GMA: Stem Cells May Help Heart Patients

April 2, 2001 -- Several new studies in which researchers used stem cells from bone marrow to repair heart tissue in animals could signal a revolutionary way of treating heart attack patients — without surgery or drugs.

If the procedure works on humans, it would mean that instead of getting organ transplants, heart attack patients could simply have cells extracted from their own bone marrow, or a donor's, then have the cells injected via a shot into their heart, or the bloodstream. Those cells would head to the damaged area and grow new heart muscle cells.

The studies found that stem cells, which normally differentiate into specific kinds of blood cells such as red or white blood cells, can differentiate into heart cells once they are placed in the heart.

Regenerated Heart Tissue

Heart disease is the top killer in the United States, and is responsible for more than 40 percent of the 2.3 million American deaths each year. If developed, a new treatment could impact the more than one million Americans suffer heart attacks every year.

ABCNEWS' Dr. Tim Johnson said researchers do not know what the study will mean for humans — but the animal studies reveal that there is enormous potential.

"Some of them [researchers] are talking about the possibility ofstarting human studies within a year. It would be a wonderful development," said Johnson on ABCNEWS' Good Morning America.

In the first of the three studies, researchers used stem cells from human bone marrow, injecting it into rats that had heart attacks. The rats formed new blood vessels in their hearts, and there was a 30 percent recovery rate of heart function in rats.

In a second study, researchers took marrow from mice, injected it into mice, which led to a 40 percent improvement in heart function.

A third study demonstrated that stem cells were used to strengthen pig hearts. Researchers injected marrow stem cells into pig hearts and were able to prove that new heart muscle cells developed in the pig hearts.

Human Testing Years Away

The three groups of researchers were based at Columbia University, New York Medical College in Valhalla, N.Y., the National Institutes of Health and Osiris Therapeutics of Baltimore.

Researchers from all three studies say there is more work to be done. For instance, there is no published research yet on how long the new cells will live, or whether instead of turning into heart muscle, the cells might instead mature into the wrong kind of tissue, which would be damaging.

Stem cells are unspecialized cells that can turn into mature cells and replenish themselves, so that they are a constant source of new cells. They are primitive cells found in developing embryos and fetuses, as well as some parts of the adult body.

Johnson points out that the cells used in the study were from bone marrow, not embryonic stem cells, which have generated fierce controversy, because they are harvested from aborted fetuses and discarded embryos. In fact, President Bush has signaled that he may block federal funding for medical studies that use those embryonic stem cells.