Harvard Apparatus Regenerative Technology (HRGN) 10-Q 14 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 10, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Registrant Name	Biostage, Inc.
Entity Central Index Key	0001563665
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Trading Symbol	BSTG
Entity Common Stock, Shares Outstanding		6,672,223
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Small Business	true

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash	$ 1,065	$ 1,305
Restricted cash	50	50
Grant receivable	114	176
Prepaid expenses and other current assets	499	623
Total current assets	1,728	2,154
Property, plant and equipment, net	466	479
Right-of-use assets	143	0
Total non-current assets	609	479
Total assets	2,337	2,633
Current liabilities:
Accounts payable	311	160
Accrued and other current liabilities	441	404
Warrant liability	105	98
Current portion of operating lease liability	99	0
Total current liabilities	956	662
Operating lease liability, net of current portion	44	0
Total liabilities	1,000	662
Commitments and contingencies (Note 6)
Stockholders' equity:
Undesignated preferred stock, $0.01 par value; 984,000 shares authorized and none issued and outstanding at March 31, 2019 and December 31, 2018	0	0
Common stock, $0.01 par value; 120,000,000 shares authorized at March 31, 2019 and December 31, 2018; 6,169,645 and 5,669,645 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	62	57
Additional paid-in capital	58,965	57,677
Accumulated deficit	(57,690)	(55,763)
Total stockholders' equity	1,337	1,971
Total liabilities and stockholders' equity	$ 2,337	$ 2,633

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	6,169,645	5,669,645
Common stock, shares outstanding	6,169,645	5,669,645
Undesignated Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	984,000	984,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues	$ 0	$ 0
Operating expenses:
Research and development	1,034	552
Selling, general and administrative	1,000	928
Total operating expenses	2,034	1,480
Operating loss	(2,034)	(1,480)
Other income (expense):
Grant income	114	59
Change in fair value of warrant liability	(7)	(124)
Total other income (expense), net	107	(65)
Net loss	$ (1,927)	$ (1,545)
Basic and diluted net loss per share	$ (0.32)	$ (0.56)
Weighted-average common shares, basic and diluted	6,003	2,751

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS USED IN OPERATING ACTIVITIES
Net loss	$ (1,927)	$ (1,545)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	293	75
Depreciation	61	63
Amortization of right-of-use assets	23	0
Change in fair value of warrant liability	7	124
Changes in operating assets and liabilities:
Grant receivable	62	(59)
Prepaid expenses and other current assets	124	(67)
Accounts payable	127	(698)
Accrued and other current liabilities	37	47
Lease liabilities	(23)	0
Net cash used in operating activities	(1,216)	(2,060)
CASH FLOWS USED IN INVESTING ACTIVITIES
Additions to property and equipment	(24)	(3)
Cash received from sale of property, plant and equipment	0	49
Net cash (used in) provided by investing activities	(24)	46
CASH FLOWS USED IN FINANCING ACTIVITIES
Return of related party advance	0	(300)
Proceeds from issuance of common stock and warrants, net of offering costs	0	1,095
Proceeds from exercise of warrants	1,000	0
Net cash provided by financing activities	1,000	795
Net decrease in cash and restricted cash	(240)	(1,219)
Cash and restricted cash at beginning of period	1,355	4,038
Cash and restricted cash at end of period	1,115	2,819
Supplemental disclosure of non-cash investing and financing activities:
Equipment purchases included in accounts payable	$ 24	$ 14

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Series D Convertible Preferred Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2017	$ 3,423	$ 25	$ 1,475	$ 50,157	$ (48,234)
Balance (in shares) at Dec. 31, 2017		2,507	3
Net loss	(1,545)	$ 0	$ 0	0	(1,545)
Share-based compensation	75	0	0	75	0
Issuance of common stock, net of offering costs	1,044	$ 4	$ 0	1,040	0
Issuance of common stock, net of offering costs (in shares)		352	0
Issuance of warrants to purchase common stock in connection with issuance of common stock above	51	$ 0	$ 0	51	0
Balance at Mar. 31, 2018	3,048	$ 29	$ 1,475	51,323	(49,779)
Balance (in shares) at Mar. 31, 2018		2,859	3
Balance at Dec. 31, 2018	1,971	$ 57	$ 0	57,677	(55,763)
Balance (in shares) at Dec. 31, 2018		5,670	0
Net loss	(1,927)	$ 0	$ 0	0	(1,927)
Share-based compensation	293	0	0	293	0
Issuance of common stock from exercise of warrants	1,000	$ 5	$ 0	995	0
Issuance of common stock from exercise of warrants (in shares)		500	0
Balance at Mar. 31, 2019	$ 1,337	$ 62	$ 0	$ 58,965	$ (57,690)
Balance (in shares) at Mar. 31, 2019		6,170	0

