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Injection grows new capillaries

Scientists have made human hearts grow tiny new blood vessels by injecting proteins, raising hopes that the procedure may one day be used to treat people with clogged heart arteries.

The study was published in Monday's issue of Circulation, a journal of the American Heart Association.Growing new vessels, or angiogenesis, "has huge possibilities," said Dr. Ronald Crystal, who is pursuing a somewhat different method. "I think that it is going to be a major strategy in parallel with bypass surgery and angioplasty."

In bypass surgery, doctors graft a piece of blood vessel to create a detour around a clog. With angioplasty, a doctor inserts a balloon-tipped catheter into a clogged artery to push the blockage aside.

The angiogenesis study was conducted by scientists at the Fulda Medical Center in Fulda, Germany. They studied 14 men and six women, all at least 50 years old.

The patients received an injection of the protein, a human growth factor known as FGF-1, directly into areas of their hearts where blood flow was reduced by clogged arteries. The injections were delivered while the patients were undergoing bypass surgery because of blockages.

In all 20 of the patients, new networks of blood vessels began growing as early as four days after the procedure, said Dr. Thomas-Joseph Stegmann, one of the researchers.

Stegmann said that on average, the patients had a two- to threefold increase in blood flow to the heart. But how much of that was due to the surgery or the new vessels is not known, he said.

So far, the procedure has produced only capillaries, blood vessels that are smaller in diameter than human hairs. But scientists hope to grow larger vessels.

"If we prolong the study, maybe we can say in a one- or two-year period that it is efficient to bypass capillaries and larger vessels," Stegmann said.

It is too soon to say whether the procedure would eventually be used by itself or in addition to bypass surgery or angioplasty.

The new therapy could be especially useful for treating patients whose blocked arteries cannot be treated with bypass surgery, said Dr. Elizabeth Nabel, chief of the cardiology division at the University of Michigan.

Previously, scientists have used gene therapy to grow vessels in other parts of the body, including the legs. Patients with severely clogged arteries in their legs received injections of laboratory-made versions of the human gene that makes vascular endothelial growth factor, a protein that prompts blood vessel development during growth in the womb.