As of December 31,
	2016			2015
	(in thousands)
U.S.	$	(15,838	)	$	(31,382	)
Foreign		(369	)		(691	)

Total	$	(16,208	)	$	(32,073	)

Schedule of Reconciliation of Income Tax Expense (Benefit) Computed at Statutory Federal Income Tax Rate

A reconciliation of income tax expense (benefit) computed at the statutory federal income tax rate to income taxes as reflected in the financial statements is as follows:


	As of December 31,
	2016			2015
Federal income tax (benefit) at statutory rate		34.0	%		34.0	%
(Increase) decrease income tax benefit resulting from:
Permanent differences		29.0			(1.2	)
Net Operating Loss Limitation		(111.1	)		—
R&D Credit Limitation		(1.5	)		—
Change in valuation allowance		48.7			(31.7	)
Other		0.9			(1.2	)

Income tax expense (benefit)		0.0	%		0.0	%

Components of Deferred Tax Assets and Liabilities


	As of December 31,
	2016			2015
Deferred tax assets:
Net operating loss carryforwards	$	16,146		$	28,200
Depreciation and amortization		6,229			6,688
Accrued expenses		2,082			1,183
Capitalized start-up costs		10,037			8,531
Other		75			259

Deferred tax assets before valuation allowance		34,569			44,861
Valuation allowance		(34,569	)		(43,751	)

		—			1,110
Deferred tax liabilities
IPR&D		—			(36	)
Change in accounting method		—			(1,074	)

		—			(1,110	)

Net deferred tax assets	$	—		$	—

Summary of Changes In Unrecognized Tax Benefits

The changes in the Company’s unrecognized tax benefits are summarized as follows:


	As of December 31,
	2016			2015
	(in thousands)
Unrecognized tax benefit, beginning of year	$	687		$	811
Increase (decrease) related to current year positions		(125	)		(124	)
Settlements		—			—

Unrecognized tax benefit, end of year	$	562		$	687

Nature of Business - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended	12 Months Ended
	Sep. 29, 2016	Dec. 03, 2014	May 13, 2011	Jan. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Nature Of Business And Basis Of Presentation [Line Items]
Proceeds from issuance of issuance of common stock, preferred stock and warrants, net of issuance costs	$ 27,600				$ 27,630
Accumulated deficit					$ (181,773)	$ (165,565)
Net proceeds from initial public offering		$ 61,300
ProChon [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Business acquisition date					May 13, 2011
Consideration paid to acquisition			$ 2,200
IPO [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Sale of common stock shares		5,909,091
Initial public offering price per share		$ 11.00
Gross proceeds from initial public offering		$ 65,000
Overallotment Option [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Sale of common stock shares				465,000
Initial public offering price per share				$ 11.00
Gross proceeds from initial public offering				$ 5,100

Summary of Significant Accounting Policies - Additional Information (Detail)			12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 03, 2014 USD ($)	Dec. 31, 2016 USD ($) Segment	Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments \| Segment			2
Number of reporting segment \| Segment			1
Transfers between Levels 1, 2 and 3			$ 0	$ 0
Cash and cash equivalents, carrying amount	$ 58,527,000		31,908,000	30,915,000
Impairment of intangible assets			200,000	$ 310,000
Discount rate				13.00%
Net Book Value				$ 200,000
IPO costs reclassified to additional paid-in capital		$ 3,900,000		377,000
Payments related to IPO			$ 377,000
Maximum percentage of recognition of tax benefits from uncertain tax positions			50.00%
IPO [Member]
Summary Of Significant Accounting Policies [Line Items]
Payments related to IPO	2,900,000
Remaining amount of IPO costs included in accounts payable	$ 1,000,000
IPR&D [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment of intangible assets			$ 200,000	300,000
Net Book Value			0	200,000
Quoted Prices in Active Markets (Level 1) [Member]
Summary Of Significant Accounting Policies [Line Items]
Assets, fair value disclosure, recurring			0	0
Liabilities, fair value disclosure, recurring			0	0
Quoted Prices in Active Markets (Level 1) [Member] \| Money Market Funds [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents, fair value			30,300,000	25,800,000
Significant Other Observable Inputs (Level 2) [Member]
Summary Of Significant Accounting Policies [Line Items]
Assets, fair value disclosure, recurring			0	0
Liabilities, fair value disclosure, recurring			0	0
Significant Unobservable Inputs (Level 3) [Member]
Summary Of Significant Accounting Policies [Line Items]
Assets, fair value disclosure, recurring			0	0
Liabilities, fair value disclosure, recurring			$ 0	$ 0

