Background and Basis of Presentation	3 Months Ended
Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation	Background and Basis of Presentation Background: We are an international biotechnology company focused in the field of regenerative medicine and operate in one business segment. Our operations consist of research, preclinical development and clinical development activities, and our most advanced program is in Phase 3 clinical development. We have incurred losses since our inception in 1995 and had an accumulated deficit of $433.3 million at March 31, 2020, and we will not commence sales of our clinical product candidates until they receive regulatory approval for commercialization. We will require significant additional capital to continue our research and development programs, including progressing our clinical product candidates to commercialization and preparing for commercial-scale manufacturing and sales. At March 31, 2020, we had available cash and cash equivalents of $32.7 million. In April 2020, we completed an underwritten public offering of common stock generating gross proceeds of approximately $57.6 million. Also, in March 2020, HEALIOS K.K. (“Healios”), our collaborator in Japan, elected to exercise its warrant in full, and we generated proceeds of approximately $7.0 million received in April 2020. We believe that these recent proceeds combined with our cash on hand, expected cash receipts primarily attributed to our collaboration with Healios and proceeds from the equity facility that we have in place are sufficient to meet our obligations as they come due at least for a period of twelve months from the date of the issuance of these unaudited condensed consolidated financial statements. We expect that our near-term milestones and clinical trial results, including the results of Healios’ clinical trials, will have a significant impact, favorable or unfavorable, on our ability to access capital from potential third-party commercial partners or the equity capital markets. Depending on the outcome of these milestones and clinical trial results, we may accelerate, defer or stage the timing of certain programs until we become cash flow positive from the sales of our clinical products, if they are approved for marketing. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2019. The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and Regulation S-X. Accordingly, since they are interim statements, the accompanying financial statements do not include all of the information and notes required by GAAP for complete financial statements. The accompanying financial statements reflect all adjustments, consisting of normal recurring adjustments, that are, in the opinion of management, necessary for a fair presentation of financial position and results of operations for the interim periods presented. Interim results are not necessarily indicative of results for a full year. Use of Estimates: The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Our critical accounting policies, estimates and assumptions are described in “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” which is included in this Quarterly Report on Form 10-Q.

Background and Basis of Presentation

Background: We are an international biotechnology company focused in the field of regenerative medicine and operate in one business segment. Our operations consist of research, preclinical development and clinical development activities, and our most advanced program is in Phase 3 clinical development.

We have incurred losses since our inception in 1995 and had an accumulated deficit of $433.3 million at March 31, 2020, and we will not commence sales of our clinical product candidates until they receive regulatory approval for commercialization. We will require significant additional capital to continue our research and development programs, including progressing our clinical product candidates to commercialization and preparing for commercial-scale manufacturing and sales. At March 31, 2020, we had available cash and cash equivalents of $32.7 million. In April 2020, we completed an underwritten public offering of common stock generating gross proceeds of approximately $57.6 million. Also, in March 2020, HEALIOS K.K. (“Healios”), our collaborator in Japan, elected to exercise its warrant in full, and we generated proceeds of approximately $7.0 million received in April 2020. We believe that these recent proceeds combined with our cash on hand, expected cash receipts primarily attributed to our collaboration with Healios and proceeds from the equity facility that we have in place are sufficient to meet our obligations as they come due at least for a period of twelve months from the date of the issuance of these unaudited condensed consolidated financial statements. We expect that our near-term milestones and clinical trial results, including the results of Healios’ clinical trials, will have a significant impact, favorable or unfavorable, on our ability to access capital from potential third-party commercial partners or the equity capital markets. Depending on the outcome of these milestones and clinical trial results, we may accelerate, defer or stage the timing of certain programs until we become cash flow positive from the sales of our clinical products, if they are approved for marketing.

The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2019. The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and Regulation S-X. Accordingly, since they are interim statements, the accompanying financial statements do not include all of the information and notes required by GAAP for complete financial statements. The accompanying financial statements reflect all adjustments, consisting of normal recurring adjustments, that are, in the opinion of management, necessary for a fair presentation of financial position and results of operations for the interim periods presented. Interim results are not necessarily indicative of results for a full year.

Use of Estimates: The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Our critical accounting policies, estimates and assumptions are described in “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” which is included in this Quarterly Report on Form 10-Q.