Athersys, Inc / New (ATHXQ) 10-Q 7 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Aug. 02, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Registrant Name	ATHERSYS, INC / NEW
Entity Central Index Key	0001368148
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		152,677,751

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 44,237	$ 51,059
Prepaid expenses and other	849	1,791
Total current assets	48,074	57,840
Equipment, net	3,062	3,002
Deposits and other	2,111	888
Total assets	53,247	61,730
Current liabilities:
Accounts payable	10,527	9,163
Accrued compensation and related benefits	814	1,901
Accrued clinical trial related costs	2,469	1,276
Accrued expenses and other	869	461
Total current liabilities	14,681	15,475
Other long-term liabilities	273	0
Stockholders’ equity:
Preferred stock, at stated value; 10,000,000 shares authorized, and no shares issued and outstanding at June 30, 2019 and December 31, 2018	0	0
Common stock, $0.001 par value; 300,000,000 shares authorized, and 151,777,751 and 144,292,739 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	152	144
Additional paid-in capital	428,785	416,014
Accumulated deficit	(395,686)	(373,042)
Total stockholders’ equity	33,251	43,116
Total liabilities and stockholders’ equity	53,247	61,730
Consolidated entity excluding, related party
Current assets:
Accounts receivable	80	262
Healios
Current assets:
Accounts receivable	1,778	1,108
Unbilled accounts receivable from Healios	1,130	3,620
Current liabilities:
Deposit from Healios	0	2,000
Deferred revenue	2	674
Advance from Healios	$ 5,042	$ 3,139

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	151,777,751	144,292,739
Common stock, shares outstanding (in shares)	151,777,751	144,292,739

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive (Loss) Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues
Revenues	$ 4,262	$ 19,391	$ 5,707	$ 20,457
Costs and expenses
Research and development	11,139	10,093	22,554	18,943
General and administrative	2,867	2,382	5,973	5,038
Depreciation	157	191	341	376
Total costs and expenses	14,163	12,666	28,868	24,357
Gain from insurance proceeds	0	20	0	383
(Loss) income from operations	(9,901)	6,745	(23,161)	(3,517)
Other income, net	213	188	517	295
Net (loss) income and comprehensive (loss) income	$ (9,688)	$ 6,933	$ (22,644)	$ (3,222)
Net (loss) income per share, basic (in dollars per share)	$ (0.06)	$ 0.05	$ (0.15)	$ (0.02)
Weighted average shares outstanding, basic (in shares)	150,163	138,225	148,075	132,592
Net (loss) income per share, diluted (in dollars per share)	$ (0.06)	$ 0.05	$ (0.15)	$ (0.02)
Weighted average shares outstanding, diluted (in shares)	150,163	139,375	148,075	132,592
Royalty and other contract revenue
Revenues
Revenues	$ 0	$ 591	$ 0	$ 992
Grant revenue
Revenues
Revenues	69	45	73	362
Healios | Contract revenue
Revenues
Revenues	$ 4,193	$ 18,755	$ 5,634	$ 19,103

