Every year, millions of people all around the world die because because they have damaged organs which no longer function properly. Hearts, kidneys, livers and many other organs can be replaced by transplantation, but only if there is a donor organ available. Doctors and patients badly need a limitless supply of new organs – and preferably ones which will not cause any rejection problems when they have been transplanted.

A team of researchers at the Weizmann Institute of Science in Israel has taken human and pig kidney stem cells and transplanted them into mice. The cells formed miniature functioning kidneys that produced urine! What is more the kidneys produced seemed to have little or no effect on the immune system of the recipients – they didn’t cause rejection!

In the future it is possible that embryo stem cells will be able to supply enough rejection proof organs to prevent anyone from dying because they need a transplant.