Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Patent License Agreements Duke University In March 2006, the Company entered into a license agreement with Duke University (“Duke”), which was subsequently amended in 2011, 2014, 2015, 2018, 2019 and 2022. Under this license agreement, Duke granted the Company a worldwide, exclusive, sublicensable license to certain patents related to decellularized tissue engineering, referred to as the patent rights, as well as a non-exclusive license to use and practice certain know-how related to the patent rights. The relevant licensed patent on decellularization of tissue expired in 2021. The Company has agreed to use commercially reasonable efforts to develop, register, market and sell products utilizing the patent rights, referred to as the licensed products. Any services provided to a third party utilizing licensed products are referred to as licensed services. The Company has also agreed to meet certain benchmarks in its development efforts, including as to development events, clinical trials, regulatory submissions and marketing approval, within specified timeframes. Under the license agreement, Duke retains the right to use the patent rights for its own educational and research purposes, and to provide the patent rights to other non-profit, governmental or higher-learning institutions for non-commercial purposes without paying royalties or other fees. In connection with the Company’s entry into the license agreement, the Company granted equity consideration to Duke in the form of 52,693 shares of Common Stock. Under the license agreement, the Company also agreed to pay Duke: •a low single-digit percentage royalty on eligible sales of licensed products and licensed services, plus a low double-digit percentage of any sublicensing revenue; •an annual minimum royalty beginning in 2012, which increases in the calendar year immediately following the first commercial sale of licensed products or licensed services (whichever occurs first); and •an additional amount in license fees, as certain milestones are met. The license agreement remains effective until the later of (i) the last of the patent rights expires or (ii) four years after the Company’s first commercial sale, unless terminated earlier. Either party may terminate the agreement for fraud, willful misconduct or illegal conduct, or uncured material breach. Duke may terminate the agreement if the Company becomes insolvent. Duke may also terminate the license, convert the license into a non-exclusive license or seek assignment of any sublicense if the Company fails to reach diligence milestones within the applicable time period. If the Company abandons any claim, patent or patent application, its rights under the license with respect to such patent rights will be terminated in the territory in which the Company abandons such rights. The Company may terminate the license agreement unilaterally upon three months’ prior notice to Duke. The Company agrees to indemnify Duke against certain third-party claims. In December 2023, the Company filed a BLA with the FDA for urgent arterial repair following extremity vascular trauma when synthetic graft is not indicated, and when autologous vein use is not feasible. Based on the achievement of this milestone under the Duke license agreement, the Company recorded license expense payable of $0.5 million in accounts payable in the Company’s condensed consolidated balance sheets as of December 31, 2023. The Company paid the $0.5 million license fee to Duke during the first quarter of 2024. Other payments to Duke under the license agreement were immaterial during the periods presented. Yale University In August 2019, the Company entered into a license agreement with Yale University (“Yale”) that granted the Company a worldwide license to the patents related to the biovascular pancreas (“BVP”) product candidate (the “BVP License Agreement”). The license granted under the BVP License Agreement is exclusive in the field of engineered vascular tissues that deliver pancreatic islet cells to patients, except that it is subject to Yale’s non-exclusive right, on behalf of itself and all other non-profit academic institutions, to use the licensed products for research, teaching, and other non-commercial purposes. The Company has agreed to pay to Yale an annual maintenance fee, increasing between the first and fourth anniversaries of the BVP License Agreement up to a maximum of less than $0.1 million per year for this license. In August 2019, the Company entered into a license agreement with Yale that granted the Company a worldwide license to the patents related to tubular prostheses (the “Tubular Prosthesis License Agreement”). The license granted under the Tubular Prosthesis License Agreement is exclusive in the field of engineered urinary conduits, engineered tracheas/airways, and engineered esophagi, except that it is subject to Yale’s non-exclusive right, on behalf of itself and all other non-profit academic institutions, to use the licensed products for research, teaching, and other non-commercial purposes. The Company has agreed to pay to Yale an annual maintenance fee, increasing between the first and fourth anniversaries of the Tubular Prosthesis License Agreement up to a maximum of less than $0.1 million per year for this license. The Company has agreed to use reasonable commercial efforts to develop and commercialize the licensed patents and any licensed products and methods, and to use reasonable efforts to make the licensed products available to patients in low and low-middle income countries. The Company is also obligated to provide Yale periodically an updated and revised copy of its plan for each license, which must indicate progress of its development and commercialization. The Company may also sublicense the Company’s rights without Yale’s prior written consent, but such sublicense is subject to certain conditions. In connection with its entry into the Tubular Prosthesis License Agreement, the Company paid Yale upfront cash fees. The Company has also agreed to pay Yale: •annual maintenance fees, increasing annually until the fifth anniversary for the BVP License Agreement and until the fourth anniversary for the Tubular Prostheses License Agreement up to a maximum of less than $0.1 million per year; •milestone payments upon achievement of certain regulatory and commercial milestones of $0.2 million and $0.6 million, respectively; •a low single-digit percentage royalty on worldwide net sales, subject to reductions for third-party license fees; and •a low double-digit percentage of sublicensing income. If the Company or any of its future sublicensees bring a patent challenge against Yale or assists another party in bringing a patent challenge against Yale, the license fees described above will be subject to certain increases and