Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2015	Mar. 08, 2016	Jun. 30, 2015
Document and Entity Information
Entity Registrant Name	Vericel Corp
Entity Central Index Key	0000887359
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		23,852,412
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 86,924,377

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash	$ 14,581	$ 30,343
Accounts receivable (net of allowance for doubtful accounts of $68 and $40, respectively)	10,919	8,191
Inventory	1,379	1,920
Other current assets	464	1,036
Total current assets	27,343	41,490
Property and equipment, net	4,049	2,892
Intangible assets	2,917	3,197
Total assets	34,309	47,579
Current liabilities:
Accounts payable	7,588	5,824
Accrued expenses	3,603	4,714
Warrant liabilities	757	1,081
Other	160	210
Total current liabilities	12,108	11,829
Long term debt	71	109
Total liabilities	$ 12,179	$ 11,938
COMMITMENTS AND CONTINGENCIES
Shareholders’ equity:
Common stock, no par value; shares authorized — 75,000; shares issued and outstanding — 23,789 and 23,786, respectively	$ 307,766	$ 305,008
Treasury stock — 1,250 shares	(3,150)	0
Other comprehensive loss	0	(71)
Accumulated deficit	(324,025)	(307,685)
Total shareholders’ equity	22,130	35,641
Total liabilities and shareholders’ equity	34,309	47,579
Series A
Shareholders’ equity:
Series B-2 voting convertible preferred stock, no par value: shares authorized and reserved — 39, shares issued and outstanding — 12	3,150	0
Series B-2
Shareholders’ equity:
Series B-2 voting convertible preferred stock, no par value: shares authorized and reserved — 39, shares issued and outstanding — 12	$ 38,389	$ 38,389

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts	$ 68	$ 40
Par value of common stock (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	75,000	75,000
Common stock, shares issued	23,789	23,786
Common stock, shares outstanding	23,789	23,786
Treasury stock, shares reserved	1,250	1,250
Series A
Par value of convertible preferred stock (in dollars per share)	$ 0	$ 0
Convertible preferred stock, shares authorized	1	1
Convertible preferred stock, shares reserved	1	1
Convertible preferred stock, shares issued	1	1
Convertible preferred stock, shares outstanding	1	1
Series B-2
Par value of convertible preferred stock (in dollars per share)	$ 0	$ 0
Convertible preferred stock, shares authorized	39	39
Convertible preferred stock, shares reserved	39	39
Convertible preferred stock, shares issued	12	12
Convertible preferred stock, shares outstanding	12	12

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
Product sales	$ 51,168	$ 28,796	$ 19
Total revenues	51,168	28,796	19
Costs and expenses:
Cost of product sales	26,470	17,293	4
Gross profit	24,698	11,503	15
Research and development	18,890	21,263	15,104
Selling, general and administrative	22,479	13,774	5,875
Total operating expenses	41,369	35,037	20,979
Loss from operations	(16,671)	(23,534)	(20,964)
Other income (expense):
(Increase) decrease in fair value of warrants	324	(27)	5,337
Bargain purchase gain	0	3,473	0
Foreign currency translation gain (loss)	(67)	152	0
Interest income	36	24	16
Other income (expense)	47	(2)	0
Interest expense	(9)	(6)	(11)
Total other income (expense)	331	3,614	5,342
Net loss	$ (16,340)	$ (19,920)	$ (15,622)
Net loss per share attributable to common shareholders (basic and diluted) (in dollars per share)	$ (0.97)	$ (2.23)	$ (6.95)
Weighted average number of common shares outstanding (Basic and Diluted)	23,760	11,642	3,016

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock	Common Stock	Treasury Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance, Shares at Dec. 31, 2013		12	4,723	0
Beginning balance at Dec. 31, 2013	$ 3,894	$ 38,389	$ 253,270	$ 0	$ 0	$ (287,765)
Increase (Decrease) in Shareholders' Equity
Net loss	(19,920)					(19,920)
Compensation expense related to stock options granted	839		$ 839
Exercise of stock purchase warrants (in shares)			408
Exercise of stock purchase warrants	2,490		$ 2,490
Issuance of common stock, net of issuance costs of [ ] and $3,167 for 2015 and 2014, respectively (in shares)			18,655
Issuance of common stock, net of issuance costs of [ ] and $3,167 for 2015 and 2014, respectively	48,409		$ 48,409
Shares issued under the Employee Stock Purchase Plan	(71)				(71)
Ending balance, Shares at Dec. 31, 2014		12	23,786	0
Ending balance at Dec. 31, 2014	35,641	$ 38,389	$ 305,008	$ 0	(71)	(307,685)
Increase (Decrease) in Shareholders' Equity
Net loss	(16,340)
Common stock exchanged for preferred stock and held in treasury shares, Shares		1		(1,250)
Common stock exchanged for preferred stock and held in treasury shares		$ 3,150		$ (3,150)
Compensation expense related to stock options granted	2,747		$ 2,747
Exercise of stock purchase warrants (in shares)			3
Exercise of stock purchase warrants	11		$ 11
Shares issued under the Employee Stock Purchase Plan	71				71
Ending balance, Shares at Dec. 31, 2015		13	23,789	(1,250)
Ending balance at Dec. 31, 2015	$ 22,130	$ 41,539	$ 307,766	$ (3,150)	$ 0	$ (324,025)

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net loss	$ (16,340)	$ (19,920)	$ (15,622)
Other comprehensive loss
Foreign currency translation	71	(71)	0
Comprehensive loss	$ (16,269)	$ (19,991)	$ (15,622)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net loss	$ (16,340)	$ (19,920)	$ (15,622)
Adjustments to reconcile net loss to net cash used for operating activities:
Depreciation and amortization	1,592	752	489
Stock compensation expense	2,747	839	926
Inventory provision	627	0	0
Change in fair value of warrants	(324)	27	(5,337)
Bargain purchase gain	0	(3,473)	0
Foreign currency translation loss (gain)	67	(152)	0
(Gain) loss on sale of fixed assets	(35)	139	0
Write down of asset retirement obligation	(268)	(1,102)	0
Changes in operating assets and liabilities:
Inventory	(86)	119	0
Accounts receivable	(2,728)	(8,139)	0
Other current assets	572	(455)	(65)
Accounts payable	1,726	2,773	(571)
Accrued expenses	(764)	3,007	237
Asset retirement obligation	(80)	0	0
Other non-current assets and liabilities, net	(52)	175	0
Net cash used for operating activities	(13,346)	(25,410)	(19,943)
Investing activities:
Acquisition of CTRM business, net of cash acquired	0	(1,450)	0
Expenditures for property, plant and equipment	(2,427)	(829)	(40)
Other	35	101	0
Net cash used for investing activities	(2,392)	(2,178)	(40)
Financing activities:
Net proceeds from issuance of common stock and warrants	11	49,934	14,438
Payments on long-term debt	(35)	(8)	(34)
Net cash provided by financing activities	(24)	49,926	14,404
Effect of exchange rate changes on cash	0	(54)	0
Net increase (decrease) in cash	(15,762)	22,284	(5,579)
Cash at beginning of period	30,343	8,059	13,638
Cash at end of period	14,581	30,343	8,059
Supplemental cash flow information (non-cash):
Acquisition of business through promissory note	0	2,500	0
Accretion of convertible preferred stock	0	0	1,263
Common shares exchanged for preferred stock	3,150	0	0
Warrants exchanged for common stock	0	965	0
Additions to equipment in process included in accounts payable	42	199	0
Equipment acquired under capital lease	$ 0	$ 153	$ 0

Organization	12 Months Ended
Organization	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Vericel Corporation, a Michigan corporation, which was formerly known as Aastrom Biosciences, Inc. (the Company, Vericel, we, us or our), was incorporated in March 1989 and began employee-based operations in 1991. On May 30, 2014, Vericel completed the acquisition of certain assets and assumed certain liabilities of Sanofi, a French société anonyme (Sanofi), including all of the outstanding equity interests of Genzyme Biosurgery ApS (Genzyme Denmark or the Danish subsidiary) (now known as Vericel Denmark ApS), a wholly-owned subsidiary of Sanofi, and over 250 patent applications of Sanofi and certain of its subsidiaries for purposes of acquiring the portion of the cell therapy and regenerative medicine business (the CTRM Business), which researches, develops, manufactures, markets and sells the Carticel^®, MACI™, and Epicel^® products. The Company is a fully integrated, commercial-stage biopharmaceutical company dedicated to the identification, development and commercialization of innovative therapies that enable the body to repair and regenerate damaged tissues and organs to restore normal structure and function. Vericel has marketed products as well as developmental stage product candidates and the Company’s goal is to become the leader in cell therapy and regenerative medicine by developing, manufacturing and marketing best-in-class therapies for patients with significant unmet medical needs. The Company operates its business primarily in the U.S. in one reportable segment — the research, product development, manufacture and distribution of patient-specific, expanded cellular therapies for use in the treatment of specific diseases. Successful future operations are subject to several technical hurdles and risk factors, including satisfactory product development, timely initiation and completion of clinical trials, regulatory approval and market acceptance of the Company’s products.

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Principles of Consolidation The consolidated financial statements include the accounts of Vericel and its wholly-owned subsidiaries, Marrow Donation, LLC, located in San Diego, California, and Vericel Denmark ApS, in Kastrup, Demark (collectively, the Company). All inter-company transactions and accounts have been eliminated in consolidation. Aastrom Biosciences GmbH ceased operations in 2014 and Marrow Donation, LLC and Vericel Denmark ApS ceased operations in 2015. Use of Estimates The preparation of financial statements in accordance with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reported period. Actual results could differ from those estimates. Inventory Inventories are measured at the lower of cost or market value. Cost is calculated based upon standard-cost which approximates costs determined on the first-in, first-out method. Utilization reserves are established for estimated obsolescence or un-marketable inventory in an amount equal to the cost of inventory. Accounts Receivable Accounts receivable are initially recorded at the contractual amount owed by the customer. Allowances for doubtful accounts are established when the facts and circumstances indicate that a receivable may not be collectible. Property, Plant and Equipment Property, plant and equipment are initially measured and recognized at acquisition cost, including any directly attributable cost of preparing the asset for its intended use or, in the case of assets acquired in a business combination, at fair value as at the date of the combination. After initial measurement, property, plant and equipment are carried at cost less accumulated depreciation and impairment. Repair and maintenance costs of property, plant and equipment are expensed as incurred. The depreciable value of property, plant and equipment, net of any residual value, is depreciated on a straight line basis over the useful life of the asset. The useful life of an asset is usually equivalent to its economic life. The useful lives of property, plant and equipment are as follows: •Equipment and computers: 3 to 5 years •Furniture and fixtures: 5 years •Building improvements and leasehold improvements: Shorter of the remaining life of the lease or 7 years The costs of assets retired or otherwise disposed of and the accumulated depreciation thereon are removed from the accounts, with any gain or loss realized upon sale or disposal credited or charged to operations. Intangible Assets and Other Long Lived Assets Intangible assets are initially measured at acquisition cost, including any directly attributable costs of preparing the asset for its intended use or, in the case of assets acquired in a business combination at fair value as at the date of the combination. Identifiable intangible assets related to commercial rights are amortized on a straight line basis over their expected useful lives. Amortization of intangible assets is recognized in these financial statements under Costs of product sales. Intangible assets and long-lived assets are assessed for potential impairment when there is evidence that events or changes in circumstances indicate that the carrying amount of an asset may not be recovered. An impairment loss would be recognized when an asset’s fair value, determined based on undiscounted cash flows expected to be generated by the asset, is less than its carrying amount. The impairment loss would be measured as the amount by which the asset’s carrying value exceeds its fair value and recognized in these financial statements. Intangible assets are carried at cost less accumulated amortization and impairment. Revenue Recognition Total revenues are comprised of product sales of Carticel, Epicel, MACI, bone marrow and surgical kits. Revenue is recognized when persuasive evidence of an arrangement exists, the goods are shipped or delivered, depending on shipping terms, title and risk of loss pass to the customer and collectability is reasonably assured. Shipping and handling costs are included as a component of revenue. Revenue is recorded net of a provision for rebates and cash discounts. These rebates and cash discounts are established by the Company at the time of sale, based on historical experience adjusted to reflect known changes in the factors that impact such reserves. For instance, distributors are entitled to chargeback incentives for services that are provided for based on the selling price to the end customer, under specific contractual arrangements. Cash discounts may also be granted for prompt payment. Research and Development Expense Research and development activities represent a significant part of the Company’s business. These expenditures relate to the development of new products, improvement of existing products, technical support of products and compliance with governmental regulations for the protection of consumers and patients. Research and development expenses are expensed as incurred. Diversity of Credit Risk The Company has established guidelines relative to diversification in an effort to limit risk. These guidelines are periodically reviewed and modified to take advantage of trends in yields and interest rates. Stock-Based Compensation The Company’s accounting for stock-based compensation requires it to determine the fair value of common stock issued in the form of stock option awards. The Company uses the value of its common stock at the date of the grant in the calculation of the fair value of its share-based awards. The fair value of stock options held by the employees is determined using a Black-Scholes option valuation method, which is a valuation technique that is acceptable for share-based payment accounting. Key assumptions in determining fair value include volatility, risk-free interest rate, dividend yield and expected term. The assumptions used in calculating the fair value of stock options represent the Company’s best estimates, however; these estimates involve inherent uncertainties and the application of management judgment. As a result, if factors change and different assumptions are used, the stock-based compensation expense could be materially different in the future. In addition, the Company is required to estimate the expected forfeiture rate and only recognize expense for those stock options expected to vest over the service period. The estimated forfeiture rate considers the historical experience of the Company’s stock-based awards. If the actual forfeiture rate is different from the estimate, expense is adjusted accordingly. The Company also has an Employee Stock Purchase Plan (ESPP) which is a compensatory plan. Compensation expense is recorded based on the fair value of the purchase options at the grant date, which corresponds to the first day of each purchase period, and is amortized over the purchase period. Comprehensive Loss Comprehensive loss is the change in common stockholders’ equity during a period arising from any gain or loss realized related to foreign currency translation. Income Taxes Deferred tax assets are recognized for deductible temporary differences and tax credit carryforwards and deferred tax liabilities are recognized for taxable temporary differences. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will not be realized. Net Loss Per Share Attributable to Common Shareholders Basic earnings (loss) per 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 holders of the Series B preferred stock. The Series B preferred stock shares contain participation rights in undistributed earnings, but do not share in the losses of the Company. The accumulated but undeclared dividends on the Series B preferred stock of $6.7 million are treated as a reduction of earnings attributable to common shareholders. Financial Instruments The Company’s financial instruments include receivables for which the current carrying amounts approximate market value based upon their short-term nature. Warrants Warrants that could be cash settled or have anti-dilution price protection provisions are recorded as liabilities at their estimated fair value at the date of issuance, with subsequent changes in estimated fair value recorded in other income (expense) in our statement of operations in each subsequent period. In general, warrants are measured using the Black-Scholes valuation model. The methodology is based, in part, upon inputs for which there is little or no observable market data, requiring the Company to develop its own assumptions. The assumptions used in calculating the estimated fair value of the warrants represent our best estimates; however, these estimates involve inherent uncertainties and the application of management judgment. As a result, if factors change and different assumptions are used, the warrant liability and the change in estimated fair value could be materially different.

