Preliminary research could open the door to ready-to-use bioengineered veins
Small-scale animal studies suggest that surgeons might one day be able to simply open the refrigerator when the need for patient-ready bioengineered blood vessels presents itself.
Patients with coronary artery disease or peripheral arterial disease are often treated with bypass surgeries — in which the blood vessel that has narrowed as a consequence of the illness is closed off and circumvented by the implantation of an unrestricted ‘conduit’. To avoid complications, surgeons prefer to use vessels taken from a patient’s own body — harvesting a portion of vein from the leg, for example. But alternatives are often necessary for patients who have had to go under the knife many times, or who merely lack enough robust blood vessels.
Current alternatives have different limitations. Synthetic blood vessels made from polytetrafluorethylene only last for a median time of about 10 months before their flow is reduced as a result of complications such as infection or clotting. Meanwhile, the risk of hardening, clotting and aneurysm has limited the use of grafts taken from human cadavers.
One particularly promising option has been the development of tissue-engineered vascular grafts, which are made using a patient’s own cells — limiting the likelihood of rejection. However, these types of patient-specific grafts take up to 9 months to grow and can cost more than $15,000 per vessel.
Now Shannon Dahl, co-founder of biotechnology firm Humacyte in Durham, North Carolina, and her collaborators have developed a way to grow ‘bioengineered veins’ from donor cells by introducing the cells into scaffolds made of polyglycolic acid. Once these vascular grafts have grown in a bioreactor, the team strips them of cellular material using specialized detergents, leaving collagen tubes that are non-immunogenic — that is, unlikely to be rejected by patients’ immune systems. Using this method, the researchers say that instead of making one vascular graft at a time with one patient’s cells, they could use cell banks to make as many as 37 large or 74 smaller blood vessels per donor, and cell banks put together from multiple donors could hold even more.