Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 45,887	$ 55,673
Short-term investments	12,342	6,162
Accounts receivable	1,336	712
Inventory	362	336
Prepaid expenses and other current assets	1,918	1,432
Total current assets	61,845	64,315
Non-current assets:
Property and equipment, net	16,200	13,736
Operating lease right-of-use assets	5,454
Intangible assets, net	825	924
Goodwill	278	278
Other assets	353	913
Total non-current assets	23,110	15,851
TOTAL ASSETS	84,955	80,166
Current liabilities:
Accounts payable and accrued expenses	5,977	6,508
Other current liabilities	2,646	316
Current portion of long-term note payable	538	529
Deferred revenue	44	170
Total current liabilities	9,205	7,523
Long-term note payable, net	236	479
Operating lease liabilities	3,833
Other long-term liabilities	1,315	131
Total liabilities	14,589	8,133
Commitments and Contingencies
STOCKHOLDERS' EQUITY:
Preferred stock - 25,000,000 shares authorized, 0 shares issued and outstanding at June 30, 2019 and December 31, 2018
Common stock - $.001 par value; 250,000,000 shares authorized; 25,218,606 and 21,447,088 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	25	21
Additional paid-in capital	461,491	414,840
Accumulated other comprehensive income	79	36
Accumulated deficit	(391,229)	(342,864)
Total stockholders' equity	70,366	72,033
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 84,955	$ 80,166