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Release: Sept. 23, 1999

Researchers examine new way to possibly induce vascular growth

IOWA CITY, Iowa — By lowering an individual's heart rate, doctors someday may be able to trigger the sprouting of new blood vessels without having to resort to invasive methods, according to results from a University of Iowa Health Care study.

In recent years, a substance known as vascular endothelial growth factor (VEGF) has attracted the attention of researchers who are looking for ways to develop new blood vessels to replace those either damaged or blocked due to coronary conditions.

Until now, the focus has been on using either injections of the needed VEGF or the gene therapy strategy, which involves delivering the VEGF to its intended destination via a disabled cold virus carrier. Robert J. Tomanek, Ph.D., UI professor of anatomy and cell biology, and his research team are looking at a less intrusive, more natural approach.

"Gene therapy is one avenue to bring about vascular growth, but if you can use either pharmacological interventions or some interventions that change the physiology of the heart so that the heart does it naturally, then I think that is better because it is noninvasive," Tomanek said.

Wei Zheng, Ph.D., a postdoctoral fellow in Tomanek's lab, was able to get laboratory rats to produce the needed VEGF by using a heart rate lowering drug. A lowered rate allows the heart to fill with more blood between each beat. The increased blood causes the heart to stretch, which Tomanek believes induces the animal to produce VEGF.

VEGF then triggers endothelial cells, the building blocks of the blood vessels, to proliferate.

"VEGF causes the endothelial cells to migrate, line up and actually form the vascular structures," Tomanek explained.

Tomanek and his colleagues are continuing to study VEGF and other growth factors, attempting to learn more about the mechanisms involved with coronary vascular growth.

"Hopefully, this can get to the stage where it can be applied to humans," Tomanek said.

A grant from the National Institutes of Health supplied funding for the study, which recently appeared in the journal Circulation Research. Other scientists who contributed to the study are

Margaret D. Brown, Ph.D., a lecturer at the University of Birmingham; Tommy Brock, Ph.D., director of pharmacology at Texas Biotechnology Corp.; and Robert J. Bjercke, Ph.D., senior scientist at Texas Biotechnology Corp.

University of Iowa Health Care describes the partnership between the UI College of Medicine and the UI Hospitals and Clinics and the patient care, medical education and research programs and services they provide.