Recent Accounting Pronouncements	12 Months Ended
Recent Accounting Pronouncements	Dec. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Revenue Recognition In May 2014, the Financial Accounting Standards Board (FASB) issued authoritative guidance requiring entities to apply a new model for recognizing revenue from contracts with customers. The guidance will supersede the current revenue recognition guidance and require entities to evaluate their revenue recognition arrangements using a five step model to determine when a customer obtains control of a transferred good or service. The guidance is currently effective for annual reporting periods beginning after December 15, 2017, with early adoption permitted for annual reporting periods beginning after December 15, 2016, and may be adopted using a full or modified retrospective application. The Company is currently in the process of evaluating its revenue arrangements under the issued guidance and has not yet determined the impact to its consolidated financial statements. Going Concern Assessment The FASB has issued authoritative guidance for management on how to assess whether substantial doubt exists regarding an entity’s ability to continue as a going concern and guidance on how to prepare related footnote disclosures. The guidance will require management to evaluate whether there are conditions or events that raise substantial doubt about an entity’s ability to continue as a going concern for one year from the date the financial statements are issued. The guidance is effective for annual reporting periods beginning after December 15, 2016. As of December 31, 2015, the Company does not expect the guidance to impact future disclosures. Balance Sheet Classification of Deferred Taxes The FASB simplified the balance sheet classification of deferred taxes guidance to require all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. The new guidance eliminates the requirement to classify deferred taxes between current and noncurrent and is expected to simplify financial reporting. The guidance is effective for annual reporting periods beginning after December 15, 2016, with early adoption permitted for interim or annual reporting periods beginning after December 15, 2015. The guidance may be applied either prospectively, for all deferred tax assets and liabilities, or retrospectively by reclassifying the comparative balance sheet for prior periods. The Company has early adopted the guidance beginning for the year ended December 31, 2015 on a prospective basis. The guidance did not have a material impact for the year ended December 31, 2015. Presentation and Subsequent Measurement of Debt Issuance Costs The FASB issued guidance which requires entities to present debt issuance costs related to a recognized debt liability as a direct deduction from the carrying amount of that debt liability. For debt issuance costs related to line-of-credit arrangements, companies are able to defer and present debt issuance costs as an asset and subsequently amortize the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. The guidance is effective for annual reporting periods beginning after December 15, 2015. The Company is currently determining the impact on future periods. Accounting for Leases The FASB issued guidance to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. In accordance with the updated guidance, lessees are required to recognize the assets and liabilities arising from operating leases on the balance sheet. The guidance is effective for annual reporting periods beginning after December 15, 2018, including interim periods including interim periods within 2018. The Company is currently determining the impact on future periods.

- Definition

The entire disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6507316

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Direct Effects of a Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6510796

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=28359718&loc=d3e22583-107794

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Indirect Effects of a Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6515603

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=28359718&loc=d3e22580-107794

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-Section S99
-Paragraph 1
-Subparagraph (SX 210.10-01.(b)(6))
-URI http://asc.fasb.org/extlink&oid=27015980&loc=d3e46468-122699

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Accounting Change
-URI http://asc.fasb.org/extlink&oid=6503790

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
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-URI http://asc.fasb.org/extlink&oid=28359718&loc=d3e22499-107794

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Retrospective Application
-URI http://asc.fasb.org/extlink&oid=6523989

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Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 01
-Paragraph b
-Subparagraph 6
-Article 10

+ Details

Acquisitions

12 Months Ended

Dec. 31, 2015

Business Combinations [Abstract]

Acquisitions

CTRM Business acquisition

On May 30, 2014, Vericel completed its acquisition of certain assets of Sanofi, including all of the outstanding equity interests of Genzyme Denmark, a wholly-owned subsidiary of Sanofi, and over 250 patents and patent applications and assumed certain liabilities for purposes of acquiring portions of the CTRM Business. Vericel is a leader in developing patient-specific expanded cellular therapies for use in the treatment of patients with severe diseases and conditions and the CTRM Business expands the Company’s portfolio of cellular therapies to include products which treat severe burns and as well as cartilage defects. Pursuant to the terms of the asset purchase agreement, the Company paid a total purchase price of $6.5 million, including $4.0 million in cash and a $2.5 million promissory note which was repaid on July 30, 2014.

The total purchase price consideration was as follows:



Acquisition consideration (In thousands):	Fair Value
Cash payment	$	4,000
Promissory note	2,500
Total acquisition consideration	$	6,500

The Company recognized tangible and intangible assets and liabilities acquired based upon their respective estimated fair values as of the acquisition date. The table below shows the fair values assigned to the assets acquired and liabilities assumed. Based on this analysis, the transaction resulted in a bargain purchase gain.

The final purchase price allocation was as follows:



Purchase price allocation (In thousands):	Fair Value
Cash	$	5,050
Accounts receivable	53
Inventory	2,039
Other current assets	192
Accounts payable and accrued expenses	(939		)
Asset retirement obligation	(1,600		)
Property and equipment	1,818
Intangible assets	3,360
Bargain purchase gain	(3,473		)
Total consideration	$	6,500

As part of the acquisition, $5.0 million in cash was received from Sanofi in order to fund the restructuring of the Denmark operations and close the facility. In 2014, the Company implemented its restructuring plans for the Danish subsidiary after the consummation of the acquisition of the CTRM Business and recorded restructuring charges in the U.S. and Denmark of $3.0 million. See Note 5 “Restructuring” below for additional information.

The intangible assets acquired represent commercial use rights for certain products acquired in the transaction. The fair value of $3.4 million was determined using the income approach based on projected cash flows attributed to the commercial rights. The calculated value of the commercial rights intangible assets are amortized using the straight line method over an estimated useful life of 12 years

Pro forma Financial Information

The following pro forma condensed combined information for the year ended December 31, 2014, and 2013, respectively are presented as if the acquisition of the CTRM Business had occurred on January 1, 2013.

In management’s opinion, all adjustments necessary to reflect the significant effects of this transaction have been made. These statements are based on assumptions and estimates considered appropriate by management; however, they are not necessarily, and should not be assumed to be, an indication of Vericel’s financial position or results of operations that would have been achieved had the acquisitions been completed as of the dates indicated or that may be achieved in the future.



	Year Ended December 31,
(in thousands)	2014			2013
Pro forma revenue	$	44,906		$	43,863
Pro forma net loss	(30,115		)	(49,124		)
Pro forma net loss per share - basic and diluted	(3.10		)	(18.06		)

An error was identified in the December 31, 2014 acquisition disclosure with respect to the amount recorded for pro forma condensed combined information for the year ended December 31, 2014. The pro forma revenue, net loss and net loss per share (basic and diluted) was understated by $0.1 million, $4.0 million and $0.33 per share, respectively. In accordance with the guidance set forth by the SEC, we evaluated the error and, based on an analysis of quantitative and qualitative factors determined that the error was immaterial to the prior reporting periods affected. As the error has no impact on any amounts presented in a previously issued balance sheet, statement of operations or statement of cash flows for any prior periods, we determined that it is appropriate to revise the 2014 prior year amounts presented above to reflect the corrected disclosure.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1497-128463

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+ Details

Restructuring	12 Months Ended
Restructuring	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring Acquisition Restructuring In June 2014, the Company announced a strategic plan to maximize the profitability and growth potential of the CTRM Business (the Plan). Under the Plan, the Company discontinued manufacturing MACI in Denmark and temporarily suspended sales of MACI in Europe. Furthermore, the Company eliminated approximately 80 full time employee positions, which represented approximately 30% of the Company’s current total workforce. Employees terminated as part the Plan were provided with severance payments and outplacement assistance. As a result of the Plan, the Company recorded a restructuring charge of $3.0 million for the year ended December 31, 2014, related to the operations in the United States and Denmark, primarily representing cash payments for severance and other personnel-related expenses. Of the total restructuring charge, $2.5 million was recorded in cost of product sales, and $0.5 million was recorded in selling, general and administrative expenses. There was no restructuring reserve as of December 31, 2014 or 2015 as a result of cash payments made for severance and other personnel-related expenses. R&D Restructuring In 2013, the Company changed its strategy for research and development programs to focus on the clinical development of ixmyelocel-T for the treatment of advanced heart failure due to ischemic dilated cardiomyopathy (DCM). As a result of the strategic change, the Company stopped enrollment of the Phase 3 REVIVE clinical trial in patients with critical limb ischemia (CLI) and the Company recorded a one-time restructuring charge of $0.4 million in 2013 in research and development expenses. The restructuring accrual for the strategic changes decreased to less than $0.1 million as of December 31, 2013 as a result of cash payments made for severance and other personnel-related expenses. There was no restructuring reserve related to the strategic change in 2014 or 2015.

Selected Balance Sheet Components

12 Months Ended

Dec. 31, 2015

Balance Sheet Related Disclosures [Abstract]

Selected Balance Sheet Components

Inventory as of December 31, 2015 and 2014:



(In thousands)	2015		2014
Raw materials	$	1,228	$	1,078
Work-in-process	131		458
Finished goods	20		384
Inventory	$	1,379	$	1,920

Property and Equipment, net as of December 31, 2015 and 2014:



(In thousands)	2015			2014
Machinery and equipment	$	3,280		$	3,135
Furniture, fixtures and office equipment	931			777
Computer equipment and software	2,662			667
Leasehold improvements	2,393			1,691
Construction in process	421			1,019
	9,687			7,289
Less accumulated depreciation	(5,638		)	(4,397		)
Property and Equipment	$	4,049		$	2,892

Depreciation expense for the years ended December 31, 2015, 2014 and 2013 were $1.3 million , $0.8 million, and $0.5 million, respectively.

Intangible assets, net as of December 31, 2015 and 2014:



(In thousands)	2015			2014
Commercial rights	$	3,360		$	3,360
Less accumulated amortization	(443		)	(163		)
Intangible assets	$	2,917		$	3,197

Amortization expense was $0.3 million and $0.2 million for the years ended December 31, 2015 and 2014, respectively. There was no amortization expense in 2013.

Estimated future amortization expense is as follows:



Calendar Years Ending December 31, (In thousands)
2016	$	280
2017	280
2018	280
2019	280
2020	280
Thereafter	1,517
Total	$	2,917

Accrued Expenses as of December 31, 2015 and 2014:



(In thousands)	2015		2014
Bonus	$	1,956	$	2,044
Employee related accruals	1,341		1,281
Accrued expenses	75		605
Asset retirement obligation^(a)	—		348
Other	231		436
Accrued expenses	$	3,603	$	4,714

(a) The reduction in the asset retirement obligation is based on a change to the estimate of the obligation to restore the Denmark facility to its original state and final payment of the obligation.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2015

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

Stock-Based Compensation

Stock Option and Equity Incentive Plans

The Company has historically had various stock incentive plans and agreements that provide for the issuance of nonqualified and incentive stock options as well as other equity awards. Such awards may be granted by the Company’s Board of Directors to certain of the Company’s employees, directors and consultants. Options granted under these plans expire no later than ten years from the date of grant, and other than those granted to non-employee directors, generally become exercisable over a four period, under a graded-vesting methodology, following the date of grant. The Company generally issues new shares upon the exercise of stock options.