Overview and Basis of Presentat

Overview and Basis of Presentation	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Business Description and Basis of Presentation [Text Block]	1. Overview and Basis of Presentation Overview Biostage, Inc. (Biostage or the Company) is a biotechnology company developing bioengineered organ implants based on the Company’s novel Cellframe TM On October 31, 2013, Harvard Bioscience, Inc. (Harvard Bioscience) contributed its regenerative medicine business assets, plus $15 million of cash, into Biostage, Inc. (formerly “Harvard Apparatus Regenerative Technologies” at time of spin-off.) On November 1, 2013, the spin-off of the Company from Harvard Bioscience was completed. On that date, the Company became an independent company that operates the regenerative medicine business previously owned by Harvard Bioscience. The spin-off was completed through the distribution of all the shares of common stock of Biostage to stockholders of Harvard Bioscience (the “HBIO Distribution”). The Company’s common stock is currently traded on the OTCQB Venture Market under the symbol “BSTG”. Basis of Presentation The consolidated financial statements reflect the Company’s financial position, results of operations and cash flows in conformity with accounting principles generally accepted in the United States (GAAP). Going Concern The Company has incurred substantial operating losses since its inception, and as of March 31, 2019 has an accumulated deficit of approximately $57.7 million and will require additional financing to fund future operations. The Company expects that its cash at March 31, 2019 of $1.1 million will enable it to fund its operating expenses and capital expenditure requirements into the second quarter of 2019. Therefore, these conditions raise substantial doubt about the Company’s ability to continue as a going concern. The Company will need to raise additional funds to fund its operations. In the event the Company does not raise additional capital from outside sources in the near future, it may be forced to curtail or cease its operations. Cash requirements and cash resource needs will vary significantly depending upon the timing of the financial and other resource needs that will be required to complete ongoing development, pre-clinical and clinical testing of products, as well as regulatory efforts and collaborative arrangements necessary for the Company’s products that are currently under development. The Company will seek to raise necessary funds through a combination of public or private equity offerings, debt financings, other financing mechanisms, research grants, or strategic collaborations and licensing arrangements. The Company may not be able to obtain additional financing on favorable terms, if at all. The Company’s operations will be adversely affected if it is unable to raise or obtain needed funding and such circumstance may materially affect the Company’s ability to continue as a going concern. The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern and therefore, the consolidated financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amount and classifications of liabilities that may result from the outcome of this uncertainty. Net Loss Per Share Basic net loss per share is computed using the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed using the sum of the weighted average number of common shares outstanding during the period and, if dilutive, the weighted average number of potential shares of common stock, including the assumed exercise of stock options, warrants, and the impact of unvested restricted stock. The Company applies the two-class method to calculate basic and diluted net loss per share attributable to common stockholders as its warrants to purchase common stock are participating securities. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders. However, the two-class method does not impact the net loss per share of common stock as the Company has been in a net loss position and the warrant holders do not participate in losses. Basic and diluted shares outstanding are the same for each period presented as all common stock equivalents would be antidilutive due to the net losses incurred. Unaudited Interim Financial Information The accompanying interim consolidated balance sheet as of March 31, 2019 and consolidated interim statements of operations and cash flows for the three months ended March 31, 2019 and 2018 are unaudited. The interim unaudited consolidated financial statements have been prepared in accordance with GAAP on the same basis as the annual audited financial statements and, in the opinion of management, reflect all adjustments necessary for a fair statement of the Company’s financial position as of March 31, 2019 and its results of operations and cash flows for the three-month periods ended March 31, 2019 and 2018. The financial data and other information disclosed in these notes related to the three-month periods ended March 31, 2019 and 2018 are unaudited. The results for the three months ended March 31, 2019 are not necessarily indicative of results to be expected for the year ending December 31, 2019, any other interim periods or any future year or period.

Summary of Significant Accounti

Summary of Significant Accounting Policies and Recently Issued Accounting Pronouncements	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	2. Summary of Significant Accounting Policies and Recently Issued Accounting Pronouncements Summary of Significant Accounting Policies The accounting policies underlying the accompanying unaudited consolidated financial statements are those set forth in Note 2 to the consolidated financial statements for the year ended December 31, 2018 included in the Company’s Annual Report on Form 10-K. SBIR Award On March 28, 2018, the Company was awarded a Fast-Track Small Business Innovation Research (SBIR) grant by the Eunice Kennedy National Institute of Child Health and Human Development to support testing of pediatric Cellspan™ Esophageal Implants. The award for Phase I, which was earned over the nine months ended September 30, 2018, provided for the reimbursement for up to $225,000 of qualified research and development costs. On October 26, 2018, the Company was awarded Phase II of the SBIR grant for $1.1 million to support development, testing, and translation to the clinic through September 2019. The Phase II grant includes an additional $0.5 million for future period support through September 2020, subject to availability of funding and satisfactory progress on the project. Accordingly, the SBIR grant has the potential to provide a total award of $1.8 million. Grant income is recognized when qualified research and development costs are incurred and recorded in other income (expense), net in the consolidated statements of operations. When evaluating grant revenue from the SBIR grant, the Company considered accounting requirements under the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 606, Revenue From Contracts With Customers The Company recognized $114,000 of grant income from the Phase II award during the three months ended March 31, 2019 and $59,000 of grant income from the Phase I award during the three months ended March 31, 2018. Restricted Cash Restricted cash consists of $50,000 held as collateral for the Company’s credit card program as of March 31, 2019 and December 31, 2018. The Company’s statements of cash flows include restricted cash with cash when reconciling the beginning-of-period and end-of-period total amounts shown on such statements. A reconciliation of the cash and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows: March 31, December 31, 2019 2018 Cash $ 1,065 $ 1,305 Restricted cash 50 50 Total cash and restricted cash as shown on the statements of cash flows $ 1,115 $ 1,355 Recently Adopted Accounting Pronouncements In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting (ASU 2018-07) . The new standard simplifies the accounting for share-based payments to nonemployees by aligning it with the accounting for share-based payments to employees, with certain exceptions. The Company adopted ASU 2018-07 as required on January 1, 2019, and its adoption did not have any material impact on the Company’s consolidated results of operations. In July 2017, the FASB issued ASU 2017-11, Earnings Per Share, Distinguishing Liabilities from Equity, Derivatives and Hedging (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (ASU 2017-11) . This guidance is intended to reduce the complexity associated with accounting for certain financial instruments with characteristics of liabilities and equity. Specifically, a down round feature would no longer cause a freestanding equity-linked financial instrument (or an embedded conversion option) to be considered “not indexed to an entity’s own stock” and therefore accounted for as a derivative liability at fair value with changes in fair value recognized in current earnings. Down round features are most often found in warrants and conversion options embedded in debt or preferred equity instruments. In addition, the guidance re-characterized the indefinite deferral of certain provisions on distinguishing liabilities from equity to a scope exception with no accounting effect. The Company adopted ASU 2017-11 as of the required effective date of January 1, 2019, and the adoption of ASU 2017-11 did not have a material impact on its consolidated financial statements and related disclosures. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , a new standard issued to increase transparency and comparability among organizations related to their leasing activities. This standard established a right-of-use model that requires all lessees to recognize right-of-use assets and lease liabilities on their balance sheet that arise from leases as well as provide disclosures with respect to certain qualitative and quantitative information related to a company's leasing arrangements to meet the objective of allowing users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. The FASB subsequently issued the following amendments to ASU 2016-02 that have the same effective date and transition date: ASU 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 , ASU 2018-10, Codification Improvements to Topic 842, Leases , ASU 2018-11, Leases (Topic 842): Targeted Improvements, ASU 2018-20, Narrow-Scope Improvement for Lessors , and ASU 2019-01, Leases (Topic 842): Codification Improvements . The Company adopted these amendments with ASU 2016-02 (collectively, the new leasing standards) effective January 1, 2019 using the modified retrospective transition approach with no restatement of prior periods or cumulative adjustment to accumulated deficit. Upon adoption, the Company elected the package of transition practical expedients, which allowed the Company to carry forward prior conclusions related to whether any expired or existing contracts are or contain leases, the lease classification for any expired or existing leases and initial direct costs for existing leases. The Company also elected the practical expedient to not reassess certain land easements and made an accounting policy election to not recognize leases with an initial term of 12 months or less within its consolidated balance sheets and to recognize those lease payments on a straight-line basis in its consolidated statements of operations over the lease term. Upon adoption of the new leasing standards the Company recognized a right-of-use asset of approximately $0.2 million and a corresponding operating lease liability of approximately $ 0.2 The Company determines if an arrangement is a lease at contract inception. Operating lease assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses the implicit rate when readily determinable and uses its incremental borrowing rate when the implicit rate is not readily determinable based upon the information available at the commencement date in determining the present value of the lease payments. Since the Company does not have similar term secured borrowing arrangements as its lease arrangements and, therefore, its incremental borrowing rate is not readily determinable, the Company has used an incremental borrowing rate based on the lowest grade of debt available in the marketplace for the same term as the associated lease. The lease payments used to determine the Company’s operating lease assets may include lease incentives, stated rent increases and escalation clauses linked to rates of inflation when determinable and are recognized in the Company’s right-of-use assets in the Company’s consolidated balance sheets The Company’s operating leases are reflected in right to use assets, current portion of operating lease liability and operating lease liability, net of current portion, in the Company’s consolidated balance sheets. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. For additional information on the adoption of the new leasing standards, see Note 7, Leases, to the consolidated financial statements. Recently Issued Accounting Pronouncements In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820), Disclosure Framework – Changes to the Disclosure Requirement for Fair Value Measurement Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Capital Stock

