Vericel (VCEL) 10-K 24 Feb 22 2021 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 18, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-35280
Entity Registrant Name	VERICEL CORPORATION
Entity Incorporation, State or Country Code	MI
Entity Tax Identification Number	94-3096597
Entity Address, Address Line One	64 Sidney Street
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02139
City Area Code	617
Local Phone Number	588-5555
Title of 12(b) Security	Common Stock (No par value)
Trading Symbol	VCEL
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 2,430,875,370
Entity Common Stock, Shares Outstanding		46,967,681
Documents Incorporated by Reference	Document Form 10-K Reference Proxy Statement for the Annual Meeting of Shareholders scheduled for April 27, 2022 Items 10, 11, 12, 13 and 14 of Part III
Entity Central Index Key	0000887359
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2021
Audit Information [Abstract]
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Boston, Massachusetts

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 68,330	$ 33,620
Short-term investments	35,068	42,187
Accounts receivable (net of allowance for doubtful accounts of $40 and $143, respectively)	37,437	34,504
Inventory	13,381	9,356
Other current assets	4,246	3,893
Total current assets	158,462	123,560
Property and equipment, net	13,308	7,633
Restricted cash	211	211
Right-of-use assets	45,720	50,105
Long-term investments	25,687	24,099
Other long-term assets	317	0
Total assets	243,705	205,608
Current liabilities:
Accounts payable	9,016	6,755
Accrued expenses	14,045	11,293
Current portion of operating lease liabilities	2,950	4,394
Other current liabilities	41	41
Total current liabilities	26,052	22,483
Operating lease liabilities	47,147	48,789
Other long-term liabilities	44	76
Total liabilities	73,243	71,348
COMMITMENTS AND CONTINGENCIES
Shareholders’ equity:
Common stock, no par value; shares authorized — 75,000; shares issued and outstanding — 46,880 and 45,804, respectively	553,902	510,061
Accumulated other comprehensive (loss) income	(154)	14
Accumulated deficit	(383,286)	(375,815)
Total shareholders’ equity	170,462	134,260
Total liabilities and shareholders’ equity	$ 243,705	$ 205,608

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 40	$ 143
Common Stock, Par or Stated Value Per Share	$ 0	$ 0
Common stock, shares authorized (in shares)	75,000,000	75,000,000
Common stock, shares issued (in shares)	46,880,000	45,804,000
Common stock, shares outstanding (in shares)	46,880,000	45,804,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Product sales, net	$ 153,075	$ 121,968	$ 117,850
Other revenue	3,109	2,211	0
Total revenue	156,184	124,179	117,850
Cost of product sales	50,159	39,951	37,571
Gross profit	106,025	84,228	80,279
Research and development	16,287	13,020	30,391
Selling, general and administrative	97,592	68,836	61,139
Total operating expenses	113,879	81,856	91,530
(Loss) income from operations	(7,854)	2,372	(11,251)
Other income (expense):
Interest income	224	691	1,614
Interest expense	(4)	(6)	(8)
Other income (expense)	52	(13)	(20)
Total other income (expense)	272	672	1,586
(Loss) income before income taxes	(7,582)	3,044	(9,665)
Income tax (benefit) expense	(111)	180	0
Net (loss) income	$ (7,471)	$ 2,864	$ (9,665)
Net income (loss) per common share (Basic) (in USD per share)	$ (0.16)	$ 0.06	$ (0.22)
Net income (loss) per common share (Diluted) (in USD per share)	$ (0.16)	$ 0.06	$ (0.22)
Weighted average common shares outstanding (basic) (in shares)	46,472	45,221	44,180
Weighted average common shares outstanding (diluted) (in shares)	46,472	47,282	44,180
Revenue, Product and Service [Extensible List]	Product [Member]	Product [Member]	Product [Member]
Cost, Product and Service [Extensible List]	Product [Member]	Product [Member]	Product [Member]

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (7,471)	$ 2,864	$ (9,665)
Other comprehensive (loss) income:
Unrealized (loss) gain on investments	(168)	(7)	60
Comprehensive (loss) income	$ (7,639)	$ 2,857	$ (9,605)

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Warrants	Accumulated Other Comprehensive Gain (loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2018		43,578,000
Beginning balance at Dec. 31, 2018	$ 102,231	$ 471,180	$ 104	$ (39)	$ (369,014)
Increase (Decrease) in Shareholders' Equity
Net (loss) income	(9,665)				(9,665)
Stock-based compensation expense	13,179	$ 13,179
Stock option exercises (in shares)		1,197,000
Stock option exercises	4,354	$ 4,354
Shares issued under the Employee Stock Purchase Plan (in shares)		69,000
Shares issued under the Employee Stock Purchase Plan	932	$ 932
Exercise of warrants resulting in issuance of common stock (in shares)		20,000
Exercise of warrants resulting in issuance of common stock	0	$ 104	(104)
Unrealized loss on investments	60			60
Ending balance (in shares) at Dec. 31, 2019		44,864,000
Ending balance at Dec. 31, 2019	111,091	$ 489,749	0	21	(378,679)
Increase (Decrease) in Shareholders' Equity
Net (loss) income	2,864				2,864
Stock-based compensation expense	13,843	$ 13,843
Stock option exercises (in shares)		790,000
Stock option exercises	5,582	$ 5,582
Shares issued under the Employee Stock Purchase Plan (in shares)		117,000
Shares issued under the Employee Stock Purchase Plan	1,050	$ 1,050
Issuance of stock for restricted stock units vesting (shares)		47,000
Issuance of stock for restricted stock unit vesting	0
Restricted stock withheld for employee tax remittance (in shares)		(14,000)
Restricted stock withheld for employee tax remittance	(163)	$ (163)
Unrealized loss on investments	(7)			(7)
Ending balance (in shares) at Dec. 31, 2020		45,804,000
Ending balance at Dec. 31, 2020	134,260	$ 510,061	0	14	(375,815)
Increase (Decrease) in Shareholders' Equity
Net (loss) income	(7,471)				(7,471)
Stock-based compensation expense	$ 34,322	$ 34,322
Stock option exercises (in shares)	968,261	968,000
Stock option exercises	$ 9,928	$ 9,928
Shares issued under the Employee Stock Purchase Plan (in shares)		43,000
Shares issued under the Employee Stock Purchase Plan	1,256	$ 1,256
Issuance of stock for restricted stock units vesting (shares)		96,000
Issuance of stock for restricted stock unit vesting	0
Restricted stock withheld for employee tax remittance (in shares)		(31,000)
Restricted stock withheld for employee tax remittance	(1,665)	$ (1,665)
Unrealized loss on investments	(168)			(168)
Ending balance (in shares) at Dec. 31, 2021		46,880,000
Ending balance at Dec. 31, 2021	$ 170,462	$ 553,902	$ 0	$ (154)	$ (383,286)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities:
Net (loss) income	$ (7,471)	$ 2,864	$ (9,665)
Adjustments to reconcile net (loss) income to net cash flows from operating activities:
Depreciation and amortization	2,965	2,383	1,744
Stock-based compensation expense	34,322	13,843	13,179
Amortization of premiums and discounts on marketable securities	949	318	(610)
Non-cash lease cost	4,422	4,445	2,787
Other	7	93	42
Changes in operating assets and liabilities:
Inventory	(4,025)	(2,540)	(3,258)
Accounts receivable	(2,933)	(2,336)	(8,714)
Other current assets	(353)	(940)	(106)
Accounts payable	1,491	33	(1,024)
Accrued expenses	2,752	3,345	1,018
Operating lease liabilities	(3,086)	(3,951)	(2,512)
Other non-current assets and liabilities, net	0	15	(64)
Net cash provided by (used in) operating activities	29,040	17,572	(7,183)
Investing activities:
Purchases of investments	(60,021)	(63,057)	(72,346)
Sales and maturities of investments	64,435	48,523	85,577
Expenditures for property and equipment	(7,915)	(2,626)	(2,616)
Net cash (used in) provided by investing activities	(3,501)	(17,160)	10,615
Financing activities:
Net proceeds from common stock issuance	11,184	6,632	5,286
Payments on employee’s behalf for taxes related to vesting of restricted stock unit awards	(1,665)	(163)	0
Other	(348)	(28)	(26)
Net cash provided by financing activities	9,171	6,441	5,260
Net increase in cash, cash equivalents, and restricted cash	34,710	6,853	8,692
Cash, cash equivalents, and restricted cash at beginning of period	33,831	26,978	18,286
Cash, cash equivalents, and restricted cash at end of period	68,541	33,831	26,978
Supplemental disclosure of cash flow information:
Warrants exercised for common stock	0	0	104
Right-of-use asset and lease liability recognized	192	29,573	2,599
Additions to property and equipment included in accounts payable	1,373	531	217
Restricted stock held for employee tax remittance included in accounts payable	46	0	0
Interest paid	4	6	8
Taxes paid	379	147	80
Reconciliation of amounts within the consolidated balance sheets:
Cash and cash equivalents	68,330	33,620	26,889
Restricted cash	211	211	89
Total cash, cash equivalents, and restricted cash at end of period	$ 68,541	$ 33,831	$ 26,978