The 2009 Second Amended and Restated Omnibus Incentive Plan (2009 Plan) provides incentives through the grant of stock options, stock appreciation rights, restricted stock awards and restricted stock units. The exercise price of stock options granted under the 2009 Plan shall not be less than the fair market value of the Company’s common stock on the date of grant. The 2009 Plan replaced the 1992 Stock Option Plan, the 2001 Stock Option Plan and the Amended and Restated 2004 Equity Incentive Plan (Prior Plans), and no new awards have been granted under the Prior Plans. However, the expiration or forfeiture of options previously granted under the Prior Plans will increase the awards available for issuance under the 2009 Plan.

As of December 31, 2015, there were 1,962,168 shares available for future grant under the 2009 Plan.

Employee Stock Purchase Plan

In May 2015, the board of directors and shareholders approved the Vericel Corporation Employee Stock Purchase Plan (ESPP), which was implemented effective October 1, 2015 for the first offering period. The ESPP allows for the issuance of an aggregate of 1,000,000 shares of common stock. Participation in this plan is available to substantially all employees. The ESPP is a compensatory plan accounted for under the expense recognition provisions of the share-based payment accounting standards. Compensation expense is recorded based on the fair market value of the purchase options at the grant date, which corresponds to the first day of each purchase period and is amortized over the purchase period. In January 2016, employees purchased 63,193 shares resulting in proceeds from the sale of common stock of $0.1 million under the ESPP for the first offering period. The total share-based compensation expense for the ESPP for the year ended December 31, 2015 was less than $0.1 million.

Service-Based Stock Options

During the year ended December 31, 2015, the Company granted 2,216,600 service-based options to purchase common stock. The exercise price of the options is the fair market value per share of common stock on the grant date, generally vest over four years (other than 136,000 non-employee options which vest over one year) and have a term of ten years. The weighted average grant-date fair value of service-based options granted during the years ended December 31, 2015, 2014, and 2013 was $2.22, $2.85 and $14.07, respectively.

The net compensation costs recorded for the service-based stock options related to employees and directors (including the impact of the forfeitures) for the years ended December 31, 2015, 2014, and 2013 were $2.7 million, $0.8 million and $0.9 million, respectively.

The fair value of each service-based stock option grant for the reported periods is estimated on the date of the grant using the Black-Scholes option-pricing model using the weighted average assumptions noted in the following table.



	Year Ended December 31,
Service-Based Stock Options	2015	2014	2013
Expected dividend rate	—%	—%	—%
Expected stock price volatility	77.4 – 88.1%	82.4 – 88.2%	74.0 – 87.9%
Risk-free interest rate	1.5 – 2.0%	1.7 – 2.2%	0.1 – 2.1%
Expected life (years)	5.5 – 6.3	5.5 – 6.3	5.0 – 6.3

The following table summarizes the activity for service-based stock options for the indicated periods:



Service-Based Stock Options	Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding at December 31, 2012	499,374		$	47.60	7.5	$	—
Granted	75,751		$	21.32
Exercised	—		$	—		$	—
Expired	(164,189	)	$	51.76
Forfeited	(113,076	)	$	45.38
Outstanding at December 31, 2013	297,860		$	39.53	7.9	$	—
Granted	242,029		$	3.91
Exercised	—		$	—		$	—
Expired	(32,012	)	$	42.63
Forfeited	(30,347	)	$	32.13
Outstanding at December 31, 2014	477,530		$	36.43	8.0	$	—
Granted	2,216,600		$	3.11
Exercised	(3,566	)	$	3.02		$	1,000
Expired	(17,791	)	$	40.02
Forfeited	(149,373	)	$	3.35
Outstanding at December 31, 2015	2,523,400		$	6.36	8.7	$	5,000
Exercisable at December 31, 2015	661,229		$	14.27	7.9	$	—

As of December 31, 2015 there was approximately $2.7 million, of total unrecognized compensation cost related to non-vested service-based stock options granted under the 2009 Plan and the Prior Plans. That cost is expected to be recognized over a weighted-average period of 3.0 years.

The total fair value of stock options vested for the years ended December 31, 2015, 2014, and 2013 was $1.7 million, $1.5 million and $2.3 million, respectively.

Shareholders' Equity	12 Months Ended
Shareholders' Equity	Dec. 31, 2015
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders’ Equity 2013 Stock and Warrant Sale On August 16, 2013, the Company completed the sale of 1.5 million shares of common stock and warrants to purchase up to an aggregate of 1.5 million shares of common stock (including 50,000 shares of common stock and warrants sold to the underwriter pursuant to the exercise of its over-allotment option). Each share of common stock and its associated warrant was sold at a public offering price of $6.00 per share. The Company received $8.2 million in net proceeds from the sale of the shares of common stock and warrants (including the partial exercise of the over-allotment option), after underwriting discounts, commissions and other offering expenses. The total fair market value of the warrants at the date of issuance was $5.9 million. The sales proceeds were first allocated to the warrants based on the total fair market value and the residual amount of the sales proceeds were allocated to common stock. 2014 Warrant Exercise Agreement On July 9, 2014, the Company entered into a Warrant Exercise Agreement with one holder of warrants issued by the Company on August 16, 2013 (the 2013 Warrants) to purchase an aggregate of 362,500 shares of the Company’s common stock, no par value. Pursuant to the Warrant Exercise Agreement, the holder agreed to exercise the 2013 Warrants at the existing exercise price of $4.80. The net proceeds to the Company in connection with the exercise of the 2013 Warrants, after deducting a warrant inducement payment and expenses, were approximately $1.5 million. 2014 Stock Purchase Agreement On January 21, 2014, the Company entered into a purchase agreement (Purchase Agreement), together with a registration rights agreement, for the sale of up to $15.0 million of shares of its common stock to Lincoln Park, subject to certain limitations, from time to time over a 30-month period, which began on April 3, 2014 and ends on October 3, 2016. The Company may direct Lincoln Park, at its sole discretion, to purchase up to 50,000 shares of common stock in regular purchases, increasing to amounts of up to 100,000 shares depending upon the closing sale price of the common stock. In addition, the Company may direct Lincoln Park to purchase additional amounts as accelerated purchases if on the date of a regular purchase the closing sale price of the common stock equals or exceeds $3.00 per share. The purchase price of shares of common stock related to the future funding will be based on the prevailing market prices of such shares at the time of sales (or over a period of up to 10 business days leading up to such time), but in no event will shares be sold to Lincoln Park on a day the common stock closing price is less than the floor price of $2.50, subject to adjustment. The Company controls the timing and amount of any sales of common stock to Lincoln Park. The Company’s sales of shares of common stock to Lincoln Park under the Purchase Agreement are limited to no more than the number of shares that would result in the beneficial ownership by Lincoln Park and its affiliates, at any single point in time, of more than 9.99% of the then outstanding shares of the common stock. For the year ended December 31, 2014, the Company issued 935,499 shares of common stock to Lincoln Park and raised gross proceeds of $3.7 million (with the ability to sell up to an additional $11.3 million more in common stock). No shares were issued in 2015. At-the-Market Sales Agreement During the years ended December 31, 2014 and 2013, the Company raised net proceeds of $7.1 million and $4.8 million utilizing the At-the-Market Sales Agreement (ATM) with MLV & Co. LLC (formerly McNicoll, Lewis & Vlak) (MLV). The Company originally entered into the ATM with MLV in June 2011 in which the Company may sell shares of its common stock through MLV, as sales agent, in registered transactions from its shelf registration statement filed in July 2011, for aggregate proceeds of up to $20.3 million. The Form S-3 registration statement filed in June 2011 expired in July 2014. Shares of common stock sold under the ATM are to be sold at market prices. The Company will pay up to 3% of the gross proceeds to MLV as a commission. At December 31, 2015 there was approximately $7.8 million of net capacity remaining on the ATM. 2014 Public Equity Offering On September 17, 2014, the Company closed on a public equity offering whereby it sold 15,784,313 shares of common stock at an offering price of $2.55 per share. The proceeds of $37.5 million, net of $2.4 million of underwriters’ discount and $0.3 million of issuance costs consisting primarily of legal and accounting fees, were recorded as a common stock issuance. Treasury Stock On December 23, 2015 Stonepine Capital, LLC (Stonepine) exchanged 1,250,000 shares of the Company's common stock held by Stonepine for 1,250 shares of Series A Convertible Preferred Stock. The common stock transferred from Stonepine to the Company during the share exchange is reserved as treasury shares. The value transferred to Series A Convertible Preferred Stock of $3.2 million is equal to the fair market value of the common stock as of December 23, 2015. See further discussion in note 9 of the consolidated financial statements. Dividends No cash dividends have been declared or paid by the Company since its inception.

- 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
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Preferred Stock	12 Months Ended
Preferred Stock	Dec. 31, 2015
Equity [Abstract]
Preferred Stock	Preferred Stock Shareholder Rights Plan In August 2011, the Board of Directors of the Company adopted a Shareholder Rights Plan, as set forth in the Shareholder Rights Agreement between the Company and the rights agent, the purpose of which is, among other things, to enhance the Board’s ability to protect shareholder interests and to ensure that shareholders receive fair treatment in the event any coercive takeover attempt of the Company is made in the future. The Shareholder Rights Plan could make it more difficult for a third party to acquire, or could discourage a third party from acquiring, the Company or a large block of the Company’s common stock. In March 2012, the Board approved an amendment to the Shareholder Rights Plan to enable Eastern Capital Limited and its affiliates to purchase up to 49.9% of the shares of common stock of the Company without becoming an “acquiring person” and thereby triggering the stockholder rights, with the limitations under the Shareholder Rights Plan remaining in effect for all other stockholders of the Company. In connection with the adoption of the Shareholder Rights Plan, the Board of Directors of the Company declared a dividend distribution of one preferred stock purchase right (Right) for each outstanding share of common stock to stockholders of record as of the close of business on August 15, 2011. In addition, one Right will automatically attach to each share of common stock issued between August 15, 2011 and the distribution date. As a result of the October 2013 reverse stock split, the number of Rights associated with each share of common stock was automatically proportionately adjusted so that (i) twenty rights were then associated with each outstanding share of common stock and (ii) so long as the Rights are attached to the common stock, twenty rights shall be deemed to be delivered for each share of common stock issued or transferred by the Company in the future. The Rights currently are not exercisable and are attached to and trade with the outstanding shares of common stock. Each Right entitles the registered holder of common stock to purchase from the Company a unit consisting of one ten-thousandth of a share (Unit) of Series A Junior Participating Preferred Stock, no par value per share, at a cash exercise prices of $30.00 per Unit. There are currently 45,000 shares authorized and zero issued and outstanding. Under the Shareholder Rights Plan, the Rights become exercisable if a person or group becomes an “acquiring person” by acquiring 15% or more of the outstanding shares of common stock or if a person or group commences a tender offer that would result in that person owning 15% or more of the common stock. If a person or group becomes an “acquiring person,” each holder of a Right (other than the acquiring person and its affiliates, associates and transferees) would be entitled to purchase, at the then-current exercise price, such number of shares of the Company’s preferred stock which are equivalent to shares of common stock having a value of twice the exercise price of the Right. If the Company is acquired in a merger or other business combination transaction after any such event, each holder of a Right would then be entitled to purchase, at the then-current exercise price, shares of the acquiring company’s common stock having a value of twice the exercise price of the Right. The Rights may be redeemed in whole, but not in part, at a price of $0.001 per Right (payable in cash, common stock or other consideration deemed appropriate by the Board of Directors) by the Board of Directors only until the earlier of (i) the time at which any person becomes an “acquiring person” or (ii) the expiration date of the Rights Agreement. Immediately upon the action of the Board of Directors ordering redemption of the Rights, the Right will terminate and thereafter the only right of the holders of Rights will be to receive the redemption price. The Rights will expire at the close of business on August 15, 2021, unless previously redeemed or exchanged by the Company as described above. Series B Convertible Preferred Stock On March 9, 2012, the Company completed the sale of 12,308 shares of Series B-1 Non-Voting Convertible Preferred Stock (Series B-1 preferred stock) at an offering price of $3,250 per share. In addition to the Series B-1 preferred stock, which was issued at the closing, the Company also authorized Series B-2 Voting Convertible preferred Stock (Series B-2 preferred stock). The Series B-1 preferred stock and Series B-2 preferred stock collectively are referred to as the Series B preferred stock. The Series B preferred stock is convertible, at the option of the holder thereof at any time after the five year anniversary of the closing of the offering, into shares of common stock at a conversion price of $3.25 per share of common stock, at a conversion ratio of one share of preferred stock for fifty shares of common stock. At any time after the five year anniversary of issuance, the Company may elect to convert any or all outstanding shares of Series B preferred stock into shares of common stock, subject to certain limitations. Dividends on the Series B preferred stock will be cumulative and compound daily, at a rate of 11.5% per annum, payable upon conversion, liquidation, redemption or other similar events, and payable in cash or Series B-1 preferred stock until the five year anniversary of issuance. As of December 31, 2015, there are 338,710 accumulated but undeclared Series B-1 dividends. Unless prohibited by Michigan law governing distributions to shareholders, the Series B-1 preferred stock shall be redeemable at the option of holder of the Series B-1 preferred stock commencing at any time after the five year anniversary of issuance, liquidation, winding up, dissolution or other similar events, subject to certain terms and limitations. The Series B preferred stock does not, in its entirety, require liability classification and was evaluated for embedded features to determine if those features require bifurcation and separate classification as derivative liabilities. The Series B preferred stock host contract was evaluated for equity or mezzanine classification based upon the nature of the redemption and conversion features. Generally, any feature that could require cash redemption for matters not within the Company’s control, irrespective of probability of the event occurring, requires classification outside of shareholders’ equity. The Series B preferred stock was initially recorded as mezzanine in the Consolidated Balance Sheets and was accreted to its redemption value through charges to accumulated deficit using the effective interest method. On August 12, 2013, the Company amended the Series B preferred stock agreement to remove the cash redemption provision, modify the liquidation preferences for the Series B-2 preferred stock and to increase the redemption price for the Series B-1 preferred stock. The redemption price, prior to the five year anniversary, is now equal to $7,430 multiplied by the number of Series B-1 preferred shares redeemed minus the Company’s closing stock price multiplied by the number of common shares into which the outstanding Series B-2 preferred stock are convertible. The redemption price, after the five year anniversary, is the amount equal to the greater of the Series B offering price plus accrued dividends or the conversion value in common stock. As a result of the amendment to the agreement, the total amount of $38.4 million Series B preferred stock was reclassified from mezzanine into shareholders’ equity. Series A Convertible Preferred Stock On December 18, 2015, Vericel entered into a Securities Exchange Agreement (Exchange Agreement) with Stonepine pursuant to which Stonepine exchanged an aggregate of 1,250,000 shares of its common stock held by Stonepine for 1,250 shares of the Company’s Series A Convertible Preferred Stock (the Exchange). The Exchange closed on December 23, 2015. In connection with the Exchange, the Company designated 1,250 shares of its authorized and unissued preferred stock as Series A Convertible Preferred Stock. Each share of Series A Convertible Preferred Stock is convertible into 1,000 shares of its common stock at any time at the holder’s option. The holder, however, will be prohibited from converting Series A Convertible Preferred Stock into shares of common stock if, as a result of such conversion, the holder, together with its affiliates, would own more than 9.99% of the shares of the Company's common stock then issued and outstanding or, upon such holder’s written election, 14.99% of the shares of our common stock then issued and outstanding. In the event of our liquidation, dissolution, or winding up, holders of Series A Convertible Preferred Stock will receive a payment equal to any declared but unpaid dividends before any proceeds are distributed to the holders of common stock, after any proceeds are distributed to the holder of our Series B-1 Non-Voting Convertible Preferred Stock and Series B-2 Voting Convertible Preferred Stock (together, the Series B Convertible Preferred Stock) and pari passu with any distributions to the holders of the Company's common stock. Shares of Series A Convertible Preferred Stock have no voting rights, except as required by law and except where the consent of holders of a majority of the outstanding Series A Convertible Preferred Stock would be required to amend the terms of the Series A Convertible Preferred Stock. Shares of Series A Convertible Preferred Stock are entitled to receive dividends at the same time as the shares of Common Stock.

