Artificial vessels that serve as a platform for "controlled regeneration" are the vision for the future in the development of tubes, vessels and ducts to be implanted in the human body.

Such vessels would encourage the ingrowth of natural cells. As the artificial tube systematically degraded away, new biologic tissue would replace it, ultimately restructuring the diseased body part that had required replacement.Researchers are working to develop implantable materials compatible with the variety of chemicals that would be encountered in different parts of the body.

"The equations we make on paper do not always represent just what happens inside the body," said Dr. Donald J. Lyman, professor of bioengineering and materials science/engineering, adjunct professor of chemistry and research associate in surgery, University of Utah.

Using man-made materials to encourage regeneration of tissues will require joint efforts of the biological disciplines with those involved in creating artificial parts, Lyman said.

Finding ways to foster regeneration of natural tissues would be particularly helpful in replacing sphincters, Lyman said, because of the corrosive nature of urine and fecal matter.

Progress in this direction would be good news to thousands who undergo ileostomy, colostomy and urostomy surgeries each year.

Basic research into the structure of polymers is leading to a clearer understanding of potential interactions inside the body, Lyman said, and to the development of new polymers to meet specific needs.

Lyman has been involved in development of artificial blood vessels. The technology is now wending its way through the approval process that is expected to lead to human experimentation this year, he said. Companies in Utah and Japan are prepared to market the vessels.

Initially, the blood vessels will be used in the extremities, but Lyman expects that the technology will be expanded in the future to include implants in the coronary arteries and in the brain. Occlusion of heart and brain vessels leads to major illness and death for hundreds of thousands of Americans every year.

Lyman also has worked on small-diameter vessels that would be useful in treating conditions such as urinary disease. But he said the research, at least in Utah, has dwindled for lack of financial support. An artificial ureter would present different problems from blood vessels, he said, because of the chemical content of urine. A vessel surface in this environment would have to discourage the creation of crystals.

"I think as this science progresses, we'll find that not just one polymer, but a whole family of materials will be found necessary for the best results," Lyman said. "As we come to understand how the body's chemistry works, we'll be able to develop products that will make better implants.

"We may eventually be able to insert polymers into the body to make diagnoses and to treat disease. Perhaps there will be a material that will absorb white blood cells, for instance, which would have implications in the treatment of leukemia. It all gets back to knowing how polymers interact with natural systems."