Organization

Organization	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Vericel Corporation, a Michigan corporation (together with its consolidated subsidiaries referred to herein as the Company, or Vericel), was incorporated in March 1989 and began employee-based operations in 1991. The Company is a fully-integrated, commercial-stage biopharmaceutical company and is a leader in advanced therapies for the sports medicine and severe burn care markets. Vericel currently markets two cell therapy products in the U.S., MACI ® (autologous cultured chondrocytes on porcine collagen membrane) and Epicel ® (cultured epidermal autografts). MACI (autologous cultured chondrocytes on porcine collagen membrane) is an autologous cellularized scaffold product indicated for the repair of symptomatic, single or multiple full-thickness cartilage defects of the knee with or without bone involvement in adults. Epicel (cultured epidermal autografts) is a permanent skin replacement for the treatment of adult and pediatric patients with deep-dermal or full-thickness burns comprising greater than or equal to 30 percent of total body surface area (“TBSA”). The Company also holds an exclusive license from MediWound Ltd. (“MediWound”) for North American rights to NexoBrid ® , a registration-stage biological orphan product for debridement of severe thermal burns. The Company operates its business primarily in the U.S. in one reportable segment — the research, product development, manufacture and distribution of cellular therapies for use in the treatment of specific diseases. COVID-19 The ongoing pandemic caused by the spread of a novel strain of coronavirus (“COVID-19”) has created significant disruptions to the U.S. and global economy and has contributed to significant volatility in financial markets. The global impact of the outbreak has fluctuated since early 2020. At times, many state, local and national governments – including those in Massachusetts and Michigan, where the Company’s operations are located – have responded by issuing, extending and supplementing orders requiring quarantines, restrictions on travel, and the mandatory closure of certain non-essential businesses, among other actions. In the U.S., the status and application of these orders have varied on a state-by-state basis since the early days of the pandemic. Many of the restrictions have been periodically updated as infection rates in the U.S. have risen and fallen, as new virus variants have emerged, as vaccines have been distributed and administered, and as world health leaders learn more about the virus, its transmission pathway and who is most at risk. Because Vericel is deemed an essential business, the Company has been exempted from government orders requiring the closure of workplaces and the cessation of business operations. Notwithstanding being an essential business, the Company’s business and operations at times have been adversely impacted by the ongoing effects of the COVID-19 pandemic. For example, as a result of periodic restrictions placed on the performance of elective surgical procedures, Vericel experienced a significant increase in cancellations of scheduled MACI procedures, as well as a slowdown in new MACI orders during March and April of 2020. The widespread suspension of surgical procedures impacted the Company’s business and operations during the first and second quarters of 2020. The level and degree of restriction on elective surgeries, on the ability of patients to seek treatment and on U.S. business operations generally fluctuated throughout 2020 as COVID-19 infection rates rose and fell during the summer months and into the autumn. By the first quarter of 2021, the pandemic’s effects on the Company’s MACI business had largely dissipated. During the summer of 2021, however, the pandemic’s direct and ancillary effects again began to cause some disruption to our MACI business. Following the cessation of COVID-19-related travel restrictions in many parts of the U.S. and the availability of vaccinations in May and June 2021, some MACI patients postponed or delayed treatment – opting instead to take vacation and/or travel. Further, surges of new COVID-19 cases during the second half of 2021 caused by the spread of the “Delta” and “Omicron” variants again caused disruptions to health care networks including restrictions on the performance of elective surgical procedures, the availability of physicians and/or their treatment prioritizations, the level of healthcare facility staffing and, in some instances, the willingness or ability of patients to seek treatment. Consequently, and notwithstanding the widespread distribution of vaccines, these factors contributed to a slowdown of MACI procedures during the third and fourth quarters of 2021. Although hospitals are now better prepared for subsequent surges in COVID-19 patients, the risk remains that regional or local restrictions could again be placed on the performance of elective surgical procedures if the number of COVID-19 infections in the U.S. were to continue to rise, or if new or existing COVID-19 variants render current vaccine treatments ineffective. Because Epicel is used almost exclusively in an emergent setting by burn centers and surgeons throughout the country, Epicel revenue and procedure volumes have been less affected by the pandemic. Nevertheless, large burns and burn admissions can be affected by restrictions on human activity resulting from more severe government lockdown orders. At the outset of the pandemic, the Company put in place a comprehensive workplace protection plan, which instituted protective measures in response to COVID-19. Vericel’s workplace protection plan has closely followed guidance issued by the Centers for Disease Control and Prevention (“CDC”) and has complied with applicable federal and state law. To date, Vericel has been successful in sustaining its operations and providing MACI and Epicel to patients in need. The Company continues to review its policies and procedures regularly, including its workplace protection plan, as the pandemic evolves and the Company may take additional actions to the extent required. Liquidity The accompanying consolidated financial statements have been prepared on a basis which assumes that the Company will continue as a going concern and contemplates the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. As of December 31, 2021, the Company had an accumulated deficit of $383.3 million and had a net loss of $7.5 million for the year ended December 31, 2021. The Company had cash and cash equivalents of $68.3 million and investments of $60.8 million as of December 31, 2021. The Company expects that cash from the sales of its products and existing cash, cash equivalents and investments will be sufficient to support the Company’s current operations through at least 12 months from the issuance of these consolidated financial statements. The effects of the COVID-19 pandemic continue to evolve, however. To the extent the U.S. experiences a continued worsening in COVID-19 infections or the emergence of additional virus variants that result in more serious disease or limit the effectiveness of existing vaccines, subsequent healthcare measures – to include the postponement or cessation of elective and other surgical procedures – may cause the Company to experience a reduction in business and resulting revenue. This, consequently, may result in irrecoverable losses of customers and significantly impact long-term liquidity, requiring the Company to engage in layoffs, furloughs and/or reductions in salaries. The Company also may need to access additional capital; however, the Company may not be able to obtain financing on acceptable terms or at all, particularly in light of the impact of COVID-19 on the global economy and financial markets. The terms of any financing may adversely affect the holdings or the rights of the Company’s shareholders.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements have been prepared in accordance with U.S. GAAP. The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and accounts have been eliminated in consolidation. Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. The Company is monitoring the potential impact of the ongoing COVID-19 pandemic on its business and the consolidated financial statements. The more significant estimates reflected in the Company’s consolidated financial statements include, but are not limited to, certain judgments regarding revenue recognition, inventory valuation, stock option valuation, deferred tax assets and liabilities and accrued expenses. The Company is not aware of any specific event or circumstance that would require an update to its estimates or judgments reflected in these consolidated financial statements or a revision of the carrying value of its assets or liabilities as of the issuance of these consolidated financial statements. These estimates may change as new events occur and additional information is obtained. Actual results could materially differ from those estimates. Cash Equivalents Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase and consist primarily of demand deposits, money market funds, overnight repurchase agreements and short duration agency bonds and commercial paper. Restricted Cash Amounts included in restricted cash represent those required to be set aside to meet contractual terms of a lease agreement held by the Company. Investments Investments classified as short-term have maturities of less than one year. Investments classified as long-term are those that: (i) have a maturity of greater than one year, and (ii) the Company does not intend to liquidate within the next twelve months, although these funds are available for use and, therefore, are classified as available-for-sale. The Company’s investment strategy is to buy short-duration marketable securities with a high credit rating. As of December 31, 2021 and 2020, all marketable securities held by the Company had remaining contractual maturities of three years or less. Unrealized gains are included as a component of accumulated other comprehensive income in the consolidated balance sheets and consolidated statements of shareholders’ equity and a component of total comprehensive (loss) income in the consolidated statements of comprehensive (loss) income, until realized. Unrealized losses are evaluated for impairment under ASC 326 , Financial Instruments - Credit Losses (“ASC 326”), to determine if the impairment is credit-related or non-credit-related. Credit-related impairment is recognized as an allowance on the balance sheet with a corresponding adjustment to earnings, and non-credit-related impairment is recognized in other comprehensive (loss) income, net of taxes. Leases The Company determines if an arrangement is a lease at inception, in accordance with ASC Topic 842, Leases . All operating lease commitments with a lease term greater than 12 months are recognized as right-of-use assets and liabilities, on a discounted basis on the balance sheet. Leases with an initial term of 12 months or less are not recorded on the balance sheet. Certain of the Company’s lease agreements include lease payments that are adjusted periodically for an index or rate. The leases are initially measured using the present value of the projected payments adjusted for the index or rate in effect at the commencement date. In addition to rent, the leases may require the Company to pay additional amounts for taxes, insurance, maintenance and other expenses, which do not transfer a good or service to the Company and are generally referred to as non-lease components. Variable non-lease components are not measured as part of the right-of-use asset and liability. Only when lease components and their associated non-lease components are fixed are they accounted for as a single lease component and are recognized as part of a right-of-use asset and liability. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. The Company has options to renew lease terms for facilities and other assets. Some leases contain clauses for renewal at the Company’s option with renewal terms that generally extend the lease term from 1 to 5 years. The exercise of lease renewal options is generally at the Company’s sole discretion. The Company evaluates renewal and termination options at the lease commencement date to determine if it is reasonably certain to exercise the option on the basis of economic factors. For certain leases, the Company’s exercise of the renewal option was determined to be probable and the renewal period was accordingly included in the lease term and related calculations. Certain lease agreements contain options to purchase the leased property and options to terminate the lease. A portfolio approach is applied to certain lease contracts with similar characteristics. Inventory Inventories are measured at the lower of cost or net realizable value. Cost is calculated based upon standard-cost which approximates costs determined on the first-in, first-out method. The Company periodically reviews its inventories for excess or obsolescence and writes down obsolete or other unmarketable inventory to its estimated net realizable value. If the actual net realizable value is less than that estimated by the Company, or if it is determined that inventory utilization will further diminish based on estimates of demand, additional inventory write-downs may be required. In all cases, product inventory is carried at the lower of cost or its estimated net realizable value. Amounts written down are charged to cost of product sales. Accounts Receivable Accounts receivable are initially recorded at the contractual amount owed by the customer or based on expected payments from the insurance provider, hospital or patient. Allowances for doubtful accounts are established when the facts and circumstances indicate that a receivable may not be collectible. Potential credit risk exposure has been evaluated for the Company’s accounts receivable in accordance with ASC 326 . The Company assesses risk and determines a loss percentage by pooling account receivables based on similar risk characteristics. The loss percentage is calculated through the use of forecasts that are based on current and historical economic and financial information. Property and Equipment, net Property and equipment are initially measured and recognized at acquisition cost, including any directly attributable cost of preparing the asset for its intended use. After initial measurement, property and equipment are carried at cost less accumulated depreciation and impairment. Repair and maintenance costs of property and equipment are expensed as incurred. The depreciable value of property and equipment 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 and equipment are as follows: • Machinery and Equipment: 5 years • Furniture, fixtures, and office equipment: 3 to 5 years • Computer equipment and software: 3 years • Building improvements and leasehold improvements: Shorter of the remaining life of the lease or 10 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. Revenue Recognition and Net Product Sales The Company recognizes product revenue from sales to a customer (whether a distributor, or hospital ) following the five step model in Accounting Standards Codification 606, Revenue Recognition (“ ASC 606”): (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenues when (or as) the Company satisfies the performance obligation. Under this revenue standard, the Company recognizes revenue when its customer obtains control of the promised goods, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods. There are no contractual rights of returns, refunds or similar obligations related to MACI, kits, Epicel or NexoBrid; however, in certain limited cases the Company will accept a product return if a surgery is canceled. Revenue is not recognized in certain canceled cases. For MACI, MACI kits and Epicel there are no variable pricing arrangements related to warranties or rebates offered to customers. The majority of orders are due within 60 to 90 days of delivery. Shipping and handling fees are included as a component of revenue. The Company recognizes any commission fees as an expense when incurred. These fees are included in selling, general, and administrative expenses. See Note 3, “Revenue” for further discussion on revenues. Research and Development Expense Research and development expenses are expensed as incurred. 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. 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 and restricted stock units. The fair value of restricted stock units held by the employees is determined based on the fair value of the Company’s common stock on the date of the grant. Compensation expense is recorded for restricted stock units that are expected to vest over the expected vesting period. The fair value of stock options held by the employees is determined using a Black-Scholes option valuation method. 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’s 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 estimates the expected forfeiture rate and only recognizes 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. For certain non-employee consultants, stock option awards continue to vest post-termination. 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 purchased options at the grant date, which corresponds to the first day of each purchase period, and is amortized over the purchase period. Comprehensive (Loss) Income Comprehensive (loss) income is the change in shareholders’ equity during a period arising from any gain or loss unrealized related to the Company’s investments. 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 based on the weight of available evidence. When evaluating the realizability of the deferred tax assets, all evidence, both positive and negative, is considered. Items considered when evaluating the need for a valuation allowance include the ability to carry back losses, future reversals of existing temporary differences, tax planning strategies, and expectations of future earnings. The Company records uncertain tax positions in the consolidated financial statements only if it is more likely than not that the uncertain tax position will be sustained upon examination by the taxing authorities. The Company records interest and penalties related to uncertain tax positions in income tax expense. Net (Loss) Income Per Common Share Basic earnings per common share is computed by dividing net income by the weighted-average number of shares of common stock outstanding during the period. Diluted earnings per common share is computed by dividing net income by the weighted-average number of shares of common stock outstanding during the period, plus the potential dilutive effect of other securities if those securities were converted or exercised. During periods in which the Company incurs net losses, both basic and diluted loss per common share is calculated by dividing the net loss by the weighted-average shares of common stock outstanding and potentially dilutive securities are excluded from the calculation because their effect would be antidilutive. Financial Instruments The Company’s financial instruments include accounts receivables, accounts payable and accrued expenses for which the current carrying amounts approximate market value, based upon their short-term nature and marketable debt securities which are classified as available-for-sale and carried at fair value on a settlement date basis. Recent Accounting Pronouncements Accounting Standards adopted during the year ended December 31, 2021. Standard Description Effective Date for Company Effect on the consolidated financial statements ASU 2019-12, Simplifying the Accounting for Income Taxes (ASC 740) The ASU enhances and simplifies various aspects of the income tax accounting guidance in ASC 740, including requirements related to hybrid tax regimes, the tax basis step-up in goodwill obtained in a transaction that is not a business combination, separate financial statements of entities not subject to tax, the intra-period tax allocation exception to the incremental approach, ownership changes in investments, changes from a subsidiary to an equity method investment, interim-period accounting for enacted changes in tax law, and the year-to-date loss limitation in interim-period tax accounting. January 1, 2021 The adoption of this standard did not have a material impact on the Company’s consolidated financial statements.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2021
Risks and Uncertainties [Abstract]
Revenue	Revenue Revenue Recognition and Net Product Sales As disclosed in Note 2, the Company recognizes product revenue from sales of MACI biopsy kits, MACI implants, Epicel grafts and other sources following the five-step model in ASC 606. MACI Biopsy Kits MACI biopsy kits are sold directly to hospitals and ambulatory surgical centers based on contracted rates in an approved contract or sales order. The Company recognizes MACI kit revenue upon delivery of the biopsy kit, at which time the customer (the facility) is in control of the kit. The kit is used by the doctor to provide a sample of cartilage tissue to the Company, which can later be used to manufacture a MACI implant. The ordering of the kit does not obligate the Company to manufacture an implant nor does the receipt of the cartilage tissue. The customer’s order of an implant is separate from the process of ordering the biopsy kit. Therefore, the sale of the biopsy kit and any subsequent sale of an implant are distinct contracts and are accounted for separately. MACI Implants The Company contracts with two specialty pharmacies, Orsini Pharmaceutical Services, Inc. (“Orsini”) and AllCare Plus Pharmacy, Inc. (“AllCare”) to distribute MACI in a manner in which the Company retains the credit and collection risk from the end customer. The Company pays both specialty pharmacies a fee for each patient to whom MACI is dispensed. Both Orsini and AllCare perform collection activities to collect payment from customers. The Company engages a third-party to provide services in connection with a patient support program to manage patient cases and to ensure complete and correct billing information is provided to the insurers and hospitals. In addition, the Company also sells MACI directly to DMS Pharmaceutical (“DMS”) for patients treated at military treatment facilities. The sales directly to DMS are made at a contracted rate. Prior authorization and confirmation of coverage level by the patient’s private insurance plan, hospital or government payer is a prerequisite to the shipment of product to a patient. The Company recognizes product revenue from sales of all MACI implants upon delivery at which time the customer obtains control of the implant and the claim is billable. The total consideration which the Company expects to collect in exchange for MACI implants (the transaction price) may be fixed or variable. Direct sales to hospitals or distributors are recorded at a contracted price, and there are typically no forms of variable consideration. When the Company sells MACI the patient is responsible for payment; however, the Company is typically reimbursed by a third-party insurer or government payer, subject to a patient co-pay amount. Reimbursements from third-party insurers and government payers vary by patient and payer and are based on either contracted rates, publicly available rates, fee schedules or past payer precedents. Net product revenue is recognized net of estimated contractual allowances, which considers historical collection experience from both the payer and patient, denial rates and the terms of the Company’s contractual arrangements. The Company estimates expected collections for these transactions using the portfolio approach. The Company records a reduction to revenue at the time of sale for its estimate of the amount of consideration that will not be collected. In addition, potential credit risk exposure has been evaluated for the Company’s accounts receivable in accordance with ASC 326. The Company assesses risk and determines a loss percentage by pooling account receivables based on similar risk characteristics. The loss percentage is calculated through the use of forecasts that are based on current and historical economic and financial information. This loss percentage was applied to the accounts receivables as of December 31, 2021. The total allowance for uncollectible consideration was $7.0 million and $5.3 million as of December 31, 2021, and 2020, respectively. Changes to the estimate of the amount of consideration that will not be collected could have a material impact to the revenue recognized. A 50 basis points change to the estimated uncollectible percentage could result in approximately $0.3 million decrease or increase in the revenue recognized for the year ended December 31, 2021. Changes in estimates of the transaction price are recorded through revenue in the period in which such change occurs. Changes in estimates related to prior periods are shown in the Revenue by Product and Customer table below and relate primarily to changes in the initial expected reimbursement or collection expectation upon completion of the billing claims process for MACI implants that occurred in a prior year. Epicel The Company sells Epicel directly to hospitals and burn centers based on contracted rates stated in an approved contract or purchase order. Similar to MACI, there is no obligation to manufacture Epicel grafts upon receipt of a skin biopsy, and Vericel has no contractual right to receive payment until the product is delivered to the hospital. The Company recognizes product revenue from sales of Epicel upon delivery to the hospital, at which time the customer is in control of the Epicel grafts and the claim is billable to the hospital. NexoBrid The Company entered into exclusive license and supply agreements with MediWound in May 2019, under which MediWound will manufacture and supply NexoBrid on a unit price basis, which may be increased pursuant to the terms of the agreement. The U.S. Biomedical Advanced Research and Development Authority (“BARDA”) has committed to procure NexoBrid from MediWound and, as of December 31, 2021, the Company did not hold a direct contract or distribution agreement with BARDA, or take title to the product. The Company recognizes revenue based on a percentage of gross profits for sales of NexoBrid to BARDA upon delivery, at which time BARDA is in control of the product. Revenue by Product and Customer The following table and descriptions below shows the products from which the Company generated its revenue: Year Ended December 31, Revenue by product (in thousands) 2021 2020 2019 MACI implants and kits Implants based on contracted rate sold through a specialty pharmacy (a) $ 71,969 $ 57,593 $ 56,185 Implants subject to third party reimbursement sold through a specialty pharmacy (b) 16,000 16,320 17,076 Implants sold direct based on contracted rates (c) 18,714 15,144 13,933 Implants sold direct subject to third-party reimbursement (d) 2,821 2,754 1,529 Biopsy kits - direct bill 2,194 1,908 2,243 Change in estimates related to prior periods (e) (144) 713 654 Total MACI implants and kits 111,554 94,432 91,620 Epicel Direct bill (hospital) 41,521 27,536 26,230 NexoBrid revenue (f) 3,109 2,211 — Total revenue $ 156,184 $ 124,179 $ 117,850 (a) Represents implants sold through Orsini and AllCare whereby such specialty pharmacies have a direct contract with the underlying insurance provider. The amount of reimbursement is based on contracted rates at the time of sale supported by the pharmacy’s direct contracts. (b) Represents implants sold through Orsini or AllCare whereby such specialty pharmacy does not have a direct contract with the underlying payer. The amount of reimbursement is established based on a payer or state fee schedule and/or payer history. (c) Represents implants sold directly from the Company to the facility based on a contract and known price agreed upon prior to the surgery date. Also represents direct sales under a contract to specialty distributor DMS. (d) Represents implants sold directly from the Company to the facility based on a contract and known price agreed upon prior to the surgery date. The payment terms are subject to third-party reimbursement from an underlying insurance provider. (e) Primarily represents changes in estimates related to implants sold through Orsini or AllCare in which such specialty pharmacy does not have a direct contract with the underlying payer. The initial estimate of the amount of reimbursement is established based on a payer or state fee schedule and/or payer history. The change in estimates is a result of additional information, changes in collection expectations or actual cash collections received in the current period. (f) Represents revenue based on a percentage of gross profits for sales of NexoBrid to BARDA, pursuant to the license agreement between the Company and MediWound. Concentration of Credit Risk The Company’s total revenue concentration from an Epicel customer for the year ended December 31, 2021 was 10%. There was no revenue concentration for the years ended December 31, 2020 or 2019, greater than 10%. For the Company’s total accounts receivable balances, there were no customers for the year ended December 31, 2021, 2020 and 2019, respectively, with a concentration greater than 10%.

