Offering a revolutionary advance that may be used to repair defective hearts in the future, scientists have grown human heart valves for the first time using stem cells from the fluid that cushions babies in the womb.

In order to have them ready to implant in a baby with heart defects after it is born, the thought is to generate these new valves in the lab while the pregnancy progresses.

The Swiss experiment suggests that people may one day be able to grow their own replacement heart parts