Summary of Significant Accounting Policies - Summary of Operations in Different Geographic Regions (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Long-lived assets	$ 3,860	$ 5,213
United States [Member]
Segment Reporting Information [Line Items]
Long-lived assets	$ 3,860	5,204
Israel [Member]
Segment Reporting Information [Line Items]
Long-lived assets		$ 9

Summary of Significant Accounting Policies - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Warrant Liability [Member]
Liabilities:
Liabilities, fair value	$ 13,197
Money Market Funds [Member]
Assets:
Assets, fair value	30,318	$ 25,764
Quoted Prices in Active Markets (Level 1) [Member] \| Money Market Funds [Member]
Assets:
Assets, fair value	30,318	$ 25,764
Significant Unobservable Inputs (Level 3) [Member] \| Warrant Liability [Member]
Liabilities:
Liabilities, fair value	$ 13,197

Summary of Significant Accounting Policies - Schedule of Reconciliation of Liabilities Measured at Fair Value (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value of warrant liability	$ 17,507
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuance of warrants,	30,704
Change in fair value of warrant liability	(17,507)
Ending balance	$ 13,197

Summary of Significant Accounting Policies - Schedule of Depreciation and Amortization using Straight-line Method over Estimated Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2016
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	Shorter of the remaining lease term or useful life
Minimum [Member] \| Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Minimum [Member] \| Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Maximum [Member] \| Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Maximum [Member] \| Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years

Summary of Significant Accounting Policies - Summary of Intangible Assets, Net of Accumulated Impairment Charges (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Cost	$ 630	$ 630
Accumulated Impairment	(630)	(430)
Net Book Value		200
IPR&D [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	630	630
Accumulated Impairment	(630)	(430)
Net Book Value	$ 0	$ 200

Loss Per Common Share - Schedule of Basic and Diluted Loss Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net loss	$ (16,208)	$ (32,024)
Net Loss attributable to Series A Preferred Stock	(2,345)
Numerator for basic EPS-Earnings (loss) attributable to common stockholders	(13,863)	(32,024)
Effect of dilutive securities:
Deduct change in fair value of warrant liability	(17,507)
Numerator for diluted EPS-Earnings (loss) attributable to common stockholders after assumed conversions	$ (31,370)	$ (32,024)
Denominator:
Weighted-average number of common shares used in earnings (loss) per share-basic	14,256,954	13,231,126
Effect of dilutive securities:
Nonparticipating warrants	132,238
Denominator for diluted EPS-adjusted weighted average shares	14,389,192	13,231,126
Earnings (loss) per share-basic	$ (0.97)	$ (2.42)
Earnings (loss) per share-diluted	$ (2.18)	$ (2.42)

Loss Per Common Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Series A Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	5,962,817
Unvested Restricted Stock and Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	1,578,905	1,227,957
Warrants Exercisable into Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	166,403	166,403

Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Prepaid Expense and Other Assets, Current [Abstract]
Deposits	$ 10	$ 67
Undelivered laboratory and office equipment		17
Insurance	95	42
Other current assets	68	195
Prepaid expenses and other current assets	$ 173	$ 321

Property and Equipment - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 13,247	$ 13,202
Less: accumulated depreciation	(9,387)	(7,989)
Property and equipment, net	3,860	5,213
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	266	539
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	4,443	4,337
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	7,683	7,683
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	759	547
Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 96	$ 96

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 1,673	$ 1,614

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Accrued compensation	$ 1,402	$ 758
Accrued clinical expenses	187	138
Accrued other	508	548
Total accrued expenses	$ 2,097	$ 1,444

