Stem cells (search) can restore a heart damaged from a heart attack to its original condition, research shows.

Current heart attack treatments do not repair the damaged heart, says cardiologist Joshua Hare, MD, professor of medicine at The Johns Hopkins University School of Medicine and its Heart Institute, in a news release.

Heart attack damage can lead to sudden cardiac death, and decreased blood pumping can lead to heart failure, says study co-researcher and interventional cardiologist Alan Heldman, MD, assistant professor of medicine at Johns Hopkins, in a news release.

The researchers based their findings on experiments with pigs. However, if the results are duplicated in humans, it could improve the health prospects of the nearly 8 million American heart attack survivors living today.

Hare and colleagues tested the effects of adult stem cells, which serve as templates to produce other cells. The study was presented at the American Heart Association'sScientific Sessions 2004.

The stem cells used in the study weren’t the embryonic kind. Instead, they came from an adult pig’s bone marrow. Stem cells, which are very immature cells, have the ability to transform into other types of functioning cells. While embryonic stem cells are better at this, adult stem cells also have this ability to some degree.

The researchers studied 14 pigs, which have circulation systems similar to humans. All of the pigs had suffered heart attacks. Three days after their heart attacks, half of the pigs had stem cells from another pig’s bone marrow injected into their heart. In order to thoroughly cover the area of damaged heart muscle — approximately the size of a $1 coin — researchers gave between 12 and 15 microscopic injections of adult stem cells, each injection containing nearly 200 million cells. The other pigs received placebo injections containing no cells.

The pigs that received the stem cells fared better. After eight weeks, their hearts were virtually back to normal. Damaged heart tissue all but disappeared, and heart function returned to normal. The placebo group showed no improvement. The procedure was shown to be safe with no serious side effects.

The researchers don’t know exactly how the stem cells repaired the heart muscle or how long the results last, but they say the finding deserves further study.

The types of stem cells used in the study – called mesenchymal cells — have several advantages. They’re plentiful, can be reproduced, and don’t trigger immune responses, says Hare. Adult stem cells also avoid ethical issues, he adds.

By Miranda Hitti, reviewed by Michael W. Smith, MD

SOURCES: American Heart Association Scientific Sessions 2004, New Orleans, Nov. 7-9, 2004. WebMD Medical News: “Q&A on Stem Cells.” News release, American Heart Association.