Capital Stock	3 Months Ended
	Mar. 31, 2019
Stockholders' Equity Note [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	3. Capital Stock On January 3, 2018, the Company issued 50,000 shares of our common stock to Connecticut Children’s Medical Center (Connecticut Children’s) at $2.00 per share and warrants to purchase 75,000 shares of common stock at an exercise price of $2.00 per share, in exchange for aggregate gross proceeds of $100,000 in a private placement transaction of unregistered shares. The warrants were immediately exercisable and expire in January 2023. The Company has allocated $51,000 of consideration to the warrants using the relative fair-value method and included such amount in additional paid-in capital. The Company classified these warrants as permanent equity versus liability warrants as the warrants do not have any redemption features nor a right to put for cash that is outside the control of the Company. Connecticut Children’s Chief Executive Officer, James Shmerling, is a member of the Company’s Board of Directors as well as the Board of Directors of Connecticut Children’s. On February 20, 2018, the Company issued 302,115 shares of common stock to an investor at a purchase price of $3.31 per share for aggregate gross and net proceeds of approximately $1.0 million in an unregistered private placement transaction. On May 23, 2018, the Company issued 1,000,000 shares of common stock to two new investors at a purchase price of $3.60 per share for aggregate gross and net proceeds of approximately $3.6 million and $3.4 million, respectively, in an unregistered private placement. Following the issuance of these shares, the holders of Series D preferred stock exercised their right to convert all of the 3,108 outstanding shares of Series D preferred stock into 1.554 million shares of common stock as provided for under the Series D preferred stock agreement. On June 29, 2018, the Company issued 250,000 shares of common stock to an investor at a purchase price of $ 3.60 On January 31, 2019, the Company issued 500,000 shares of its common stock to an investor in connection with the exercise of a portion of the warrants issued on December 27, 2017. Such warrants were exercised in exchange for the payment to the Company of the aggregate cash exercise price of $1.0 million.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	4. Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The Company utilizes a valuation hierarchy for disclosure of the inputs to the valuations used to measure fair value that prioritizes the inputs into three broad levels. Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. Level 3 inputs are unobservable inputs based on the Company’s own assumptions used to measure assets and liabilities at fair value. A financial asset or liability’s classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. The Company had no assets or liabilities classified as Level 2 as of March 31, 2019 and December 31, 2018. The Company’s restricted cash that serves as collateral for the Company’s credit card program is held in a demand money market account and is measured at fair value based on quoted prices, which are Level 1 inputs. The Company classifies warrants to purchase common stock that are accounted for as liabilities as discussed below as Level 3 liabilities. The following fair value hierarchy table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2019: Fair Value Measurement as of March 31, 2019 (In thousands) Level 1 Level 2 Level 3 Total Assets: Restricted cash $ 50 $ - $ - $ 50 Total $ 50 $ - $ - $ 50 Liabilities: Warrant liability $ - $ - $ 105 $ 105 Total $ - $ - $ 105 $ 105 The following fair value hierarchy table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2018: Fair Value Measurement as of December 31, 2018 (In thousands) Level 1 Level 2 Level 3 Total Assets: Restricted cash $ 50 $ - $ - $ 50 Total $ 50 $ - $ - $ 50 Liabilities: Warrant liability $ - $ - $ 98 $ 98 Total $ - $ - $ 98 $ 98 The following table presents a reconciliation of the Company’s liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three months ended March 31, 2019: Warrant Liability (In thousands) Balance at December 31, 2018 $ 98 Change in fair value upon re-measurement 7 Balance at March 31, 2019 $ 105 There were no transfers between Level 1, Level 2 and Level 3 in any of the periods reported. The Company has re-measured the warrant liability to estimated fair value at inception, prior to modification and at each reporting date using the Black-Scholes option pricing model with the following weighted average assumptions: March 31, 2019 December 31, 2018 Risk-free interest rate 2.49 % 2.46 % Expected volatility 118.3 % 121.9 % Expected term (in years) 2.9 3.1 Expected dividend yield - - Exercise price $ 8.00 $ 8.00 Market value of common stock $ 2.35 $ 2.06 Warrants to purchase shares of common stock 92,212 92,212

