"Approximately 15 percent of patients suffering from a heart attack die within two to three years of sudden death due to the development of ventricular arrhythmias," Bernd Fleischmann of the University of Bonn in Germany, one of the researchers, said by e-mail.

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 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.

'FUNCTIONAL CONNECTION'

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

The cells they used are called myoblasts, which are adult skeletal muscle stem cells.

"If we put in cells of a certain type, we really prove that these cells, in fact, are activated by the surrounding heart tissue during the normal heart beat. So this is really the first demonstration that these cells can establish functional connection and contract during normal heart function," Michael Kotlikoff of Cornell University in Ithaca, New York, who worked on the study, said in a telephone interview.

Kotlikoff said the study results suggest that doctors may be able to take thigh muscle cells from a person who has had a heart attack, genetically alter them to make connexin43, and then put them into the person's heart to protect against arrhythmia.

Because the cells are taken from the same person, the body should not reject the transplanted cells, Kotlikoff said.

Doctors previously have tried to improve heart function by implanting bone marrow cells or skeletal myoblasts into heart tissue to help it recover from heart attack damage. Fleischmann said those efforts were mainly for another purpose -- to improve heart pump function.

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