Medical researchers are reporting progress on creating so-called bionic veins that can be used off the shelf in the operating room.
They've grown blood vessels from human tissues that surgeons could eventually use for heart bypass and dialysis patients.
Typically, a heart patient's own vein is taken from the leg and sewn into the heart during coronary artery bypass graft surgery to circumvent a blockage. More than 500,000 such procedures are done in the U.S. each year. But not all patients have suitable vessels for transplant, and the grafts may not be the correct size, doctors say.
A new study published in Wednesday's issue of the journal Science Translational Medicine shows the potential of an innovative solution: bioengineered veins. They would be made ahead of time in bulk and supplied to hospitals.
The veins would be available for heart bypass surgery or when patients come in for dialysis.
Researchers say the bioengineered veins come with less risk of infection, obstruction or clotting than current synthetic grafts that heart surgeons say have poorer clinical outcomes.
"Imagine if we were to create blood vessels that are grown and are on a shelf, so that when you come into the operating room as a patient, we don't have to cut your legs and take the veins out of them," said study author Dr. Alan Kypson, a professor of cardiothoracic surgery at the Brody School of Medicine at East Carolina University.
"It saves time, it saves patient discomfort, potentially maybe even reducing length of stays in the hospital. It eliminates things like leg infections that you know happen in a small percentage of patients," Kypson added in an interview.
Avoiding artery mismatch
Perhaps more exciting, the blood vessels can be made to fit the artery surgeons aim to bypass, he said.
Arteries are only two to three millimeters in diameter but a vein from a leg could be up to one centimeter in size. Such mismatches may lead veins to become blocked over time after surgery as blood stagnates and clots, Kypson noted.
In the experiment, investigators grew blood vessels from human cadaver tissues on tube-like scaffolds made from a biodegradable polymer used in sutures. When the scaffold degraded, fully formed blood vessels were left. These were then stripped of the original donor cells to make sure they wouldn't trigger an immune response when transplanted.
In a series of tests, the human blood vessels kept their strength and elasticity, and remained unclogged after scientists stored them for a year.
For heart patients, Prof. Jeremy Pearson, associate medical director at the British Heart Foundation, noted that synthetic veins can be an important part of treatment but are not always suitable.
"This study shows that bioengineering can be used to create a novel type of vascular graft that has the potential to improve outcomes for patients. We look forward to the results of clinical trials designed to test this," Pearson said in an email.
"For the first time, a bioengineered vein produced from human cells can be stored for up to 12 months in a simple manner," the study's lead author, Shannon Dahl, senior director of scientific operations and co-founder of Humacyte, said in a journal podcast.
When the grafts were tested on baboons and dogs that had surgery, the vessel acted like a pipe between an artery and vein to restore blood flow. Doctors use the same graft approach in kidney dialysis, which filters blood through a machine to clean out waste products when kidneys no longer carry out that function properly.
The researchers believe they are ready to try clinical testing for dialysis, which is typically less risky than heart surgery. Krypson said the first human trials could be two or three years from now.
One of the study's authors has served as a consultant for Humacyte, a privately held company focused on bioengineering. The author also received research support from the company through Duke University.