Note 1 - Basis of Presentation and Summary of Significant Accounting Policies (Details Textual) - USD ($)			1 Months Ended
	May 18, 2018	Mar. 28, 2018	Jun. 30, 2018	Dec. 31, 2017
Units Issued, Price per Unit	$ 0.60
Proceeds from Issuance or Sale of Equity, Total	$ 5,500,000
Proceeds from Issuance or Sale of Equity, Net	4,819,000
Payments of Stock Issuance Costs	$ 681,000	$ 171,000
Common Stock, Par or Stated Value Per Share	$ 0.001		$ 0.001	$ 0.001
Cash and Cash Equivalents, at Carrying Value, Ending Balance			$ 3,071,000	$ 3,513,000
Working Capital			5,006,000
Retained Earnings (Accumulated Deficit), Ending Balance			$ (217,337,000)	$ (187,640,000)
Common Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.60
Warrants and Rights Outstanding, Term	5 years
Units [Member]
Number of Units Issued	6,475,001
Convertible Units, Number of Common Shares Called by Each Unit	1
Convertible Units, Number of Common Warrants Called by Each Unit	1
Units [Member] | Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right	1
Pre-funded Units [member]
Number of Units Issued	2,691,666
Convertible Units, Number of Common Warrants Called by Each Unit	1
Convertible Units, Number of Pre-funded Warrants Called by Each Unit	1
Number of Units Exercised			2,691,666
Pre-funded Units [member] | Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right	1
Pre-funded Units [member] | Pre-funded Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right	1
Boyalife Investment Fund II, Inc. [Member] | Revolving Credit Facility [Member]
Long-term Line of Credit, Total			$ 7,200,000
Line of Credit Facility, Maximum Borrowing Capacity			$ 10,000,000