Share-Based Compensation

Share-Based Compensation	3 Months Ended
	Mar. 31, 2019
Share-based Compensation [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	5. Share-Based Compensation Biostage 2013 Equity Incentive Plan The Company maintains the for the benefit of certain of its officers, employees, non-employee directors, and other key persons (including consultants and advisory board members). All options and awards granted under the Plan consist of the Company’s shares of common stock. In May 2018, the Company’s shareholders approved the increase of the number of shares of the Company’s common stock available for issuance pursuant to the Plan by 1,600,000 shares, which increased the total shares authorized to be issued under the Plan to 2,098,000. The Company also issued equity awards under the Plan at the time of the HBIO Distribution to all holders of Harvard Bioscience equity awards as part of an adjustment (the Adjustment Awards) to prevent a loss of value due to the HBIO Distribution. Compensation expense recognized under the Plan relates to service provided by employees, board members and a non-employee of the Company. There was no required compensation associated with the Adjustment Awards to employees who remained at Harvard Bioscience. As of December 31, 2018 and since there was no unrecognized compensation costs as all the Adjustment Awards have fully vested. The Company has granted options to purchase common stock and restricted stock units (RSUs) under the Plan. Stock option and restricted stock unit activity during the three months ended March 31, 2019 was as follows: Stock Options Restricted Stock Units Amount Weighted – average exercise price Amount Weighted – average grant date fair value Outstanding at December 31, 2018 1,577,983 $ 6.58 7,735 $ 7.68 Granted 7,500 2.48 - - Vested (RSUs) - - (2,578 ) 7.68 Canceled (19 ) 100.47 - - Outstanding at March 31, 2019 1,585,464 $ 6.55 5,157 $ 7.68 The underlying common shares for the 2,578 The Company uses the Black-Scholes option pricing model to value its stock options. The weighted average assumptions for valuing options granted during the three months ended March 31, 2019 were as follows: Expected volatility 117.4 % Expected dividends n/a Expected term 5.75 Risk-free rate 2.55 % The Company’s outstanding stock options include 583,921 performance-based awards as of March 31, 2019 that have vesting provisions subject to the achievement of certain business milestones. Total compensation expense for performance-based awards is approximately $1.6 million. No expense has been recognized as of March 31, 2019 for such awards given that the milestone achievements have not yet been deemed probable for accounting purposes. The Company recorded share-based compensation expense in the following expense categories of its consolidated statements of operations: Three Months ended March 31, 2019 2018 (In thousands) Research and development $ 72 $ 9 General and administrative 221 66 Total share-based compensation $ 293 $ 75

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	6. Commitments and Contingencies First Pecos Breach Notice In June, 2017, the Company entered into a binding Memorandum of Understanding with First Pecos, LLC (First Pecos), pursuant to which the Company agreed to issue to First Pecos in a private placement 485,000 shares of its common stock on a post-reverse split basis at a purchase price of $6.30 per share or, to the extent First Pecos, following the transaction, would own more than 19.9% of the Company’s common stock, shares of a new class of preferred stock of the Company with a per-share purchase price of $1,000. In October 2017, as a result of the First Pecos failure to deliver the Purchase Price to the Company following satisfaction of all closing conditions in the Purchase Agreement, the Company delivered a notice to First Pecos and its manager, Leon “Chip” Greenblatt III, stating that First Pecos was in breach of the Purchase Agreement. None of the shares of common stock, shares of preferred stock or warrants were issued to First Pecos. Also in October 2017, First Pecos delivered a notice to the Company stating that, as a result of alleged breaches by the Company of its obligations pursuant to the Purchase Agreement, First Pecos terminated the Purchase Agreement and demanded that the Company pay a $500,000 termination fee pursuant to the terms of the Purchase Agreement. The Company believes that it was not in breach of the Purchase Agreement at any time, and that the First Pecos notice was unjustified and without any legal merit or factual basis. Accordingly, the Company believes that First Pecos was not entitled to terminate the Purchase Agreement, and was not entitled to any termination fee thereunder, as the failure to consummate the Pecos Placement resulted from the First Pecos breach of the Purchase Agreement. The Company has not accrued for this liability as the Company believes the claim to be without merit. Other On April 14, 2017, representatives for the estate of a deceased individual filed a civil lawsuit in the Suffolk Superior Court, in Boston, Massachusetts, against the Company and Harvard Bioscience. The complaint alleges that the decedent’s injury and death were caused by two tracheal implants that incorporated synthetic trachea scaffolds and a biologic component combined by the implanting surgeon with a bioreactor, and surgically implanted in the decedent in two surgeries performed in 2012 and 2013. The civil complaint seeks a non-specific sum of money to compensate the plaintiffs. This civil lawsuit relates to the Company’s first-generation trachea scaffold technology for which the Company discontinued development in 2014, and not to the Company’s current Cellframe technology nor to its lead development product candidate, the Cellspan Esophageal Implant. The Company intends to vigorously defend this case. While the Company believes that such claim lacks merit, the Company is unable to predict the ultimate outcome of such litigation. In accordance with a separation and distribution agreement between Harvard Bioscience and the Company relating to the spin-off, the Company would be required to indemnify Harvard Bioscience against losses that Harvard Bioscience may suffer as a result of this litigation. The Company has been informed by its insurance provider that the case has been accepted as an insurable claim under the Company’s product liability insurance policy. The Company has not accrued for a potential liability as it is not considered probable at this time. From time to time, the Company may be involved in various claims and legal proceedings arising in the ordinary course of business. Other than the above matter, there are no such matters pending that the Company expects to be material in relation to its business, financial condition, and results of operations or cash flows.

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Lessee, Operating Lease, Disclosure [Table Text Block]	7. Leases The Company leases laboratory and office space, and certain equipment. The Company leases have remaining lease terms ranging from 1 year to 4 years. The facility sublease with Harvard Bioscience currently runs through May 31, 2020 and automatically extends annually unless the Company or Harvard Bioscience provides a notice of termination within one hundred and eighty days prior to May 31 of each year. The equipment lease, which has a lease term thru April 2023, includes the purchase or return of the equipment, or continuation of the lease at 180-day intervals at the end of the lease, at the Company’s sole discretion. All of the Company’s leases qualify as operating leases. The following table summarizes the presentation in the Company’s condensed consolidated balance sheets of its operating leases: (In thousands) Balance sheet location As of March 31, 2019 Assets: Operating lease assets Right-of-use asset $ 143 Liabilities: Current operating lease liabilities Current portion of operating lease liabilities $ 99 Non-current operating lease liabilities Operating lease liabilities, net of current portion 44 Total operating lease liabilities $ 143 The following table summarizes the effect of lease costs in the Company’s condensed consolidated statements of income: (In thousands) Income Statement Location For the Three Months Ended March 31, 2019 Operating lease cost Research and development $ 18 Selling, general and administrative 10 $ 28 The minimum lease payments for the next five years and thereafter is expected to be as follows: (In thousands) As of March 31, 2019 2019 (remaining nine months) $ 84 2020 53 2021 11 2022 11 2023 4 Thereafter 0 Total lease payments $ 163 Less: interest 20 Present value of operating lease liabilities $ 143 The weighted average remaining lease term and weighted average discount rate of the Company’s operating leases are as follows: As of March 31, 2019 Weighted average remaining lease term in years 2.0 Weighted average discount rate 13.55 %