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Consolidated entity excluding, related party	Consolidated entity excluding, related partyCommon Stock	Consolidated entity excluding, related partyAdditional Paid-in Capital	Healios	HealiosCommon Stock	HealiosAdditional Paid-in Capital
Preferred stock shares, beginning balance (in shares) at Dec. 31, 2017		0
Common stock, beginning balance (in shares) at Dec. 31, 2017			122,077,453
Beginning balance at Dec. 31, 2017	$ 23,376	$ 0	$ 122	$ 373,884	$ (350,630)
Stock-based compensation	813			813
Issuance of warrant to Healios at fair value	5,300			5,300
Issuance of common stock, net of issuance costs (in shares)							3,750,000			12,000,000
Issuance of common stock, net of issuance cost						$ 5,416	$ 4	$ 5,412	$ 20,995	$ 12	$ 20,983
Issuance of common stock under equity compensation plan (in shares)			131,092
Issuance of common stock under equity compensation plan	(84)			(84)
Cumulative effect of accounting change	1,871				1,871
Net comprehensive income (loss)	(10,155)				(10,155)
Preferred stock shares, ending balance (in shares) at Mar. 31, 2018		0
Common stock, ending balance (in shares) at Mar. 31, 2018			137,958,545
Ending balance at Mar. 31, 2018	47,532	$ 0	$ 138	406,308	(358,914)
Preferred stock shares, beginning balance (in shares) at Dec. 31, 2017		0
Common stock, beginning balance (in shares) at Dec. 31, 2017			122,077,453
Beginning balance at Dec. 31, 2017	23,376	$ 0	$ 122	373,884	(350,630)
Net comprehensive income (loss)	(3,222)
Preferred stock shares, ending balance (in shares) at Jun. 30, 2018		0
Common stock, ending balance (in shares) at Jun. 30, 2018			138,583,673
Ending balance at Jun. 30, 2018	56,249	$ 0	$ 139	408,091	(351,981)
Preferred stock shares, beginning balance (in shares) at Mar. 31, 2018		0
Common stock, beginning balance (in shares) at Mar. 31, 2018			137,958,545
Beginning balance at Mar. 31, 2018	47,532	$ 0	$ 138	406,308	(358,914)
Stock-based compensation	824			824
Issuance of common stock, net of issuance costs (in shares)							500,000
Issuance of common stock, net of issuance cost						1,215	$ 1	1,214	$ (149)		$ (149)
Issuance of common stock under equity compensation plan (in shares)			125,128
Issuance of common stock under equity compensation plan	(106)			(106)
Net comprehensive income (loss)	6,933				6,933
Preferred stock shares, ending balance (in shares) at Jun. 30, 2018		0
Common stock, ending balance (in shares) at Jun. 30, 2018			138,583,673
Ending balance at Jun. 30, 2018	$ 56,249	$ 0	$ 139	408,091	(351,981)
Preferred stock shares, beginning balance (in shares) at Dec. 31, 2018	0	0
Common stock, beginning balance (in shares) at Dec. 31, 2018	144,292,739		144,292,739
Beginning balance at Dec. 31, 2018	$ 43,116	$ 0	$ 144	416,014	(373,042)
Stock-based compensation	1,090			1,090
Issuance of common stock, net of issuance costs (in shares)							3,825,000
Issuance of common stock, net of issuance cost						5,607	$ 4	5,603
Issuance of common stock under equity compensation plan (in shares)			158,494
Issuance of common stock under equity compensation plan	(69)			(69)
Net comprehensive income (loss)	(12,956)				(12,956)
Preferred stock shares, ending balance (in shares) at Mar. 31, 2019		0
Common stock, ending balance (in shares) at Mar. 31, 2019			148,276,233
Ending balance at Mar. 31, 2019	$ 36,788	$ 0	$ 148	422,638	(385,998)
Preferred stock shares, beginning balance (in shares) at Dec. 31, 2018	0	0
Common stock, beginning balance (in shares) at Dec. 31, 2018	144,292,739		144,292,739
Beginning balance at Dec. 31, 2018	$ 43,116	$ 0	$ 144	416,014	(373,042)
Net comprehensive income (loss)	$ (22,644)
Preferred stock shares, ending balance (in shares) at Jun. 30, 2019	0	0
Common stock, ending balance (in shares) at Jun. 30, 2019	151,777,751		151,777,751
Ending balance at Jun. 30, 2019	$ 33,251	$ 0	$ 152	428,785	(395,686)
Preferred stock shares, beginning balance (in shares) at Mar. 31, 2019		0
Common stock, beginning balance (in shares) at Mar. 31, 2019			148,276,233
Beginning balance at Mar. 31, 2019	36,788	$ 0	$ 148	422,638	(385,998)
Stock-based compensation	1,152			1,152
Issuance of common stock, net of issuance costs (in shares)							3,350,000
Issuance of common stock, net of issuance cost						$ 5,106	$ 4	$ 5,102
Issuance of common stock under equity compensation plan (in shares)			151,518
Issuance of common stock under equity compensation plan	(107)			(107)
Net comprehensive income (loss)	$ (9,688)				(9,688)
Preferred stock shares, ending balance (in shares) at Jun. 30, 2019	0	0
Common stock, ending balance (in shares) at Jun. 30, 2019	151,777,751		151,777,751
Ending balance at Jun. 30, 2019	$ 33,251	$ 0	$ 152	$ 428,785	$ (395,686)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating activities
Net loss	$ (22,644)	$ (3,222)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	341	376
Stock-based patent license and settlement expense	0	315
Stock-based compensation	2,242	1,637
Discount on revenue from issuance of warrant	0	1,080
Deferred revenue from prior period	0	(250)
Changes in operating assets and liabilities:
Prepaid expenses, deposits and other	677	(2,014)
Accounts payable and accrued expenses	1,192	6,267
Net cash used in operating activities	(16,959)	(1,286)
Investing activities
Purchases of equipment	(400)	(749)
Net cash used in investing activities	(400)	(749)
Financing activities
Shares retained for withholding tax payments on stock-based awards	(176)	(191)
Net cash provided by financing activities	10,537	26,072
(Decrease) increase in cash and cash equivalents	(6,822)	24,037
Cash and cash equivalents at beginning of the period	51,059	29,316
Cash and cash equivalents at end of the period	44,237	53,353
Consolidated entity excluding, related party
Changes in operating assets and liabilities:
Accounts receivable	182	41
Financing activities
Proceeds from issuance of common stock, net	10,713	5,416
Healios
Changes in operating assets and liabilities:
Accounts receivable	1,820	(8,649)
Deferred revenue - Healios	(672)	1,402
Advances and deposits from Healios	(97)	1,731
Financing activities
Proceeds from issuance of common stock, net	$ 0	$ 20,847

Background and Basis of Present

Background and Basis of Presentation	6 Months Ended
	Jun. 30, 2019
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 that is focused primarily in the field of regenerative medicine and operate in one business segment. Our operations consist of research and clinical-stage product development activities. We have incurred losses since our inception in 1995 and had an accumulated deficit of $395.7 million at June 30, 2019 . We will require additional capital to continue our research and development programs, including progressing our clinical product candidates to commercialization and preparing for commercial-scale manufacturing. At June 30, 2019 , we had available cash and cash equivalents of $44.2 million . We believe that these funds, expected cash receipts primarily attributed to our collaboration with HEALIOS K.K. (“Healios”) and proceeds from our equity facility and our open market sale agreement 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. In the longer term, we will have to continue to generate additional capital to meet our needs through new and existing collaborations and related license fees and milestones, the sale of equity securities from time to time including through our equity facilities, grant-funding opportunities, deferring certain discretionary costs and staging certain development costs, as needed. 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, 2018 . The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and Article 10 of 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.

