Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 21,732	$ 28,821
Marketable securities	6,178	6,179
Accounts receivable	64	143
Inventory	37	37
Prepaid expenses and other current assets	4,100	3,672
Total current assets	32,111	38,852
Restricted cash	58	58
Operating lease right-of-use assets	4,046	4,168
Property and equipment, net	8,854	9,263
TOTAL ASSETS	45,069	52,341
Current liabilities:
Accounts payable	1,645	1,504
Accrued liabilities	3,905	3,720
Operating lease obligations, current portion	599	576
Finance lease obligations, current portion	7	27
Notes payable, current portion	14,987	14,627
Convertible notes payable, current portion	5,042	4,876
Total current liabilities	26,185	25,330
Operating lease obligations, net of current portion	4,720	4,903
Notes payable, net of current portion	1,820	1,894
Convertible notes payable, net of current portion	5,265	5,258
Common stock warrant liabilities	2,790	1,481
Clene Nanomedicine contingent earn-out liability	22	75
Initial Stockholders contingent earn-out liability	3	10
TOTAL LIABILITIES	40,805	38,951
Commitments and contingencies (Note 9)
Stockholders’ equity:
Common stock, $0.0001 par value: 300,000,000 and 300,000,000 shares authorized at March 31, 2024 and December 31, 2023, respectively; 128,433,721 and 128,422,851 shares issued and outstanding at March 31, 2024 and December 31, 2023, respectively	13	13
Additional paid-in capital	257,914	255,901
Accumulated deficit	(253,803)	(242,723)
Accumulated other comprehensive income	140	199
TOTAL STOCKHOLDERS’ EQUITY	4,264	13,390
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 45,069	$ 52,341