CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		288 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013
Revenues:
Product sales and rentals	$ 8	$ 2	$ 1,906
Research and development agreements			2,105
Grants			9,901
Total revenues	8	2	13,912
Costs and expenses:
Cost of product sales and rentals	2	2	3,049
Research and development	5,538	6,796	222,268
Selling, general and administrative	1,633	1,762	94,231
Total costs and expenses	7,173	8,560	319,548
Loss from operations	(7,165)	(8,558)	(305,636)
Other income (expense):
(Increase) decrease in fair value of warrants	1,619	(900)	18,156
Other income			1,249
Interest income	5	6	10,827
Interest expense	(3)	(3)	(494)
Total other income (expense)	1,621	(897)	29,738
Net loss	(5,544)	(9,455)	(275,898)
Accretion of convertible preferred stock	1,263	289	6,224
Net loss attributable to common shareholders	$ (6,807)	$ (9,744)	$ (282,122)
Net loss per share attributable to common shareholders (Basic and Diluted) (in dollars per share)	$ (0.15)	$ (0.25)
Weighted average number of common shares outstanding (Basic and Diluted)	44,864	38,742