Biomedical engineers from the University of Minnesota have created artificial blood vessels. If confirmed in humans, the grafts, bioengineered in the lab and tested in young lambs, could prevent repeated surgeries for children with congenital heart defects.

University of Minnesota Department of Biomedical Engineering Professor Robert Tranquillo 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.

To develop the graft material, researchers combined sheep skin cells in a gelatin-like material, called fibrin. After forming a tube, the team used a bioreactor to rhythmically pump in the nutrients necessary for cell growth. The pumping bioreactor provided both nutrients and “exercise” to strengthen and stiffen the tube.

The researchers then used special detergents to wash away all the sheep cells, leaving behind a cell-free matrix that prevents an immune reaction when implanted.

When the vessel graft replaced a part of the pulmonary artery in three lambs at five weeks of age, the implanted vessels were soon populated by the lambs’ own cells, causing the vessel to bend its shape and grow together with the recipient until adulthood.

“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.”