Not long after creating a functioning rat lung in her lab, Yale University Professor of Anesthesiology and Biomedical Engineering Laura Niklason is testing bioengineered human veins that could benefit some 500,000 patients a year who need to undergo vascular surgeries such as coronary artery bypass.

Researchers are testing 6mm (above) and 3mm bioengineered human veins.

The tissue-engineered vascular grafts (TEVGs) were generated in a bioreactor using a relatively new tissue engineering method called decellularization--a process by which researchers remove a tissue's individual cells while leaving its structure intact. The veins are off the shelf and available at the time of surgery, and are said to be less likely to result in obstruction, clotting, or infection.

The findings, published this week in the journal Science Translational Medicine by researchers from East Carolina University, Duke, Yale, and Niklason's company Humacyte, suggest the veins could work in both large- and small-diameter applications (6mm and 3mm), be stored up to 12 months in refrigerated conditions, and provide unobstructed blood flow in large animal models for up to a year.

"Currently, grafting using the patient's own veins remains the gold standard," said co-author Dr. Alan P. Kypson, an associate professor of cardiothoracic surgery at East Carolina University. "But harvesting a vein from the patient's leg can lead to complications, and for patients who don't have suitable veins, the bioengineered veins could serve as an important new way to provide a coronary bypass."

And, with some 110,000 more people requiring dialysis each year--a figure that is growing at a rate of at least 3 percent annually, according to the National Kidney Foundation--these second-gen veins could help the roughly half of dialysis patients who must first undergo an arteriovenous graft placement due to unhealthy veins.

"While there is still considerable research to be done before a product is available for widespread use, we are highly encouraged by the results outlined in this paper and eager to move forward with additional study," said Shannon Dahl, lead author of the report and co-founder of Humacyte, which funded the research.