penalties. The BVP License Agreement and Tubular Prosthesis License Agreement expire on a country-by-country basis on the date on which the last of the patents in such country expires, lapses or is declared invalid. Yale may terminate the BVP License Agreement and Tubular Prosthesis License Agreement if the Company fails to (i) provide written diligence reports, (ii) provide commercially reasonable diligence plans, (iii) implement the plans in accordance with the obligations under the agreements, or (iv) reach certain research and development milestones within the scheduled timeframe set forth in the agreements; however, any such termination right would be limited in scope to the country to which such failure relates. Yale may also terminate for the Company’s non-payment, uncured material breach, failure to obtain adequate insurance, bringing or assisting in bringing of a patent challenge against Yale, abandonment of the research and development of the Company’s products or insolvency. The Company may terminate the BVP License Agreement and Tubular Prosthesis License Agreement (i) on 90 days’ prior written notice to Yale, provided the Company is not in breach of the license agreements and has made all required payments to Yale thereunder and (ii) on written notice to Yale following an uncured material breach. With respect to the BVP License Agreement, the Company’s rights under the agreement will also terminate automatically with respect to a patent application or patent within the licensed patents in a specified country if, upon receipt of written notice from Yale, the Company does not agree to pay the patent filing, prosecution and maintenance fees incurred by Yale for such patent applications or patents in the specified country. Under certain circumstances, Yale may, at its option, convert the exclusive licenses to non-exclusive licenses if the Company declines to initiate certain infringement or interference proceedings with respect to the licensed patents. The Company has agreed to indemnify Yale against certain third-party claims. Payments to Yale under the BVP License Agreement and Tubular Prosthesis License Agreement were immaterial during the periods presented. JDRF Agreement On April 1, 2023, the Company entered into an Industry Discovery and Development Partnership Agreement with JDRF International (“JDRF,” and such agreement, the “JDRF Agreement”) to further develop and perform preclinical testing of the BVP, a product candidate designed to deliver insulin-producing islets using the ATEV as a means of treating patients with type 1 diabetes. According to the terms of the JDRF Agreement, JDRF will provide funding up to $0.8 million (“JDRF Award”) based on the achievement of certain research and development milestones related to the Company’s BVP. The JDRF Agreement refers to the total cumulative payments the Company has received from JDRF as of any point in time as the “Actual Award.” The Company received the first milestone payment of $80 thousand in April 2023 upon execution of the JDRF Agreement. In May 2024, the Company received the second milestone payment of $90 thousand and the third milestone payment of $150 thousand, based upon the achievement of certain research and development milestones specified in the JDRF Agreement. As of June 30, 2024, the Actual Award totaled $320 thousand. The Company determined that the JDRF Actual Award payments are to be classified as long-term debt under ASC 470, Debt in the condensed consolidated balance sheets. The JDRF liability related to the Actual Award payments is reported at amortized cost and is included in other long-term liabilities in the condensed consolidated balance sheets. As of June 30, 2024 and December 31, 2023, the carrying value of the JDRF liability is $228 thousand and $69 thousand, respectively. There was an insignificant amount of interest expense related to the JDRF liability recorded in each period presented. In accordance with the JDRF Agreement, the Company has agreed to pay JDRF: •a one-time royalty in an amount equal to four times the Actual Award, to be paid in three equal installments following the first commercial sale of any product containing the Company’s technology identified in the JDRF Agreement; •an additional royalty equal to the Actual Award at a specified payment date after net sales exceed $250 million; and •in the event of a license, sale or transfer of the Company’s rights to the product’s technology identified in the JDRF Agreement or a change of control transaction, a payment equal to 10% of any license or purchase price payments received by the Company up to an amount equal to four times the Actual Award (the “Royalty Cap”), less any previous royalty payments paid towards the Royalty Cap (the “Disposition Payment”). The Disposition Payment was determined to meet the definition of an embedded derivative requiring bifurcation and is measured at fair value each reporting period with changes in fair value recognized as other income (expense) in the condensed consolidated statements of operations and comprehensive loss, classified in change in fair value of derivative liabilities. The JDRF Agreement expires on the date on which the Company has paid all of the royalty payments described above. Either party may terminate the JDRF Agreement for cause by providing the other party with written notice and allowing the other party 30 days to cure such breach. JDRF may terminate the JDRF Agreement without cause by providing 90 days’ notice to the Company at any time after April 1, 2024. Royalties on previously received milestone payments would remain due after a termination by JDRF without cause. Legal Matters The Company currently is not aware of any legal proceedings or claims that management believes will have, individually or in the aggregate, a material adverse effect on the Company’s business, financial condition, results of operations, or cash flows. Indemnification To the extent permitted under Delaware law, the Company has agreed to indemnify its directors and officers for certain events or occurrences while the director or officer is, or was serving, at the Company’s request in such capacity. The indemnification period covers all pertinent events and occurrences during the director’s or officer’s service. The maximum potential amount of future payments the Company could be required to make under these indemnification arrangements is not specified in such arrangements; however, the Company has director and officer insurance coverage that is intended to reduce its exposure and enable the Company to recover a portion of any potential future amounts the Company could be required to make. To date, the Company has not incurred any costs as a result of such obligations and has not accrued any liabilities related to such obligations in the condensed consolidated financial statements.