The body's master cells can repair the damage caused by a heart attack, a study suggests.
The technique could offer hope to heart attack victims
Tests on rats have shown that stem cells can restore up to 90% of the heart's ability to pump blood around the body, which is often reduced following an attack.
Stem cells, which can be obtained from bone marrow, are unique in that they have the potential to turn into any other cell in the body.
Doctors have injected these cells into a small number of patients with heart disease. However, the results of these trials are not yet known.
This latest study adds to the growing body of evidence that stem cells could provide real hope to patients with heart problems.
Up until now, the technique has proved problematic because the stem cells tended to die shortly after being transplanted.
This has meant that the stem cells have not been able to turn into new muscle, replacing tissue that has died as a result of a heart attack.
Dr Victor Dzau and colleagues at Brigham & Women's Hospital in Boston, United States, have tried to get around this problem by engineering these cells to enable them to survive longer.
They added the Akt gene to cells in the laboratory. Akt is a protein that prevents cell death.
These engineered cells were then injected into the hearts of rats, which had had a heart attack.
Tests showed that cells with this gene were much more likely to survive compared to other stem cells.
The treatment restored between 80% and 90% of the heart's volume.
Writing in the journal Nature Medicine, they said it also dramatically improved the heart's ability to pump blood around the body.
"Stem cells genetically enhanced with Akt can repair infracted myocardium, prevent remodelling and nearly normalize cardiac performance," they said.
Doctors elsewhere in the US announced in April that they had carried out stem cell transplants on 15 patients with advanced heart disease.
One of these patients died 14 weeks later. Doctors at the Texas Heart Institute have yet to reveal how the other patients have fared.
They are also considering carrying out much larger trials. If successful, they could pave the way for stem cell transplants for other patients with heart disease around the world.