Heart doctors report promising results with gene therapy

November 8, 1999
Web posted at: 1:47 p.m. EST (1847 GMT)

In this story: Researchers say deaths not related to therapy Heart valves for sheep grown in lab RELATED STORIES, SITES

ATLANTA (CNN) -- Several heart doctors meeting in Atlanta this week reported success in experimental trials using gene therapy to help keep patients' arteries unclogged. And one researcher continued to defend his work from recent press reports that two deaths in a gene therapy experiment were not properly documented.

Gene therapy is cutting-edge research for heart disease. Cardiologists watch it eagerly, because half the 500,000 U.S. bypasses each year fail because the arteries clog up again with fatty plaque after surgery.

One of the most promising studies presented at the American Heart Association conference tested gene therapy along with bypass surgery for blocked leg arteries in 40 people. Before the procedure, patient Arnold Schutzberg could not walk without pain.

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CNN's Rhonda Rowland reports on the new gene therapy treatment being used to help heart patients. Windows Media 28K 80K

"I was living with that condition, having to stop every two blocks for a period of time until the blood flow managed to get through," he said.

During surgery, the veins to be used for the bypass were bathed in a solution of altered genes, designed to prevent the arteries from re-clogging.

Researchers followed the patients for a year and say the gene therapy has worked.

"We saw that the failure rate among this early group of patients who were at very high risk for failure was cut by more than half over that 12-month period," said Dr. Michael Mann, Boston Brigham & Women's Hospital.

Mann's tests of the genetic solution will now move to heart bypass surgeries.

Dr. Jeffrey Isner runs some of the most advanced trials of gene therapy, currently involving 72 patients, and at the AHA meeting he again disputed recent charges that two deaths were not properly reported.

"Both of these cases were reported properly to the FDA. In both cases the FDA agreed they were not related to the gene therapy, and there was no need to interrupt the trial," said Isner.

Considering that he was working with very ill heart-disease patients, this was a low death rate, Isner added.

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Summing up the latest gene therapy research in heart disease, Dr. Valentin Fuster told reporters, "Today we can say it is almost clinically applicable." Fuster is director of the cardiovascular institute at Mount Sinai Medical Center in New York.

In another experiment called "tissue engineering," researchers reported growing new heart valves for sheep in a laboratory and successfully implanting the working valves in six animals, who survived for several months.

Researchers started with cells from a lamb's own arteries, and they hope this approach will eventually produce better replacement valves for people.

Because they are made from the patient's own cells, the valves could have at least two major advantages over the artificial valves and pig valves currently used: They will grow as the recipient does, and they will work without the need of blood-thinning drugs.

Medical Correspondent Rhonda Rowland and the Associated Press contributed to this story.