Net Loss Per Common Share

12 Months Ended

Dec. 31, 2015

Earnings Per Share [Abstract]

Net Loss Per Common Share

The following reflects the net loss attributable to common shareholders and share data used in the basic and diluted earnings per share computations using the two class method:



	Year Ended December 31,
(Amounts in thousands, except per share amounts)	2015			2014			2013
Numerator:
Net loss	$	(16,340	)	$	(19,920	)	$	(15,622	)
Less: earnings attributable to convertible preferred stock	6,736			6,005			5,352
Numerator of basic and diluted EPS	$	(23,076	)	$	(25,925	)	$	(20,974	)
Denominator:
Denominator for basic and diluted EPS: weighted-average common shares outstanding	23,760			11,642			3,016
Net loss per share attributable to common shareholders (basic and diluted)	$	(0.97	)	$	(2.23	)	$	(6.95	)

Common equivalent shares and treasury stock are not included in the diluted per share calculation where the effect of their inclusion would be anti-dilutive. The aggregate number of common equivalent shares (related to options, warrants, preferred stock and treasury stock) that have been excluded from the computations of diluted net loss per common share for the years ended December 31, 2015, 2014 and 2013 was 6.7 million, 2.3 million and 2.4 million, respectively.

Stock Purchase Warrants

12 Months Ended

Dec. 31, 2015

Warrants and Rights Note Disclosure [Abstract]

Stock Purchase Warrants

The Company has historically issued warrants to purchase shares of the Company’s common stock in connection with certain common stock offerings. The following warrants were outstanding during the year ended December 31, 2015, and include provisions that could require cash settlement of the warrants or have anti-dilution price protection provisions requiring the warrants to be recorded as liabilities of the Company at the estimated fair value at the date of issuance, with changes in estimated fair value recorded as income or expense (non-cash) in the Company’s statement of operations in each subsequent period:



		August 2013 Warrants
Exercise price		$4.80
Expiration date		August 16, 2018
Total shares issuable on exercise		724,950

In July and December 2015, the January and December 2010 Class A warrants convertible into 226,299 and 15,405 shares of common stock, respectively, expired unexercised. The fair value of the remaining August 2013 warrants are measured using the Black-Scholes valuation model. Inherent in the Black-Scholes valuation model are assumptions related to expected stock-price volatility, expected life, risk-free interest rate and dividend yield. The Company estimates the volatility of its common stock based on historical volatility that matches the expected remaining life of the warrants. The risk-free interest rate is based on the U.S. Treasury zero-coupon yield curve on the grant date for a maturity similar to the expected remaining life of the warrants. The expected life of the warrants is assumed to be equivalent to their remaining contractual term. The dividend yield is based on the historical rate, which the Company anticipates to remain at zero.

The assumptions used by the Company are summarized in the following table:



August 2013 Warrants	December 31, 2015			December 31, 2014
Closing stock price	$	2.58		$	3.04
Expected dividend yield	—		%	—		%
Expected stock price volatility	91.4		%	83.2		%
Risk-free interest rate	1.31		%	1.20		%
Expected life (years)	2.63			3.63

Fair Value Measurements

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Fair Value Measurements

The Company’s fair value measurements are classified and disclosed in one of the following three categories:


•	Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;


•	Level 2: Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability;


•	Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity).

The following table summarizes the valuation of the Company’s financial instruments that are measured at fair value on a recurring basis:



	December 31, 2015								December 31, 2014
	Fair value measurement category								Fair value measurement category
(In thousands)	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Liabilities:
Warrant liabilities	$	757	$	—	$	757	$	—	$	1,081	$	—	$	1,061	$	20

The fair values of the warrants are measured using the Black-Scholes valuation model. See Note 11 for further discussion of the significant observable inputs use to measure the warrant liabilities.

The following table summarizes the change in the estimated fair value of the Company’s warrant liabilities:



Warrant Liabilities (In thousands)
Balance at December 31, 2013	$	2,019
Warrant exercises	(965		)
Increase in fair value	27
Balance at December 31, 2014	1,081
Decrease in fair value	(324		)
Balance at December 31, 2015	$	757

A reconciliation of beginning and ending balances for the Company’s fair value measurements using Level 3 inputs is as follows:



	Year Ended December 31,
(In thousands)	2015			2014
Beginning balance	$	20		$	85
Decrease in fair value	(20		)	(65		)
Ending balance	$	—		$	20

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Income Taxes

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Income Taxes

Income (loss) before income taxes for U.S and non-U.S operations was as follows:



	Year Ended December 31,
	2015			2014			2013
U.S. loss	$	(16,235	)	$	(18,078	)	$	(15,622	)
Non U.S. loss	(105		)	(1,842		)	—
	$	(16,340	)	$	(19,920	)	$	(15,622	)

A reconciliation of income taxes computed using the federal statutory rate to the taxes reported in the consolidated statements of operations is as follows:



	Year Ended December 31,
(In thousands)	2015			2014			2013
Loss before income taxes	$	(16,340	)	$	(19,920	)	$	(15,622	)
Federal statutory rate	34		%	34		%	34		%
Taxes computed at federal statutory rate	(5,556		)	(6,773		)	(5,311		)
State taxes (net of federal benefit)	(392		)	(463		)	—
Warrants	(118		)	(10		)	(1,815		)
Nondeductible stock compensation	543			48			81
Michigan NOL benefit	—			—			(791		)
Net operating loss expirations	—			655			612
Write-off of Section 382 limited NOL’s	—			67,781			—
Write-off of Section 383 limited R&D credits	—			1,600			—
Other	57			352			(27		)
Adjustment to prior year filed returns	(5,203		)	—			—
Change in valuation allowance	10,669			(63,190		)	7,251
Reported income taxes	$	—		$	—		$	—

Deferred tax assets consist of the following:



	Year Ended December 31,
(In thousands)	2015			2014
Net operating loss carryforwards	$	13,998		$	7,092
Employee benefits and stock compensation	2,485			1,897
Research and development costs	4,903			2,184
Fixed assets	453			254
Intangible assets	(477		)	(510		)
Asset retirement obligation	—			127
Inventory reserve	510			186
Other, net	143			115
Total deferred tax assets	22,015			11,345
Valuation allowance	(22,015		)	(11,345		)
Net deferred tax assets	$	—		$	—

In 2014, the Company underwent a change in control as defined by Section 382 of the Internal Revenue Code. A change in control is generally defined as a cumulative change of 50% or more in the ownership positions of certain stockholders during a rolling three year period. This change in control resulted in substantial limitations being placed on certain tax attributes including net operating losses and tax credit carryforwards. The limitations are computed based upon several variable factors including the value of the Company on the date of the change in control. The projected annual limitation on the use of the net operating losses that existed prior to September 17, 2014 is $0.8 million. As a result, a significant portion of the net operating losses and tax credit carryforwards will expire prior to their utilization, regardless of the level of future profitability. Accordingly, the Company reduced its net operating losses and tax credit carryforwards in 2014 (with a corresponding adjustment to the valuation allowance) to reflect the amount available to offset future profits. There was not a change of control in 2015.

During the finalization of the 2014 federal tax return, the Company determined there was a net unrealized built-in gain of $8.9 million, which increases pre-ownership change net operating losses available to the Company to offset taxable income in the future. This results in a partial restoration of the net operating losses previously written-off as discussed above. A corresponding valuation allowance was recorded for the increase in deferred tax asset.

As of December 31, 2015, the Company’s U.S. federal, and state tax net operating loss carryforwards available to offset future profits, after considering the aforementioned annual Section 382 limit, are $39.3 million and $17.0 million, respectively. These net operating loss carryforwards will expire between 2016 and 2035.

In accordance with the accounting guidance for income taxes, the Company estimated whether recoverability of its deferred tax assets is “more likely than not,” based on forecasts of taxable income in the related tax jurisdictions. In this estimate, the Company uses historical results, projected future operating results based upon approved business plans, eligible carry forward periods, tax planning opportunities and other relevant considerations. Based on these factors, including historical losses incurred by the Company, a full valuation allowance for the deferred tax assets, including the deferred tax assets for the aforementioned net operating losses and credits, has been provided since they are not more likely than not to be realized. If the Company achieves profitability, these deferred tax assets may be available to offset future income taxes. The change in the valuation allowance was an increase of $10.7 million and decrease of $63.2 million for the years ended December 31, 2015 and 2014, respectively.

The Company assesses uncertain tax positions in accordance with the guidance for accounting for uncertain tax positions. This pronouncement prescribes a recognition threshold and measurement methodology for recording within the financial statements uncertain tax positions taken, or expected to be taken, in the Company’s income tax returns. To the extent the uncertain tax positions do not meet the “more likely than not” threshold, the Company has derecognized such positions. To the extent the uncertain tax positions meet the “more likely than not” threshold, the Company has measured and recorded the highest probable benefit, and have established appropriate reserves for benefits that exceed the amount likely to be sustained upon examination.

A reconciliation of the beginning and ending amounts of uncertain tax provision is as follows:



	Unrecognized Income Tax
(In thousands)	Benefits
Balance at December 31, 2013	$	900
Decrease in prior year tax positions	(900		)
Balance at December 31, 2014 and 2015	$	—

It is not anticipated that the unrecognized tax benefits will significantly increase or decrease within the next twelve months.

The Company files U.S. federal, Michigan, Massachusetts, Colorado, Illinois and California income tax returns. Due to the Company’s net operating loss carryforwards, Federal income tax returns from incorporation are still subject to examination. Michigan tax returns for the year ended December 31, 2013 and forward are subject to examination. California tax returns for the year ended December 31, 2013 and forward are subject to examination.

Employee Savings Plan	12 Months Ended
Employee Savings Plan	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Employee Savings Plan	Employee Savings Plan The Company has a 401(k) savings plan that allows participating employees to contribute a portion of their salary, subject to annual limits and minimum qualifications. The Board may, at its sole discretion, approve Company matching contributions to the plan. The Company made contributions of $0.5 million, $0.3 million and $0.1 million for the years ended December 31, 2015, 2014 and 2013, respectively.