Recently Issued Accounting Stan

Recently Issued Accounting Standards	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Recently Issued Accounting Standards	Recently Issued Accounting Standards In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-15, Intangibles-Goodwill and Other-Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract (“ASU 2018-15”) . ASU 2018-15 requires implementation costs incurred by customers in cloud computing arrangements (i.e., hosting arrangements) to be capitalized under the same premises of authoritative guidance for internal-use software and deferred over the noncancellable term of the cloud computing arrangements plus any option renewal periods that are reasonably certain to be exercised by the customer or for which the exercise is controlled by the service provider. The guidance is effective for the annual and interim periods beginning after December 15, 2019, with early adoption permitted. We are currently evaluating the potential impact of adoption of this standard on our consolidated financial statements, and we do not intend to early adopt. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurements (“Topic 820”): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement , which adds, modifies and removes several disclosure requirements relative to the three levels of inputs used to measure fair value in accordance with Topic 820, Fair Value Measurement . This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year. Early adoption is permitted. We are currently assessing the effect that this ASU will have on our disclosures. In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (“Topic 808”): Clarifying the Interaction between Topic 808 and Topic 606 . The amendments in this update (i) clarify that certain transactions between collaborative arrangement participants should be accounted for as revenue under Topic 606 when the collaborative arrangement participant is a customer in the context of a unit of account and in those situations, all the guidance in Topic 606 should be applied, including recognition, measurement, presentation and disclosure requirements; (ii) add unit-of-account guidance in Topic 808 to align with the guidance in Topic 606 (that is, a distinct good or service) when an entity is assessing whether the collaborative arrangement or a part of the arrangement is within the scope of Topic 606; and (iii) require that in a transaction with a collaborative arrangement participant that is not directly related to sales to third parties, presenting the transaction together with revenue recognized under Topic 606 is precluded if the collaborative arrangement participant is not a customer. The provisions of ASU 2018-18 are effective for years beginning after December 15, 2019, with early adoption permitted. We are currently evaluating the impact of this clarifying guidance. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), and subsequently issued additional guidance that modified ASU 2016-13. ASU 2016-13 and the subsequent modifications are identified as Accounting Standards Codification (“ASC”) 326. The standard requires an entity to change its accounting approach in determining impairment of certain financial instruments, including trade receivables, from an “incurred loss” to a “current expected credit loss” model. The standard will be effective for fiscal years beginning after December 15, 2019, including interim periods within such fiscal years. Early adoption is permitted. We are currently assessing the effect that ASC 326 will have on our financial position, results of operations and disclosures and monitoring the FASB's evaluation of potential deferment of the adoption date for smaller reporting companies.

Leases Adoption

Leases Adoption	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Leases Adoption	Leases Adoption In February 2016, the FASB issued ASU 2016-02, Leases (“Topic 842”), which requires lessees to record most leases with a term greater than 12 months on their balance sheets, but recognize expenses on their statement of operations in a manner similar to current accounting practice. Under the guidance, lessees initially recognize a lease liability for the obligation to make lease payments and a right-of-use (“ROU”) asset for the right to use the underlying asset for the lease term. The lease liability is measured at the present value of the lease payments over the lease term. The ROU asset is measured at the lease liability amount, adjusted for lease prepayments, lease incentives received and the lessee’s initial direct costs. We adopted Topic 842 effective January 1, 2019, using the modified retrospective transition option. The adoption of the standard resulted in the recording of ROU assets, primarily consisting of operating leases of facilities and minor equipment, and lease liabilities of $1.0 million as of the commencement date. The adoption did not have a material impact on our unaudited condensed consolidated statements of operations and comprehensive loss or cash flows related to existing leases. As a result, there was no cumulative-effect adjustment. We elected certain practical expedients as part of the adoption, which allow us to not reassess our prior conclusions about lease identification, lease classification and initial direct costs. We also elected the short-term lease recognition exemption for all leases that qualify and will not recognize ROU assets or lease liabilities for those leases. Lastly, we elected to separate lease and non-lease components only for contract manufacturing assets based on an assessment of the contract terms. We did not separate lease and non-lease components for all other existing asset classes. Most leases do not contain an implicit discount rate, therefore we estimate our incremental borrowing rate to discount the lease payments based on information available at lease commencement. Our facilities leases contain one or more options to renew after the noncancellable term. The exercise of lease renewal options is not reasonably certain upon lease commencement and is at management's sole discretion. Our ROU assets are included within deposits and other in our unaudited condensed consolidated balance sheet at June 30, 2019 . Associated lease liabilities are included in accrued expenses and other, and other long-term liabilities in our unaudited condensed consolidated balance sheet at June 30, 2019 . Lease expense for lease payments is recognized on a straight-line basis over the lease term within loss from operations on the unaudited condensed consolidated statements of operations and comprehensive loss. Payments for certain lease agreements are adjusted annually for changes in an index or rate. We had no finance leases, residual value guarantees, restrictive covenants, subleases or sale leasebacks at June 30, 2019 . As of June 30, 2019 , ROU assets and lease liabilities were each $0.7 million. The weighted-average remaining term for lease contracts was 1.8 years at June 30, 2019 , with maturities ranging from 12 months to 56 months. The weighted-average discount rate was 5.3% at June 30, 2019 . We paid $0.1 million and $0.2 million for operating leases included in the measurement of lease liabilities during the three and six month periods ended June 30, 2019 , respectively. Aside from facilities and minor equipment, we have various supply agreements with third-party manufacturers, which involve the lease of manufacturing facilities and equipment, as defined in Topic 842. We have elected to separate lease and non-lease components for these arrangements. These manufacturing agreements have variable lease payments, which typically become binding once certain manufacturing milestones are achieved, and as such, are not included in ROU assets and liabilities until such payments are no longer variable. Lease Costs The table below presents certain information related to the lease costs (in thousands) for operating leases as of June 30, 2019 : Three months ended June 30, 2019 Six months ended Operating lease cost $ 122 $ 242 Short-term lease cost 11 22 Variable lease cost (1) 52 157 Total lease cost $ 185 $ 421 (1) Includes lease components from our third-party manufacturing agreements. Undiscounted Cash Flows The following table summarizes future minimum lease payments (in thousands) for noncancellable operating leases as of June 30, 2019 : 2019 (1) $ 246 2020 407 2021 101 2022 14 2023 12 Thereafter 2 Total minimum lease payments 782 Less: amount of lease payments representing interest 37 Present value of operating lease liabilities $ 745 (1) Excluding the six months ended June 30, 2019 .

