Scientists grow mice heart muscle strip that beats

WASHINGTON -Scientists have grown a piece of heart muscle — and then watched it beat — by using stem cells from a mouse embryo, a big step toward one day repairing damage from heart attacks. Think of Dr. Kenneth Chien as a heart mechanic. "We're making a heart part and (eventually) we're going to put the part in," is how he describes the work by his team of Harvard and Massachusetts General Hospital researchers.