CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		291 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013
Revenues:
Product sales and rentals	$ 3		$ 11	$ 2	$ 1,909
Research and development agreements					2,105
Grants					9,901
Total revenues	3		11	2	13,915
Costs and expenses:
Cost of product sales and rentals	1		3	2	3,050
Research and development	3,676	7,069	9,214	13,865	225,944
Selling, general and administrative	1,560	2,231	3,193	3,993	95,791
Total costs and expenses	5,237	9,300	12,410	17,860	324,785
Loss from operations	(5,234)	(9,300)	(12,399)	(17,858)	(310,870)
Other income (expense):
Decrease in fair value of warrants	345	1,948	1,964	1,048	18,501
Other income					1,249
Interest income	3	20	8	26	10,830
Interest expense	(3)	(3)	(6)	(6)	(497)
Total other income	345	1,965	1,966	1,068	30,083
Net loss	(4,889)	(7,335)	(10,433)	(16,790)	(280,787)
Accretion of convertible preferred stock		1,231	1,263	1,520	6,224
Net loss attributable to common shareholders	$ (4,889)	$ (8,566)	$ (11,696)	$ (18,310)	$ (287,011)
Net loss per share attributable to common shareholders (Basic and Diluted) (in dollars per share)	$ (0.11)	$ (0.22)	$ (0.26)	$ (0.47)
Weighted average number of common shares outstanding (Basic and Diluted)	45,664	38,882	45,266	38,812