Net Loss per Share

Net Loss per Share	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per Share Basic and diluted net loss per share have been computed using the weighted-average number of shares of common stock outstanding during the period. We have outstanding stock-based awards that are not used in the calculation of diluted net loss per share because to do so would be anti-dilutive. In connection with the purchase of shares of our common stock by Healios in March 2018, a warrant was issued to Healios (the “Healios Warrant”) to purchase up to 20,000,000 shares of common stock (the “Warrant Shares”), of which 16,000,000 Warrant Shares expired as of June 30, 2019 prior to being exercisable. The exercise price of Healios' 4,000,000 Warrant Shares is contractually stated to exceed the market price and is therefore anti-dilutive as of June 30, 2019 . Refer to Note 7 for additional details. The following instruments (in thousands) were excluded from the calculation of diluted net loss per share because their effects would be antidilutive: Three months ended Six months ended 2019 2018 2019 2018 Stock-based awards 16,791 5,939 16,791 12,847 Healios Warrant – see Note 7 4,000 20,000 4,000 20,000 Total 20,791 25,939 20,791 32,847

Collaborative Arrangements and

Collaborative Arrangements and Revenue Recognition	6 Months Ended
	Jun. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Arrangements and Revenue Recognition	Collaborative Arrangements and Revenue Recognition Healios Collaboration In 2016, we entered into a licensing collaboration with Healios to develop and commercialize our cell therapy technologies for certain disease indications in Japan, among other things. The collaboration was expanded in June 2018 to include additional indications and licenses, with the core programs under development in Japan being ischemic stroke and acute respiratory distress syndrome (“ARDS”). We received nonrefundable license fee payments from Healios and are entitled to royalties on net sales. We also have the right to receive development and commercial milestone payments from Healios, subject to certain potential credits that have been negotiated from time-to-time associated with modifications to the arrangement. Under the collaboration, Healios is responsible for the development and commercialization of the licensed products in the licensed territories, and we provide certain services to Healios for which we are paid. In 2017, our agreement for clinical product supply services was amended to clarify a cost-sharing arrangement associated with our supply of clinical material for Healios' stroke trial, and certain adjustments were made to potential milestone payments that Healios may owe us in the future. Also, in 2017, we entered into a technology transfer services agreement with Healios, pursuant to which Healios provides financial support to establish a contract manufacturer in Japan to manufacture product for Healios. Both clinical supply and technology transfer services to Healios are ongoing and are modified from time-to-time to include, for example, expanded indications and manufacturing-related services. Healios Revenue Recognition At the inception of the Healios arrangement and again each time that the arrangement is modified, all material performance obligations are identified, which currently include (i) licenses to our technology, (ii) product supply services, and (iii) services to transfer technology to a contract manufacturer on Healios’ behalf. It was determined that these performance obligations are separate and distinct within the context of the contract. We develop assumptions that require judgment to determine the standalone selling price in order to account for our collaborative agreements, as these assumptions typically include probabilities of obtaining marketing approval for the product candidates, estimated timing of commercialization, estimated future cash flows from potential product sales of our product candidates, estimating the cost and markup of providing product supply and technical services, and appropriate discount rates. In order to determine the transaction price, in addition to the fixed payments, we estimate the amount of variable consideration utilizing the expected value or most likely amount method, depending on the facts and circumstances relative to the contract, and the estimates for variable consideration are reassessed each reporting period. We constrain, or reduce, the estimates of variable consideration if it is probable that a significant reversal of previously recognized revenue could occur throughout the life of the contract, and both the likelihood and magnitude of a potential reversal of revenue are taken into consideration. At inception and upon each modification date, once the estimated transaction price is established, amounts are allocated to each separate performance obligation on a relative standalone selling price basis. These performance obligations include any remaining, undelivered elements at the time of modifications and any new elements from a modification to the arrangement if the conditions are not met for being treated as a separate agreement. For performance obligations satisfied over time, we apply an appropriate method of measuring progress each reporting period and, if necessary, adjust the estimates of performance and the related revenue recognition. Our technology transfer services are satisfied over time, and we recognize revenue in proportion to the contractual services provided. For performance obligations satisfied at a point in time (i.e., product supply), we recognize revenue upon delivery, as defined. The remaining transaction price for the performance obligations that were not yet delivered amounted to $1.5 million at June 30, 2019 , which is expected to be recognized within one year as the goods and services are delivered. At June 30, 2019 , the contract liability, included in Deferred revenue - Healios on the unaudited condensed consolidated balance sheets, is properly classified as a current liability since the rights to consideration are expected to be satisfied, in all material respects, within one year. Deposit from Healios In connection with the June 2018 expansion, Healios obtained an exclusive, time-limited right of first negotiation (“ROFN Period”) to enter into an option for a license to develop and commercialize certain MultiStem treatments in China. In December 2018, the ROFN Period was extended to June 30, 2019 in exchange for a $2.0 million nonrefundable payment from Healios, which was recorded as a deposit from Healios on the unaudited condensed consolidated balance sheet until June 2019, when the ROFN Period expired. In June 2019, this extension payment was included in the transaction price of the overall Healios arrangement and was allocated to the performance obligations as of the related June 2018 expansion. As a result, $1.9 million of the extension payment was recognized as revenue in June 2019 and the remaining $0.1 million will be recognized as the remaining undelivered performance obligations are delivered. Refer to Note 7 regarding the equity investment in us made by Healios in 2018 in connection with the June 2018 expansion. Advance from Healios In 2017, in connection with our amendment to the clinical supply agreement to clarify the cost-sharing arrangement, the proceeds from Healios that relate specifically to the cost-sharing arrangement may either (i) result in a reduction in the proceeds we receive from Healios upon the achievement of two potential milestones and an increase to a commercial milestone under the license agreement for stroke or (ii) be repaid to Healios at our election, as defined. The cost-sharing proceeds received are recognized in advance from Healios on the unaudited condensed consolidated balance sheet until the earlier of the milestones being achieved or such amounts being repaid to Healios at our election, at which time, the culmination of the earnings process will be complete and revenue will be recognized. Disaggregation of Revenues We recognize license-related amounts, including upfront payments, exclusivity fees, additional disease indication fees and milestones at a point in time when earned. Similarly, product supply revenue is recognized at a point in time, while service revenue (e.g., technology transfer) is recognized when earned over time. The following table presents our contract revenues disaggregated by timing of revenue recognition and excludes royalty revenue (in thousands): Three months ended Three months ended Point in Time Over Time Point in Time Over Time Contract Revenue from Healios License fee revenue $ 1,624 $ — $ 17,530 $ — Product supply revenue 905 — 223 — Service revenue — 1,664 — 1,002 Other contract revenue — — 250 — Total disaggregated revenues $ 2,529 $ 1,664 $ 18,003 $ 1,002 Six months ended Six months ended Point in Time Over Time Point in Time Over Time Contract Revenue from Healios License fee revenue $ 1,624 $ — $ 17,530 $ — Product supply revenue 1,871 — 450 — Service revenue — 2,139 — 1,123 Other contract revenue — — 250 — Total disaggregated revenues $ 3,495 $ 2,139 $ 18,230 $ 1,123

