WASHINGTON - Stem cells help rejuvenate heart muscles by drawing on cells that develop into heart muscle, according to a new research conducted on mice.

In the past, stem cells have been successfully used to halt or reverse cardiac injury following heart attack but not to prevent injury before it occurs.

A new study that delivered embryonic stem cells to mouse embryos in the earliest stages of development found that the resulting mice developed the capacity to recover from cardiac injury in adulthood.

The study provides the first evidence that preventive regenerative medicine can successfully treat myocardial infarction (death of heart muscle from the sudden attack) through such intervention.

Led by Andre Terzic of the Mayo Clinic in Minnesota, US, researchers injected mouse embryos with embryonic stem cells that had been successfully used to treat ischemic heart disease (reduced blood supply to the organ) following heart attack.

The resulting animals incorporated between five and 20 percent of labelled stem cell-derived tissue. They were born with no apparent abnormalities, and the tested and control groups had similar overall baseline cardiac disease risk profiles.

They also demonstrated similar cardiac performance during the one year follow-up. Researchers induced cardiac injury in both groups by tying off the left artery, causing complete coronary blockage.

The group that had received the embryonic stem cell treatment recovered cardiac function, while the other group deteriorated, indicative of progression towards heart failure, said a Mayo Clinic release.

Overall, the group treated with stem cells displayed a favourable disease course, with superior exercise workload capacity and stress test performance, as well as increased survival.

The study was published in the journal Stem Cells.