Concentration of Credit	12 Months Ended
Concentration of Credit	Dec. 31, 2015
Risks and Uncertainties [Abstract]
Concentration of Credit	Concentration of Credit Revenue from one customer, a distributor in the U.S., represented 66% and 76% of total revenue during the years ended December 31, 2015 and 2014, respectively. Accounts receivable from the same customer accounted for 76% and 71% of the outstanding accounts receivable as of December 31, 2015 and 2014, respectively. The next largest customer represented 12% and 10% of revenue for the year ended December 31, 2015 and 2014, respectively. Accounts receivable from the next largest customer accounted for 8% and 14% of the outstanding accounts receivable as of December 31, 2015 and 2014, respectively.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2015

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Licenses, Royalties and Collaborative Agreements

Corning Incorporated — In December 2002, the Company entered into an agreement with Corning Incorporated (Corning) that granted Corning an exclusive sublicense relating to the Company’s cell transfection technology. Under the terms of the agreement, the Company retains exclusive rights to the applications of the technologies involving cells for therapeutic applications. In addition, the agreement provides for future royalty payments on net sales of licensed products sold under the sublicense amounting to 5% of such sales up to $50.0 million. However, the Company does not expect to receive material revenue from this source for several years, if ever.

RealBio Technologies — In May 2009, the Company entered into an agreement with RealBio Technologies, Inc. (RealBio) that granted RealBio an exclusive license to utilize our technology outside of the Company’s core area of focus - human regenerative medicine. In return for this license, the Company received a minority equity interest in RealBio, which was not material as of December 31, 2015 or 2014.

Matricel — In October 2015, the Company signed a long-term supply agreement with Matricel GmbH for the ACI-Maix collagen membrane used in the manufacture of MACI™. Matricel supplied ACI-Maix membranes used in the production of MACI when it was previously marketed outside the U.S. by Genzyme Corporation, a Sanofi company. Under the agreement, the Company has committed to purchase $0.3 million of material in 2016. In the event that the Biologics License Application is approved for MACI, annual purchase commitments would equal approximately $0.6 million per year. The agreement is effective until December 31, 2022 and contains a 5-year renewal option by the Company and an additional 5-year automatic renewal, unless otherwise terminated.

Manufacture, Supply and Other Agreements — The Company has entered into various agreements relating to the manufacture of its products and the supply of certain components. If the manufacturing or supply agreements expire or are otherwise terminated, the Company may not be able to identify and obtain ancillary materials that are necessary to develop its product and such expiration and termination could have a material effect on the Company’s business.

Contractual Obligations

The Company leases facilities in Ann Arbor, Michigan; Cambridge, Massachusetts and Kastrup, Denmark. In March 2016, the Company amended its current lease in Cambridge to extend the terms until March 2022. In addition to the property leases, the Company also leases an offsite warehouse, various vehicles and computer equipment.

Future minimum payments related to Vericel’s operating and capital leases are as follows:



			Payments Due by Period
Contractual Obligations	Total		2016		2017		2018		2019		2020		More than 5 Years
Operating leases	$	27,693	$	4,310	$	4,890	$	4,572	$	4,260	$	4,386	$	5,275
Purchase commitments	300		300		—		—		—		—		—
Capital leases	118		43		43		32		—		—		—
Total	$	28,111	$	4,653	$	4,933	$	4,604	$	4,260	$	4,386	$	5,275

Rent expense for the years ended December 31, 2015, 2014 and 2013, was $4.9 million, $2.5 million and $1.0 million, respectively.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On March 8, 2016, Vericel entered into a $15.0 million debt financing with Silicon Valley Bank (SVB). The debt financing consists of a $3.0 million term loan available immediately upon the closing, $2.0 million term loan available upon the FDA's approval of the MACI BLA and up to $10.0 million revolving line of credit. The term loans are interest only (indexed to Wall Street Journal (WSJ) Prime plus 0.75%) until March 1, 2017 followed by 36 equal monthly payments of principal plus interest maturing February 1, 2020. The revolving credit is limited to a borrowing base calculated using eligible accounts receivable and maturing March 8, 2018 with an interest rate indexed to WSJ Prime plus 0.25% up to 0.75%. Monthly, the Company must remain in compliance with an adjusted quick ratio greater than or equal to 1.10 to 1.0. The adjusted quick ratio is the ratio of (a) unrestricted cash and cash equivalents and net billed accounts receivable to (b) current liabilities minus the current portion of deferred revenue and warrant liabilities.

Supplementary Quarterly Financial Information (unaudited)

12 Months Ended

Dec. 31, 2015

Supplementary Quarterly Financial Information (unaudited) [Abstract]

Supplementary Quarterly Financial Information (unaudited)

Quarterly earnings per share amounts may not sum to the totals for each of the years, since quarterly computations are based on weighted average common shares outstanding during each quarter.



In thousands, except per share data)	First Quarter			Second Quarter			Third Quarter			Fourth Quarter			Year
2015
Revenues	$	10,849		$	13,590		$	11,309		$	15,420		$	51,168
Gross profit	5,281			6,689			4,537			8,191			24,698
Loss from operations	(4,572		)	(2,265		)	(4,877		)	(4,957		)	(16,671		)
Net loss	(4,862		)	(2,152		)	(4,416		)	(4,910		)	(16,340		)
Net loss per share (Basic and Diluted)	(0.27		)	(0.16		)	(0.26		)	(0.28		)	(0.97		)
2014
Revenues^(a)	$	—		$	4,432		$	9,658		$	14,706		$	28,796
Gross profit (loss)	—			(577		)	4,126			7,954			11,503
Loss from operations	(4,645		)	(8,522		)	(8,022		)	(2,345		)	(23,534		)
Net loss^(b)	(5,995		)	(4,638		)	(6,917		)	(2,370		)	(19,920		)
Net loss per share (Basic and Diluted)	(1.26		)	(0.94		)	(0.82		)	(0.17		)	(2.23		)

(a) Revenue from commercial operations began in June 2014 following the acquisition of the CTRM business. Prior to June 2014, Vericel was a development stage entity.

(b) The net loss in the second quarter of 2014 includes a $3.5 million bargain purchase gain as a result of the CTRM business acquisition.

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2015
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of Vericel and its wholly-owned subsidiaries,
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reported period. Actual results could differ from those estimates.
Inventory	Inventory Inventories are measured at the lower of cost or market value. Cost is calculated based upon standard-cost which approximates costs determined on the first-in, first-out method. Utilization reserves are established for estimated obsolescence or un-marketable inventory in an amount equal to the cost of inventory
Accounts Receivable	Accounts Receivable Accounts receivable are initially recorded at the contractual amount owed by the customer. Allowances for doubtful accounts are established when the facts and circumstances indicate that a receivable may not be collectible.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are initially measured and recognized at acquisition cost, including any directly attributable cost of preparing the asset for its intended use or, in the case of assets acquired in a business combination, at fair value as at the date of the combination. After initial measurement, property, plant and equipment are carried at cost less accumulated depreciation and impairment. Repair and maintenance costs of property, plant and equipment are expensed as incurred. The depreciable value of property, plant and equipment, net of any residual value, is depreciated on a straight line basis over the useful life of the asset. The useful life of an asset is usually equivalent to its economic life. The useful lives of property, plant and equipment are as follows: •Equipment and computers: 3 to 5 years •Furniture and fixtures: 5 years •Building improvements and leasehold improvements: Shorter of the remaining life of the lease or 7 years The costs of assets retired or otherwise disposed of and the accumulated depreciation thereon are removed from the accounts, with any gain or loss realized upon sale or disposal credited or charged to operations.
Intangible Assets and Other Long Lived Assets	Intangible Assets and Other Long Lived Assets Intangible assets are initially measured at acquisition cost, including any directly attributable costs of preparing the asset for its intended use or, in the case of assets acquired in a business combination at fair value as at the date of the combination. Identifiable intangible assets related to commercial rights are amortized on a straight line basis over their expected useful lives. Amortization of intangible assets is recognized in these financial statements under Costs of product sales. Intangible assets and long-lived assets are assessed for potential impairment when there is evidence that events or changes in circumstances indicate that the carrying amount of an asset may not be recovered. An impairment loss would be recognized when an asset’s fair value, determined based on undiscounted cash flows expected to be generated by the asset, is less than its carrying amount. The impairment loss would be measured as the amount by which the asset’s carrying value exceeds its fair value and recognized in these financial statements. Intangible assets are carried at cost less accumulated amortization and impairment.
Revenue Recognition	Revenue Recognition Total revenues are comprised of product sales of Carticel, Epicel, MACI, bone marrow and surgical kits. Revenue is recognized when persuasive evidence of an arrangement exists, the goods are shipped or delivered, depending on shipping terms, title and risk of loss pass to the customer and collectability is reasonably assured. Shipping and handling costs are included as a component of revenue. Revenue is recorded net of a provision for rebates and cash discounts. These rebates and cash discounts are established by the Company at the time of sale, based on historical experience adjusted to reflect known changes in the factors that impact such reserves. For instance, distributors are entitled to chargeback incentives for services that are provided for based on the selling price to the end customer, under specific contractual arrangements. Cash discounts may also be granted for prompt payment.
Research and Development Expense	Research and Development Expense Research and development activities represent a significant part of the Company’s business. These expenditures relate to the development of new products, improvement of existing products, technical support of products and compliance with governmental regulations for the protection of consumers and patients. Research and development expenses are expensed as incurred.
Diversity of Credit Risk	Diversity of Credit Risk The Company has established guidelines relative to diversification in an effort to limit risk. These guidelines are periodically reviewed and modified to take advantage of trends in yields and interest rates.
Stock-Based Compensation	Stock-Based Compensation The Company’s accounting for stock-based compensation requires it to determine the fair value of common stock issued in the form of stock option awards. The Company uses the value of its common stock at the date of the grant in the calculation of the fair value of its share-based awards. The fair value of stock options held by the employees is determined using a Black-Scholes option valuation method, which is a valuation technique that is acceptable for share-based payment accounting. Key assumptions in determining fair value include volatility, risk-free interest rate, dividend yield and expected term. The assumptions used in calculating the fair value of stock options represent the Company’s best estimates, however; these estimates involve inherent uncertainties and the application of management judgment. As a result, if factors change and different assumptions are used, the stock-based compensation expense could be materially different in the future. In addition, the Company is required to estimate the expected forfeiture rate and only recognize expense for those stock options expected to vest over the service period. The estimated forfeiture rate considers the historical experience of the Company’s stock-based awards. If the actual forfeiture rate is different from the estimate, expense is adjusted accordingly. The Company also has an Employee Stock Purchase Plan (ESPP) which is a compensatory plan. Compensation expense is recorded based on the fair value of the purchase options at the grant date, which corresponds to the first day of each purchase period, and is amortized over the purchase period.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is the change in common stockholders’ equity during a period arising from any gain or loss realized related to foreign currency translation.
Income Taxes	Income Taxes Deferred tax assets are recognized for deductible temporary differences and tax credit carryforwards and deferred tax liabilities are recognized for taxable temporary differences. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will not be realized.
Net Loss Per Share Attributable to Common Shareholders	Net Loss Per Share Attributable to Common Shareholders Basic earnings (loss) per 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 holders of the Series B preferred stock. The Series B preferred stock shares contain participation rights in undistributed earnings, but do not share in the losses of the Company. The accumulated but undeclared dividends on the Series B preferred stock of $6.7 million are treated as a reduction of earnings attributable to common shareholders.
Financial Instruments	Financial Instruments The Company’s financial instruments include receivables for which the current carrying amounts approximate market value based upon their short-term nature.
Warrants	Warrants Warrants that could be cash settled or have anti-dilution price protection provisions are recorded as liabilities at their estimated fair value at the date of issuance, with subsequent changes in estimated fair value recorded in other income (expense) in our statement of operations in each subsequent period. In general, warrants are measured using the Black-Scholes valuation model. The methodology is based, in part, upon inputs for which there is little or no observable market data, requiring the Company to develop its own assumptions. The assumptions used in calculating the estimated fair value of the warrants represent our best estimates; however, these estimates involve inherent uncertainties and the application of management judgment. As a result, if factors change and different assumptions are used, the warrant liability and the change in estimated fair value could be materially different.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Revenue Recognition In May 2014, the Financial Accounting Standards Board (FASB) issued authoritative guidance requiring entities to apply a new model for recognizing revenue from contracts with customers. The guidance will supersede the current revenue recognition guidance and require entities to evaluate their revenue recognition arrangements using a five step model to determine when a customer obtains control of a transferred good or service. The guidance is currently effective for annual reporting periods beginning after December 15, 2017, with early adoption permitted for annual reporting periods beginning after December 15, 2016, and may be adopted using a full or modified retrospective application. The Company is currently in the process of evaluating its revenue arrangements under the issued guidance and has not yet determined the impact to its consolidated financial statements. Going Concern Assessment The FASB has issued authoritative guidance for management on how to assess whether substantial doubt exists regarding an entity’s ability to continue as a going concern and guidance on how to prepare related footnote disclosures. The guidance will require management to evaluate whether there are conditions or events that raise substantial doubt about an entity’s ability to continue as a going concern for one year from the date the financial statements are issued. The guidance is effective for annual reporting periods beginning after December 15, 2016. As of December 31, 2015, the Company does not expect the guidance to impact future disclosures. Balance Sheet Classification of Deferred Taxes The FASB simplified the balance sheet classification of deferred taxes guidance to require all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. The new guidance eliminates the requirement to classify deferred taxes between current and noncurrent and is expected to simplify financial reporting. The guidance is effective for annual reporting periods beginning after December 15, 2016, with early adoption permitted for interim or annual reporting periods beginning after December 15, 2015. The guidance may be applied either prospectively, for all deferred tax assets and liabilities, or retrospectively by reclassifying the comparative balance sheet for prior periods. The Company has early adopted the guidance beginning for the year ended December 31, 2015 on a prospective basis. The guidance did not have a material impact for the year ended December 31, 2015. Presentation and Subsequent Measurement of Debt Issuance Costs The FASB issued guidance which requires entities to present debt issuance costs related to a recognized debt liability as a direct deduction from the carrying amount of that debt liability. For debt issuance costs related to line-of-credit arrangements, companies are able to defer and present debt issuance costs as an asset and subsequently amortize the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. The guidance is effective for annual reporting periods beginning after December 15, 2015. The Company is currently determining the impact on future periods. Accounting for Leases The FASB issued guidance to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. In accordance with the updated guidance, lessees are required to recognize the assets and liabilities arising from operating leases on the balance sheet. The guidance is effective for annual reporting periods beginning after December 15, 2018, including interim periods including interim periods within 2018. The Company is currently determining the impact on future periods.