Stock-based Compensation

Stock-based Compensation	6 Months Ended
	Jun. 30, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based Compensation	Stock-based Compensation The Athersys, Inc. 2019 Equity and Incentive Compensation Plan (the “EICP”) authorizes an aggregate of approximately 18,500,000 shares of common stock for awards to employees, directors and consultants. The EICP was approved in June 2019 and replaced our prior long-term incentive plan. In the three-month period ended June 30, 2019 , we granted 3,245,800 stock options and 1,350,150 restricted stock units to our employees and directors primarily in connection with our annual incentive programs. The EICP authorizes the issuance of stock-based compensation in the form of stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares and units, and other stock-based awards. As of June 30, 2019 , a total of 13,867,787 shares were available for issuance under our EICP, and stock-based awards to purchase 16,780,535 shares of common stock were outstanding under our current and former equity incentive plans. For the three-month periods ended June 30, 2019 and 2018 , stock-based compensation expense was approximately $1.2 million and $0.8 million , respectively. At June 30, 2019 , total unrecognized estimated compensation cost related to unvested stock-based awards was approximately $ 11.6 million which is expected to be recognized by the end of 2023 using the straight-line method.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2019
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Equity Issuance—Healios In March 2018, Healios purchased 12,000,000 shares of our common stock for $21.1 million , or approximately $1.76 per share, and the Healios Warrant to purchase up to an additional 20,000,000 shares. In connection with this investment, we entered into an Investor Rights Agreement that governs certain rights of Healios and us relating to Healios’ ownership of our common stock. As a result of Healios’ investment, Healios became a related party, and the transactions with Healios are separately identified within these financial statements as related party transactions. At the time of the investment in March 2018, the 20,000,000 Warrant Shares would not become exercisable until the planned collaboration expansion was completed, which at that time included an option to commercialize in China. At the time of the June 2018 expansion, however, the parties had not reached agreement on the option so Athersys agreed to provide Healios with a right of first negotiation with respect to the option, and therefore, the parties bifurcated the Healios Warrant so that 4,000,000 Warrant Shares became exercisable with the June 2018 expansion and the remaining 16,000,000 Warrant Shares would only become exercisable if Healios agrees to execute an option for a license in China. As of June 30, 2019, the 16,000,000 contingent Warrant Shares expired according to their terms, since an option for a license in China was not executed. The 4,000,000 Warrant Shares are exercisable at the greater of $1.76 and a defined reference price, which is generally 110% of the average closing price per share of our common stock for the ten previous trading days. The 4,000,000 Warrant Shares are subject to a general expiration date in September 2020 , as defined, and an exercise cap triggered at Healios’ ownership of 19.9% of our common stock, and may be terminated by us under certain conditions. The value of the Healios Warrant was considered as an element of compensation in the transaction price of the Healios collaboration expansion. We evaluated the various terms of the Healios Warrant and concluded that it was accounted for as an equity instrument at inception and $5.3 million was computed as the best estimate of the fair value of the Healios Warrant at the time of issuance in March 2018. The fair value was computed using a Monte Carlo simulation model that included probability-weighted estimates of potential milestone points in time that could impact the value of the Healios Warrant during its term. The fair value was recorded as additional paid-in capital in the first quarter of 2018, with the offset being included in other assets, which would be included as an element of compensation in the transaction price upon the consummation of the expansion that was planned at the time of the March 2018 investment. Upon the modification of the Healios Warrant in June 2018 in connection with the expansion of the collaboration that included the bifurcation of the Healios Warrant due to the change related to China rights, we reassessed the fair value of the Healios Warrant immediately before and after the modification using the same valuation methodology, which resulted in no incremental fair value to be recorded. The value of the 4,000,000 tranche of Warrant Shares that became exercisable upon the June 2018 expansion of $1.1 million was recorded as a reduction to the revenue recognized for the delivered licenses in June 2018. However, since the June 2018 expansion agreements made the 16,000,000 Warrant Shares contingent on entering into an option for a license in China, we considered the ability to apply the $4.2 million value of such Warrant Shares as an element of compensation to be constrained. Therefore, the remaining $4.2 million asset was reversed against additional paid-in-capital. Equity Purchase Agreement We have had equity purchase agreements in place since 2011 with Aspire Capital Fund LLC (“Aspire Capital”) that provide us the ability to sell shares to Aspire Capital from time to time. The current agreement with Aspire Capital was entered into in February 2018 and includes Aspire Capital’s commitment to purchase up to an aggregate of $100.0 million of shares of our common stock over a three -year period. The terms of the 2018 equity facility are similar to the previous arrangements, and we issued 450,000 shares of our common stock to Aspire Capital as a commitment fee in February 2018 and filed a registration statement for the resale of 24,700,000 shares of common stock in connection with the new equity facility. Also in connection with this equity facility, in February 2018, Aspire Capital invested $1.0 million in us at $2.00 per share of common stock. We sold 3,350,000 shares to Aspire Capital at an average price of $1.52 in the second quarter of 2019 , generating proceeds of $5.1 million . We sold 7,175,000 shares to Aspire Capital at an average price of $1.49 per share during the six months ended June 30, 2019, generating proceeds of $10.7 million . We did not sell shares to Aspire Capital in the second quarter of 2018 . We sold 3,300,000 shares to Aspire Capital at an average price of $1.67 per share during the six months ended June 30, 2018, generating proceeds of $5.5 million . Open Market Sale Agreement In May 2019, we entered into an open market sale agreement with Jefferies LLC (“Jefferies”), as sales agent, pursuant to which we may offer and sell, from time to time, through Jefferies, shares of our common stock having an aggregate offering price of up to $50.0 million . The shares will be offered and sold pursuant to our effective “shelf” registration on Form S-3 that is on file with the SEC. We did not sell any shares of our common stock under this agreement during the quarter ended June 30, 2019. License Agreement and Settlement In 2017, we entered into an agreement to settle longstanding intellectual property disagreements with a third party, paid $0.5 million and issued 1,000,000 shares of our common stock with a fair value of $2.3 million in 2017 and received a license to certain intellectual property. In 2018, we paid an additional $1.0 million and issued 500,000 shares of our common stock related to a patent issuance. There are no royalty, milestone or other payments due to the third party associated with the development and commercialization of our cell therapy products, and our payment obligations are concluded.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We have United States (“U.S.”) federal net operating loss and research and development tax credit carryforwards, as well as state and city net operating loss carryforwards, which may be used to reduce future taxable income and tax liabilities. We also have foreign net operating loss and tax credit carryforwards, and the foreign net operating loss carryforwards do not expire. All of our deferred tax assets have been fully offset by a valuation allowance due to our cumulative losses. The carrying value of our deferred tax assets and liabilities is determined by the enacted U.S. corporate income tax rate. Consequently, any changes in the U.S. corporate income tax rate impacts the carrying value of our deferred tax assets and liabilities. Also, there are significant limitations on our ability to utilize our net operating loss and tax credit carryforwards under Section 382 of the Internal Revenue Code of 1986, as amended.