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended		3 Months Ended	12 Months Ended
	Sep. 30, 2015 USD ($)	Jun. 30, 2012 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) Options	Dec. 31, 2015 USD ($)
Loss Contingencies [Line Items]
Rent expense under operating lease agreements				$ 1,000,000	$ 1,100,000
Research and development expense				$ 21,577,000	23,243,000
Waltham [Member]
Loss Contingencies [Line Items]
Number of additional renewal terms \| Options				2
Additional operating lease term				5 years
Lexington [Member]
Loss Contingencies [Line Items]
Number of additional renewal terms \| Options				1
Additional operating lease term				5 years
Hydrogel License Agreement [Member]
Loss Contingencies [Line Items]
Research and development expense				$ 3,200,000
One-time payment amount			$ 3,000,000	3,000,000
Tissue Regeneration License Agreement [Member]
Loss Contingencies [Line Items]
Research and development expense				700,000
One-time payment amount			300,000	$ 300,000
Percentage of royalty offsetting				50.00%
Maximum [Member] \| Waltham [Member]
Loss Contingencies [Line Items]
Construction allowance to total cost of tenant improvements				$ 3,200,000,000
Maximum [Member] \| Lexington [Member]
Loss Contingencies [Line Items]
Construction allowance to total cost of tenant improvements				1,000,000
Minimum [Member] \| Tissue Regeneration License Agreement [Member]
Loss Contingencies [Line Items]
Non-refundable royalty fee				10,000
Tissue Processor Sub License Agreement [Member]
Loss Contingencies [Line Items]
Research and development expense				1,000,000
Reimbursement for development cost		$ 300,000
Potential milestone payments			10,200,000	10,200,000
Additional non-refundable royalty fee				$ 30,000
Additional non-refundable royalty fee payment description				2016 through 2019
Tissue Processor Sub License Agreement [Member] \| Minimum [Member]
Loss Contingencies [Line Items]
Non-refundable royalty fee				$ 20,000
Engineering Agreement [Member]
Loss Contingencies [Line Items]
Amount paid to suppliers			200,000	600,000
Additional payments due			0	$ 0
Collagen Supply Agreement [Member]
Loss Contingencies [Line Items]
Minimum amount of material and/or services	$ 200,000
Non-refundable payment					$ 100,000
Initial term of the agreement	3 years
Supplier agreement description				The initial term of the agreement is three years and will automatically renew from year to year thereafter unless otherwise terminated with at least 180 days' notice by either party.
OCS Agreement [Member]
Loss Contingencies [Line Items]
Accrued and received grants, aggregate			$ 1,100,000	$ 1,100,000
OCS Agreement [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Royalties payment, rate				5.00%
Royalty payment percentage as percentage of grant received				300.00%
OCS Agreement [Member] \| Minimum [Member]
Loss Contingencies [Line Items]
Royalties payment, rate				3.00%
Royalty payment percentage as percentage of grant received				100.00%

Commitments and Contingencies - Schedule of Minimum Annual Lease Commitments Under Non-Cancellable Operating Leases (Detail) $ in Thousands	Dec. 31, 2016 USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2017	$ 2,266
2018	754
2019	586
2020	596
2021	605
Thereafter	926
Total minimum lease payments	$ 5,733

Capital Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Sep. 29, 2016	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Common stock, shares issued		20,647,612	13,273,470
Common stock price per share		$ 0.01	$ 0.01
Conversion of preferred stock in to common stock, preferred stock converted	10,737,275
Proceeds from issuance of issuance of common stock, preferred stock and warrants, net of issuance costs	$ 27,600	$ 27,630
Warrant expense		$ 3,100	$ 11
Common stock, shares authorized		100,000,000	100,000,000
Preferred stock, shares authorized		30,000,000
Minimum threshold percentage of beneficial common stock interest	4.99%
Maximum threshold percentage of beneficial common stock interest on holder's discretion	9.99%
Convertible preferred stock, terms of conversion		The Series A Preferred Stock shall not be converted if, after giving effect to the conversion, the holder and its affiliated persons would own beneficially more than 4.99% of our common stock (subject to adjustment up to 9.99% solely at the holder's discretion upon 61 days' prior notice to us or, solely as to a holder, if such limitation is waived by such holder upon execution of the private placement agreement).
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	24,158.8693
Preferred stock par value	$ 0.01
Private Placement [Member]
Class of Stock [Line Items]
Gross proceeds from issuance of common stock, preferred stock and warrants	$ 30,000
Common stock, shares issued	2,596,059
Common stock price per share	$ 2.25
Conversion of preferred stock in to common stock, preferred stock converted	10,737,275	444.44
Class of Warrants or right to purchase common stock	13,333,334
Class of Warrants or right to purchase common stock, exercise price	$ 2.25	$ 2.25
Warrants granted to placement agent	133,333
Proceeds from issuance of issuance of common stock, preferred stock and warrants, net of issuance costs	$ 27,600
Warrants granted to placement agent, exercise price	$ 2.25
Minimum percentage of outstanding common stock		50.00%
Warrants expiry period		5 years
Warrants exercisable period		6 months
Fair value of warrants		$ 30,700
Excess fair value of warrant liability		400
Warrant expense		$ 3,100
Preferred stock par value		$ 0.01
Private Placement [Member] \| Members of Board of Directors [Member]
Class of Stock [Line Items]
Common stock, shares issued		283,046
Preferred stock, shares issued		2,563.1439
Class of Warrants or right to purchase common stock		1,422,221
Class of Warrants or right to purchase common stock, exercise price		$ 2.25
Private Placement [Member] \| Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	24,158.8693
Conversion of preferred stock in to common stock, preferred stock converted	444.44