Selected Balance Sheet Componen

Selected Balance Sheet Components	12 Months Ended
	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Selected Balance Sheet Components	Selected Balance Sheet Components Inventory Inventory as of December 31, 2021 and 2020: (In thousands) 2021 2020 Raw materials $ 12,676 $ 8,775 Work-in-process 644 537 Finished goods 61 44 Total inventory $ 13,381 $ 9,356 Property and Equipment Property and Equipment, net as of December 31, 2021 and 2020: (In thousands) 2021 2020 Machinery and equipment $ 4,522 $ 3,672 Furniture, fixtures and office equipment 1,551 809 Computer equipment and software 7,769 6,846 Leasehold improvements 10,617 5,560 Construction in process 3,097 2,021 Financing right-of-use lease 74 111 Total property and equipment, gross 27,630 19,019 Less accumulated depreciation (14,322) (11,386) Total property and equipment, net $ 13,308 $ 7,633 Depreciation expense for the years ended December 31, 2021, 2020 and 2019 was $3.0 million, $2.4 million and $1.7 million, respectively. Accrued Expenses Accrued Expenses as of December 31, 2021 and 2020: (In thousands) 2021 2020 Bonus related compensation $ 6,305 $ 5,721 Employee related accruals 3,616 3,482 Insurance reimbursement-related liabilities 3,973 2,016 Other accrued expenses 151 74 Total accrued expenses $ 14,045 $ 11,293

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Leases	Leases The Company leases facilities in Ann Arbor, Michigan and Cambridge, Massachusetts. The Ann Arbor facility includes office space, and the Cambridge facilities includes clean rooms, laboratories for MACI and Epicel manufacturing and office space. The Company also leases offsite warehouse space, vehicles and computer equipment. See Note 15, “Subsequent Events” for discussion on a material lease entered into in January 2022. Effective October 21, 2020 the Company entered into an agreement with one of its Cambridge, Massachusetts facility leases. The agreement extended the terms of the lease to expire on February 29, 2032, with monthly contractual lease payments ranging from $0.4 million to $0.6 million. The agreement also provides a tenant improvement allowance of approximately $4.3 million, available through December 31, 2023. At the onset of the lease, the estimated contribution by the landlord toward the cost of tenant improvements is recorded as a reduction of the right-of-use asset and operating lease liability. For the year ended December 31, 2021 and 2020, lease expense of less than $0.1 million was recorded related to short-term leases. For the years ended December 31, 2021, 2020 and 2019, the Company recognized $7.3 million, $6.3 million and $5.4 million, respectively, of operating lease expense. For the years ended December 31, 2021, 2020 and 2019, the Company recognized less than $0.1 million of financing lease expense. Operating and finance lease assets and liabilities are as follows: December 31, (In thousands) Classification 2021 2020 Assets Operating Right-of-use assets $ 45,720 $ 50,105 Finance Property and equipment, net 73 111 Total leased assets $ 45,793 $ 50,216 Liabilities Current Operating Current portion of operating lease liabilities $ 2,950 $ 4,394 Finance Other current liabilities 41 41 $ 2,991 $ 4,435 Non-current Operating Operating lease liabilities $ 47,147 $ 48,789 Finance Other long-term liabilities 44 76 Total leased liabilities $ 47,191 $ 48,865 Cash paid for amounts included in the measurement of the Company’s operating lease liabilities was $6.0 million, $5.8 million, and $5.0 million for the year ended December 31, 2021, 2020, and 2019, respectively. Future minimum lease payments under non-cancellable lease as of December 31, 2021 are as follows: (In thousands) Operating Leases Finance Leases Total 2022 $ 2,950 $ 41 $ 2,991 2023 6,634 44 6,678 2024 6,946 — 6,946 2025 6,348 — 6,348 2026 6,530 — 6,530 Thereafter 36,977 — 36,977 Total lease payments $ 66,385 $ 85 $ 66,470 Less: interest (16,288) — (16,288) Present value of lease liabilities $ 50,097 $ 85 $ 50,182 An explicit rate is not provided in some of the Company’s leases, therefore the Company uses a mix of incremental borrowing rate based on the information available at commencement date through market sources including relevant peer borrowing rates, as well as implicit and explicit rates in determining the present value of lease payments. Lease terms and discount rates as of December 31, 2021 and 2020 are as follows: December 31, 2021 2020 Weighted-average remaining lease term (years) Operating leases 9.8 10.6 Finance leases 1.5 2.5 Weighted-average discount rate Operating leases 5.4% 5.4% Finance leases 5.0% 5.0%
Leases	Leases The Company leases facilities in Ann Arbor, Michigan and Cambridge, Massachusetts. The Ann Arbor facility includes office space, and the Cambridge facilities includes clean rooms, laboratories for MACI and Epicel manufacturing and office space. The Company also leases offsite warehouse space, vehicles and computer equipment. See Note 15, “Subsequent Events” for discussion on a material lease entered into in January 2022. Effective October 21, 2020 the Company entered into an agreement with one of its Cambridge, Massachusetts facility leases. The agreement extended the terms of the lease to expire on February 29, 2032, with monthly contractual lease payments ranging from $0.4 million to $0.6 million. The agreement also provides a tenant improvement allowance of approximately $4.3 million, available through December 31, 2023. At the onset of the lease, the estimated contribution by the landlord toward the cost of tenant improvements is recorded as a reduction of the right-of-use asset and operating lease liability. For the year ended December 31, 2021 and 2020, lease expense of less than $0.1 million was recorded related to short-term leases. For the years ended December 31, 2021, 2020 and 2019, the Company recognized $7.3 million, $6.3 million and $5.4 million, respectively, of operating lease expense. For the years ended December 31, 2021, 2020 and 2019, the Company recognized less than $0.1 million of financing lease expense. Operating and finance lease assets and liabilities are as follows: December 31, (In thousands) Classification 2021 2020 Assets Operating Right-of-use assets $ 45,720 $ 50,105 Finance Property and equipment, net 73 111 Total leased assets $ 45,793 $ 50,216 Liabilities Current Operating Current portion of operating lease liabilities $ 2,950 $ 4,394 Finance Other current liabilities 41 41 $ 2,991 $ 4,435 Non-current Operating Operating lease liabilities $ 47,147 $ 48,789 Finance Other long-term liabilities 44 76 Total leased liabilities $ 47,191 $ 48,865 Cash paid for amounts included in the measurement of the Company’s operating lease liabilities was $6.0 million, $5.8 million, and $5.0 million for the year ended December 31, 2021, 2020, and 2019, respectively. Future minimum lease payments under non-cancellable lease as of December 31, 2021 are as follows: (In thousands) Operating Leases Finance Leases Total 2022 $ 2,950 $ 41 $ 2,991 2023 6,634 44 6,678 2024 6,946 — 6,946 2025 6,348 — 6,348 2026 6,530 — 6,530 Thereafter 36,977 — 36,977 Total lease payments $ 66,385 $ 85 $ 66,470 Less: interest (16,288) — (16,288) Present value of lease liabilities $ 50,097 $ 85 $ 50,182 An explicit rate is not provided in some of the Company’s leases, therefore the Company uses a mix of incremental borrowing rate based on the information available at commencement date through market sources including relevant peer borrowing rates, as well as implicit and explicit rates in determining the present value of lease payments. Lease terms and discount rates as of December 31, 2021 and 2020 are as follows: December 31, 2021 2020 Weighted-average remaining lease term (years) Operating leases 9.8 10.6 Finance leases 1.5 2.5 Weighted-average discount rate Operating leases 5.4% 5.4% Finance leases 5.0% 5.0%

