How To Mend A Broken Heart

Every year some 400,000 Americans undergo bypass surgery to shunt the flow of blood around blocked arteries in their heart; 500,000 other patients opt for a different procedure called angioplasty, which clears a channel through the bottlenecks with thin, inflatable balloons. Most people who have these operations get what they so desperately want--a second chance at life. But the results are usually temporary. After a few years the bypass graft or the reopened artery becomes clogged with new deposits, which often require a second round of treatment. For an estimated 1 in 10 patients, the heart becomes so scarred that nothing more can be done.

That grim outlook may be about to change. Scientists have been experimenting with a new way--based on a form of gene therapy--to coax the heart into growing new blood vessels to replace old worn-out ones, and doctors who have been performing the procedure are becoming more and more excited by the results. Reports of their progress have spread through the scientific community for the past year. But not until last week, when the leading researchers gathered in Atlanta at a brainstorming meeting to which TIME was given exclusive access, did it become clear how far they have gone. Says Dr. Todd Rosengart of the Northwestern University Medical School: "Because we're looking at a different way of providing blood flow, we're making a step toward what could be a long-term cure for heart disease."

Already, 1,000 patients have received the experimental therapy at 50 different medical centers. In most cases the treatment was part of a conventional bypass or angioplasty. But the preliminary results were so encouraging that doctors have started offering the new therapy to patients who are too sick to undergo any more conventional operations. There are still many unanswered questions, and some patients have died (although researchers insist their deaths did not occur as a consequence of the treatment). Yet if the new therapy lives up to its promise, hundreds of thousands of men and women with heart disease will, over the next few years, be able to heal themselves.

Doctors have long known that the heart can, in response to a drop in the level of oxygen-rich blood it's receiving, grow extra blood vessels. But the process, called angiogenesis, is often too slow and not extensive enough to stave off a heart attack. About 10 years ago, scientists started identifying certain proteins, called growth factors, that the body uses to build new blood vessels. The proteins act like foremen at a construction site, making sure that all the pieces of the project come together smoothly. Animal experiments showed that there were several ways to get growth factors into the heart. You could inject a gene--either by itself or wrapped in a viral envelope--that tells the heart muscle how to make growth factor. Or you could skip the gene and just use the finished product, the growth-factor protein itself. The advantage of gene therapy is that you have to do it only once; the gene will keep generating growth-factor protein. Using the protein by itself gives doctors a little more control. The disadvantage is that they may have to repeat the process, perhaps as frequently as every few months.