Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 34,948	$ 55,673
Short-term investments	9,706	6,162
Accounts receivable	788	712
Inventory	309	336
Prepaid expenses and other current assets	1,844	1,432
Total current assets	47,595	64,315
Non-current assets:
Property and equipment, net	16,528	13,736
Operating lease right-of-use assets	4,960
Intangible assets, net	873	924
Goodwill	278	278
Other assets	378	913
Total non-current assets	23,017	15,851
TOTAL ASSETS	70,612	80,166
Current liabilities:
Accounts payable and accrued expenses	5,344	6,508
Other current liabilities	2,550	316
Current portion of long-term note payable	529	529
Deferred revenue	90	170
Total current liabilities	8,513	7,523
Long-term note payable, net	494	479
Operating lease liabilities	3,566
Other long-term liabilities	1,446	131
Total liabilities	14,019	8,133
Commitments and Contingencies
STOCKHOLDERS' EQUITY:
Preferred stock - 25,000,000 shares authorized, 0 shares issued and outstanding at March 31, 2019 and December 31, 2018
Common stock - $.001 par value; 250,000,000 shares authorized; 21,749,239 and 21,447,088 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	22	21
Additional paid-in capital	424,955	414,840
Accumulated other comprehensive income	53	36
Accumulated deficit	(368,437)	(342,864)
Total stockholders' equity	56,593	72,033
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 70,612	$ 80,166