Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 503	$ 2,408
Marketable securities	1,800	3,460
Accounts receivable	42
Assets held for sale	764	764
Prepaid expenses and other current assets	626	309
Total current assets	3,735	6,941
Property and equipment, net	8,795	9,514
Patent and trademark rights, net	860	872
Other assets	1,335	1,546
Total assets	14,725	18,873
Current liabilities:
Accounts payable	460	887
Accrued expenses	1,740	1,548
Total current liabilities	2,200	2,435
Long- term
Note payable	1,466
Redeemable warrants	1,018	940
Commitments and contingencies (Note 6 and Note 13)
Stockholders’ equity:
Preferred stock, par value $0.01 per share, authorized 5,000,000; issued and outstanding; none
Common stock, par value $0.001 per share, authorized 350,000,000 shares; issued and outstanding 31,077,372 and 24,202,921, respectively	31	24
Additional paid-in capital	316,748	315,980
Accumulated other comprehensive income (loss)	29	(5)
Accumulated deficit	(306,767)	(300,501)
Total stockholders’ equity	10,041	15,498
Total liabilities and stockholders’ equity	$ 14,725	$ 18,873