Recently Issued Accounting St_2

Recently Issued Accounting Standards (Policies)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Recently Issued Accounting Standards	In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-15, Intangibles-Goodwill and Other-Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract (“ASU 2018-15”) . ASU 2018-15 requires implementation costs incurred by customers in cloud computing arrangements (i.e., hosting arrangements) to be capitalized under the same premises of authoritative guidance for internal-use software and deferred over the noncancellable term of the cloud computing arrangements plus any option renewal periods that are reasonably certain to be exercised by the customer or for which the exercise is controlled by the service provider. The guidance is effective for the annual and interim periods beginning after December 15, 2019, with early adoption permitted. We are currently evaluating the potential impact of adoption of this standard on our consolidated financial statements, and we do not intend to early adopt. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurements (“Topic 820”): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement , which adds, modifies and removes several disclosure requirements relative to the three levels of inputs used to measure fair value in accordance with Topic 820, Fair Value Measurement . This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year. Early adoption is permitted. We are currently assessing the effect that this ASU will have on our disclosures. In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (“Topic 808”): Clarifying the Interaction between Topic 808 and Topic 606 . The amendments in this update (i) clarify that certain transactions between collaborative arrangement participants should be accounted for as revenue under Topic 606 when the collaborative arrangement participant is a customer in the context of a unit of account and in those situations, all the guidance in Topic 606 should be applied, including recognition, measurement, presentation and disclosure requirements; (ii) add unit-of-account guidance in Topic 808 to align with the guidance in Topic 606 (that is, a distinct good or service) when an entity is assessing whether the collaborative arrangement or a part of the arrangement is within the scope of Topic 606; and (iii) require that in a transaction with a collaborative arrangement participant that is not directly related to sales to third parties, presenting the transaction together with revenue recognized under Topic 606 is precluded if the collaborative arrangement participant is not a customer. The provisions of ASU 2018-18 are effective for years beginning after December 15, 2019, with early adoption permitted. We are currently evaluating the impact of this clarifying guidance. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), and subsequently issued additional guidance that modified ASU 2016-13. ASU 2016-13 and the subsequent modifications are identified as Accounting Standards Codification (“ASC”) 326. The standard requires an entity to change its accounting approach in determining impairment of certain financial instruments, including trade receivables, from an “incurred loss” to a “current expected credit loss” model. The standard will be effective for fiscal years beginning after December 15, 2019, including interim periods within such fiscal years. Early adoption is permitted. We are currently assessing the effect that ASC 326 will have on our financial position, results of operations and disclosures and monitoring the FASB's evaluation of potential deferment of the adoption date for smaller reporting companies.
Leases Adoption	In February 2016, the FASB issued ASU 2016-02, Leases (“Topic 842”), which requires lessees to record most leases with a term greater than 12 months on their balance sheets, but recognize expenses on their statement of operations in a manner similar to current accounting practice. Under the guidance, lessees initially recognize a lease liability for the obligation to make lease payments and a right-of-use (“ROU”) asset for the right to use the underlying asset for the lease term. The lease liability is measured at the present value of the lease payments over the lease term. The ROU asset is measured at the lease liability amount, adjusted for lease prepayments, lease incentives received and the lessee’s initial direct costs. We adopted Topic 842 effective January 1, 2019, using the modified retrospective transition option. The adoption of the standard resulted in the recording of ROU assets, primarily consisting of operating leases of facilities and minor equipment, and lease liabilities of $1.0 million as of the commencement date. The adoption did not have a material impact on our unaudited condensed consolidated statements of operations and comprehensive loss or cash flows related to existing leases. As a result, there was no cumulative-effect adjustment. We elected certain practical expedients as part of the adoption, which allow us to not reassess our prior conclusions about lease identification, lease classification and initial direct costs. We also elected the short-term lease recognition exemption for all leases that qualify and will not recognize ROU assets or lease liabilities for those leases. Lastly, we elected to separate lease and non-lease components only for contract manufacturing assets based on an assessment of the contract terms. We did not separate lease and non-lease components for all other existing asset classes. Most leases do not contain an implicit discount rate, therefore we estimate our incremental borrowing rate to discount the lease payments based on information available at lease commencement. Our facilities leases contain one or more options to renew after the noncancellable term. The exercise of lease renewal options is not reasonably certain upon lease commencement and is at management's sole discretion. Our ROU assets are included within deposits and other in our unaudited condensed consolidated balance sheet at June 30, 2019 . Associated lease liabilities are included in accrued expenses and other, and other long-term liabilities in our unaudited condensed consolidated balance sheet at June 30, 2019 . Lease expense for lease payments is recognized on a straight-line basis over the lease term within loss from operations on the unaudited condensed consolidated statements of operations and comprehensive loss. Payments for certain lease agreements are adjusted annually for changes in an index or rate. We had no finance leases, residual value guarantees, restrictive covenants, subleases or sale leasebacks at June 30, 2019 . As of June 30, 2019 , ROU assets and lease liabilities were each $0.7 million. The weighted-average remaining term for lease contracts was 1.8 years at June 30, 2019 , with maturities ranging from 12 months to 56 months. The weighted-average discount rate was 5.3% at June 30, 2019 . We paid $0.1 million and $0.2 million for operating leases included in the measurement of lease liabilities during the three and six month periods ended June 30, 2019 , respectively. Aside from facilities and minor equipment, we have various supply agreements with third-party manufacturers, which involve the lease of manufacturing facilities and equipment, as defined in Topic 842. We have elected to separate lease and non-lease components for these arrangements. These manufacturing agreements have variable lease payments, which typically become binding once certain manufacturing milestones are achieved, and as such, are not included in ROU assets and liabilities until such payments are no longer variable.