Capital Stock - Schedule of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Common stock reserved for future issuance	15,211,975	1,394,360
Warrants Exercisable into Common Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	13,633,070	166,403
Restricted Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	1,889	5,190
Stock Options [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	1,577,016	1,222,767

Warrants - Additional Information (Detail) - USD ($)						9 Months Ended	12 Months Ended
Warrants - Additional Information (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 21, 2015	Dec. 03, 2014	Jul. 20, 2012	Sep. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2016	Mar. 31, 2015
Class of Warrant or Right [Line Items]
Warrant expense							$ 3,100,000	$ 11,000
Investor Warrants [Member]
Class of Warrant or Right [Line Items]
Class of Warrants or right to purchase common stock									13,333,334
Class of Warrants or right to purchase common stock, exercise price									$ 2.25
Warrants exercisable period							6 months
Warrants expiry period							5 years
Warrant expense	$ 2.28						$ 2.28
Placement Agent Warrant [Member]
Class of Warrant or Right [Line Items]
Class of Warrants or right to purchase common stock									133,333
Class of Warrants or right to purchase common stock, exercise price									$ 2.25
Warrants expiry period							5 years
Warrant expense							$ 2.28
Consulting Agreement Warrant [Member]
Class of Warrant or Right [Line Items]
Class of Warrants or right to purchase common stock										7,398
Class of Warrants or right to purchase common stock, exercise price										$ 9.75
Warrants exercisable period						24 months
Warrants expiry period						10 years
Warrants, forfeiture			(3,699)
Warrants vested and exercisable	3,699	3,699
Warrants, percentage of forfeiture			50.00%
Affiliates Of Advisor Warrant [Member]
Class of Warrant or Right [Line Items]
Class of Warrants or right to purchase common stock	156,138	156,138			161,977		156,138	156,138
Class of Warrants or right to purchase common stock, exercise price	$ 0.01	$ 0.01			$ 0.01		$ 0.01	$ 0.01
Warrants expiry period					10 years
Fair value of the warrants, risk-free interest rate					0.22%
Fair value of the warrants, implied volatility					99.00%
Fair value of the warrants, expected term to liquidity even					1 year 8 months 12 days
Surrender of warrant to satisfy related liability				5,839

Equipment Loan Payable - Schedule of Outstanding Borrowing Obligations (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Less: current portion	$ (583)	$ (583)
Long-term debt, net	178	761
Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Total debt	$ 761	$ 1,344

Equipment Loan Payable - Additional Information (Detail) - Silicon Valley Bank [Member] - USD ($)	1 Months Ended
	Jul. 31, 2014	Dec. 31, 2016	Dec. 31, 2015
Class of Warrant or Right [Line Items]
Amount of loan to purchase equipment	$ 1,800,000
Line of credit facility, interest rate, stated percentage	3.25%
Bank loan and security agreement, repayment period	36 months
Net exercise of warrants, shares	6,566
Net exercise of warrants, exercise price per share	$ 7.99
Borrowings outstanding under line of credit		$ 800,000	$ 1,300,000
Prime Rate [Member]
Class of Warrant or Right [Line Items]
Amount of loan bears interest basis spread on variable rate	2.75%