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	8. Related Party Transactions Relationship with Harvard Bioscience On November 1, 2013, Harvard Bioscience completed the HBIO Distribution. At the time of the HBIO Distribution, the Company entered into a 10-year product distribution agreement with Harvard Bioscience under which each company became the exclusive distributor for the other party for products such other party develops for sale in the markets served by the other. In addition, Harvard Bioscience agreed that except for certain existing activities of its German subsidiary, to the extent that any Harvard Bioscience business desires to resell or distribute any bioreactor that is then manufactured by the Company, the Company would be the exclusive manufacturer of such bioreactors and Harvard Bioscience would purchase such bioreactors from the Company. On November 3, 2017, in exchange for settlement of approximately $0.1 million of outstanding rent and operating expenses due to Harvard Bioscience, Biostage sold all of its current stock of research bioreactor parts, a royalty free perpetual sublicensable and transferable right and license to use the intellectual property, including but not limited to certain patents covering research bioreactors, and relinquished exclusive manufacturing or distribution rights with respect to research bioreactors to Harvard Bioscience. The Company had ceased the manufacture of research bioreactors in late 2016, to concentrate its efforts solely on development of its clinical product candidates. This settlement only covers research bioreactors, not to be used for clinical purposes. The Company retains full exclusive rights to all assets and rights associated with the clinical bioreactor used in the development of the Company’s current Cellframe technology. Due to Related Party In connection with the Company’s private placement transaction in December 2017, an investor placed a deposit in the amount of $0.3 million with the Company, which was subsequently repaid in January 2018.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	9. Net Loss Per Share The following potential common shares were excluded from the calculation of diluted net loss per share attributable to common stockholders for the three months ended March 31, 2019 and 2018 because including them would have had an anti-dilutive effect: Three Months Ended March 31, 2019 2018 Unvested restricted common stock units 5,517 7,735 Warrants to purchase common stock 3,678,647 4,178,647 Options to purchase common stock 1,585,464 156,968 Series D convertible preferred stock - 1,554,000 Total 5,269,268 5,897,350

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	10. Income Taxes The Company did not provide for any income taxes in its statement of operations for the three-month periods ended March 31, 2019 and 2018. The Company has provided a valuation allowance for the full amount of its net deferred tax assets because, at March 31, 2019 and December 31, 2018, it was more likely than not that any future benefit from deductible temporary differences and net operating loss and tax credit carryforwards would not be realized. The Company has not recorded any amounts for unrecognized tax benefits as of March 31, 2019 or December 31, 2018. As of March 31, 2019, and December 31, 2018, the Company had no accrued interest or tax penalties recorded related to income taxes. The Company is subject to U.S. federal income tax and Massachusetts state income tax. The statute of limitations for assessment by the IRS and state tax authorities is open for all periods from inception through December 31, 2018; currently, no federal or state income tax returns are under examination by the respective taxing authorities. Under the provisions of the Internal Revenue Code, the net operating loss and tax credit carryforwards are subject to review and possible adjustment by the IRS and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50 percent, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has recently completed several equity financing transactions which have either individually or cumulatively resulted in a change in control as defined by Sections 382 and 383 of the Internal Revenue Code, or could result in a change in control in the future. The Company does not believe the impact of any limitation on the use of its net operating loss or credit carryforwards will have a material impact on the Company’s consolidated financial statements since the Company has a full valuation allowance against its deferred tax assets due to the uncertainty regarding future taxable income for the foreseeable future. For all periods through March 31, 2019, the Company generated research credits but has not conducted a study to document the qualified activities. This study may result in an adjustment to the Company’s research and development credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the deferred tax asset established for the research and development credit carryforwards and the valuation allowance.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events [Text Block]	11. Subsequent Events On April 24, 2019 and May 3, 2019, the Company issued a total of 500,000 shares of its common stock to an investor in connection with the exercise of a total of 500,000 warrants, which were previously issued on December 27, 2017, at $2.00 per share for gross proceeds in the amount of $1.0 million.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies and Recently Issued Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Small Business Innovation Research [Policy Text Block]	SBIR Award On March 28, 2018, the Company was awarded a Fast-Track Small Business Innovation Research (SBIR) grant by the Eunice Kennedy National Institute of Child Health and Human Development to support testing of pediatric Cellspan™ Esophageal Implants. The award for Phase I, which was earned over the nine months ended September 30, 2018, provided for the reimbursement for up to $225,000 of qualified research and development costs. On October 26, 2018, the Company was awarded Phase II of the SBIR grant for $1.1 million to support development, testing, and translation to the clinic through September 2019. The Phase II grant includes an additional $0.5 million for future period support through September 2020, subject to availability of funding and satisfactory progress on the project. Accordingly, the SBIR grant has the potential to provide a total award of $1.8 million. Grant income is recognized when qualified research and development costs are incurred and recorded in other income (expense), net in the consolidated statements of operations. When evaluating grant revenue from the SBIR grant, the Company considered accounting requirements under the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 606, Revenue From Contracts With Customers The Company recognized $114,000 of grant income from the Phase II award during the three months ended March 31, 2019 and $59,000 of grant income from the Phase I award during the three months ended March 31, 2018.
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	Restricted Cash Restricted cash consists of $50,000 held as collateral for the Company’s credit card program as of March 31, 2019 and December 31, 2018. The Company’s statements of cash flows include restricted cash with cash when reconciling the beginning-of-period and end-of-period total amounts shown on such statements. A reconciliation of the cash and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows: March 31, December 31, 2019 2018 Cash $ 1,065 $ 1,305 Restricted cash 50 50 Total cash and restricted cash as shown on the statements of cash flows $ 1,115 $ 1,355
Recently Adopted Accounting Pronouncements [Policy Text Block]	Recently Adopted Accounting Pronouncements In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting (ASU 2018-07) . The new standard simplifies the accounting for share-based payments to nonemployees by aligning it with the accounting for share-based payments to employees, with certain exceptions. The Company adopted ASU 2018-07 as required on January 1, 2019, and its adoption did not have any material impact on the Company’s consolidated results of operations. In July 2017, the FASB issued ASU 2017-11, Earnings Per Share, Distinguishing Liabilities from Equity, Derivatives and Hedging (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (ASU 2017-11) . This guidance is intended to reduce the complexity associated with accounting for certain financial instruments with characteristics of liabilities and equity. Specifically, a down round feature would no longer cause a freestanding equity-linked financial instrument (or an embedded conversion option) to be considered “not indexed to an entity’s own stock” and therefore accounted for as a derivative liability at fair value with changes in fair value recognized in current earnings. Down round features are most often found in warrants and conversion options embedded in debt or preferred equity instruments. In addition, the guidance re-characterized the indefinite deferral of certain provisions on distinguishing liabilities from equity to a scope exception with no accounting effect. The Company adopted ASU 2017-11 as of the required effective date of January 1, 2019, and the adoption of ASU 2017-11 did not have a material impact on its consolidated financial statements and related disclosures. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , a new standard issued to increase transparency and comparability among organizations related to their leasing activities. This standard established a right-of-use model that requires all lessees to recognize right-of-use assets and lease liabilities on their balance sheet that arise from leases as well as provide disclosures with respect to certain qualitative and quantitative information related to a company's leasing arrangements to meet the objective of allowing users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. The FASB subsequently issued the following amendments to ASU 2016-02 that have the same effective date and transition date: ASU 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 , ASU 2018-10, Codification Improvements to Topic 842, Leases , ASU 2018-11, Leases (Topic 842): Targeted Improvements, ASU 2018-20, Narrow-Scope Improvement for Lessors , and ASU 2019-01, Leases (Topic 842): Codification Improvements . The Company adopted these amendments with ASU 2016-02 (collectively, the new leasing standards) effective January 1, 2019 using the modified retrospective transition approach with no restatement of prior periods or cumulative adjustment to accumulated deficit. Upon adoption, the Company elected the package of transition practical expedients, which allowed the Company to carry forward prior conclusions related to whether any expired or existing contracts are or contain leases, the lease classification for any expired or existing leases and initial direct costs for existing leases. The Company also elected the practical expedient to not reassess certain land easements and made an accounting policy election to not recognize leases with an initial term of 12 months or less within its consolidated balance sheets and to recognize those lease payments on a straight-line basis in its consolidated statements of operations over the lease term. Upon adoption of the new leasing standards the Company recognized a right-of-use asset of approximately $0.2 million and a corresponding operating lease liability of approximately $ 0.2 The Company determines if an arrangement is a lease at contract inception. Operating lease assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses the implicit rate when readily determinable and uses its incremental borrowing rate when the implicit rate is not readily determinable based upon the information available at the commencement date in determining the present value of the lease payments. Since the Company does not have similar term secured borrowing arrangements as its lease arrangements and, therefore, its incremental borrowing rate is not readily determinable, the Company has used an incremental borrowing rate based on the lowest grade of debt available in the marketplace for the same term as the associated lease. The lease payments used to determine the Company’s operating lease assets may include lease incentives, stated rent increases and escalation clauses linked to rates of inflation when determinable and are recognized in the Company’s right-of-use assets in the Company’s consolidated balance sheets The Company’s operating leases are reflected in right to use assets, current portion of operating lease liability and operating lease liability, net of current portion, in the Company’s consolidated balance sheets. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. For additional information on the adoption of the new leasing standards, see Note 7, Leases, to the consolidated financial statements.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Pronouncements In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820), Disclosure Framework – Changes to the Disclosure Requirement for Fair Value Measurement Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies and Recently Issued Accounting Pronouncements (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Restrictions on Cash and Cash Equivalents [Table Text Block]	A reconciliation of the cash and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows: March 31, December 31, 2019 2018 Cash $ 1,065 $ 1,305 Restricted cash 50 50 Total cash and restricted cash as shown on the statements of cash flows $ 1,115 $ 1,355