Investments

Investments	12 Months Ended
	Dec. 31, 2021
Cash and Cash Equivalents [Abstract]
Investments	Investments Marketable debt securities held by the Company are classified as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities , and carried at fair value in the accompanying consolidated balance sheets on a settlement date basis. The following tables summarize the gross unrealized gains and losses of the Company’s marketable securities as of December 31, 2021 and 2020: December 31, 2021 Gross Unrealized (In thousands) Amortized Cost Gains Losses Credit Losses Estimated Fair Value Commercial paper $ 10,243 $ — $ (12) $ — $ 10,231 Corporate notes 50,666 — (142) — 50,524 $ 60,909 $ — $ (154) $ — $ 60,755 Classified as: Short-term investments $ 35,068 Long-term investments 25,687 $ 60,755 December 31, 2020 Gross Unrealized (In thousands) Amortized Cost Gains Losses Credit Losses Estimated Fair Value Commercial paper $ 8,993 $ 1 $ — $ — $ 8,994 Corporate notes 35,917 — — (6) 35,911 U.S. government securities 12,828 14 — — 12,842 U.S. government agency bonds 5,000 1 — — 5,001 U.S. asset-backed securities 3,534 4 — — 3,538 $ 66,272 $ 20 $ — $ (6) $ 66,286 Classified as: Short-term investments $ 42,187 Long-term investments 24,099 $ 66,286

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation Stock Option, Restricted Stock Units and Equity Incentive Plans The Company has historically had various stock incentive plans and agreements that provide for the issuance of non-qualified and incentive stock options and restricted stock units 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 and restricted stock units granted to employees and non-employees under these plans expire no later than ten years from the date of grant. Options and restricted stock units generally become exercisable or vest over a four year period (other than options and restricted stock units awarded annually to non-employee directors, which generally vest over one year, and options and restricted stock units awarded to non-employee directors upon initial appointment to the Vericel Board of Directors, which generally vest over a three year period), under a graded-vesting methodology for stock options and annually on the anniversary grant date for restricted stock units, following the date of grant. The Company generally issues new shares upon the exercise of stock options or vesting of restricted stock units. The Company’s Amended and Restated 2019 Omnibus Incentive Plan (“2019 Plan”) was approved on April 29, 2020 and 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 2019 Plan shall not be less than the fair market value of the Company’s common stock on the date of grant. The 2019 Plan replaced the 1992 Stock Option Plan, the 2001 Stock Option Plan, the Amended and Restated 2004 Equity Incentive Plan, the 2009 Second Amended and Restated Omnibus Incentive Plan and the 2017 Omnibus Incentive Plan (“Prior Plans”), and no new grants have been granted under the Prior Plans after approval of the 2019 Plan. However, the expiration or forfeiture of options previously granted under the Prior Plans will increase the number of shares available for issuance under the 2019 Plan. As of December 31, 2021, there were 2,822,710 shares available for future grant under the 2019 Plan. Stock Compensation Expense Non-cash stock-based compensation expense (service-based stock options, restricted stock units and employee stock purchase plan) is summarized in the following table: Years Ended December 31, (in thousands) 2021 2020 2019 Cost of product sales $ 3,681 $ 1,949 $ 2,029 Research and development 4,120 1,884 2,428 Selling, general and administrative 26,521 10,010 8,722 Total non-cash stock-based compensation expense $ 34,322 $ 13,843 $ 13,179 Service-Based Stock Options 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 assumptions noted in the following table: Year Ended December 31, Service-Based Stock Options 2021 2020 2019 Expected dividend rate —% —% —% Expected stock price volatility 71.5 - 76.7% 71.1 - 78.7% 77.9 - 85.5% Risk-free interest rate 0.53 - 1.5% 0.33 - 1.7% 1.4 - 2.7% Expected life (years) 5.3 - 6.3 5.3 - 6.3 5.3 - 6.3 The weighted-average grant-date fair value of service-based options granted during the years ended December 31, 2021, 2020, and 2019 was $32.96, $8.86 and $12.62, respectively. 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 (Years) Aggregate Intrinsic Value (Thousands) Outstanding at December 31, 2020 5,236,044 $ 11.34 7.3 $ 102,654 Granted 1,683,568 50.84 Exercised (968,261) 10.25 Expired (12,126) 43.48 Forfeited (269,535) 26.05 Outstanding at December 31, 2021 5,669,690 $ 22.49 7.2 $ 113,985 Exercisable at December 31, 2021 3,169,562 $ 13.07 6.1 $ 86,141 As of December 31, 2021, 5,359,392 shares are vested and expected to vest. As of December 31, 2021, there was approximately $36.0 million of total unrecognized compensation cost related to non-vested service-based stock options granted under the 2019 Plan and the Prior Plans. That cost is expected to be recognized over a weighted-average period o f 3.0 y ears. The total intrinsic value of stock options exercised for the years ended December 31, 2021, 2020, and 2019 was $39.5 million, $10.5 million and $16.1 million, respectively. Restricted Stock Units The following table summarizes the activity for restricted stock units for the indicated periods: Restricted Stock Units Number of Restricted Stock Units Weighted-Average Grant Date Fair Value Outstanding at December 31, 2020 270,639 $ 13.57 Granted 266,759 52.07 Vested (98,597) 18.88 Forfeited (40,053) 30.63 Unvested at December 31, 2021 398,748 $ 36.30 The weighted-average grant-date fair value of restricted stock units granted during the years ended December 31, 2021, 2020, and 2019 was $52.07, $11.41 and $17.71, respectively. At December 31, 2021 the total unrecognized compensation cost related to the restricted stock units was $8.8 million, and the weighted-average period over which that cost is expected to be recognized was 2.9 years. The total fair value of restricted stock units vested in the years ended December 31, 2021 and 2020 was $5.3 million and $0.6 million, respectively. Employee Stock Purchase Plan

Net (Loss) Income Per Common Sh

Net (Loss) Income Per Common Share	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Net (Loss) Income Per Common Share	Net (Loss) Income Per Common Share A summary of net (loss) income per common share is presented below: Year Ended December 31, (Amounts in thousands, except per share amounts) 2021 2020 2019 Net (loss) income $ (7,471) $ 2,864 $ (9,665) Basic weighted-average common shares outstanding 46,472 45,221 44,180 Effect of dilutive stock options and restricted stock units — 2,061 — Diluted weighted-average common shares outstanding 46,472 47,282 44,180 Basic (loss) income per common share $ (0.16) $ 0.06 $ (0.22) Diluted (loss) income per common share $ (0.16) $ 0.06 $ (0.22) Anti-dilutive shares excluded from diluted net (loss) income per common share: Stock options 5,670 2,204 5,053 Restricted stock units 399 — 157

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2021
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholder’s Equity At-the-Market Offering On August 27, 2021, the Company entered into a Sales Agreement with SVB Leerink LLC, as sales agent (“SVB Leerink”), pursuant to which it may offer and sell up to $200.0 million of shares of the Company’s common stock, no par value per share (“ATM Shares”). The ATM Shares to be offered and sold under the Sales Agreement will be issued and sold pursuant to an automatically effective shelf registration statement on Form S-3ASR (File No. 333-259119) filed by the Company on August 27, 2021, which expires three years from the filing date. The Company also filed a prospectus supplement relating to the offering and sale of the ATM Shares on August 27, 2021. The Company is not obligated to make any sales of ATM Shares, and SVB Leerink is not required to sell any specific number or dollar amount of the ATM Shares under the Sales Agreement. The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process stock financings as deferred offering costs until such financings are consummated. As of December 31, 2021, the Company has sold no shares pursuant to the Sales Agreement.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	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). Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The commercial paper, corporate notes, U.S. government securities, U.S. government agency bonds and U.S. asset-backed securities are classified as Level 2 as they were valued based upon quoted market prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. There were no transfers into or out of Level 3 from December 31, 2019 to December 31, 2021. The following table summarizes the valuation of the Company’s financial instruments that are measured at fair value on a recurring basis: December 31, 2021 December 31, 2020 Fair value measurement category Fair value measurement category (In thousands) Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 1,258 $ 1,258 $ — $ — $ 3,698 $ 3,698 $ — $ — Commercial paper (a) 18,229 — 18,229 — 8,994 — 8,994 — Corporate notes 50,524 — 50,524 — 35,911 — 35,911 — U.S. government securities — — — — 12,842 — 12,842 — U.S. government agency bonds — — — — 5,001 — 5,001 — U.S. asset-backed securities — — — — 3,538 — 3,538 — $ 70,011 $ 1,258 $ 68,753 $ — $ 69,984 $ 3,698 $ 66,286 $ — (a) Approximately $8.0 million of commercial paper has an original maturity of 90 days or less and is recorded as a cash equivalent as of December 31, 2021. The fair values of the cash equivalents and marketable securities are based on observable market prices. The Company’s accounts receivables, accounts payable and accrued expenses are valued at cost which approximates fair value.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of (loss) income before income taxes are summarized as follows: Year Ended December 31, (In thousands) 2021 2020 2019 U.S. $ (7,367) $ 2,767 $ (9,632) Foreign (104) 97 (33) (Loss) income before income taxes $ (7,471) $ 2,864 $ (9,665) A reconciliation of income taxes computed using the U.S. federal statutory rate to the taxes reported in the consolidated statements of operations is as follows: Year Ended December 31, (In thousands) 2021 2020 2019 (Loss) income before income taxes $ (7,471) $ 2,864 $ (9,665) Federal statutory rate 21 % 21 % 21 % Taxes computed at federal statutory rate (1,569) 601 (2,030) State and local income taxes (345) 200 (484) Nondeductible stock-based compensation (4,311) 437 (1,329) Federal and state rate change 47 249 (164) Research and orphan drug credits (413) (8,827) — Other (87) 132 (49) Change in valuation allowance 6,567 7,388 4,056 Reported income taxes $ (111) $ 180 $ — Deferred tax assets (liabilities) consist of the following: Year Ended December 31, (In thousands) 2021 2020 Deferred tax assets: Net operating loss carryforwards $ 11,571 $ 8,411 Employee benefits and stock-based compensation 11,470 5,692 Research and development costs 5,059 6,411 Intangible assets 2,544 3,279 Operating lease liabilities 12,822 13,687 Inventory reserve 2,833 3,813 Tax credit carryforward 10,498 10,085 Other, net 13 38 Total deferred tax assets 56,810 51,416 Less: valuation allowance (43,947) (37,379) Total net deferred tax assets 12,863 14,037 Deferred tax liabilities: Right-of-use assets (12,266) (13,463) Property and equipment, net (597) (574) Total net deferred tax liabilities (12,863) (14,037) Net deferred tax assets and liabilities $ — $ — As of December 31, 2021, the Company’s U.S. federal and state tax net operating loss carryforwards available to offset future profits, after considering the annual Section 382 limit described below, are $44.3 million and $29.3 million, respectively. These net operating loss carryforwards will expire between 2022 and 2039 with the exception of the federal net operating losses generated in 2018 and 2021. The federal net operating losses of $1.5 million generated in 2018 and $6.4 million generated in 2021 can be carried forward indefinitely. The projected annual limitation on the use of the net operating losses that existed prior to September 17, 2014 resulting from the Company’s change in control in 2014 per Section 382 of the Internal Revenue Code 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. As of December 31, 2021, the Company’s U.S. federal tax credit carryforwards available to offset future profits are $10.5 million. Based on the research and development and orphan drug credit tax studies performed during 2020, the Company had a sufficient basis to claim the credits and recognized a tax credit carryforward in the 2020 tax year. These credit carryforwards will expire between 2034 and 2040. In accordance with the accounting guidance for income taxes, the Company estimates 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 sufficient positive evidence exists in future periods to support a release of some or all of the valuation allowance, such a release would likely have a material impact on the Company’s results of operations. The change in the valuation allowance was an increase of $6.6 million and $7.4 million for the years ended December 31, 2021 and 2020, 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 consolidated 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 derecognizes such positions. To the extent the uncertain tax positions meet the “more likely than not” threshold, the Company measures and records the highest probable benefit, and establishes appropriate reserves for benefits that exceed the amount likely to be sustained upon examination. The Company currently has not recorded any uncertain tax positions and does not anticipate that the unrecognized tax benefits will significantly increase or decrease within the next twelve months.

