Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues
Revenues	$ 5,633	$ 24,291	$ 3,708
Costs and expenses
Research and development (including stock compensation expense of $2,217, $1,609 and $1,232 in 2019, 2018 and 2017, respectively)	39,045	38,656	27,841
General and administrative (including stock compensation expense of $2,634, $2,240 and $1,812 in 2019, 2018 and 2017, respectively)	11,378	10,442	8,466
Depreciation	698	855	684
Total costs and expenses	51,121	49,953	36,991
Gain from insurance proceeds, net	0	617	0
Loss from operations	(45,488)	(25,045)	(33,283)
Income from change in fair value of warrants, net	0	0	728
Other income, net	906	762	314
Net loss and comprehensive loss	$ (44,582)	$ (24,283)	$ (32,241)
Net loss per common share, basic and diluted (in dollars per share)	$ (0.29)	$ (0.18)	$ (0.29)
Weighted average shares outstanding, basic and diluted (in shares)	151,696	136,641	112,053
Royalty and other contract revenue
Revenues
Revenues	$ 0	$ 1,461	$ 1,925
Grant revenue
Revenues
Revenues	116	554	865
Healios \| Contract revenue
Revenues
Revenues	$ 5,517	$ 22,276	$ 918

The amount of costs and expenses before other expenses.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

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