Leases Adoption (Tables)

Leases Adoption (Tables)	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Components of Lease Costs	The table below presents certain information related to the lease costs (in thousands) for operating leases as of June 30, 2019 : Three months ended June 30, 2019 Six months ended Operating lease cost $ 122 $ 242 Short-term lease cost 11 22 Variable lease cost (1) 52 157 Total lease cost $ 185 $ 421 (1) Includes lease components from our third-party manufacturing agreements.
Future Minimum Lease Payments for Operating Leases	The following table summarizes future minimum lease payments (in thousands) for noncancellable operating leases as of June 30, 2019 : 2019 (1) $ 246 2020 407 2021 101 2022 14 2023 12 Thereafter 2 Total minimum lease payments 782 Less: amount of lease payments representing interest 37 Present value of operating lease liabilities $ 745 (1) Excluding the six months ended June 30, 2019 .

Net Loss per Share (Tables)

Net Loss per Share (Tables)	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
Instruments Excluded from Calculation of Diluted Net Loss Per Share	The following instruments (in thousands) were excluded from the calculation of diluted net loss per share because their effects would be antidilutive: Three months ended Six months ended 2019 2018 2019 2018 Stock-based awards 16,791 5,939 16,791 12,847 Healios Warrant – see Note 7 4,000 20,000 4,000 20,000 Total 20,791 25,939 20,791 32,847

Collaborative Arrangements an_2

Collaborative Arrangements and Revenue Recognition Table (Tables)	6 Months Ended
	Jun. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Disaggregation of Revenue	The following table presents our contract revenues disaggregated by timing of revenue recognition and excludes royalty revenue (in thousands): Three months ended Three months ended Point in Time Over Time Point in Time Over Time Contract Revenue from Healios License fee revenue $ 1,624 $ — $ 17,530 $ — Product supply revenue 905 — 223 — Service revenue — 1,664 — 1,002 Other contract revenue — — 250 — Total disaggregated revenues $ 2,529 $ 1,664 $ 18,003 $ 1,002 Six months ended Six months ended Point in Time Over Time Point in Time Over Time Contract Revenue from Healios License fee revenue $ 1,624 $ — $ 17,530 $ — Product supply revenue 1,871 — 450 — Service revenue — 2,139 — 1,123 Other contract revenue — — 250 — Total disaggregated revenues $ 3,495 $ 2,139 $ 18,230 $ 1,123

Background and Basis of Prese_2

Background and Basis of Presentation - Additional Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)Segment	Dec. 31, 2018USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of business segments | Segment	1
Accumulated deficit	$ 395,686	$ 373,042
Cash and cash equivalents	$ 44,237	$ 51,059

Leases Adoption - Additional In

Leases Adoption - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Right-of-use assets	$ 700	$ 700
Lease liabilities	$ 745	$ 745
Weighted average remaining lease term	1 year 9 months 26 days	1 year 9 months 26 days
Weighted average discount rate (percent)	5.30%	5.30%
Payment for operating leases	$ 100	$ 200
Minimum
Lessee, Lease, Description [Line Items]
Lease term	12 months	12 months
Maximum
Lessee, Lease, Description [Line Items]
Lease term	56 months	56 months
ASU 2016-02
Lessee, Lease, Description [Line Items]
Right-of-use assets			$ 1,000
Lease liabilities			$ 1,000