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		12 Months Ended
	Jun. 16, 2016	Dec. 03, 2014	Oct. 31, 2014	Jul. 31, 2012	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to outstanding options						$ 2,600	$ 3,900
Intrinsic value of options exercised						$ 10	300
Weighted average grant date fair value of vested options						$ 4.71
Weighted average grant date fair value of options outstanding						$ 3.67
Stock-based compensation expense						$ 1,548	1,228
2012 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance								609,389
Stock options vesting period				3 years
Term of stock options granted				10 years
2012 Equity Incentive Plan [Member] \| First Anniversary of Original Vesting Date [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vesting percentage				25.00%
2013 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vesting period			3 years
Term of stock options granted			10 years
2013 Equity Incentive Plan [Member] \| First Anniversary of Original Vesting Date [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vesting percentage			25.00%
2013 Equity Incentive Plan [Member] \| EIP Amendment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in authorized shares of common stock amount	300,000
Increase in authorized shares, percentage of common stock outstanding			4.00%
2013 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance		103,665
Increase in authorized shares of common stock amount		51,832
Increase in authorized shares, percentage of common stock outstanding		1.00%
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense						1,057	777
Restricted stock-based compensation expense						$ 2	$ 4
Scenario, Forecast [Member] \| 2013 Equity Incentive Plan [Member] \| EIP Amendment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in authorized shares of common stock amount					825,904
Scenario, Forecast [Member] \| 2013 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in authorized shares of common stock amount					206,476
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, recognition period						2 years 4 days	2 years 8 months 5 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, recognition period						3 months 18 days	1 year 2 months 12 days
Unrecognized compensation cost related to restricted stock awards						$ 1	$ 4

Stock-Based Compensation - Summary of Stock Option Activity Under the 2012 and 2013 Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Options, Outstanding Beginning Balance	1,229,339
Number of Options, Granted	464,240
Number of Options, Exercised	(3,685)
Number of Options, Cancelled	(112,878)
Number of Options, Outstanding Ending Balance	1,577,016	1,229,339
Number of Options, Vested and expected to vest outstanding	1,492,341
Number of Options, Exercisable	561,693
Weighted Average Exercise Price, Outstanding Beginning Balance	$ 7.32
Weighted Average Exercise Price, Granted	2.02
Weighted Average Exercise Price, Exercised	0.76
Weighted Average Exercise Price, Cancelled	4.97
Weighted Average Exercise Price, Outstanding Ending Balance	5.95	$ 7.32
Weighted Average Exercise Price, Vested and expected to vest outstanding	5.97
Weighted Average Exercise Price, Exercisable	$ 6.79
Weighted Average Remaining Contractual Term, Outstanding	8 years 4 months 24 days	9 years
Weighted Average Remaining Contractual Term, Vested and expected to vest outstanding	8 years 4 months 24 days
Weighted Average Remaining Contractual Term, Exercisable	7 years 9 months 18 days
Aggregate Intrinsic Value, Outstanding	$ 71	$ 4,679
Aggregate Intrinsic Value, Vested and expected to vest outstanding	69
Aggregate Intrinsic Value, Exercisable	$ 52

Stock-Based Compensation - Additional Information about Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted-average grant date fair value per share of employee option grants within the year	$ 1.26	$ 4.08
Cash received upon exercise of options	$ 2	$ 39

Stock-Based Compensation - Schedule of Restricted Stock Awards Under the 2012 and 2013 Plans (Detail) - Restricted Stock [Member]	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, Unvested beginning balance \| shares	5,190
Vesting of restricted stock \| shares	(3,301)
Number of shares, Unvested ending balance \| shares	1,889
Weighted-average grant date fair value, Unvested beginning balance \| $ / shares	$ 1.07
Vesting of restricted stock \| $ / shares	0
Weighted-average grant date fair value, Unvested ending balance \| $ / shares	$ 0.83

Stock-Based Compensation - Summary of Stock-Based Compensation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,548	$ 1,228
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	491	451
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,057	$ 777

Stock-Based Compensation - Summary of Weighted-Average Assumptions Used in the Black-Scholes Option Pricing Model to Determine the Fair Value of the Employee Stock Option Grants (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate	1.73%	1.68%
Expected volatility	72.50%	62.60%
Expected term (in years)	6 years 29 days	6 years 15 days
Expected dividend yield	0.00%	0.00%

Stock-Based Compensation - Summary of Weighted-Average Assumptions Used in the Black-Scholes Option Pricing Model to Determine the Fair Value of the Non-Employee Stock Option Grants (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Share-based Goods and Nonemployee Services Transaction [Abstract]
Risk-free interest rate	1.57%	1.79%
Expected volatility	63.50%	63.20%
Expected term (in years)	7 years	6 years 1 month 28 days
Expected dividend yield	0.00%	0.00%