Acquisitions (Tables)

12 Months Ended

Dec. 31, 2015

Business Combinations [Abstract]

Schedule of total purchase price consideration

The total purchase price consideration was as follows:



Acquisition consideration (In thousands):	Fair Value
Cash payment	$	4,000
Promissory note	2,500
Total acquisition consideration	$	6,500

Schedule of final purchase price allocation

The final purchase price allocation was as follows:



Purchase price allocation (In thousands):	Fair Value
Cash	$	5,050
Accounts receivable	53
Inventory	2,039
Other current assets	192
Accounts payable and accrued expenses	(939		)
Asset retirement obligation	(1,600		)
Property and equipment	1,818
Intangible assets	3,360
Bargain purchase gain	(3,473		)
Total consideration	$	6,500

Schedule of unaudited pro forma condensed combined statements



	Year Ended December 31,
(in thousands)	2014			2013
Pro forma revenue	$	44,906		$	43,863
Pro forma net loss	(30,115		)	(49,124		)
Pro forma net loss per share - basic and diluted	(3.10		)	(18.06		)

Selected Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2015

Balance Sheet Related Disclosures [Abstract]

Schedule of inventory

Inventory as of December 31, 2015 and 2014:



(In thousands)	2015		2014
Raw materials	$	1,228	$	1,078
Work-in-process	131		458
Finished goods	20		384
Inventory	$	1,379	$	1,920

Schedule of property and equipment, net

Property and Equipment, net as of December 31, 2015 and 2014:



(In thousands)	2015			2014
Machinery and equipment	$	3,280		$	3,135
Furniture, fixtures and office equipment	931			777
Computer equipment and software	2,662			667
Leasehold improvements	2,393			1,691
Construction in process	421			1,019
	9,687			7,289
Less accumulated depreciation	(5,638		)	(4,397		)
Property and Equipment	$	4,049		$	2,892

Schedule of intangible assets, net

Intangible assets, net as of December 31, 2015 and 2014:



(In thousands)	2015			2014
Commercial rights	$	3,360		$	3,360
Less accumulated amortization	(443		)	(163		)
Intangible assets	$	2,917		$	3,197

Schedule of estimated future amortization expense

Estimated future amortization expense is as follows:



Calendar Years Ending December 31, (In thousands)
2016	$	280
2017	280
2018	280
2019	280
2020	280
Thereafter	1,517
Total	$	2,917

Schedule of accrued expenses

Accrued Expenses as of December 31, 2015 and 2014:



(In thousands)	2015		2014
Bonus	$	1,956	$	2,044
Employee related accruals	1,341		1,281
Accrued expenses	75		605
Asset retirement obligation^(a)	—		348
Other	231		436
Accrued expenses	$	3,603	$	4,714

(a) The reduction in the asset retirement obligation is based on a change to the estimate of the obligation to restore the Denmark facility to its original state and final payment of the obligation.

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

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

Schedule of weighted average assumptions used to estimate fair value of each service-based stock option grant



	Year Ended December 31,
Service-Based Stock Options	2015	2014	2013
Expected dividend rate	—%	—%	—%
Expected stock price volatility	77.4 – 88.1%	82.4 – 88.2%	74.0 – 87.9%
Risk-free interest rate	1.5 – 2.0%	1.7 – 2.2%	0.1 – 2.1%
Expected life (years)	5.5 – 6.3	5.5 – 6.3	5.0 – 6.3

Summary of activity for service-based stock options

The following table summarizes the activity for service-based stock options for the indicated periods:



Service-Based Stock Options	Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding at December 31, 2012	499,374		$	47.60	7.5	$	—
Granted	75,751		$	21.32
Exercised	—		$	—		$	—
Expired	(164,189	)	$	51.76
Forfeited	(113,076	)	$	45.38
Outstanding at December 31, 2013	297,860		$	39.53	7.9	$	—
Granted	242,029		$	3.91
Exercised	—		$	—		$	—
Expired	(32,012	)	$	42.63
Forfeited	(30,347	)	$	32.13
Outstanding at December 31, 2014	477,530		$	36.43	8.0	$	—
Granted	2,216,600		$	3.11
Exercised	(3,566	)	$	3.02		$	1,000
Expired	(17,791	)	$	40.02
Forfeited	(149,373	)	$	3.35
Outstanding at December 31, 2015	2,523,400		$	6.36	8.7	$	5,000
Exercisable at December 31, 2015	661,229		$	14.27	7.9	$	—

Net Loss Per Common Share (Tables)

12 Months Ended

Dec. 31, 2015

Earnings Per Share [Abstract]

Schedule of net loss attributable to common shareholders and share data used in the basic and diluted earnings per share computations using the two class method

The following reflects the net loss attributable to common shareholders and share data used in the basic and diluted earnings per share computations using the two class method:



	Year Ended December 31,
(Amounts in thousands, except per share amounts)	2015			2014			2013
Numerator:
Net loss	$	(16,340	)	$	(19,920	)	$	(15,622	)
Less: earnings attributable to convertible preferred stock	6,736			6,005			5,352
Numerator of basic and diluted EPS	$	(23,076	)	$	(25,925	)	$	(20,974	)
Denominator:
Denominator for basic and diluted EPS: weighted-average common shares outstanding	23,760			11,642			3,016
Net loss per share attributable to common shareholders (basic and diluted)	$	(0.97	)	$	(2.23	)	$	(6.95	)

Stock Purchase Warrants (Tables)

12 Months Ended

Dec. 31, 2015

Warrants and Rights Note Disclosure [Abstract]

Schedule of warrants outstanding

The following warrants were outstanding during the year ended December 31, 2015, and include provisions that could require cash settlement of the warrants or have anti-dilution price protection provisions requiring the warrants to be recorded as liabilities of the Company at the estimated fair value at the date of issuance, with changes in estimated fair value recorded as income or expense (non-cash) in the Company’s statement of operations in each subsequent period:



		August 2013 Warrants
Exercise price		$4.80
Expiration date		August 16, 2018
Total shares issuable on exercise		724,950

Schedule of assumptions used in calculating estimated fair value of warrants

The assumptions used by the Company are summarized in the following table:



August 2013 Warrants	December 31, 2015			December 31, 2014
Closing stock price	$	2.58		$	3.04
Expected dividend yield	—		%	—		%
Expected stock price volatility	91.4		%	83.2		%
Risk-free interest rate	1.31		%	1.20		%
Expected life (years)	2.63			3.63

- Definition

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

+ References + Details

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Summary of valuation of the Company's investments and financial instruments that are measured at fair value on a recurring basis

The following table summarizes the valuation of the Company’s financial instruments that are measured at fair value on a recurring basis:



	December 31, 2015								December 31, 2014
	Fair value measurement category								Fair value measurement category
(In thousands)	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Liabilities:
Warrant liabilities	$	757	$	—	$	757	$	—	$	1,081	$	—	$	1,061	$	20

Summary of change in estimated fair values of warrant liabilities

The following table summarizes the change in the estimated fair value of the Company’s warrant liabilities:



Warrant Liabilities (In thousands)
Balance at December 31, 2013	$	2,019
Warrant exercises	(965		)
Increase in fair value	27
Balance at December 31, 2014	1,081
Decrease in fair value	(324		)
Balance at December 31, 2015	$	757

Schedule of reconciliation of beginning and ending balances for the Company's fair value measurements using Level 3 inputs

A reconciliation of beginning and ending balances for the Company’s fair value measurements using Level 3 inputs is as follows:



	Year Ended December 31,
(In thousands)	2015			2014
Beginning balance	$	20		$	85
Decrease in fair value	(20		)	(65		)
Ending balance	$	—		$	20

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Summary of income (loss) before income taxes for U.S. and non-U.S. operations

Income (loss) before income taxes for U.S and non-U.S operations was as follows:



	Year Ended December 31,
	2015			2014			2013
U.S. loss	$	(16,235	)	$	(18,078	)	$	(15,622	)
Non U.S. loss	(105		)	(1,842		)	—
	$	(16,340	)	$	(19,920	)	$	(15,622	)

Schedule of reconciliation of income taxes computed using the federal statutory rate to the taxes reported in consolidated statements of operations

A reconciliation of income taxes computed using the federal statutory rate to the taxes reported in the consolidated statements of operations is as follows:



	Year Ended December 31,
(In thousands)	2015			2014			2013
Loss before income taxes	$	(16,340	)	$	(19,920	)	$	(15,622	)
Federal statutory rate	34		%	34		%	34		%
Taxes computed at federal statutory rate	(5,556		)	(6,773		)	(5,311		)
State taxes (net of federal benefit)	(392		)	(463		)	—
Warrants	(118		)	(10		)	(1,815		)
Nondeductible stock compensation	543			48			81
Michigan NOL benefit	—			—			(791		)
Net operating loss expirations	—			655			612
Write-off of Section 382 limited NOL’s	—			67,781			—
Write-off of Section 383 limited R&D credits	—			1,600			—
Other	57			352			(27		)
Adjustment to prior year filed returns	(5,203		)	—			—
Change in valuation allowance	10,669			(63,190		)	7,251
Reported income taxes	$	—		$	—		$	—

Schedule of deferred tax assets

Deferred tax assets consist of the following:



	Year Ended December 31,
(In thousands)	2015			2014
Net operating loss carryforwards	$	13,998		$	7,092
Employee benefits and stock compensation	2,485			1,897
Research and development costs	4,903			2,184
Fixed assets	453			254
Intangible assets	(477		)	(510		)
Asset retirement obligation	—			127
Inventory reserve	510			186
Other, net	143			115
Total deferred tax assets	22,015			11,345
Valuation allowance	(22,015		)	(11,345		)
Net deferred tax assets	$	—		$	—

Schedule of reconciliation of uncertain tax provision

A reconciliation of the beginning and ending amounts of uncertain tax provision is as follows:



	Unrecognized Income Tax
(In thousands)	Benefits
Balance at December 31, 2013	$	900
Decrease in prior year tax positions	(900		)
Balance at December 31, 2014 and 2015	$	—

Supplementary Quarterly Financial Information (unaudited) (Tables)

12 Months Ended

Dec. 31, 2015

Supplementary Quarterly Financial Information (unaudited) [Abstract]

Schedule of quarterly financial information



In thousands, except per share data)	First Quarter			Second Quarter			Third Quarter			Fourth Quarter			Year
2015
Revenues	$	10,849		$	13,590		$	11,309		$	15,420		$	51,168
Gross profit	5,281			6,689			4,537			8,191			24,698
Loss from operations	(4,572		)	(2,265		)	(4,877		)	(4,957		)	(16,671		)
Net loss	(4,862		)	(2,152		)	(4,416		)	(4,910		)	(16,340		)
Net loss per share (Basic and Diluted)	(0.27		)	(0.16		)	(0.26		)	(0.28		)	(0.97		)
2014
Revenues^(a)	$	—		$	4,432		$	9,658		$	14,706		$	28,796
Gross profit (loss)	—			(577		)	4,126			7,954			11,503
Loss from operations	(4,645		)	(8,522		)	(8,022		)	(2,345		)	(23,534		)
Net loss^(b)	(5,995		)	(4,638		)	(6,917		)	(2,370		)	(19,920		)
Net loss per share (Basic and Diluted)	(1.26		)	(0.94		)	(0.82		)	(0.17		)	(2.23		)

(a) Revenue from commercial operations began in June 2014 following the acquisition of the CTRM business. Prior to June 2014, Vericel was a development stage entity.

(b) The net loss in the second quarter of 2014 includes a $3.5 million bargain purchase gain as a result of the CTRM business acquisition.

