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When someone suffers a severe arterial injury to an arm or leg, such as from a gunshot wound, they sometimes require urgent restoration of blood flow to avoid an amputation.
In December 2024 the Food and Drug Administration (FDA) approved a laboratory-grown blood vessel (SYMVESS), which surgeons can use to restore blood flow in such patients during a procedure known as revascularization.[1] The product has a boxed warning for graft failure that “can result in life threatening hemorrhage.”[2]...
When someone suffers a severe arterial injury to an arm or leg, such as from a gunshot wound, they sometimes require urgent restoration of blood flow to avoid an amputation.
In December 2024 the Food and Drug Administration (FDA) approved a laboratory-grown blood vessel (SYMVESS), which surgeons can use to restore blood flow in such patients during a procedure known as revascularization.[1] The product has a boxed warning for graft failure that “can result in life threatening hemorrhage.”[2] The single-use product costs $29,500.[3]
The approval came despite the concerns that the tissue-engineered vessel could rupture with no warning, poorly conducted preapproval studies, and without a public review of the data at a public advisory committee meeting, as subsequently reported by the New York Times.[4] An FDA medical reviewer, who previously worked as a vascular surgeon and cared for patients wounded by gunshots, retired in protest. According to the reviewer, the “unpredictable, catastrophic and life-threatening” adverse events posed “an unacceptable risk for whatever slim benefit, if any, this product provides above the current standard treatments.”[5]
The acellular-tissue-engineered vessel is manufactured using vascular smooth muscle cells derived from human aortic tissue and is composed of extracellular matrix proteins typically found in human blood vessels.[6]
Patients with a blood vessel injury to an extremity often receive an autologous vein graft (a surgical procedure using the person’s own blood vessels) or have a synthetic graft (a tube made of Gore-Tex) implanted.[7] These treatments, however, are not suitable or possible for some patients. The FDA approved the bioengineered vessel as a vascular conduit in adults with extremity artery injury when urgent revascularization is required to avoid imminent limb loss and autologous vein graft is not feasible.[8]
In a preapproval study conducted in the United States, 54 participants were evaluated. Although 39 had blood flow through the tissue-engineered vessel 30 days after implantation, five (9%) underwent amputation of the treated limb within the first 30 days and eight (15%) had amputations by the end of the study at three years.[9] Agency records did not indicate whether vessel failures directly resulted in the deaths or amputations.
However, 37 (69%) of the patients were not assessed in a safety check four months after the implant surgery; some were dead and others were lost to follow-up.[10] Thus, there is great uncertainty over whether the tissue-engineered vessel is safe and effective beyond 30 days. Moreover, in a safety review of 71 cases, seven people (10%) had vessel failures leading to major bleeding, which the FDA reviewer considered “unheard-of in his experience with Gore-Tex grafts.”[11]
When in doubt about the safety and effectiveness of a drug or another medical product, the FDA should protect patients by not approving the product and by requiring more data and better studies. The approval of Symvess is another recent example of the FDA failing patients. This is an urgent problem that Dr. Martin Makary, the new FDA Commissioner, should fully address.
References
[1] FDA approves first acellular tissue engineered vessel to treat vascular trauma in extremities. December 20, 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-first-acellular-tissue-engineered-vessel-treat-vascular-trauma-extremities. Accessed April 16, 2025.
[2] Package insert. Symvess. December 20, 2024. https://www.fda.gov/media/184625/download. Accessed April 16, 2025.
[3] Jewett C. F.D.A. approved lab-grown blood vessel despite warnings. New York Times. March 24, 2025. https://www.nytimes.com/2025/03/24/health/fda-artificial-blood-vessel-trauma-humacyte.html. Accessed April 16, 2025.
[4] Ibid.
[5] Ibid.
[6] FDA approves first acellular tissue engineered vessel to treat vascular trauma in extremities. December 20, 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-first-acellular-tissue-engineered-vessel-treat-vascular-trauma-extremities. Accessed April 16, 2025.
[7] FDA approves first acellular tissue engineered vessel to treat vascular trauma in extremities. December 20, 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-first-acellular-tissue-engineered-vessel-treat-vascular-trauma-extremities. Accessed April 16, 2025.
[8] Package insert. Symvess. December 20, 2024. https://www.fda.gov/media/184625/download. Accessed April 16, 2025.
[9] FDA approves first acellular tissue engineered vessel to treat vascular trauma in extremities. December 20, 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-first-acellular-tissue-engineered-vessel-treat-vascular-trauma-extremities. Accessed April 16, 2025.
[10] Jewett C. F.D.A. approved lab-grown blood vessel despite warnings. New York Times. March 24, 2025. https://www.nytimes.com/2025/03/24/health/fda-artificial-blood-vessel-trauma-humacyte.html. Accessed April 16, 2025.
[11] Ibid.
