A master heart stem cell gives rise to the different tissues in the mammalian heart, a discovery that could be great news for future heart repair.

In Wednesday's online issue of the journal Cell, three teams of researchers in the U.S. identified the embryonic stem cells in mice and say the cells could be cloned for use in developing new drug therapies.

Embryonic stem cells have the ability to develop into any type of cell.

One team led by Kenneth Chien of the Massachusetts General Hospital in Boston, and another led by Gordon Keller of Mount Sinai School of Medicine in New York, said the cells gave rise to three types of cells in the mammalian heart.

The three types are: cardiac muscle cells, smooth muscle lining the aorta, and endothelial cells that form coronary blood vessels.

"These cells offer new prospects for drug discovery and genetically based models of human disease," said Chien. They also offer a new strategy for regenerating cardiac muscle, coronary artery and pacemaker cells, he added.

Heart formation resembles how blood is formed, in that the diverse cells all come from the same source, the researchers said. Previously, scientists thought each muscle type might need different source cells. 

A third study by Stuart Orkin of the Children’s Hospital in Boston and his colleagues identified the precursors for cardiac and smooth muscle.

Although researchers can isolate cardiac stem cells from mice, they are not able to do so from heart patients. Scientists would need to overcome that hurdle before attempting therapeutic stem cell transplants in humans.

Using immune cells from the same embryonic lines may help scientists to overcome immune rejection problems.