Lab-grown blood vessels could soon become reality

Researchers around the world are working to grow heart valves, lungs and more from human cells. They have succeeded in bringing some to market such as knee cartilage and skin grafts, but advances for more complicated anatomy have been slow-going for years.

Now scientists are gaining ground in tissue engineering that could help a host of people who deal with circulatory-system problems.

One of the companies furthest along is Humacyte, a Durham, N.C.-based biotech that makes lab-grown blood vessels, which could help patients with traumatic injuries along with those who use catheters for dialysis or suffer pain from narrowed circulation to the limbs.

Using new, lab-grown blood vessels to replace the old would offer surgeons a drastically different method than today’s to help patients whose arteries have been torn in explosions or car crashes, for example. Doctors typically go with synthetic grafts made of plastic, which can cause clotting and other problems, or a patient’s own blood vessels cut from a different part of the body.

“This is spare parts for people," said Dr. Laura Niklason, chief executive of Humacyte. The company’s blood vessels, which have thick walls similar to arteries, can also replace veins, though surgeons rarely repair or replace those.

The company starts the process with a 40-centimeter-long tube of degradable plastic mesh in a bag filled with nutrition for cells, such as proteins, growth factors, vitamins, minerals and glucose.

Next, they add blood-vessel cells from human donors to the bag. Over two months, the plastic scaffold dissolves, while the cells form a human artery complete with the collagen and proteins that give blood vessels their strength.

Humacyte then washes the living cells away with a special detergent. What’s left behind is a pale, white tube that feels and works like a blood vessel.

The company has already begun to test its technology in patients and applied for approval from the Food and Drug Administration for treating trauma injuries.

The approval would be a milestone in the field of tissue engineering, and if approved, Humacyte could offer the blood vessels in different sizes and for different uses in the future. Humacyte has already implanted more than 500 of its blood vessels in humans.

When a surgeon implants the collagen tube, the device begins shuttling blood through the body. Then, the patient’s own cells begin to populate the tube.

“What we implant is like an empty apartment building," Niklason said. “Once cells move in and they feel all the collagen and proteins around them, they say, ‘Oh, I’m in a blood vessel,’" and they become blood-vessel cells over time."

Sixteen weeks later, the patient has grown their own layer of living blood vessel cells along the implanted collagen tube, the company’s research shows.

The artery—dubbed the “acellular tissue-engineered vessel," or ATEV—will first be used, pending FDA approval, in situations where surgeons don’t have time to look for a piece of blood vessel from somewhere else in a patient’s body, or when there are no other healthy blood vessels available.

The company said there haven’t been unexpected concerns about safety from its technology, but in clinical trials some patients experienced anemia, blood clots, constipation, fever and swelling. People treated with synthetic grafts often experience those, too. The lab-grown blood vessels will be priced based on the value linked to reducing costly complications such as infections and amputations that were exhibited in clinical studies, according to Humacyte.

Humacyte’s lab-grown vessel will be ready off the shelf and won’t require thawing or rehydrating as some other types of tissues and blood products do, making it easy for hospitals to store. And the company’s data shows it performs better than synthetic versions, often made of plastic fabric such as Gore-Tex, which can cause clotting and infections.

The technology has already shown to be effective in some trauma patients. The company’s approach has helped treat 69 people who participated in a clinical trial in the U.S. and Israel, with injuries from gunshots, workplace accidents, car crashes and other traumas. Humacyte’s product has also been used on 19 soldiers in Ukraine via a special humanitarian program that was approved by the FDA. Many of the soldiers were wounded by explosives.

Data collected by Humacyte showed the patients had better blood flow and were less likely to need amputations than historically needed with synthetic grafts. Niklason and her colleagues didn’t expect to test their technology in Ukraine, but got calls from Ukrainian surgeons, asking them to send their product to the war zone. Humacyte trained the Ukrainian surgeons how to use the lab-grown vessels over Zoom.

“It has saved lives and saved limbs," said Dr. Oleksandr Sokolov, a Ukrainian vascular surgeon who operated on 10 soldiers using the Humacyte product.

Humacyte is studying whether the blood vessels could also help people undergoing dialysis, who often have to rely on plastic catheters, which can lead to infections. They are also testing them in people with peripheral artery disease, which causes pain from narrowed blood vessels.

Humacyte could help cardiac bypass patients as well, says the company. The procedure involves harvesting an artery or vein from somewhere else in the body and sewing it into the heart to circumvent a blocked vessel. The lab-grown vessels could make the harvesting unnecessary. Cardiac bypass and pediatric heart surgery are next for clinical tests.

“It’s a major, major advance, if it does what it says it’s going to do," said Dr. Allan Kirk, chairman of the Department of Surgery at Duke University School of Medicine, who doesn’t have an official role with the company and hasn’t been involved in its clinical trials but did help Humacyte apply for a grant. “The brilliance here is the realization that you don’t need to grow the blood vessel, you just need to put the scaffolding down, and the body will do the rest."

Scientists first reported growing artificial human blood vessels in 1986. Niklason implanted lab-grown arteries in pigs in 1999. Doctors sewed a tissue-engineered blood vessel into a human in 2001.

After years of research, cardiovascular medicine is ripe to be transformed by lab-grown tissue, according to Dr. Christopher Breuer, who directs the Center for Regenerative Medicine at Nationwide Children’s Hospital in Columbus, Ohio.

Breuer is overseeing a clinical trial in which doctors extract bone marrow from a child born with a heart defect, layer those bone marrow cells onto a biodegradable scaffold in a matter of hours and use it in surgery to repair the defect. Once implanted, the scaffold degrades and a new blood vessel is formed.

Children in particular could benefit from tissue-engineered heart parts, as they are likely to grow along with the patient, said Breuer, unlike synthetic fixes that have to be replaced when youngsters get bigger.

Further down the road are lab-grown organs, such as livers or hearts. Scientists have grown lungs and implanted them in rats. But anything that requires a network of tiny, delicate blood vessels is more difficult to perfect, Breuer said.

Write to Liz Essley Whyte at liz.whyte@wsj.com