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	The following fair value hierarchy table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2019: Fair Value Measurement as of March 31, 2019 (In thousands) Level 1 Level 2 Level 3 Total Assets: Restricted cash $ 50 $ - $ - $ 50 Total $ 50 $ - $ - $ 50 Liabilities: Warrant liability $ - $ - $ 105 $ 105 Total $ - $ - $ 105 $ 105 The following fair value hierarchy table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2018: Fair Value Measurement as of December 31, 2018 (In thousands) Level 1 Level 2 Level 3 Total Assets: Restricted cash $ 50 $ - $ - $ 50 Total $ 50 $ - $ - $ 50 Liabilities: Warrant liability $ - $ - $ 98 $ 98 Total $ - $ - $ 98 $ 98
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	The following table presents a reconciliation of the Company’s liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three months ended March 31, 2019: Warrant Liability (In thousands) Balance at December 31, 2018 $ 98 Change in fair value upon re-measurement 7 Balance at March 31, 2019 $ 105
Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]	The Company has re-measured the warrant liability to estimated fair value at inception, prior to modification and at each reporting date using the Black-Scholes option pricing model with the following weighted average assumptions: March 31, 2019 December 31, 2018 Risk-free interest rate 2.49 % 2.46 % Expected volatility 118.3 % 121.9 % Expected term (in years) 2.9 3.1 Expected dividend yield - - Exercise price $ 8.00 $ 8.00 Market value of common stock $ 2.35 $ 2.06 Warrants to purchase shares of common stock 92,212 92,212

Share-Based Compensation (Table

Share-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2019
Stock Based Compensation [Line Items]
Share-based Compensation, Activity [Table Text Block]	The Company has granted options to purchase common stock and restricted stock units (RSUs) under the Plan. Stock option and restricted stock unit activity during the three months ended March 31, 2019 was as follows: Stock Options Restricted Stock Units Amount Weighted – average exercise price Amount Weighted – average grant date fair value Outstanding at December 31, 2018 1,577,983 $ 6.58 7,735 $ 7.68 Granted 7,500 2.48 - - Vested (RSUs) - - (2,578 ) 7.68 Canceled (19 ) 100.47 - - Outstanding at March 31, 2019 1,585,464 $ 6.55 5,157 $ 7.68
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	The Company uses the Black-Scholes option pricing model to value its stock options. The weighted average assumptions for valuing options granted during the three months ended March 31, 2019 were as follows: Expected volatility 117.4 % Expected dividends n/a Expected term 5.75 Risk-free rate 2.55 %
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]	The Company recorded share-based compensation expense in the following expense categories of its consolidated statements of operations: Three Months ended March 31, 2019 2018 (In thousands) Research and development $ 72 $ 9 General and administrative 221 66 Total share-based compensation $ 293 $ 75