Organization (Details)	12 Months Ended
Organization (Details)	Dec. 31, 2015 segment	May. 30, 2014 patent
Business Acquisition [Line Items]
Number of reportable segments \| segment	1
CTRM Business
Business Acquisition [Line Items]
Number of patents and patents applications acquired (over) \| patent		250

Summary of Significant Accounting Policies (Details)	12 Months Ended
Summary of Significant Accounting Policies (Details)	Dec. 31, 2015
Equipment and computers \| Minimum
Property, Plant and Equipment
Useful lives	3 years
Equipment and computers \| Maximum
Property, Plant and Equipment
Useful lives	5 years
Furniture and fixtures
Property, Plant and Equipment
Useful lives	5 years
Building improvements and leasehold improvements \| Maximum
Property, Plant and Equipment
Useful lives	7 years

Acquisitions (Details) $ in Thousands		3 Months Ended		12 Months Ended
Acquisitions (Details) $ in Thousands	May. 30, 2014 USD ($) patent	Jun. 30, 2014 USD ($)	Mar. 31, 2013 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Total purchase price allocation
Asset retirement obligation				$ 0	$ (348)
Bargain purchase gain				$ 0	(3,473)	$ 0
Restructuring charge			$ 400
CTRM Business
Business Acquisition [Line Items]
Number of patents and patents applications acquired (over) \| patent	250
Total purchase price consideration
Cash payment	$ 4,000
Promissory note	2,500
Total acquisition consideration	6,500
Total purchase price allocation
Cash	5,050
Accounts receivable	53
Inventory	2,039
Other current assets	192
Accounts payable and accrued expenses	(939)
Asset retirement obligation	(1,600)
Property and equipment	1,818
Intangible assets	3,360
Bargain purchase gain	(3,473)	$ (3,500)
Total consideration	$ 6,500
Restructuring charge					3,000
Unaudited pro forma condensed combined statements
Pro forma revenue					44,906	43,863
Pro forma net loss					$ (30,115)	$ (49,124)
CTRM Business \| Commercial rights
Identifiable intangible assets acquired and their estimated useful lives
Useful Life	12 years
CTRM Business \| Sanofi \| Denmark
Total purchase price allocation
Cash received in order to fund the restructuring of the Denmark operations and close the facility	$ 5,000

Acquisitions Acquisitions - Pro forma Financial Information (Details) - CTRM Business - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Pro forma revenue	$ 44,906	$ 43,863
Pro forma net loss	$ (30,115)	$ (49,124)
Pro forma net loss per share - basic and diluted (in dollars per share)	$ (3.10)	$ (18.06)
Prior Period Adjustment, Immaterial
Business Acquisition [Line Items]
Pro forma revenue	$ 100
Pro forma net loss	$ 4,000
Pro forma net loss per share - basic and diluted (in dollars per share)	$ 0.33

Restructuring (Details)	3 Months Ended	12 Months Ended
Restructuring (Details)	Mar. 31, 2013 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2014 position	Dec. 31, 2013 USD ($)
Restructuring
Number of full time employee positions eliminated \| position			80
Percentage of full time employee positions eliminated			30.00%
Restructuring charge	$ 400,000
Restructuring reserve related to severance payments		$ 0		$ 100,000
Cost of product sales
Restructuring
Restructuring charge		2,500,000
Selling, general and administrative expenses
Restructuring
Restructuring charge		500,000
CTRM Business
Restructuring
Restructuring charge		$ 3,000,000

Selected Balance Sheet Components (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Inventory:
Raw materials	$ 1,228	$ 1,078
Work-in-process	131	458
Finished goods	20	384
Inventory	$ 1,379	$ 1,920

Selected Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property and equipment, net:
Depreciation	$ 1,300
Total property and equipment, gross	9,687	$ 7,289
Less: Accumulated amortization	(5,638)	(4,397)
Property and Equipment	4,049	2,892
Depreciation expense	1,592	752	$ 489
Machinery and equipment
Property and equipment, net:
Total property and equipment, gross	3,280	3,135
Furniture, fixtures and office equipment
Property and equipment, net:
Total property and equipment, gross	931	777
Computer equipment and software
Property and equipment, net:
Total property and equipment, gross	2,662	667
Leasehold improvements
Property and equipment, net:
Total property and equipment, gross	2,393	1,691
Construction in progress
Property and equipment, net:
Total property and equipment, gross	$ 421	$ 1,019

Selected Balance Sheet Components - Amortization Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Intangible assets, net
Intangible assets	$ 2,917,000
Amortization expense	300,000	$ 200,000	$ 0
Estimated future amortization expense
2016	280,000
2017	280,000
2018	280,000
2019	280,000
2020	280,000
Thereafter	1,517,000
Intangible assets	2,917,000
Commercial rights
Intangible assets, net
Gross amount	3,360,000	3,360,000
Accumulated amortization	(443,000)	(163,000)
Intangible assets	2,917,000	3,197,000
Estimated future amortization expense
Intangible assets	$ 2,917,000	$ 3,197,000

Selected Balance Sheet Components - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrued expenses
Bonus	$ 1,956	$ 2,044
Employee related accruals	1,341	1,281
Accrued expenses	75	605
Asset retirement obligation	0	348
Other	231	436
Total	$ 3,603	$ 4,714

Stock-Based Compensation (Details) - USD ($)	1 Months Ended	12 Months Ended
Stock-Based Compensation (Details) - USD ($)	Jan. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Oct. 01, 2015
2004, 2001 and 1992 PLANS
Stock-Based Compensation
Awards available for future grant under the Plan (in shares)		0
2009 Plan
Stock-Based Compensation
Awards available for future grant under the Plan (in shares)		1,962,168
Service-based stock options
Stock-Based Compensation
Vesting period		4 years
Weighted average grant-date fair value (in dollars per share)		$ 2.22	$ 2.85	$ 14.07
Stock-based compensation expense (less than $0.1 million - 2015 ESPP)		$ 2,700,000	$ 800,000	$ 900,000
Weighted average assumptions used to estimate fair value of each service-based stock option grant
Expected dividend rate (as a percent)		0.00%	0.00%	0.00%
Options
Outstanding at the beginning of the period (in shares)	2,523,400	477,530	297,860	499,374
Granted (in shares)		2,216,600	242,029	75,751
Exercised (in shares)		(3,566)	0	0
Expired (in shares)		(17,791)	(32,012)	(164,189)
Forfeited (in shares)		(149,373)	(30,347)	(113,076)
Outstanding at the end of the period (in shares)		2,523,400	477,530	297,860	499,374
Exercisable at the end of the period (in shares)		661,229
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 6.36	$ 36.43	$ 39.53	$ 47.60
Granted (in dollars per share)		3.11	3.91	21.32
Exercised (in dollars per share)		3.02	0.00	0.00
Expired (in dollars per share)		40.02	42.63
Cancelled (in dollars per share)				51.76
Forfeited or expired (in dollars per share)		3.35	32.13	45.38
Outstanding at the end of the period (in dollars per share)		6.36	$ 36.43	$ 39.53	$ 47.60
Exercisable at the end of the period (in dollars per share)		$ 14.27
Weighted Average Remaining Contractual Term
Outstanding		8 years 8 months 25 days	8 years	7 years 11 months	7 years 5 months 24 days
Exercisable at the end of the period		7 years 10 months 25 days
Aggregate Intrinsic Value
Outstanding		$ 5,000,000	$ 0	$ 0	$ 0
Exercised		1,000,000	0	0
Exercisable at end of period		0
Additional disclosures
Total unrecognized compensation cost		$ 2,700,000
Weighted average period over which unrecognized compensation is expected to be recognized		3 years
Total fair value of options vested		$ 1,700,000	$ 1,500,000	$ 2,300,000
Service-based stock options \| Minimum
Weighted average assumptions used to estimate fair value of each service-based stock option grant
Expected stock price volatility (as a percent)		77.40%	82.40%	74.00%
Risk-free interest rate (as a percent)		1.50%	1.70%	0.10%
Expected life		5 years 6 months	5 years	5 years 6 months
Service-based stock options \| Maximum
Stock-Based Compensation
Expiration period		10 years
Weighted average assumptions used to estimate fair value of each service-based stock option grant
Expected stock price volatility (as a percent)		88.10%	88.20%	87.90%
Risk-free interest rate (as a percent)		2.00%	2.20%	2.10%
Expected life		6 years 3 months 18 days	6 years 3 months 18 days	6 years 3 months 18 days
Service-based stock options \| Non-employee
Stock-Based Compensation
Expiration period		10 years
Vesting period		1 year
Options
Granted (in shares)		136,000
Service-based stock options \| 2009 Plan
Stock-Based Compensation
Vesting period		4 years
Employee stock
Stock-Based Compensation
Common stock available for issuance						1,000,000
Stock-based compensation expense (less than $0.1 million - 2015 ESPP)		$ 100,000
Employee stock \| Subsequent event
Stock-Based Compensation
Shares purchased during period	63,193
Value of shares purchased during period	$ 100,000

Shareholders' Equity (Details)								12 Months Ended
Shareholders' Equity (Details)	Dec. 23, 2015 USD ($) shares	Dec. 18, 2015 shares	Sep. 17, 2014 USD ($) $ / shares shares	Jul. 09, 2014 USD ($) warrant_holder $ / shares shares	Jan. 21, 2014 USD ($) $ / shares shares	Aug. 16, 2013 USD ($) $ / shares shares	Jun. 16, 2011 USD ($)	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Jul. 31, 2015 shares
Shareholders' Equity
Number of common shares sold \| shares			15,784,313
Offering price (in dollars per share) \| $ / shares			$ 2.55
Proceeds from issuance of common stock \| $			$ 37,500,000			$ 8,200,000
Number of shares of common stock sold \| shares								23,789,000	23,786,000
Underwriter's discount \| $			2,400,000
Issuance cost \| $			$ 300,000
Series A Convertible Preferred Stock
Shareholders' Equity
Shares issued upon conversion \| shares	1,250	1,250
MLV
Shareholders' Equity
Proceeds from issuance of common stock \| $								$ 7,100,000	$ 4,800,000
Amount of net capacity remaining on the ATM \| $								$ 7,800,000
Lincoln Park
Shareholders' Equity
Proceeds from issuance of common stock \| $									$ 3,700,000
Period over which shares of common stock to be purchased					30 months
Floor price for sale of shares of common stock (in dollars per share) (less than) \| $ / shares					$ 2.50
Number of shares of common stock sold \| shares									935,499
August 2013 warrants
Shareholders' Equity
Number of shares purchased on exercise of warrants \| shares				362,500				724,950		226,299
Offering price (in dollars per share) \| $ / shares								$ 2.58	$ 3.04
Number of warrant holders \| warrant_holder				1
Exercise price of warrants (in dollars per share) \| $ / shares				$ 4.80				$ 4.80
Net proceeds from exercise of warrants \| $				$ 1,500,000
Maximum \| MLV
Shareholders' Equity
Expected proceeds from sale of common stock \| $							$ 20,300,000.0
Percentage of gross proceeds payable as commission							3.00%
Maximum \| Lincoln Park
Shareholders' Equity
Value of shares of common stock to be sold \| $					$ 15,000,000.0
Number of shares of common stock to be purchased in regular purchases \| shares					50,000
Number of shares of common stock to be purchased depending upon the closing sale price of the common stock \| shares					100,000
Period of business days over which purchase price of shares of common stock will be determined					10 days
Threshold on percentage of outstanding shares of the common stock that can be beneficially owned by counterparty (more than)								9.99%
Value of remaining shares of common stock to be sold \| $									$ 11,300,000
Minimum \| Lincoln Park
Shareholders' Equity
Threshold closing sale price of the common stock on the date of a regular purchase to trigger purchase of additional amounts as accelerated purchases (in dollars per share) (equals or exceeds) \| $ / shares					$ 3.00
Common Stock
Shareholders' Equity
Number of common shares sold \| shares						1,500,000.0			18,655,000
Stock issued to underwriter for exercise of over allotment option (in shares) \| shares						50,000
Offering price (in dollars per share) \| $ / shares						$ 6.00
Shares converted \| shares	1,250,000	1,250,000
Shares issued upon conversion \| shares								3,000	408,000
Conversion of stock, amount converted \| $	$ 3,200,000
Warrants
Shareholders' Equity
Fair market value of the warrants \| $						$ 5,900,000
Warrants \| Maximum
Shareholders' Equity
Number of shares purchased on exercise of warrants \| shares						1,500,000.0

Preferred Stock (Details)		1 Months Ended		12 Months Ended
Preferred Stock (Details)	Aug. 15, 2011 right	Oct. 31, 2013 right	Mar. 31, 2012	Dec. 31, 2015 $ / shares shares
Shareholder Rights Plan
Number of rights for each outstanding share of common stock \| right	1	20
Additional number of rights per common share \| right	1
Number of rights deemed to be delivered for each share of common stock issued or transferred \| right		20
Series A Junior Participating Cumulative Preferred Stock
Shareholder Rights Plan
Number of shares purchased on exercise of warrants				0.0001
Exercise price per share (in dollars per share) \| $ / shares				$ 30.00
Preferred stock, shares authorized				45,000
Preferred stock, shares issued				0
Preferred stock, shares outstanding				0
Multiple of the value of common stock acquired (after conversion from preferred) to the exercise price of stock purchase right in the event of an acquiring person event				2
Multiple of the value of common stock acquired to the exercise price of stock purchase right in the event of a merger of the entity				2
Redemption price per right (in dollars per right) \| $ / shares				$ 0.001
Series A Junior Participating Cumulative Preferred Stock \| Minimum
Shareholder Rights Plan
Percentage of common stock to be acquired for rights to be exercisable by an individual or group				15.00%
Percentage of common stock to be owned for rights to be exercisable by an individual or group commencing a tender offer				15.00%
Eastern Capital Limited and its affiliates \| Maximum
Shareholder Rights Plan
Percentage of common stock approved to be purchased			49.90%