Income Taxes - Components of Loss Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S.	$ (15,838)	$ (31,382)
Foreign	(369)	(691)
Total	$ (16,208)	$ (32,073)

Income Taxes - Schedule of Reconciliation of Income Tax Expense (Benefit) Computed at Statutory Federal Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal income tax (benefit) at statutory rate	34.00%	34.00%
(Increase) decrease income tax benefit resulting from:
Permanent differences	29.00%	(1.20%)
Net Operating Loss Limitation	(111.10%)
R&D Credit Limitation	(1.50%)
Change in valuation allowance	48.70%	(31.70%)
Other	0.90%	(1.20%)
Income tax expense (benefit)	0.00%	0.00%

Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Net operating loss carryforwards	$ 16,146	$ 28,200
Depreciation and amortization	6,229	6,688
Accrued expenses	2,082	1,183
Capitalized start-up costs	10,037	8,531
Other	75	259
Deferred tax assets before valuation allowance	34,569	44,861
Valuation allowance	(34,569)	(43,751)
Deferred tax assets, net		1,110
Deferred tax liabilities
IPR&D		(36)
Change in accounting method		(1,074)
Total deferred tax liabilities		(1,110)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes Disclosure [Line Items]
Increase (Decrease) in valuation allowance	$ (9,200,000)	$ 11,800,000
NOL carry forwards, net of limitations	100,100,000	47,100,000
Unrecognized tax benefits	562,000	687,000	$ 811,000
Accrued interest and penalties related to unrecognized tax benefits	0	0
Interest and penalties related to uncertain tax benefits	0	0
Unrecognized tax benefits may be recognized by the end of 2016	$ 0
Income tax examination description	The Company is subject to U.S. federal, state and local income tax examinations by tax authorities for years 2001 through present. Carryforward attributes that were generated in earlier periods remain subject to examination to the extent the year in which they were used or will be used remains open for examination. The tax years which remain subject to examination by tax authorities in Israel, as of December 31, 2016, include years 2013 through the present.
U.S. Federal [Member]
Income Taxes Disclosure [Line Items]
NOL carryforwards	$ 24,500,000	55,500,000
NOL carryforwards, expiration date	Dec. 31, 2036
U.S. State [Member]
Income Taxes Disclosure [Line Items]
NOL carryforwards	$ 24,300,000	55,400,000
NOL carryforwards, expiration date	Dec. 31, 2036
Foreign [Member]
Income Taxes Disclosure [Line Items]
NOL carryforwards	$ 26,100,000	$ 25,600,000

Income Taxes - Summary of Changes In Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefit, beginning of year	$ 687	$ 811
Increase (decrease) related to current year positions	(125)	(124)
Settlements	0	0
Unrecognized tax benefit, end of year	$ 562	$ 687

Employee Benefits - Additional Information (Detail)	12 Months Ended
Employee Benefits - Additional Information (Detail)	Dec. 31, 2016 USD ($)
Defined Contribution Plan Disclosure [Line Items]
Defined benefit plan contribution by employer	$ 0
Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan eligibility years of age for employees	21 years

Related Parties - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2012
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accrued expenses due to related party		$ 1,546
Intrexon [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration Agreement cancellation notification	90 days
Collaboration Agreement cancellation with material breach that cannot be remedied	60 days
Accrued expenses due to related party	$ 3,000	1,500
Intrexon [Member] \| Commercialization Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Commercialization milestones obligation	12,000
Intrexon [Member] \| Sales Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sales milestones	$ 22,500
Intrexon [Member] \| Research and Development [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of reimbursement expenses	50.00%
Percentage of reimbursement expenses subject to acceptance	50.00%
Research and development expense from transaction with Intrexon	$ 3,000	3,100
Purpose, Co. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reimbursement for development cost, amount			$ 300
Reimbursement for development cost, paid	$ 100	$ 200

Subsequent Events - Additional Information (Detail) - Collagen Supply Agreement [Member] - USD ($) $ in Millions		12 Months Ended
	Feb. 22, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Original agreement date		Sep. 15, 2015
Scenario, Forecast [Member]
Subsequent Event [Line Items]
Repayment period	18 months
Payment in exchange of eliminating minimum annual order of material and/or services and any other amounts due supplier	$ 0.1