ISRAEL: Israeli scientists said yesterday they had successfully grown human kidneys in mice, in a breakthrough that might one day help save thousands of patients waiting for transplants.
Tens of thousands of patients worldwide, including 50,000 in the US alone, need a new kidney.
Many patients die before a suitable kidney donor is found.
The researchers, led by Dr Yair Reisner of the Weizmann Institute of Science, near Tel Aviv, said they had transplanted stem cells from human and pig foetuses into mice.
The kidneys grew into functional mouse-sized organs, filtering the blood and producing urine, they reported in Nature Medicine journal.
Stem cells are special "mother" cells that can develop into the organs and tissues of the body. The researchers used those rich in precursor kidney cells, those most likely to form kidney tissue.
But knowing when best to transplant was a challenge.
They said they had used stem cells at different stages of development and found that those which produced the healthiest kidneys came from human foetuses between seven and eight weeks old, and pig foetuses four weeks old.
Donating organs from one species to another, a field known as xenotransplantation, has long been held back because the human immune system often recognises the animal organ as foreign and rejects it.
In this case there was no dangerous immune reaction, possibly because the transplanted cells had not yet developed their own identity badge.
Even if this problem is overcome, scientists will still want reassurance that there is no risk of unknown animal viruses being passed to humans.
Kidney specialists believe that although the latest research is encouraging, many more trials must be done before there is any prospect of applying it in human medicine.
The research is in the pre-clinical stage and treatment could start within a few years if all goes well, the institute said. - (Reuters, AFP)