Employee Savings Plan

Employee Savings Plan	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
Employee Savings Plan	Employee Savings Plan The Company has a 401(k) savings plan

Nexobrid License and Supply Agr

Nexobrid License and Supply Agreements	12 Months Ended
	Dec. 31, 2021
Related Party Transactions [Abstract]
NexoBrid License and Supply Agreements	NexoBrid License and Supply Agreements On May 6, 2019, the Company entered into exclusive license and supply agreements with MediWound to commercialize NexoBrid and any improvements to NexoBrid in North America. NexoBrid is a topically-administered biological product that enzymatically removes nonviable burn tissue, or eschar, in patients with deep partial and full-thickness thermal burns. On September 16, 2020, the Company announced acceptance of MediWound’s submission of a biologics license application (“BLA”) for review by the U.S. Food and Drug Administration (“FDA”) to seek marketing approval for NexoBrid in the U.S. for the treatment of severe burns, and the FDA’s assignment of a Prescription Drug User Fee Act (“PDUFA”) target date for the product of June 29, 2021. Subsequently, on June 29, 2021, the Company announced that MediWound received a complete response letter from the FDA regarding the BLA, through which the FDA communicated to MediWound that it had completed its review of the BLA, as amended, and had determined that it cannot approve the BLA in its present form. The Company continues to work with MediWound, BARDA and the FDA to address the issues identified in the agency’s complete response letter, to prepare and submit a BLA resubmission to the FDA and to seek the potential approval of NexoBrid. Pursuant to the terms of the license agreement, if the BLA is approved, MediWound will transfer the BLA to Vericel and Vericel will market NexoBrid in the U.S. Both MediWound and Vericel, under the supervision of a Central Steering Committee comprised of members of both companies will continue to guide the development of NexoBrid in North America. NexoBrid is approved in the European Union and other international markets and has been designated as an orphan biologic in the U.S., European Union and other international markets. In May 2019, the Company paid MediWound $17.5 million in consideration for the license, which was recorded as research and development expense during 2019. The Company is also obligated to pay MediWound $7.5 million, which is contingent upon U.S. regulatory approval of the BLA for NexoBrid and up to $125.0 million contingent upon meeting certain sales milestones. The first sales milestone of $7.5 million would be triggered when annual net sales of NexoBrid or improvements to it in North America exceed $75.0 million. As of December 31, 2021, the milestone payments are not yet probable and therefore, not considered a liability. The Company also will pay MediWound tiered royalties on net sales ranging from mid-high single-digit to mid-teen percentages, subject to customary reductions. The Company also entered into a supply agreement with MediWound, under which MediWound will manufacture NexoBrid for the Company on a unit price basis which may be increased based on a published index. MediWound is obligated to supply the Company with NexoBrid for sale in North America on an exclusive basis for the first five years of the term of the supply agreement. After the exclusivity period or upon supply failure, the Company will be permitted to establish an alternate source of supply.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Manufacturing and Supply Agreements Matricel — In October 2015, the Company signed a long-term supply agreement with Matricel GmbH (“Matricel”) for the ACI-Maix collagen membrane used in the manufacture of MACI. The Company and Matricel amended the agreement on March 17, 2018. Under the agreement, the Company has committed to purchase annually approximately $0.6 million per year. The Company has fulfilled this commitment for each of the years ended December 31, 2021, 2020 and 2019, respectively. 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 products and such expiration and termination could have a material effect on the Company’s business. The Company’s purchase commitments consist of minimum purchase amounts of materials used in the Company’s cell manufacturing process to manufacture its marketed cell therapy products. In addition, the Company also pays for usage of an offsite warehouse space. In February 2021, the terms of the warehouse operating agreement were extended through March 31, 2027. Future minimum purchase commitments related to the Company’s contractual obligations are as follows: Payments Due by Period Contractual Obligations (In thousands) Total 2022 2023 2024 2025 2026 More than 5 Years Purchase commitments $ 10,135 $ 9,254 $ 881 $ — $ — $ — $ — Warehouse operating agreement 8,341 1,445 1,513 1,432 1,512 1,601 838 Total $ 18,476 $ 10,699 $ 2,394 $ 1,432 $ 1,512 $ 1,601 $ 838

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 28, 2022, the Company entered into a Lease Agreement (the “Lease”) to lease approximately 126,000 square feet of to-be-constructed manufacturing, laboratory and office space in Burlington, Massachusetts (the “Premises”). Once constructed, the Premises will serve as the Company’s new corporate headquarters and primary manufacturing facility. The term of the Lease is scheduled to begin 12 months following the landlord’s commencement of construction of the core and shell of the building in which the Premises are located, which is currently expected to be February 28, 2023 (the “Commencement Date”). The Company’s obligation to pay rent for the Premises will begin on the earlier of: 13 months from the Commencement Date; or the date on which the Company first occupies the Premises to conduct operations (the “Rent Commencement Date”). The initial term of the Lease is 144 months following the Rent Commencement Date. The Company has a one-time option to extend the term of the Lease for an additional 10 years, exercisable under certain conditions and at a market rate determined in accordance with the Lease. The annual base rent of the Lease is initially $57 per square foot per year, subject to annual increases of 2.5%. Monthly contractual payments are expected to range from $0.6 million to $0.8 million. Additionally, the Company is responsible for reimbursing the landlord for the Company’s share of the Premises’ property taxes and certain other operating expenses. The Lease also provides for a tenant improvement allowance from the landlord in an amount equal to $200 per square foot of the Premises, or approximately $25.1 million, towards the design and construction of certain tenant improvements made to the Premises, subject to the terms set forth in the Lease. In January 2022, in connection with the execution of this Lease, the Company issued a letter of credit collateralized by cash deposits of approximately $6.0 million. Such letter of credit shall be reduced to approximately $4.2 million and $1.8 million at the conclusion of the third and sixth Lease years, respectively, provided certain conditions set forth in the Lease are satisfied.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Principles of Consolidation	The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and accounts have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. The Company is monitoring the potential impact of the ongoing COVID-19 pandemic on its business and the consolidated financial statements. The more significant estimates reflected in the Company’s consolidated financial statements include, but are not limited to, certain judgments regarding revenue recognition, inventory valuation, stock option valuation, deferred tax assets and liabilities and accrued expenses. The Company is not aware of any specific event or circumstance that would require an update to its estimates or judgments reflected in these consolidated financial statements or a revision of the carrying value of its assets or liabilities as of the issuance of these consolidated financial statements. These estimates may change as new events occur and additional information is obtained. Actual results could materially differ from those estimates.
Cash Equivalents	Cash Equivalents Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase and consist primarily of demand deposits, money market funds, overnight repurchase agreements and short duration agency bonds and commercial paper.
Restricted cash	Restricted Cash Amounts included in restricted cash represent those required to be set aside to meet contractual terms of a lease agreement held by the Company.
Investments	Investments Investments classified as short-term have maturities of less than one year. Investments classified as long-term are those that: (i) have a maturity of greater than one year, and (ii) the Company does not intend to liquidate within the next twelve months, although these funds are available for use and, therefore, are classified as available-for-sale. The Company’s investment strategy is to buy short-duration marketable securities with a high credit rating. As of December 31, 2021 and 2020, all marketable securities held by the Company had remaining contractual maturities of three years or less. Unrealized gains are included as a component of accumulated other comprehensive income in the consolidated balance sheets and consolidated statements of shareholders’ equity and a component of total comprehensive (loss) income in the consolidated statements of comprehensive (loss) income, until realized. Unrealized losses are evaluated for impairment under ASC 326 , Financial Instruments - Credit Losses
Leases	Leases The Company determines if an arrangement is a lease at inception, in accordance with ASC Topic 842, Leases . All operating lease commitments with a lease term greater than 12 months are recognized as right-of-use assets and liabilities, on a discounted basis on the balance sheet. Leases with an initial term of 12 months or less are not recorded on the balance sheet. Certain of the Company’s lease agreements include lease payments that are adjusted periodically for an index or rate. The leases are initially measured using the present value of the projected payments adjusted for the index or rate in effect at the commencement date. In addition to rent, the leases may require the Company to pay additional amounts for taxes, insurance, maintenance and other expenses, which do not transfer a good or service to the Company and are generally referred to as non-lease components. Variable non-lease components are not measured as part of the right-of-use asset and liability. Only when lease components and their associated non-lease components are fixed are they accounted for as a single lease component and are recognized as part of a right-of-use asset and liability. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants.
Inventory	Inventory Inventories are measured at the lower of cost or net realizable value. Cost is calculated based upon standard-cost which approximates costs determined on the first-in, first-out method. The Company periodically reviews its inventories for excess or obsolescence and writes down obsolete or other unmarketable inventory to its estimated net realizable value. If the actual net realizable value is less than that estimated by the Company, or if it is determined that inventory utilization will further diminish based on estimates of demand, additional inventory write-downs may be required. In all cases, product inventory is carried at the lower of cost or its estimated net realizable value. Amounts written down are charged to cost of product sales.
Accounts Receivable	Accounts Receivable Accounts receivable are initially recorded at the contractual amount owed by the customer or based on expected payments from the insurance provider, hospital or patient. Allowances for doubtful accounts are established when the facts and circumstances indicate that a receivable may not be collectible. Potential credit risk exposure has been evaluated for the Company’s accounts receivable in accordance with ASC 326 .
Property and Equipment	Property and Equipment, net Property and equipment are initially measured and recognized at acquisition cost, including any directly attributable cost of preparing the asset for its intended use. After initial measurement, property and equipment are carried at cost less accumulated depreciation and impairment. Repair and maintenance costs of property and equipment are expensed as incurred. The depreciable value of property and equipment 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 and equipment are as follows: • Machinery and Equipment: 5 years • Furniture, fixtures, and office equipment: 3 to 5 years • Computer equipment and software: 3 years • Building improvements and leasehold improvements: Shorter of the remaining life of the lease or 10 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.
Revenue Recognition and Net Product Sales	Revenue Recognition and Net Product Sales The Company recognizes product revenue from sales to a customer (whether a distributor, or hospital ) following the five step model in Accounting Standards Codification 606, Revenue Recognition (“ ASC 606”): (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenues when (or as) the Company satisfies the performance obligation. Under this revenue standard, the Company recognizes revenue when its customer obtains control of the promised goods, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods. There are no contractual rights of returns, refunds or similar obligations related to MACI, kits, Epicel or NexoBrid; however, in certain limited cases the Company will accept a product return if a surgery is canceled. Revenue is not recognized in certain canceled cases. For MACI, MACI kits and Epicel there are no variable pricing arrangements related to warranties or rebates offered to customers. The majority of orders are due within 60 to 90 days of delivery. Shipping and handling fees are included as a component of revenue. The Company recognizes any commission fees as an expense when incurred. These fees are included in selling, general, and administrative expenses. See Note 3, “Revenue” for further discussion on revenues.
Research and Development Expense	Research and Development Expense
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 and restricted stock units. The fair value of restricted stock units held by the employees is determined based on the fair value of the Company’s common stock on the date of the grant. Compensation expense is recorded for restricted stock units that are expected to vest over the expected vesting period. The fair value of stock options held by the employees is determined using a Black-Scholes option valuation method. 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’s 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 estimates the expected forfeiture rate and only recognizes 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. For certain non-employee consultants, stock option awards continue to vest post-termination.
Comprehensive (Loss) Income	Comprehensive (Loss) Income Comprehensive (loss) income is the change in shareholders’ equity during a period arising from any gain or loss unrealized related to the Company’s investments.
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 based on the weight of available evidence. When evaluating the realizability of the deferred tax assets, all evidence, both positive and negative, is considered. Items considered when evaluating the need for a valuation allowance include the ability to carry back losses, future reversals of existing temporary differences, tax planning strategies, and expectations of future earnings. The Company records uncertain tax positions in the consolidated financial statements only if it is more likely than not that the uncertain tax position will be sustained upon examination by the taxing authorities. The Company records interest and penalties related to uncertain tax positions in income tax expense.
Net (Loss) Income Per Common Share	Net (Loss) Income Per Common Share
Financial Instruments	Financial Instruments The Company’s financial instruments include accounts receivables, accounts payable and accrued expenses for which the current carrying amounts approximate market value, based upon their short-term nature and marketable debt securities which are classified as available-for-sale and carried at fair value on a settlement date basis.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Standards adopted during the year ended December 31, 2021. Standard Description Effective Date for Company Effect on the consolidated financial statements ASU 2019-12, Simplifying the Accounting for Income Taxes (ASC 740) The ASU enhances and simplifies various aspects of the income tax accounting guidance in ASC 740, including requirements related to hybrid tax regimes, the tax basis step-up in goodwill obtained in a transaction that is not a business combination, separate financial statements of entities not subject to tax, the intra-period tax allocation exception to the incremental approach, ownership changes in investments, changes from a subsidiary to an equity method investment, interim-period accounting for enacted changes in tax law, and the year-to-date loss limitation in interim-period tax accounting. January 1, 2021 The adoption of this standard did not have a material impact on the Company’s consolidated financial statements.