Leases Adoption - Components of

Leases Adoption - Components of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Operating lease cost	$ 122	$ 242
Short-term lease cost	11	22
Variable lease cost	52	157
Total lease cost	$ 185	$ 421

Leases Adoption - Future Minimu

Leases Adoption - Future Minimum Lease Payments for Operating Leases (Details) $ in Thousands	Jun. 30, 2019USD ($)
Leases [Abstract]
2019	$ 246
2020	407
2021	101
2022	14
2023	12
Thereafter	2
Total minimum lease payments	782
Less: amount of lease payments representing interest	37
Present value of operating lease liabilities	$ 745

Net Loss per Share - Additional

Net Loss per Share - Additional Information (Details) - shares	1 Months Ended
	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Warrant exercisable (in shares)		4,000,000	4,000,000
Healios
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Warrants issued to purchase additional shares of common stock (in shares)	20,000,000
Expired warrants (in shares)		16,000,000

Net Loss per Share - Instrument

Net Loss per Share - Instruments Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	20,791	25,939	20,791	32,847
Stock-based awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	16,791	5,939	16,791	12,847
Healios | Healios Warrant
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	4,000	20,000	4,000	20,000

Collaborative Arrangements an_3

Collaborative Arrangements and Revenue Recognition - Additional Information (Details) $ in Thousands	1 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2017Milestone	Dec. 31, 2018USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Transaction price expected to be recognized	$ 1,500	$ 1,500
Deferred revenue recognized		0	$ 250
Healios License Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Transaction price expected to be recognized	100	$ 100
Deposit from Healios					$ 2,000
Deferred revenue recognized	$ 1,900
Regulatory and sales milestones | Healios License Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of future milestones achieved | Milestone				2

Collaborative Arrangements an_4

Collaborative Arrangements and Revenue Recognition - Summary of Revenues Disaggregated by Recognition at Point in Time and Over Time (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Point in Time
Disaggregation of Revenue [Line Items]
Revenues	$ 2,529	$ 18,003	$ 3,495	$ 18,230
Point in Time | Other contract revenue
Disaggregation of Revenue [Line Items]
Revenues	0	250	0	250
Over Time
Disaggregation of Revenue [Line Items]
Revenues	1,664	1,002	2,139	1,123
Over Time | Other contract revenue
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Healios License Agreement | Point in Time | License fee revenue
Disaggregation of Revenue [Line Items]
Revenues	1,624	17,530	1,624	17,530
Healios License Agreement | Point in Time | Product supply revenue
Disaggregation of Revenue [Line Items]
Revenues	905	223	1,871	450
Healios License Agreement | Point in Time | Service revenue
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Healios License Agreement | Over Time | License fee revenue
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Healios License Agreement | Over Time | Product supply revenue
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Healios License Agreement | Over Time | Service revenue
Disaggregation of Revenue [Line Items]
Revenues	$ 1,664	$ 1,002	$ 2,139	$ 1,123

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock authorized for equity incentive plan (in shares)	18,500,000
Stock options granted (in shares)	3,245,800
Shares available for issuance (in shares)	13,867,787
Shares of common stock outstanding (in shares)	16,780,535
Stock-based compensation expense	$ 1.2	$ 0.8
Estimated compensation cost of unvested restricted stock	$ 11.6
Restricted stock unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted (in shares)	1,350,150

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				3 Months Ended	6 Months Ended		12 Months Ended
	May 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Feb. 28, 2018	Jun. 30, 2019	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Number of first warrant shares (in shares)		4,000,000			4,000,000	4,000,000	4,000,000
Warrants exercised, percentage of average closing price per share for ten business days		110.00%
Discount on revenue from issuance of warrant		$ 1,100				$ 0	$ 1,080
Payment to acquire intellectual property rights									$ 500
Additional shares issuable upon issuance of intellectual property rights (in shares)								500,000
Aspire Capital
Class of Stock [Line Items]
Equity purchase agreement, value				$ 100,000
Equity purchase agreement, term				3 years
Common stock issued as commitment fees (in shares)				450,000
Common stock registered for resale (in shares)				24,700,000
Net proceeds from sales of common stock				$ 1,000	$ 5,100	$ 10,700	$ 5,500
Sale of additional shares at an average price (in dollars per share)				$ 2
Aspire Capital | Common Stock
Class of Stock [Line Items]
Issuance of common stock, new issues (in shares)					3,350,000	7,175,000	3,300,000
Sale of additional shares at an average price (in dollars per share)					$ 1.52	$ 1.49	$ 1.67
Jefferies
Class of Stock [Line Items]
Open market sale agreement, value	$ 50,000
Healios
Class of Stock [Line Items]
Issuance of common stock, new issues (in shares)			12,000,000
Shares of common stock issued, value			$ 21,100
Common stock issued, price per share (in dollars per share)		$ 1.76	$ 1.76
Warrants issued to purchase additional shares of common stock (in shares)			20,000,000
Contingent warrant shares (in shares)		16,000,000					16,000,000
Expired warrants (in shares)					16,000,000	16,000,000
Maximum ownership percentage that Heallios is allowed to own						19.90%
Fair value of the warrant		$ 4,200	$ 5,300				$ 4,200
Accrued License Fees | Cash Obligation
Class of Stock [Line Items]
Payment to acquire intellectual property rights								$ 1,000
Intellectual Property
Class of Stock [Line Items]
Stock issued during period, shares, issued for intellectual property rights (in shares)									1,000,000
Stock issued during period, amount, issued for intellectual property rights									$ 2,300