Scientists create beating hearts in lab

By Julie Steenhuysen

CHICAGO (Reuters) - U.S. researchers say they have coaxed hearts from dead rats to beat again in the laboratory and said the discovery may one day lead to customized organ transplants for people.

"The hope would be we could generate an organ that matched your body," said Doris Taylor of the University of Minnesota Center for Cardiovascular Repair.

Her study, which appeared on Sunday in the journal Nature Medicine, offers a way to fulfill the promise of using stem cells -- the body's master cells -- to grow tailor-made organs for transplant.

Taylor and colleagues used a process called decellularization to wash away existing cells from the hearts of dead rats while leaving the basic collagen structure intact.

They injected this gelatin-like scaffold with heart cells from newborn rats, fed them a nutrient-rich solution and left them in the lab to grow.

Four days later, the hearts started to contract.

The researchers used a pacemaker to coordinate the contractions. They hooked up the hearts to a pump so they were being filled with fluids and added a bit of pressure to simulate blood pressure.

Eight days later, the hearts started to pump.