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Right To Use Of Asset And Liability In Respect Of Operating Leases [Table Text Block]	All of the Company’s leases qualify as operating leases. The following table summarizes the presentation in the Company’s condensed consolidated balance sheets of its operating leases: (In thousands) Balance sheet location As of March 31, 2019 Assets: Operating lease assets Right-of-use asset $ 143 Liabilities: Current operating lease liabilities Current portion of operating lease liabilities $ 99 Non-current operating lease liabilities Operating lease liabilities, net of current portion 44 Total operating lease liabilities $ 143
Lease, Cost [Table Text Block]	The following table summarizes the effect of lease costs in the Company’s condensed consolidated statements of income: (In thousands) Income Statement Location For the Three Months Ended March 31, 2019 Operating lease cost Research and development $ 18 Selling, general and administrative 10 $ 28
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	The minimum lease payments for the next five years and thereafter is expected to be as follows: (In thousands) As of March 31, 2019 2019 (remaining nine months) $ 84 2020 53 2021 11 2022 11 2023 4 Thereafter 0 Total lease payments $ 163 Less: interest 20 Present value of operating lease liabilities $ 143
Schedule Of Discount Rate And Lease Term Used In Calculating Lease Liabilities And Assets [Table Text Block]	The weighted average remaining lease term and weighted average discount rate of the Company’s operating leases are as follows: As of March 31, 2019 Weighted average remaining lease term in years 2.0 Weighted average discount rate 13.55 %

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	The following potential common shares were excluded from the calculation of diluted net loss per share attributable to common stockholders for the three months ended March 31, 2019 and 2018 because including them would have had an anti-dilutive effect: Three Months Ended March 31, 2019 2018 Unvested restricted common stock units 5,517 7,735 Warrants to purchase common stock 3,678,647 4,178,647 Options to purchase common stock 1,585,464 156,968 Series D convertible preferred stock - 1,554,000 Total 5,269,268 5,897,350

Overview and Basis of Present_2

Overview and Basis of Presentation (Details Textual) - USD ($) $ in Thousands	1 Months Ended
	Oct. 31, 2013	Mar. 31, 2019	Dec. 31, 2018
Retained Earnings (Accumulated Deficit)		$ (57,690)	$ (55,763)
Cash		$ 1,065	$ 1,305
Harvard Bioscience Plan [Member]
Proceeds from Contributions from Parent	$ 15,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies and Recently Issued Accounting Pronouncements (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Cash	$ 1,065	$ 1,305
Restricted cash	50	50
Total cash and restricted cash as shown on the statements of cash flows	$ 1,115	$ 1,355

Summary of Significant Accoun_5

Summary of Significant Accounting Policies and Recently Issued Accounting Pronouncements (Details Textual) - USD ($)	1 Months Ended		3 Months Ended
	Oct. 26, 2018	Mar. 28, 2018	Mar. 31, 2019	Dec. 31, 2018
Basic And Diluted Earnings Per Share [Line Items]
Restricted Cash			$ 50,000
Maximum Research And Development Expenses Reimbursement		$ 225,000
Research and Development Arrangement, Contract to Perform for Others, Description and Terms	On October 26, 2018, the Company was awarded Phase II of the SBIR grant for $1.1 million to support development, testing, and translation to the clinic through September 2019. The Phase II grant includes an additional $0.5 million for future period support through September 2020, subject to availability of funding and satisfactory progress on the project. Accordingly, the SBIR grant has the potential to provide a total award of $1.8 million.
Operating Lease, Right-of-Use Asset			143,000	$ 0
Operating Lease, Liability			143,000
Accounting Standards Update 2016-02 [Member]
Basic And Diluted Earnings Per Share [Line Items]
Operating Lease, Right-of-Use Asset			200,000
Operating Lease, Liability			0.2
Phase One [Member]
Basic And Diluted Earnings Per Share [Line Items]
Grant Income Recognized			59,000
Phase Two [Member]
Basic And Diluted Earnings Per Share [Line Items]
Grant Income Recognized			$ 114,000

Capital Stock (Details Textual)

Capital Stock (Details Textual) - USD ($)	Jan. 03, 2018	Jun. 29, 2018	May 23, 2018	Feb. 20, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Class of Warrant or Right, Number of Securities Called by Warrants or Rights					92,212		92,212
Class of Warrant or Right, Exercise Price of Warrants or Rights					$ 8		$ 8
Proceeds from Issuance of Private Placement		$ 900,000	$ 3,600,000		$ 0	$ 1,095,000
Stock Issued During Period, Shares, New Issues		250,000
Share Price					$ 2.35		$ 2.06
Stock Issued During Period, Value, New Issues		$ 800,000	$ 3,400,000	$ 1,000,000		$ 1,044,000
Warrants and Rights Outstanding	$ 51,000
Shares Issued, Price Per Share		$ 3.60	$ 3.60
Private Placement [Member]
Stock Issued During Period, Shares, New Issues			1,000,000	302,115
Share Price				$ 3.31
Proceeds from Issuance of Common Stock	$ 100,000
Common Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	75,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 2
Proceeds from Warrant Exercises					$ 1,000,000
Stock Issued During Period, Shares, New Issues	50,000					352,000
Share Price	$ 2
Stock Issued During Period, Value, New Issues						$ 4,000
Shares Issued As A Result Of Exercise Of Warrants					500,000
Series D Preferred Stock [Member]
Conversion of Stock, Shares Converted			3,108
Conversion of Stock, Shares Issued			1,554,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 50	$ 50
Liabilities, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	105	98
Warrant [Member]
Liabilities, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	105	98
Restricted cash [Member]
Assets, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	50	50
Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	50	50
Liabilities, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	0	0
Fair Value, Inputs, Level 1 [Member] | Warrant [Member]
Liabilities, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	0	0
Fair Value, Inputs, Level 1 [Member] | Restricted cash [Member]
Assets, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	50	50
Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0	0
Liabilities, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	0	0
Fair Value, Inputs, Level 2 [Member] | Warrant [Member]
Liabilities, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	0	0
Fair Value, Inputs, Level 2 [Member] | Restricted cash [Member]
Assets, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0	0
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0	0
Liabilities, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	105	98
Fair Value, Inputs, Level 3 [Member] | Warrant [Member]
Liabilities, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	105	98
Fair Value, Inputs, Level 3 [Member] | Restricted cash [Member]
Assets, Fair Value Disclosure [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 0	$ 0

Fair Value Measurements (Deta_2

Fair Value Measurements (Details 1) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Beginning Balance	$ 98
Change in fair value upon re-measurement	7
Ending Balance	$ 105

Fair Value Measurements (Deta_3

Fair Value Measurements (Details 2) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Exercise price	$ 8	$ 8
Market value of common stock	$ 2.35	$ 2.06
Warrants to purchase shares of common stock	92,212	92,212
Measurement Input, Risk Free Interest Rate [Member]
Risk-free interest rate	2.49%	2.46%
Measurement Input, Price Volatility [Member]
Expected volatility	118.3	121.9
Measurement Input, Expected Term [Member]
Expected term (in years)	2 years 10 months 24 days	3 years 1 month 6 days
Measurement Input, Expected Dividend Rate [Member]
Expected dividend yield	0.00%	0.00%

