The researchers showed the approach worked in mice, protecting them from arrhythmia - an irregularity in the heart's natural rhythm - after the animals' hearts were damaged in a way similar to a heart attack.

They said they are hopeful the approach, with some refinement, could help people who suffer heart attacks.

'Approximately 15 per cent of patients suffering from a heart attack die within two to three years of sudden death due to the development of ventricular arrhythmias,' said one of the researchers, Dr Bernd Fleischmann of the University of Bonn in Germany.

Dr Fleischmann and his colleagues transplanted living mouse embryonic heart cells into cardiac tissue of mice with heart attack-like damage, making the animals resistant to later arrhythmias, they said in a study released on Wednesday in the journal Nature.

A protein known as connexin43 made by these transplanted embryonic heart cells improved electrical connections to other heart cells, the researchers said.

The transplanted heart cells became activated during normal heart contractions, they said.

The researchers noted that doctors could not use human embryonic heart cells for transplantation in people for ethical reasons. So they genetically engineered skeletal muscle cells to make this protein.

By transplanting these cells into the mouse heart, they said they achieved the same restorative results as with the transplanted embryonic heart cells.

REUTERS