Researchers at the University of Pennsylvania School of Medicine are utilizing a protein to “switch on” the ability to repair damaged heart tissue. By triggering the cell-cycle signal, researchers can manipulate cells in animal models to regenerate damaged heart tissue. If this research is someday successfully translated to humans, it could change the approach to treating heart disease, the nation’s leading killer. The findings, now on-line, are in Circulation, the journal of the American Heart Association.