Share-Based Compensation (Detai

Share-Based Compensation (Details) - Biostage 2013 Equity Incentive Plan [Member] - $ / shares	1 Months Ended	3 Months Ended
	May 31, 2018	Mar. 31, 2019
Amount, Granted	1,600,000
Restricted Stock Units (RSUs) [Member]
Amount, Outstanding at December 31, 2018		7,735
Amount, Granted		0
Amount, Canceled		0
Amount, Outstanding at March 31, 2018		5,157
Weighted-average exercise price, Outstanding at December 31, 2018		$ 7.68
Weighted-average exercise price, Granted		0
Weighted-average exercise price, Canceled		0
Weighted-average exercise price, Outstanding at March 31, 2018		$ 7.68
Amount, Vested (RSUs)		(2,578)
Weighted–average exercise price, Vested (RSUs)		7.68
Employee Stock Option [Member]
Amount, Outstanding at December 31, 2018		1,577,983
Amount, Granted		7,500
Amount, Canceled		(19)
Amount, Outstanding at March 31, 2018		1,585,464
Weighted-average exercise price, Outstanding at December 31, 2018		$ 6.58
Weighted-average exercise price, Granted		2.48
Weighted-average exercise price, Canceled		100.47
Weighted-average exercise price, Outstanding at March 31, 2018		$ 6.55
Amount, Vested (RSUs)		0
Weighted–average exercise price, Vested (RSUs)		0

Share-Based Compensation (Det_2

Share-Based Compensation (Details 1) - Biostage 2013 Equity Incentive Plan [Member]	3 Months Ended
	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	117.40%
Expected dividends
Expected term	5 years 9 months
Risk-free rate	2.55%

Share-Based Compensation (Det_3

Share-Based Compensation (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 293	$ 75
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	72	9
Selling, General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 221	$ 66

Share-Based Compensation (Det_4

Share-Based Compensation (Details Textual) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	May 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense		$ 293	$ 75
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number		583,921
Allocated Share-based Compensation Expense		$ 1,600
Biostage 2013 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	2,098,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	1,600,000
Biostage 2013 Equity Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number		5,157		7,735
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		2,578

Commitments and Contingencies (

Commitments and Contingencies (Details Textual) - USD ($)	1 Months Ended
	Jun. 30, 2017	Mar. 31, 2019	Dec. 31, 2018	Jan. 03, 2018	Oct. 31, 2017
Loss Contingencies [Line Items]
Share Price		$ 2.35	$ 2.06
Common Stock [Member]
Loss Contingencies [Line Items]
Share Price				$ 2
First Pecos, LLC [Member]
Loss Contingencies [Line Items]
Private Placement Shares to be Issued	485,000
Precentage of Company Common Stock	19.90%
Loss Contingencies					$ 500,000
First Pecos, LLC [Member] | Common Stock [Member]
Loss Contingencies [Line Items]
Share Price	$ 6.30
First Pecos, LLC [Member] | Preferred Stock [Member]
Loss Contingencies [Line Items]
Share Price	$ 1,000

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Operating lease assets	$ 143	$ 0
Current operating lease liabilities	99	0
Non-current operating lease liabilities	44	$ 0
Present value of operating lease liabilities	143
Property Subject to Operating Lease [Member]
Operating lease assets	143
Current operating lease liabilities	99
Non-current operating lease liabilities	44
Present value of operating lease liabilities	$ 143

Leases (Details 1)

Leases (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Research and development	$ 1,034	$ 552
Selling, general and administrative	1,000	$ 928
Property Subject to Operating Lease [Member]
Research and development	18
Selling, general and administrative	10
Operating Lease, Cost	$ 28

Leases (Details 2)

Leases (Details 2) $ in Thousands	Mar. 31, 2019USD ($)
Leases [Abstract]
2019 (remaining nine months)	$ 84
2020	53
2021	11
2022	11
2023	4
Thereafter	0
Total lease payments	163
Less: interest	20
Present value of operating lease liabilities	$ 143

Leases (Details 3)

Leases (Details 3)	Mar. 31, 2019
Leases [Abstract]
Weighted average remaining lease term in years	2 years
Weighted average discount rate	13.55%

Leases (Detail Textual)

Leases (Detail Textual)	3 Months Ended
	Mar. 31, 2019
Operating Lease, Weighted Average Remaining Lease Term	2 years
Lessee, Operating Lease, Renewal Term	180 days
Lessee, Operating Lease, Description	The Company leases laboratory and office space, and certain equipment
Lessee, Operating Sublease, Option to Extend	The facility sublease with Harvard Bioscience currently runs through May 31, 2020 and automatically extends annually unless the Company or Harvard Bioscience provides a notice of termination within one hundred and eighty days prior to May 31 of each year
Property Subject to Operating Lease [Member]
Lease Expiration Date	Apr. 30, 2023
Maximum [Member]
Operating Lease, Weighted Average Remaining Lease Term	4 years
Minimum [Member]
Operating Lease, Weighted Average Remaining Lease Term	1 year

Related Party Transactions (Det

Related Party Transactions (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2017	Nov. 03, 2017
Related Party Transaction [Line Items]
Due from Related Parties, Current		$ 0.3
Product Distribution Agreement Term	10 years
Harvard Bioscience [Member]
Related Party Transaction [Line Items]
Accrued Rent, Current			$ 0.1

Net Loss Per Share (Details 1)

Net Loss Per Share (Details 1) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	5,269,268	5,897,350
Series D Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	1,554,000
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	5,517	7,735
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,678,647	4,178,647
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,585,464	156,968

Income Taxes (Details Textual)

Income Taxes (Details Textual)	3 Months Ended
	Mar. 31, 2019USD ($)
Operating Loss Carryforwards [Line Items]
Decrease in Deferred Tax Assets, Valuation Allowance	$ 0

Subsequent Events (Details Text

Subsequent Events (Details Textual) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Apr. 24, 2019	May 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 29, 2018	May 23, 2018
Subsequent Event [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			92,212	92,212
Common Stock, Shares, Issued			6,169,645	5,669,645
Shares Issued, Price Per Share					$ 3.60	$ 3.60
Subsequent Event [Member]
Subsequent Event [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		500,000
Proceeds from Warrant Exercises	$ 1
Common Stock, Shares, Issued		500,000
Shares Issued, Price Per Share		$ 2