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2021
Risks and Uncertainties [Abstract]
Disaggregation of Revenue	The following table and descriptions below shows the products from which the Company generated its revenue: Year Ended December 31, Revenue by product (in thousands) 2021 2020 2019 MACI implants and kits Implants based on contracted rate sold through a specialty pharmacy (a) $ 71,969 $ 57,593 $ 56,185 Implants subject to third party reimbursement sold through a specialty pharmacy (b) 16,000 16,320 17,076 Implants sold direct based on contracted rates (c) 18,714 15,144 13,933 Implants sold direct subject to third-party reimbursement (d) 2,821 2,754 1,529 Biopsy kits - direct bill 2,194 1,908 2,243 Change in estimates related to prior periods (e) (144) 713 654 Total MACI implants and kits 111,554 94,432 91,620 Epicel Direct bill (hospital) 41,521 27,536 26,230 NexoBrid revenue (f) 3,109 2,211 — Total revenue $ 156,184 $ 124,179 $ 117,850 (a) Represents implants sold through Orsini and AllCare whereby such specialty pharmacies have a direct contract with the underlying insurance provider. The amount of reimbursement is based on contracted rates at the time of sale supported by the pharmacy’s direct contracts. (b) Represents implants sold through Orsini or AllCare whereby such specialty pharmacy does not have a direct contract with the underlying payer. The amount of reimbursement is established based on a payer or state fee schedule and/or payer history. (c) Represents implants sold directly from the Company to the facility based on a contract and known price agreed upon prior to the surgery date. Also represents direct sales under a contract to specialty distributor DMS. (d) Represents implants sold directly from the Company to the facility based on a contract and known price agreed upon prior to the surgery date. The payment terms are subject to third-party reimbursement from an underlying insurance provider. (e) Primarily represents changes in estimates related to implants sold through Orsini or AllCare in which such specialty pharmacy does not have a direct contract with the underlying payer. The initial estimate of the amount of reimbursement is established based on a payer or state fee schedule and/or payer history. The change in estimates is a result of additional information, changes in collection expectations or actual cash collections received in the current period. (f) Represents revenue based on a percentage of gross profits for sales of NexoBrid to BARDA, pursuant to the license agreement between the Company and MediWound.

Selected Balance Sheet Compon_2

Selected Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Schedule of inventory	Inventory as of December 31, 2021 and 2020: (In thousands) 2021 2020 Raw materials $ 12,676 $ 8,775 Work-in-process 644 537 Finished goods 61 44 Total inventory $ 13,381 $ 9,356
Schedule of property and equipment, net	Property and Equipment, net as of December 31, 2021 and 2020: (In thousands) 2021 2020 Machinery and equipment $ 4,522 $ 3,672 Furniture, fixtures and office equipment 1,551 809 Computer equipment and software 7,769 6,846 Leasehold improvements 10,617 5,560 Construction in process 3,097 2,021 Financing right-of-use lease 74 111 Total property and equipment, gross 27,630 19,019 Less accumulated depreciation (14,322) (11,386) Total property and equipment, net $ 13,308 $ 7,633
Schedule of accrued expenses	Accrued Expenses as of December 31, 2021 and 2020: (In thousands) 2021 2020 Bonus related compensation $ 6,305 $ 5,721 Employee related accruals 3,616 3,482 Insurance reimbursement-related liabilities 3,973 2,016 Other accrued expenses 151 74 Total accrued expenses $ 14,045 $ 11,293

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Total leased assets and liabilities	Operating and finance lease assets and liabilities are as follows: December 31, (In thousands) Classification 2021 2020 Assets Operating Right-of-use assets $ 45,720 $ 50,105 Finance Property and equipment, net 73 111 Total leased assets $ 45,793 $ 50,216 Liabilities Current Operating Current portion of operating lease liabilities $ 2,950 $ 4,394 Finance Other current liabilities 41 41 $ 2,991 $ 4,435 Non-current Operating Operating lease liabilities $ 47,147 $ 48,789 Finance Other long-term liabilities 44 76 Total leased liabilities $ 47,191 $ 48,865
Maturity of lease liabilities	Future minimum lease payments under non-cancellable lease as of December 31, 2021 are as follows: (In thousands) Operating Leases Finance Leases Total 2022 $ 2,950 $ 41 $ 2,991 2023 6,634 44 6,678 2024 6,946 — 6,946 2025 6,348 — 6,348 2026 6,530 — 6,530 Thereafter 36,977 — 36,977 Total lease payments $ 66,385 $ 85 $ 66,470 Less: interest (16,288) — (16,288) Present value of lease liabilities $ 50,097 $ 85 $ 50,182
Maturity of lease liabilities	Future minimum lease payments under non-cancellable lease as of December 31, 2021 are as follows: (In thousands) Operating Leases Finance Leases Total 2022 $ 2,950 $ 41 $ 2,991 2023 6,634 44 6,678 2024 6,946 — 6,946 2025 6,348 — 6,348 2026 6,530 — 6,530 Thereafter 36,977 — 36,977 Total lease payments $ 66,385 $ 85 $ 66,470 Less: interest (16,288) — (16,288) Present value of lease liabilities $ 50,097 $ 85 $ 50,182
Lease term and discount rate	Lease terms and discount rates as of December 31, 2021 and 2020 are as follows: December 31, 2021 2020 Weighted-average remaining lease term (years) Operating leases 9.8 10.6 Finance leases 1.5 2.5 Weighted-average discount rate Operating leases 5.4% 5.4% Finance leases 5.0% 5.0%

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2021
Cash and Cash Equivalents [Abstract]
Schedule of fair value of securities, not including cash	The following tables summarize the gross unrealized gains and losses of the Company’s marketable securities as of December 31, 2021 and 2020: December 31, 2021 Gross Unrealized (In thousands) Amortized Cost Gains Losses Credit Losses Estimated Fair Value Commercial paper $ 10,243 $ — $ (12) $ — $ 10,231 Corporate notes 50,666 — (142) — 50,524 $ 60,909 $ — $ (154) $ — $ 60,755 Classified as: Short-term investments $ 35,068 Long-term investments 25,687 $ 60,755 December 31, 2020 Gross Unrealized (In thousands) Amortized Cost Gains Losses Credit Losses Estimated Fair Value Commercial paper $ 8,993 $ 1 $ — $ — $ 8,994 Corporate notes 35,917 — — (6) 35,911 U.S. government securities 12,828 14 — — 12,842 U.S. government agency bonds 5,000 1 — — 5,001 U.S. asset-backed securities 3,534 4 — — 3,538 $ 66,272 $ 20 $ — $ (6) $ 66,286 Classified as: Short-term investments $ 42,187 Long-term investments 24,099 $ 66,286

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Schedule of non-cash stock-based compensation expense	Non-cash stock-based compensation expense (service-based stock options, restricted stock units and employee stock purchase plan) is summarized in the following table: Years Ended December 31, (in thousands) 2021 2020 2019 Cost of product sales $ 3,681 $ 1,949 $ 2,029 Research and development 4,120 1,884 2,428 Selling, general and administrative 26,521 10,010 8,722 Total non-cash stock-based compensation expense $ 34,322 $ 13,843 $ 13,179
Schedule of fair value assumptions	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 assumptions noted in the following table: Year Ended December 31, Service-Based Stock Options 2021 2020 2019 Expected dividend rate —% —% —% Expected stock price volatility 71.5 - 76.7% 71.1 - 78.7% 77.9 - 85.5% Risk-free interest rate 0.53 - 1.5% 0.33 - 1.7% 1.4 - 2.7% Expected life (years) 5.3 - 6.3 5.3 - 6.3 5.3 - 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 (Years) Aggregate Intrinsic Value (Thousands) Outstanding at December 31, 2020 5,236,044 $ 11.34 7.3 $ 102,654 Granted 1,683,568 50.84 Exercised (968,261) 10.25 Expired (12,126) 43.48 Forfeited (269,535) 26.05 Outstanding at December 31, 2021 5,669,690 $ 22.49 7.2 $ 113,985 Exercisable at December 31, 2021 3,169,562 $ 13.07 6.1 $ 86,141
Summary of activity for restricted stock awards	The following table summarizes the activity for restricted stock units for the indicated periods: Restricted Stock Units Number of Restricted Stock Units Weighted-Average Grant Date Fair Value Outstanding at December 31, 2020 270,639 $ 13.57 Granted 266,759 52.07 Vested (98,597) 18.88 Forfeited (40,053) 30.63 Unvested at December 31, 2021 398,748 $ 36.30

Net (Loss) Income Per Common _2

Net (Loss) Income Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2021
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	A summary of net (loss) income per common share is presented below: Year Ended December 31, (Amounts in thousands, except per share amounts) 2021 2020 2019 Net (loss) income $ (7,471) $ 2,864 $ (9,665) Basic weighted-average common shares outstanding 46,472 45,221 44,180 Effect of dilutive stock options and restricted stock units — 2,061 — Diluted weighted-average common shares outstanding 46,472 47,282 44,180 Basic (loss) income per common share $ (0.16) $ 0.06 $ (0.22) Diluted (loss) income per common share $ (0.16) $ 0.06 $ (0.22) Anti-dilutive shares excluded from diluted net (loss) income per common share: Stock options 5,670 2,204 5,053 Restricted stock units 399 — 157

