A cocktail of drugs has been found in trials with animals to heal damaged heart muscle.
According to researchers at the Children's Hospital in Boston, the first chemical overcomes a natural process that stops heart muscle cells from growing and dividing, while the second encourages blood vessels to regrow.
The drug cocktail was trialled on rats following stimulated heart attacks by constricting a coronary artery, but human trials of the treatment are not expected in the immediate future, as the work is still at the basic stages.
Cardiograms of the rats three months after treatment showed that the hearts of those given both drugs were pumping almost as well as those of healthy rats.
Rats injected with only one of the chemicals showed only a temporary improvement.
Study author Felix Engel, an instructor in pediatrics at the hospital, says he is interested in the molecular mechanisms of how the drugs work, and is currently searching for more efficient drugs in order to develop therapies that would be appropriate for humans.
The study nevertheless demonstrates that it is possible to rescue heart muscle, which does not occur naturally after a heart attack.
Following a heart attack the damaged heart muscle is replaced by scar tissue, which can impair the heart's pumping capacity and lead to life-threatening abnormal heart rhythms.
Felix Engel and Mark Keating demonstrated in earlier research that heart cells could multiply in a petri dish if a drug blocked a particular enzyme.
This new trial added a molecule designated FGF1, which stimulates growth of blood vessels, to the treatment given to some of the 120 rats with stimulated heart attacks.
Further tests are now being conducted to see if the treatment is effective when the drugs are administered many hours after a heart attack.