Researchers from Yale and a medical company called Humacyte have published the results of a long term study that shows engineered blood vessels that are implanted into humans eventually evolved into living tissue. The vessels are known as bioengineered acellular human vessels (HAVs).
The team says that at the time the faux blood vessels were implanted into humans, they were devoid of any cells. However, the fake vessels had taken on cells and transformed their structure into living tissue that could transport blood and self-heal after an injury. Researchers say that essentially the engineered blood vessels had become the patients’ own blood vessels.
The study shows that the implants stimulate the cells of the recipients’ body to repopulate the vessels and take on characteristics expected in cells. The vessels were implanted into patients that have end-stage kidney disease. The patients were on hemodialysis three times per week.
The process requires the implantation of a graft made from synthetic material like Teflon that are implanted into the arm. The big issue for the graft is that they carry a high risk of infection, clotting, and scarring to the point of the vessel closing up.
The HAVs are formed using human donor cells of smooth muscle into a tubular scaffold. They are grown in vitro and then remain in a bioreactor for eight weeks; during that time the scaffold degrades. All the cells are then removed and the structure cleansed of anything that could cause an immune response. The study followed the first implantation in humans, which happened six years ago. HAVs are currently completing a phase 3 clinical trial comparing them to synthetic grafts.