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021 December 31, 2020 Fair value measurement category Fair value measurement category (In thousands) Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 1,258 $ 1,258 $ — $ — $ 3,698 $ 3,698 $ — $ — Commercial paper (a) 18,229 — 18,229 — 8,994 — 8,994 — Corporate notes 50,524 — 50,524 — 35,911 — 35,911 — U.S. government securities — — — — 12,842 — 12,842 — U.S. government agency bonds — — — — 5,001 — 5,001 — U.S. asset-backed securities — — — — 3,538 — 3,538 — $ 70,011 $ 1,258 $ 68,753 $ — $ 69,984 $ 3,698 $ 66,286 $ — (a) Approximately $8.0 million of commercial paper has an original maturity of 90 days or less and is recorded as a cash equivalent as of December 31, 2021.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Summary of income (loss) before income taxes for U.S. and non-U.S. operations	The components of (loss) income before income taxes are summarized as follows: Year Ended December 31, (In thousands) 2021 2020 2019 U.S. $ (7,367) $ 2,767 $ (9,632) Foreign (104) 97 (33) (Loss) income before income taxes $ (7,471) $ 2,864 $ (9,665)
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 U.S. federal statutory rate to the taxes reported in the consolidated statements of operations is as follows: Year Ended December 31, (In thousands) 2021 2020 2019 (Loss) income before income taxes $ (7,471) $ 2,864 $ (9,665) Federal statutory rate 21 % 21 % 21 % Taxes computed at federal statutory rate (1,569) 601 (2,030) State and local income taxes (345) 200 (484) Nondeductible stock-based compensation (4,311) 437 (1,329) Federal and state rate change 47 249 (164) Research and orphan drug credits (413) (8,827) — Other (87) 132 (49) Change in valuation allowance 6,567 7,388 4,056 Reported income taxes $ (111) $ 180 $ —
Schedule of deferred tax assets	Deferred tax assets (liabilities) consist of the following: Year Ended December 31, (In thousands) 2021 2020 Deferred tax assets: Net operating loss carryforwards $ 11,571 $ 8,411 Employee benefits and stock-based compensation 11,470 5,692 Research and development costs 5,059 6,411 Intangible assets 2,544 3,279 Operating lease liabilities 12,822 13,687 Inventory reserve 2,833 3,813 Tax credit carryforward 10,498 10,085 Other, net 13 38 Total deferred tax assets 56,810 51,416 Less: valuation allowance (43,947) (37,379) Total net deferred tax assets 12,863 14,037 Deferred tax liabilities: Right-of-use assets (12,266) (13,463) Property and equipment, net (597) (574) Total net deferred tax liabilities (12,863) (14,037) Net deferred tax assets and liabilities $ — $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum purchase commitments related to contractual obligations	Future minimum purchase commitments related to the Company’s contractual obligations are as follows: Payments Due by Period Contractual Obligations (In thousands) Total 2022 2023 2024 2025 2026 More than 5 Years Purchase commitments $ 10,135 $ 9,254 $ 881 $ — $ — $ — $ — Warehouse operating agreement 8,341 1,445 1,513 1,432 1,512 1,601 838 Total $ 18,476 $ 10,699 $ 2,394 $ 1,432 $ 1,512 $ 1,601 $ 838

Organization (Details)

Organization (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)pharmacysegment	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of products | pharmacy	2
Number of reportable segments | segment	1
Accumulated deficit	$ (383,286)	$ (375,815)
Net income	(7,471)	2,864	$ (9,665)
Cash and cash equivalents	68,330	$ 33,620	$ 26,889
Short term investments	$ 60,800

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2021
Minimum
Property, Plant and Equipment
Duration of lease renewal terms	1 year
Maximum
Property, Plant and Equipment
Duration of lease renewal terms	5 years
Machinery and Equipment
Property, Plant and Equipment
Useful lives (in years)	5 years
Furniture, fixtures and office equipment | Minimum
Property, Plant and Equipment
Useful lives (in years)	3 years
Furniture, fixtures and office equipment | Maximum
Property, Plant and Equipment
Useful lives (in years)	5 years
Computer equipment and software
Property, Plant and Equipment
Useful lives (in years)	3 years
Building improvements and leasehold improvements
Property, Plant and Equipment
Useful lives (in years)	10 years

Revenue - Narrative (Details)

Revenue - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)pharmacy	Dec. 31, 2020USD ($)
Risks and Uncertainties [Abstract]
Number Of Contracted Specialty Pharmacies | pharmacy	2
Allowance for doubtful accounts	$ 7	$ 5.3
Change in estimate of uncollectible (percent)	0.50%
Change in revenue recognized due to 0.5% change in uncollectible percentage	$ 0.3

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Product sales, net	$ 153,075	$ 121,968	$ 117,850
Other revenue	3,109	2,211	0
Total revenue	156,184	124,179	117,850
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Disaggregation of Revenue [Line Items]
Product sales, net	(144)	713	654
M A C I Implants And Kits
Disaggregation of Revenue [Line Items]
Product sales, net	111,554	94,432	91,620
Through Intermediary | Implants | Contract rate
Disaggregation of Revenue [Line Items]
Product sales, net	71,969	57,593	56,185
Through Intermediary | Implants | Time-and-materials contract
Disaggregation of Revenue [Line Items]
Product sales, net	16,000	16,320	17,076
Time-and-materials contract | Implants | Time-and-materials contract
Disaggregation of Revenue [Line Items]
Product sales, net	2,821	2,754	1,529
Provider or Facility | Implants | Contract rate
Disaggregation of Revenue [Line Items]
Product sales, net	18,714	15,144	13,933
Provider or Facility | NexoBrid
Disaggregation of Revenue [Line Items]
Other revenue	3,109	2,211	0
Directly to consumer | Biopsy kits
Disaggregation of Revenue [Line Items]
Product sales, net	2,194	1,908	2,243
Directly to consumer | Epicel
Disaggregation of Revenue [Line Items]
Product sales, net	$ 41,521	$ 27,536	$ 26,230

Revenue - Concentration of risk

Revenue - Concentration of risk (Details)	12 Months Ended
	Dec. 31, 2021
MACI | Revenue Concentration | Customer concentration
Disaggregation of Revenue [Line Items]
Concentration risk (as a percent)	10.00%

Selected Balance Sheet Compon_3

Selected Balance Sheet Components - Schedule of inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Inventory:
Raw materials	$ 12,676	$ 8,775
Work-in-process	644	537
Finished goods	61	44
Total inventory	$ 13,381	$ 9,356

Selected Balance Sheet Compon_4

Selected Balance Sheet Components - Schedule of property and equipment, net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property and equipment, net:
Financing right-of-use lease	$ 74	$ 111
Total property and equipment, gross	27,630	19,019
Less accumulated depreciation	(14,322)	(11,386)
Total property and equipment, net	13,308	7,633
Machinery and equipment
Property and equipment, net:
Total property and equipment, gross	4,522	3,672
Furniture, fixtures and office equipment
Property and equipment, net:
Total property and equipment, gross	1,551	809
Computer equipment and software
Property and equipment, net:
Total property and equipment, gross	7,769	6,846
Leasehold improvements
Property and equipment, net:
Total property and equipment, gross	10,617	5,560
Construction in process
Property and equipment, net:
Total property and equipment, gross	$ 3,097	$ 2,021

Selected Balance Sheet Compon_5

Selected Balance Sheet Components - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization	$ 3	$ 2.4	$ 1.7

Selected Balance Sheet Compon_6

Selected Balance Sheet Components - Schedule of accrued expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accrued expenses
Bonus related compensation	$ 6,305	$ 5,721
Employee related accruals	3,616	3,482
Insurance reimbursement-related liabilities	3,973	2,016
Other accrued expenses	151	74
Total accrued expenses	$ 14,045	$ 11,293

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Millions	Oct. 21, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Short-term lease costs (less than)		$ 0.1	$ 0.1
Operating lease expense		7.3	6.3	$ 5.4
Finance lease expense		0.1	0.1	0.1
Measurement of lease liability		6	$ 5.8	$ 5
Cambridge, Massachusetts
Lessee, Lease, Description [Line Items]
Tenant improvement allowance		$ 4.3
Cambridge, Massachusetts | Minimum
Lessee, Lease, Description [Line Items]
Monthly contractual lease payments	$ 0.4
Cambridge, Massachusetts | Maximum
Lessee, Lease, Description [Line Items]
Monthly contractual lease payments	$ 0.6

Leases - Assets And Liabilities

Leases - Assets And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets
Operating	$ 45,720	$ 50,105
Finance	73	111
Total leased assets	45,793	50,216
Current
Operating	2,950	4,394
Finance	41	41
Lease liability current	2,991	4,435
Non-current
Operating	47,147	48,789
Finance	44	76
Total leased liabilities	$ 47,191	$ 48,865
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property and equipment, net	Property and equipment, net
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other current liabilities	Other current liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other long-term liabilities	Other long-term liabilities

Leases - Maturities of lease li

Leases - Maturities of lease liabilities (Details) $ in Thousands	Dec. 31, 2021USD ($)
Operating Leases
2022	$ 2,950
2023	6,634
2024	6,946
2025	6,348
2026	6,530
Thereafter	36,977
Total	66,385
Less: interest	(16,288)
Present value of lease liabilities	50,097
Finance Leases
2022	41
2023	44
2024	0
2025	0
2026	0
Thereafter	0
Total lease payments	85
Less: interest	0
Present value of lease liabilities	85
2022	2,991
2023	6,678
2024	6,946
2025	6,348
2026	6,530
Thereafter	36,977
Total lease payments	66,470
Less: interest	(16,288)
Present value of lease liabilities	$ 50,182

Leases - Lease term and discoun

Leases - Lease term and discount rate (Details)	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Weighted-average remaining lease term - Operating lease term	9 years 9 months 18 days	10 years 7 months 6 days
Weighted-average remaining lease term - Finance lease term	1 year 6 months	2 years 6 months
Weighted-average discount rate - Operating lease discount rate	5.40%	5.40%
Weighted-average discount rate - Finance lease discount rate	5.00%	5.00%

Investments - Schedule of fair

Investments - Schedule of fair value of securities, not including cash (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Marketable Securities [Line Items]
Amortized Cost	$ 60,909	$ 66,272
Gains	0	20
Losses	(154)	0
Credit Losses	0	(6)
Estimated Fair Value	60,755	66,286
Short-term investments
Marketable Securities [Line Items]
Estimated Fair Value	35,068	42,187
Long-term investments
Marketable Securities [Line Items]
Estimated Fair Value	25,687	24,099
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	10,243	8,993
Gains	0	1
Losses	(12)	0
Credit Losses	0	0
Estimated Fair Value	10,231	8,994
Corporate notes
Marketable Securities [Line Items]
Amortized Cost	50,666	35,917
Gains	0	0
Losses	(142)	0
Credit Losses	0	(6)
Estimated Fair Value	$ 50,524	35,911
U.S. government securities
Marketable Securities [Line Items]
Amortized Cost		12,828
Gains		14
Losses		0
Credit Losses		0
Estimated Fair Value		12,842
U.S. government agency bonds
Marketable Securities [Line Items]
Amortized Cost		5,000
Gains		1
Losses		0
Credit Losses		0
Estimated Fair Value		5,001
U.S. asset-backed securities
Marketable Securities [Line Items]
Amortized Cost		3,534
Gains		4
Losses		0
Credit Losses		0
Estimated Fair Value		$ 3,538

