It is being hailed as a major medical breakthrough: cardiologists are using adult stem cells, not the controversial embryonic stem cells, to rejuvenate the hearts of patients who have suffered heart attacks or whose hearts are not working properly.

VOA's Carol Pearson tells us about two studies reported at the American College of Cardiology conference that show promise for heart patients.

Joe Gasser is back on a treadmill after suffering a heart attack that left him with a grim prognosis and a weakened heart. He was one of 23 patients who had stem cells injected into his ailing heart in hopes of healing it. "It's a second chance," he says.

Researchers took the cells from muscles in the patients' own legs. Then they grew the cells in a laboratory before injecting them in the patients' hearts ? without surgery or anesthesia.

The study was led by cardiologist Dr. Nabil Dib.  He looks at an image of the heart of one of his patients. In the image on the left, black spots show where the stem cells were injected. The red spot is an area of dead tissue.

The other image shows the same heart six months later.  The damaged tissue is gone, replaced by healthy tissue. Dr. Dib says, "A patient who has no hope today will have hope in the future."

In another study, researchers took stem cells from donors, not the patients, and infused them intravenously into the patients' hearts within ten days of a heart attack.

Fifty-three patients got the stem cell therapy.  Others did not.

Dr. Josua Hare at the University of Miami School of Medicine led the study and explains, "The patients getting the cells were doing better.  Their heart function was better and their breathing was better as well."

Experts caution that these studies need to be repeated in larger groups to confirm the results. Joe Gasser says he is proof of the outcome. "I have lots of energy.  I feed good.  Nothing holds me back."