It has been a long-standing belief that human heart muscle, once damaged, cannot regenerate. But thanks to a new study by a heart institute in Los Angeles, researchers have used cardiac stem cells to regenerate heart muscle in patients who have suffered heart attacks, also known as myocardial infarction.

The recent finding has given new hope to heart patients. The preliminary study conducted by the Cedars-Sinai Heart Institute in Los Angeles, involved 25 patients who had suffered heart attacks in the previous one and a half to three months.

Seventeen of these patients received infusions of cardiac stem cells that had been harvested from their own hearts during bypass surgery. The other patients were provided standard care.

During a heart attack, heart tissue is damaged, leaving a scar. On average, scars in patients who had the stem cell infusions dropped in size from 24 per cent to 12 per cent of the heart, said Dr Eduardo Marbán, director of the Cedars-Sinai Heart Institute and lead researcher on the study, which was published online Monday in the journal The Lancet.

He said a follow-up study involving about 200 patients was planned later this year.
Researchers were surprised by the findings as conventional theories hold that cardiac scarring was permanent.