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Credit Losses	$ 0	$ 0

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended			81 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2021
Stock-Based Compensation
Expected to vest (in shares)	5,359,392
Total unrecognized compensation cost	$ 36
Intrinsic value of stock options exercised	$ 39.5	$ 10.5	$ 16.1
Prior Plans
Stock-Based Compensation
Awards available for future grant under the Plan (in shares)	0
Omnibus Incentive Plan 2019
Stock-Based Compensation
Awards available for future grant under the Plan (in shares)	2,822,710
Stock options
Stock-Based Compensation
Expiration period	10 years
Vesting period	4 years
Weighted average grant-date fair value (in dollars per share)	$ 32.96	$ 8.86	$ 12.62
Weighted average period over which unrecognized compensation is expected to be recognized	3 years
Restricted stock units
Stock-Based Compensation
Weighted average grant-date fair value (in dollars per share)	$ 52.07	$ 11.41	$ 17.71
Weighted average period over which unrecognized compensation is expected to be recognized	2 years 10 months 24 days
Unrecognized compensation cost	$ 8.8
Fair value of vested awards	$ 5.3	$ 0.6
Vested (in shares)	98,597
Restricted stock units | Awarded annually | Nonemployee directors
Stock-Based Compensation
Vesting period	1 year
Restricted stock units | Awarded upon initial appointment to the BOD | Nonemployee directors
Stock-Based Compensation
Vesting period	3 years
Employee stock
Stock-Based Compensation
Common stock available for issuance (in shares)	1,000,000
Common stock granted since inception (in shares)				745,655

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of non-cash stock-based compensation expense (Details) - Employee stock purchase plan and service-based stock options - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	$ 34,322	$ 13,843	$ 13,179
Cost of product sales
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	3,681	1,949	2,029
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	4,120	1,884	2,428
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	$ 26,521	$ 10,010	$ 8,722

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of fair value assumptions (Details) - Stock options	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-Based Compensation
Expected dividend rate	0.00%	0.00%	0.00%
Minimum
Stock-Based Compensation
Expected stock price volatility	71.50%	71.10%	77.90%
Risk-free interest rate	0.53%	0.33%	1.40%
Expected life (years)	5 years 3 months 18 days	5 years 3 months 18 days	5 years 3 months 18 days
Maximum
Stock-Based Compensation
Expected stock price volatility	76.70%	78.70%	85.50%
Risk-free interest rate	1.50%	1.70%	2.70%
Expected life (years)	6 years 3 months 18 days	6 years 3 months 18 days	6 years 3 months 18 days

Stock-Based Compensation - Sc_3

Stock-Based Compensation - Schedule of activity for service-based stock options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Options
Outstanding at the beginning of the period (in shares)	5,236,044
Granted (in shares)	1,683,568
Exercised (in shares)	(968,261)
Expired (in shares)	(12,126)
Forfeited (in shares)	(269,535)
Outstanding at the end of the period (in shares)	5,669,690	5,236,044
Exercisable at the end of the period (in shares)	3,169,562
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 11.34
Granted (in dollars per share)	50.84
Exercised (in dollars per share)	10.25
Expired (in dollars per share)	43.48
Forfeited (in dollars per share)	26.05
Outstanding at the end of the period (in dollars per share)	22.49	$ 11.34
Exercisable at the end of the period (in dollars per share)	$ 13.07
Weighted Average Remaining Contractual Term
Outstanding	7 years 2 months 12 days	7 years 3 months 18 days
Exercisable at end of period	6 years 1 month 6 days
Aggregate Intrinsic Value
Outstanding	$ 113,985	$ 102,654
Exercisable at end of period	$ 86,141

Stock-Based Compensation - Sc_4

Stock-Based Compensation - Schedule of restricted stock awards activity (Details) - Restricted stock units	12 Months Ended
	Dec. 31, 2021$ / sharesshares
Number of Restricted Stock Units
Outstanding at beginning of period (in shares) | shares	270,639
Granted (in shares) | shares	266,759
Vested (in shares) | shares	(98,597)
Forfeited (in shares) | shares	(40,053)
Unvested at end of period (in shares) | shares	398,748
Weighted-Average Grant Date Fair Value
Unvested at beginning of period (in usd per share) | $ / shares	$ 13.57
Granted (in usd per share) | $ / shares	52.07
Vested (in usd per share) | $ / shares	18.88
Forfeited (in usd per share) | $ / shares	30.63
Unvested at end of period (in usd per share) | $ / shares	$ 36.30

Net (Loss) Income Per Common _3

Net (Loss) Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net Income (Loss) Attributable to Parent [Abstract]
Net (loss) income	$ (7,471)	$ 2,864	$ (9,665)
Basic weighted-average common shares outstanding (in shares)	46,472	45,221	44,180
Effect of dilutive stock options and restricted stock units (in shares)	0	2,061	0
Diluted weighted-average common shares outstanding (in shares)	46,472	47,282	44,180
Basic (loss) income per common share (in USD per share)	$ (0.16)	$ 0.06	$ (0.22)
Diluted (loss) income per common share (in USD per share)	$ (0.16)	$ 0.06	$ (0.22)
Stock options
Anti-dilutive shares excluded from diluted net (loss) income per common share:
Anti-dilutive shares excluded from the calculation of diluted earnings per share (in shares)	5,670	2,204	5,053
Restricted stock units
Anti-dilutive shares excluded from diluted net (loss) income per common share:
Anti-dilutive shares excluded from the calculation of diluted earnings per share (in shares)	399	0	157

Shareholders' Equity - Narrativ

Shareholders' Equity - Narrative (Details) $ in Millions	Aug. 27, 2021USD ($)
Shareholders' Equity
At the market offering, sales agreement, expiration period	3 years
At The Market
Shareholders' Equity
Sale Of stock authorized value	$ 200

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	$ 60,755	$ 66,286
Corporate notes
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	50,524	35,911
U.S. government securities
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value		12,842
U.S. government agency bonds
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value		5,001
Asset-backed Securities
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value		3,538
Recurring
Liabilities that are measured at fair value on a recurring basis
Assets, fair value	70,011	69,984
Recurring | Level 1
Liabilities that are measured at fair value on a recurring basis
Assets, fair value	1,258	3,698
Recurring | Level 2
Liabilities that are measured at fair value on a recurring basis
Assets, fair value	68,753	66,286
Recurring | Level 3
Liabilities that are measured at fair value on a recurring basis
Assets, fair value	0	0
Recurring | Commercial Paper
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	18,229	8,994
Recurring | Commercial Paper | Level 1
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	0
Recurring | Commercial Paper | Level 2
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	18,229	8,994
Recurring | Commercial Paper | Level 3
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	0
Recurring | Commercial Paper | Cash and Cash Equivalents
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	8,000
Recurring | Corporate notes
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	50,524	35,911
Recurring | Corporate notes | Level 1
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	0
Recurring | Corporate notes | Level 2
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	50,524	35,911
Recurring | Corporate notes | Level 3
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	0
Recurring | U.S. government securities
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	12,842
Recurring | U.S. government securities | Level 1
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	0
Recurring | U.S. government securities | Level 2
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	12,842
Recurring | U.S. government securities | Level 3
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	0
Recurring | U.S. government agency bonds
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	5,001
Recurring | U.S. government agency bonds | Level 1
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	0
Recurring | U.S. government agency bonds | Level 2
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	5,001
Recurring | U.S. government agency bonds | Level 3
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	0
Recurring | Asset-backed Securities
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	3,538
Recurring | Asset-backed Securities | Level 1
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	0
Recurring | Asset-backed Securities | Level 2
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	3,538
Recurring | Asset-backed Securities | Level 3
Liabilities that are measured at fair value on a recurring basis
Debt securities, fair value	0	0
Recurring | Money market funds
Liabilities that are measured at fair value on a recurring basis
Money market funds	1,258	3,698
Recurring | Money market funds | Level 1
Liabilities that are measured at fair value on a recurring basis
Money market funds	1,258	3,698
Recurring | Money market funds | Level 2
Liabilities that are measured at fair value on a recurring basis
Money market funds	0	0
Recurring | Money market funds | Level 3
Liabilities that are measured at fair value on a recurring basis
Money market funds	$ 0	$ 0

Income Taxes - Components of In

Income Taxes - Components of Income (Loss) Before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
(Loss) income before income taxes	$ (7,471)	$ 2,864	$ (9,665)
U.S.
Operating Loss Carryforwards [Line Items]
(Loss) income before income taxes	(7,367)	2,767	(9,632)
Foreign
Operating Loss Carryforwards [Line Items]
(Loss) income before income taxes	$ (104)	$ 97	$ (33)

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of income taxes computed using the federal statutory rate to the taxes reported in consolidated statements of operations
(Loss) income before income taxes	$ (7,471)	$ 2,864	$ (9,665)
Federal statutory rate	21.00%	21.00%	21.00%
Taxes computed at federal statutory rate	$ (1,569)	$ 601	$ (2,030)
State and local income taxes	(345)	200	(484)
Nondeductible stock-based compensation	(4,311)	437	(1,329)
Federal and state rate change	47	249	(164)
Research and orphan drug credits	(413)	(8,827)	0
Other	(87)	132	(49)
Change in valuation allowance	6,567	7,388	4,056
Reported income taxes	(111)	180	$ 0
Deferred tax assets:
Net operating loss carryforwards	11,571	8,411
Employee benefits and stock-based compensation	11,470	5,692
Research and development costs	5,059	6,411
Intangible assets	2,544	3,279
Operating lease liabilities	12,822	13,687
Inventory reserve	2,833	3,813
Tax credit carryforward	10,498	10,085
Other, net	13	38
Total deferred tax assets	56,810	51,416
Less: valuation allowance	(43,947)	(37,379)
Total net deferred tax assets	12,863	14,037
Deferred tax liabilities:
Right-of-use assets	(12,266)	(13,463)
Property and equipment, net	(597)	(574)
Total net deferred tax liabilities	(12,863)	(14,037)
Net deferred tax assets and liabilities	$ 0	$ 0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Profit (loss) from operations	$ (7,854)	$ 2,372	$ (11,251)
Projected annual limitation on the use of the net operating losses that existed prior to September 17, 2014	800
General business tax credit carryforward	10,498	10,085
Increase (decrease) in valuation allowance	6,600	$ 7,400
Federal | Internal Revenue Service
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	44,300
Profit (loss) from operations	6,400			$ 1,500
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 29,300

Employee Savings Plan (Details)

Employee Savings Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Retirement Benefits [Abstract]
Defined contribution plan, tax status [Extensible Enumeration]	Qualified Plan [Member]
Contributions made under 401(k) savings plan	$ 1	$ 0.8	$ 0.7

NexoBrid License and Supply A_2

NexoBrid License and Supply Agreements (Details) - MediWound Ltd - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	May 31, 2019
Related Party Transaction [Line Items]
Consideration paid		$ 17.5
Contingent consideration		7.5
Max contingent consideration		125
Sales Initial milestone		$ 75
Supply commitment period	5 years

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended
	Oct. 31, 2015	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Purchase obligation, annual commitment	$ 600	$ 9,254
Purchase obligation, renewal option, term	5 years
Purchase obligation, automatic renewal, term	5 years

Commitments and Contingencies_2

Commitments and Contingencies - Future Minimum Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Oct. 31, 2015
Purchase commitments
Total	$ 10,135
2022	9,254	$ 600
2023	881
2024	0
2025	0
2026	0
More than 5 Years	0
Operating Leases
Total	8,341
2022	1,445
2023	1,513
2024	1,432
2025	1,512
2026	1,601
More than 5 Years	838
Contractual Obligation, Fiscal Year Maturity [Abstract]
Contractual Obligation, Total	18,476
2022	10,699
2023	2,394
2024	1,432
2025	1,512
2026	1,601
More than 5 Years	$ 838

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent event - 25 Network Drive, Burlington, Massachusetts ft² in Thousands, $ in Millions	Jan. 28, 2022USD ($)ft²uSDollarPerSquareFoot	Jan. 31, 2022USD ($)
Subsequent Event [Line Items]
Area of real estate property | ft²	126
Lease option to extend term	10 years
Annual lease per square foot | uSDollarPerSquareFoot	57
Annual lease base rent square subject to increase percentage	2.50%
Tenant improvement allowance per square foot | uSDollarPerSquareFoot	200
Tenant improvement allowance	$ 25.1
Letter of credit cash deposit		$ 6
Letter of credit cash deposit lease year three		4.2
Letter of credit cash deposit lease year four		$ 1.8
Minimum
Subsequent Event [Line Items]
Monthly contractual lease payments	0.6
Maximum
Subsequent Event [Line Items]
Monthly contractual lease payments	$ 0.8