By Lisa Ellis
InteliHealth News Service

CHICAGO — Scientists from Stanford University and a bioengineering firm say they have produced artificial blood vessels using only natural body cells, without any artificial supporting materials that can cause rejection by the body.

The technique, which has been tried so far only in animals, offers a significant advance, said Todd McAllister, Ph.D., CEO of Cytograft Tissue Engineering, a California firm that hopes to develop and market the artificial vessels.

Someday, he said, this tissue-engineering technology could allow new, genetically identical blood vessels to be made for patients who need a bypass operation but have run out of vessels to transplant.

McAllister described the research in a news conference at the American Heart Association’s annual Scientific Sessions.

The research is very early and mainly proves that such vessels can be built, not how well they would work in humans.

"This study documents that you can really engineer vessels suitable for transplantation and proves the principle involved," said Augustus Grant, M.D., president-elect of the American Heart Association.

The artificial vessels, which were tested in dogs, were built using human fibroblast cells, which form the outer wall of blood vessels. The endothelial cells that line the inside of the vessels came from the animals.

Researchers used a technique called sheet-based engineering to grow these two layers into a continuous, flat sheet of cells as thin as a few human hairs, McAllister said. The cell sheets then were wrapped around a tiny steel cylinder until they fused into a single vessel.

He said the vessels were implanted as leg-artery grafts in dogs. Two vessels failed because of defects, but the others survived until they were removed a week to two weeks later, he said. There were no blood clots, he said. Results have been consistent so far in a 90-day study involving rats, he said.

McAllister said his company’s product is the first one that does not use any synthetic scaffolding to grow the vessels.

If all goes well in the animal tests, he said, the technique will be tried in humans in about 12 to 18 months.

He said the vessels used in humans will be grown entirely from the patient’s own cells. The fibroblasts that form the outer walls will be obtained from a skin biopsy, while endothelial cells for the inner lining are readily available in circulating blood, he said.