CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
OPERATING ACTIVITIES:
Net loss	$ (8,149)	$ (5,067)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	929	933
Amortization of deferred financing costs	15	30
Interest expense recorded as additional revenue interest obligation	660	663
Stock-based compensation	1,105	677
Changes in operating assets and liabilities:
Accounts receivable	(14)	(1,596)
Inventory	(309)	(101)
Prepaid expenses and other	(1,580)	465
Accounts payable and accrued expenses	(492)	(1,387)
Obligations to tissue suppliers	417	276
Deferred revenue and other liabilities	68	(67)
Net cash used in operating activities	(7,350)	(5,174)
INVESTING ACTIVITIES:
Expenditures for property, plant and equipment	(34)	(131)
Net cash used in investing activities	(34)	(131)
FINANCING ACTIVITIES:
Proceeds from Private Placement, net of offering costs	(110)
Net borrowings (repayments) under revolving line of credit	1,397	(3,064)
Proceeds from stock option exercises		3
Repayments of long-term debt	(1,667)
Payments on revenue interest obligation	(681)	(665)
Proceeds from sales of common stock through Employee Stock Purchase Plan	192
Net cash used in financing activities	(869)	(3,726)
Net decrease in cash and restricted cash	(8,253)	(9,031)
Cash and restricted cash, beginning of period	30,428	39,532
Cash and restricted cash, end of period	22,175	30,501
Supplemental Cash Flow and Non-Cash Financing Activities Disclosures:
Cash paid for interest	$ 1,162	$ 1,243