Scientists have managed to grow human blood vessels in a laboratory setting and then successfully add them to a living circulatory system in human patients. The achievement involves taking tissue from the desired recipient to grow the blood vessels and then using those lab-made organs to replace arteries damaged by heart disease.
Research leader Heather Prichard explains, “The idea was that if blood vessels could be made in the lab, they could be used to treat patients with different vascular needs and possibly have less morbidity than current alternatives.”
Also a chief operations officer with the North Carolina biotech company, Humacyte, Prichard goes on to say, “The removal of the cells is important so that the vessels can be manufactured in large batches and stored on the shelf in operating rooms for implantation into any patient.”
These new vessels, she says, are called human acellular vessels (HAVs), and measure roughly 15 inches in length and ¼ inch in diameter. Their structure and strength both mimic that of living human veins and arteries.
To develop this new biomedical technology, the research team spread the original cells out on a scaffold where they could be provided with nutrients. From there, they were able to produce an extracellular matrix, which is a 3D network of proteins—which includes collagen—that can make blood vessels. When these vessels start to form, fluids push through them to simulate blood pressure.
Once they simulate blood pressure, the researchers next separated the cells from these new blood vessels and removed the proteins that might be targeted as foreign by the recipient’s immune system. The final step, then, is to simply implant these 42cm-long and 6mm-thick blood vessels into the upper arms of [60 test] patients with kidney failure.
This procedure is important, of course, because each of these patients was undergoing dialysis. Dialysis involves the filtration of waste products from the blood using an external machine: and it is time-consuming. And also complicated: traditionally surgeons would have to connect an artery to a vein in order to create a wider vessel with higher pressure for transferring blood to the machine. Everyone involved with this study was not able to do this original procedure—perhaps possessing narrow or weak blood vessels—so they received these lab-grown blood vessels instead.
Finally, the study took samples from 13 of these patients, over a four-year period, indicated that the blood vessels successfully developed into complex human tissue that self-healed.
The results of this study have been published in Science Translational Medicine.