Preferred Stock - Series B Convertible Preferred Stock (Details) $ / shares in Units, $ in Millions				12 Months Ended
	Sep. 17, 2014 shares	Aug. 12, 2013 USD ($) $ / shares	Mar. 09, 2012 $ / shares shares	Dec. 31, 2015 $ / shares shares
Series B Convertible Preferred Stock
Number of common shares sold \| shares	15,784,313
Percentage of cumulative dividend rate				11.50%
Series B voting convertible preferred stock
Series B Convertible Preferred Stock
Period of closing of offering after which shares are convertible				5 years
Conversion price per share (in dollars per share) \| $ / shares				$ 3.25
Conversion ratio, the number of shares of common stock received per share of convertible preferred stock				50
Reclassification of Series B preferred stock into shareholders' equity \| $		$ 38.4
Series B-1 non-voting convertible preferred stock
Series B Convertible Preferred Stock
Number of common shares sold \| shares			12,308
Offering price per share (in dollars per share) \| $ / shares			$ 3,250
Period of closing of offering after which shares are convertible		5 years
Accumulated shares but undeclared dividends \| shares				338,710
Redemption price (in dollars per share) \| $ / shares		$ 7,430

Preferred Stock Preferred Stock - Series A Convertible Preferred Stock (Details) - shares			12 Months Ended
	Dec. 23, 2015	Dec. 18, 2015	Dec. 31, 2015	Dec. 31, 2014
Shareholders' Equity
Maximum beneficial ownership percentage		9.99%
Maximum beneficial ownership percentage upon holder's election		14.99%
Series A Convertible Preferred Stock
Shareholders' Equity
Shares issued upon conversion	1,250	1,250
Common Stock
Shareholders' Equity
Shares converted	1,250,000	1,250,000
Shares issued upon conversion			3,000	408,000
Convertible preferred stock, shares issued upon conversion		1,000

Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net loss	$ (4,910)	$ (4,416)	$ (2,152)	$ (4,862)	$ (2,370)	$ (6,917)	$ (4,638)	$ (5,995)	$ (16,340)	$ (19,920)	$ (15,622)
Less: dividends accumulated on convertible preferred stock									6,736	6,005	5,352
Numerator of basic and diluted EPS									$ (23,076)	$ (25,925)	$ (20,974)
Denominator for basic and diluted EPS:
Weighted-average common shares outstanding									23,760	11,642	3,016
Net loss per share attributable to common shareholders (basic and diluted) (in dollars per share)	$ (0.28)	$ (0.26)	$ (0.16)	$ (0.27)	$ (0.17)	$ (0.82)	$ (0.94)	$ (1.26)	$ (0.97)	$ (2.23)	$ (6.95)
Aggregate number of common equivalent shares (related to options, warrants and preferred stock) that have been excluded from computations of diluted net loss per common share									6,700	2,300	2,400

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Stock Purchase Warrants (Details) - $ / shares	12 Months Ended
Stock Purchase Warrants (Details) - $ / shares	Dec. 31, 2015	Dec. 31, 2014	Jul. 31, 2015	Sep. 17, 2014	Jul. 09, 2014
Assumptions used in calculating the estimated fair value of the warrants
Closing stock price (in dollars per share)				$ 2.55
December 2010 Warrants
Stock Purchase Warrants
Total shares issuable on exercise	15,405
August 2013 warrants
Stock Purchase Warrants
Exercise price per share (in dollars per share)	$ 4.80				$ 4.80
Total shares issuable on exercise	724,950		226,299		362,500
Assumptions used in calculating the estimated fair value of the warrants
Closing stock price (in dollars per share)	$ 2.58	$ 3.04
Expected dividend rate	0.00%	0.00%
Expected stock price volatility	91.37%	83.20%
Risk-free interest rate	1.31%	1.20%
Expected life	2 years 7 months 17 days	3 years 7 months 17 days

Fair Value Measurements (Details) - USD ($) $ in Thousands	12 Months Ended
Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Liabilities that are measured at fair value on a recurring basis
Warrant liabilities	$ 1,081	$ 1,081
Change in the estimated fair value of warrant liabilities
Balance at the beginning of the period	1,081
Increase (decrease) in fair value	(324)	27	$ (5,337)
Balance at the end of the period	757	1,081
Recurring
Liabilities that are measured at fair value on a recurring basis
Warrant liabilities	1,081	2,019	2,019
Change in the estimated fair value of warrant liabilities
Balance at the beginning of the period	1,081	2,019
Warrant exercise		(965)
Increase (decrease) in fair value	(324)	27
Balance at the end of the period	757	1,081	$ 2,019
Recurring \| Level 2
Liabilities that are measured at fair value on a recurring basis
Warrant liabilities	1,061	1,061
Change in the estimated fair value of warrant liabilities
Balance at the beginning of the period	1,061
Balance at the end of the period	757	1,061
Recurring \| Level 3
Liabilities that are measured at fair value on a recurring basis
Warrant liabilities	20	20
Change in the estimated fair value of warrant liabilities
Balance at the beginning of the period	20
Balance at the end of the period	$ 0	$ 20

Fair Value Measurements - Level 3 Inputs (Details) - Recurring - Level 3 - Warrants - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of beginning and ending balances for the company's fair value measurements using Level 3 inputs
Beginning balance	$ 20	$ 85
Decrease in fair value	(20)	(65)
Ending balance	$ 0	$ 20

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Loss before income taxes	$ (16,340)	$ (19,920)	$ (15,622)
U.S.
Operating Loss Carryforwards [Line Items]
Loss before income taxes	(16,235)	(18,078)	(15,622)
Non U.S.
Operating Loss Carryforwards [Line Items]
Loss before income taxes	$ (105)	$ (1,842)	$ 0

Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of income taxes computed using the federal statutory rate to the taxes reported in consolidated statements of operations
Loss before income taxes	$ 16,340	$ 19,920	$ 15,622
Federal statutory rate	34.00%	34.00%	34.00%
Taxes computed at federal statutory rate	$ (5,556)	$ (6,773)	$ (5,311)
State taxes (net of federal benefit)	(392)	(463)	0
Warrants	(118)	(10)	(1,815)
Nondeductible stock compensation	543	48	81
Michigan NOL benefit	0	0	(791)
Net operating loss expirations	0	655	612
Write-off of Section 382 limited NOL’s	0	67,781	0
Write-off of Section 383 limited R&D credits	0	1,600	0
Other	57	352	(27)
Tax Adjustments, Settlements, and Unusual Provisions	(5,203)	0	0
Change in valuation allowance	10,669	(63,190)	7,251
Reported income taxes	0	0	$ 0
Deferred tax assets
Net operating loss carryforwards	13,998	7,092
Employee benefits and stock compensation	2,485	1,897
Research and development costs	4,903	2,184
Fixed assets	453	254
Intangible assets	(477)	(510)
Asset retirement obligation	0	127
Inventory reserve	510	186
Other, net	143	115
Total deferred tax assets	22,015	11,345
Valuation allowance	(22,015)	(11,345)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Operating Loss Carryforwards (Details) - USD ($) $ in Millions		12 Months Ended
	Sep. 17, 2014	Dec. 31, 2015	Dec. 31, 2014	Sep. 16, 2014
Income Tax Disclosure [Abstract]
Rolling period over which cumulative change of ownership is required for change in control	3 years
Operating Loss Carryforwards [Line Items]
Projected annual limitation on the use of the net operating losses that existed prior to September 17, 2014				$ 0.8
Increase (decrease) in net operating loss		$ (10.7)	$ 63.2
Federal \| Internal Revenue Service
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards		39.3
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards		$ 17.0

Income Taxes - Unrecognized Income Tax (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2014 USD ($)
Income Tax Disclosure [Abstract]
Balance at the beginning of the period	$ 900
Decrease in prior year tax positions	(900)
Balance at the end of the period	$ 0

Concentration of Credit (Details) - Customer concentration - customer	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Revenue \| One distributor in the U.S
CONCENTRATION
Concentration risk, Number of customers	1
Concentration risk	66.00%	76.00%
Revenue \| One customer
CONCENTRATION
Concentration risk	12.00%	10.00%
Accounts receivable \| One distributor in the U.S
CONCENTRATION
Concentration risk	76.00%	71.00%
Accounts receivable \| One customer
CONCENTRATION
Concentration risk	8.00%	14.00%

Commitments and Contingencies (Details) - USD ($)	1 Months Ended	9 Months Ended
Commitments and Contingencies (Details) - USD ($)	Dec. 31, 2002	Sep. 30, 2015	Dec. 31, 2015
Licenses, Royalties and Collaborative Agreements and Commitments
Purchase obligation, due in next twelve months		$ 300,000	$ 300,000
Purchase obligation, due in second year		$ 600,000	$ 0
Purchase obligation, renewal option, term		5 years
Purchase obligation, automatic renewal, term		5 years
Corning
Licenses, Royalties and Collaborative Agreements and Commitments
Royalty revenue as a percentage of net sales of products	5.00%
Corning \| Maximum
Licenses, Royalties and Collaborative Agreements and Commitments
Future royalty revenue	$ 50,000,000

Commitments and Contingencies - Future Minimum Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2015
Operating leases
Total	$ 27,693
2016	4,310
2017	4,890
2018	4,572
2019	4,260
2020	4,386
More than 5 years	5,275
Purchase commitments
Total	300
2016	300			$ 300
2017	0			$ 600
2018	0
2019	0
2020	0
More than 5 years	0
Capital leases
Total	118
2016	43
2017	43
2018	32
2019	0
2020	0
More than 5 years	0
Operating and capital leases and purchase commitments
Total operating and capital leases and purchase commitments	28,111
2016	4,653
2017	4,933
2018	4,604
2019	4,260
2020	4,386
More than 5 years	5,275
Rent expense	$ 4,900	$ 2,500	$ 1,000

Subsequent Events (Details) - Subsequent event - SVB	Mar. 08, 2016 USD ($) payment
Debt financing agreement
Subsequent Event [Line Items]
Debt instrument, face amount	$ 15,000,000
Debt financing agreement \| Minimum
Subsequent Event [Line Items]
Adjusted quick ratio (greater than or equal to)	1.10
Debt financing agreement \| Maximum
Subsequent Event [Line Items]
Adjusted quick ratio (greater than or equal to)	1.0
Debt financing agreement \| Revolving credit facility \| Line of credit
Subsequent Event [Line Items]
Revolving line of credit, borrowing capacity (up to)	$ 10,000,000.0
Term loan
Subsequent Event [Line Items]
Debt instrument, number of payments \| payment	36
Term loan \| Prime Rate
Subsequent Event [Line Items]
Basis spread on variable rate	0.75%
Term loan \| Prime Rate \| Minimum
Subsequent Event [Line Items]
Basis spread on variable rate	0.25%
Term loan \| Prime Rate \| Maximum
Subsequent Event [Line Items]
Basis spread on variable rate	0.75%
Term loan \| Available immediately upon closing
Subsequent Event [Line Items]
Debt instrument, face amount	$ 3,000,000
Term loan \| Available upon FDA approval of MACI BLA
Subsequent Event [Line Items]
Debt instrument, face amount	$ 2,000,000

Supplementary Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
	May. 30, 2014	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Revenues		$ 15,420	$ 11,309	$ 13,590	$ 10,849	$ 14,706	$ 9,658	$ 4,432	$ 0	$ 51,168	$ 28,796	$ 19
Gross profit (loss)		8,191	4,537	6,689	5,281	7,954	4,126	(577)	0	24,698	11,503	15
Loss from operations		(4,957)	(4,877)	(2,265)	(4,572)	(2,345)	(8,022)	(8,522)	(4,645)	(16,671)	(23,534)	(20,964)
Net loss		$ (4,910)	$ (4,416)	$ (2,152)	$ (4,862)	$ (2,370)	$ (6,917)	$ (4,638)	$ (5,995)	$ (16,340)	$ (19,920)	$ (15,622)
Net loss per share (basic and diluted) (in dollars per share)		$ (0.28)	$ (0.26)	$ (0.16)	$ (0.27)	$ (0.17)	$ (0.82)	$ (0.94)	$ (1.26)	$ (0.97)	$ (2.23)	$ (6.95)
Bargain purchase gain										$ 0	$ 3,473	$ 0
CTRM Business
Business Acquisition [Line Items]
Bargain purchase gain	$ 3,473							$ 3,500

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Issuance of stock, issuance cost	$ 3,167	$ 980

Summary of Significant Accounting Policies - Undeclared Dividends (Details) $ in Millions	Dec. 31, 2015 USD ($)
Series B voting convertible preferred stock
Net Loss Per Share Attributable to Common Shareholders
Accumulated undeclared dividends	$ 6.7

Income Taxes Income Taxes - Unrealized Built in Gain (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Income Tax Disclosure [Abstract]
Net unrealized built in gain	$ 8.9

Employee Savings Plan (Details) - USD ($) $ in Millions	12 Months Ended
Employee Savings Plan (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Contributions made under 401(k) savings plan	$ 0.5	$ 0.3	$ 0.1