DURHAM — A surgeon at Duke University performed the first U.S. implantation of a bioengineered blood vessel on Wednesday, using a new technique that may improve the lives of dialysis patients.
A non-living tube built using living cells, a bioengineered blood vessel resembles natural blood vessels in size and strength but is not made of unnatural materials like synthetic blood vessels, called grafts. Commonly made of Teflon or plastic, synthetic grafts are prone to infection, blood clotting and immune rejection.
Vascular surgeon Dr. Jeffrey Lawson and a team of doctors at Duke University Hospitals implanted into a man’s arm a bioengineered vessel that researchers hope, and animal trials suggest, will eventually replace synthetic grafts.
In dialysis, kidney patients have blood removed from their veins with one needle so it can be cleaned and filtered before being reinserted with a second needle. The treatment can damage a patient’s veins. If the veins are too small or weak for the procedure, a graft is implanted into the patient’s arm and connected to an artery.
Wednesday’s procedure is the first of 20 initial U.S. trials for the bioengineered blood vessel, at Duke and two other medical centers. The first vessels were implanted in humans in December in Poland and used for dialysis in February. Lawson helped train the Polish surgeons and witnessed the procedure.
“The current platform of synthetic materials is good structurally, but they are really just inferior,” said Lawson, who worked on the team that designed the bioengineered blood vessel. “They can be manufactured easily and sterilely and they save peoples lives, but compared to your own tissues they have a much higher rate of infection, of forming blood clots, of all things structurally and biologically inferior.”
The goal of tissue engineering, said Lawson, is to learn what materials the human body would identify as itself and use that information “to make a blood vessel that would function like your own blood vessels, both in structural characteristics and in the way the blood would interact with it as it ran through the blood vessel.”
The first U.S. trial participant, Lawrence Breakley of Danville, Va., has end-stage renal disease and has required kidney dialysis treatments three times a week for three years.
Lawson implanted a standard synthetic graft made of plastic in Breakley’s arm a year ago, but that graft became infected six months later and had to be removed. Two weeks before Wednesday’s procedure, Lawson suggested the bioengineered blood vessel, and Breakley, 62, agreed to participate.
“I wasn’t nervous because I knew I was in good hands,” Breakley said Thursday, sitting in an alcove in Duke Hospital. The morning after surgery, he was not confined to his hospital room.
Humacyte, a privately held company primarily focused on developing products for vascular disease, engineered and provided the blood vessel used in the trial. Lawson’s colleague, Dr. Laura Niklason, founded Humacyte while she held a faculty position at Duke University from 1998 to 2005. Niklason now teaches at Yale University, and Lawson serves as a consultant for Humacyte.
Humacyte’s technique begins with a biodegradable frame made from a donor’s muscular cells. When these cells grow, they form a muscular tube with the immune characteristics of the cell donor. As the cells grow into each other, they form collagen, the protein that makes up connective tissue.
To make the tube implantable into any patient and remove the risk of triggering an immune response, scientists kill the donor cells by washing them away with a solvent, leaving only the collagen structure of the tube.
“What we have left is like an empty house,” said Lawson.
Surgeons can take the grown tube and implant it in a new body. The recipient’s own blood vessel cells can then repopulate the empty tube.
In animal trials featuring dogs, pigs, and baboons, the animals’ own cells grew into the tube after it was implanted. After a few months, the implanted tube was repopulated with so many cells it appeared incorporated into the animals’ own blood vessels.
Lawson and other researchers hope to see the same thing happen in the human trials.
Originally, Lawson and researchers at Humacyte sought to develop personalized blood vessels that are seeded with the recipient’s own blood vessel cells rather than the cells of a donor. Though the process would reduce the risk of the patient’s body rejecting the engineered vein, it also eliminated the possibility of mass production and the ability for hospitals to store veins on-site. Generic, universal veins have a greater applicability because they can be stored in hospitals and are available when patients need them, said Lawson.
It’s not clear how much the bioengineered blood vessels will cost. Humacyte officials could not be reached for comment regarding the projected costs.
Depending on the outcome of the initial human trials, researchers hope the technology can eventually aid patients with other vascular conditions including heart disease, as well as patients who require new intestines, arteries, airways, and other tubular structures.