Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 1,222	$ 2,408
Marketable securities	1,989	3,460
Accounts receivable	98
Assets held for sale	764	764
Prepaid expenses and other current assets	607	309
Total current assets	4,680	6,941
Property and equipment, net	9,022	9,514
Patent and trademark rights, net	860	872
Other assets	1,546	1,546
Total assets	16,108	18,873
Current liabilities:
Accounts payable	972	887
Accrued expenses	1,771	1,548
Total current liabilities	2,743	2,435
Long- term debt
Note payable	517
Redeemable warrants	2,516	940
Commitments and contingencies (Note 6)
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 28,957,668 and 24,202,921, respectively	29	24
Additional paid-in capital	316,307	315,980
Accumulated other comprehensive income (loss)	18	(5)
Accumulated deficit	(306,022)	(300,501)
Total stockholders’ equity	10,332	15,498
Total liabilities and stockholders’ equity	$ 16,108	$ 18,873