Tranquillo leads groundbreaking, collaborative research on artificial blood vessel growth in living recipient

In a groundbreaking new study published today in Nature Communications, University of Minnesota researchers discovered that blood vessels bioengineered in the lab and implanted in young lambs are capable of growth within the recipient. If confirmed in humans, these vessel grafts would prevent the need for repeated surgeries in some children with congenital heart defects.

Professor Robert Tranquillo, who holds faculty appointments in the Department of Biomedical Engineering and Department of Chemical Engineering and Materials Science, and his colleagues generated vessel-like tubes in the lab from a post-natal donor’s skin cells and then removed the cells to minimize the chance of rejection. This also means the vessels can be stored and implanted when they are needed, without the need for customized cell growth of the recipient. When implanted in a lamb, the tube was then repopulated by the recipient’s own cells allowing it to grow.

“This might be the first time we have an ‘off-the-shelf’ material that doctors can implant in a patient, and it can grow in the body,” Tranquillo said. “In the future, this could potentially mean one surgery instead of five or more surgeries that some children with heart defects have before adulthood.”

To develop the material for this study, researchers combined sheep skin cells in a gelatin-like material, called fibrin, in the form of a tube and then rhythmically pumped in nutrients necessary for cell growth using a bioreactor for up to five weeks. The pumping bioreactor provided both nutrients and “exercise” to strengthen and stiffen the tube. The bioreactor, developed with Zeeshan Syedain, a senior research associate in Tranquillo’s lab, was a key component of developing the bioartificial vessel to be stronger than a native artery so it wouldn’t burst in the patient.

Tranquillo said the next step is talking with doctors to determine the feasibility of requesting approval from the Food and Drug Administration (FDA) for human clinical trials within the next few years. In addition to Tranquillo and Syedain, other researchers who were part of the study included, Jay Reimer and Sandra Johnson from the Department of Biomedical Engineering, and Matthew Lahti and James Berry from the University of Minnesota Experimental Surgical Services in the Academic Health Center.

The research was funded primarily by a Pediatric Device Innovation Consortium grant from the University of Minnesota Academic Health Center’s Clinical and Translational Science Institute. Funding from the National Institutes of Health’s Heart, Lung Blood Institute aimed at making vessel containing a heart valve that can grow also contributed to this research.

To read the full research paper entitled “Tissue engineering of acellular vascular grafts capable of somatic growth in young lambs,” visit the Nature Communications website.