MIT researchers have grown a tissue patch that could repair damaged hearts, using electric signals that mimic a heartbeat to force single cardiac cells to develop into tissue similar to that of the native heart.

They attached rat cardiac cells to a three-dimensional collagen scaffold and then zapped the cells with electrical pulses modeled on a rat heartbeat for several days, inducing the cells to grow into beating patches about the size of a dime.

The researchers are working on methods to make patches thick enough to actually replace heart tissue, and are also working to translate the research to human heart cells.