The findings, the result of collaboration between UK researchers at Imperial Cancer Research Fund and Imperial College School of Medicine, mean that doctors may be able to restore the function to patients suffering from kidney failure.

They may also pave the way to new gene therapy for kidney diseases.

Different types of stem cells are present throughout a person's body; one of the best-understood adult stem cells is the bone marrow stem cell.

These stem cells are blood cells at the very earliest stage of their development, before they have developed into white cells, red cells or platelets. Imperial Cancer Research Fund has already shown they can transform themselves into liver cells.

However, today's discovery published in the Journal of Pathology Online, shows they can also transform themselves into kidney cells.

Professor Nick Wright, head of Imperial Cancer Research Fund's Histopathology Unit and Warden of Queen Mary's School of Medicine and Dentistry, said, "This discovery is very exciting and means we have new ways to treat kidney damage caused by cancer or other diseases.

"Doctors could use stem cells from the patient's own bone marrow to replenish kidney cells lost by injury. This would be of huge benefit as the kidney is very poor at repairing itself. Furthermore, there would be much less complication with the kidneys rejecting the new cells, because they would come from the patient's own body.

"Another exciting development would be using bone marrow stem cells containing genes resistant to cancer or other disease, to protect the kidneys from further damage."

Professor Malcolm Alison, a research pathologist working at both Imperial Cancer and Imperial College School of Medicine, said: "Our laboratory experiments showed the presence of cells in the kidney that came from bone-marrow stem cells, but we then went a step further and proved it can actually happen in the human body. This research matches other recent studies showing how bone marrow cells may also develop into liver, nerve and muscle cells - not just blood cells."

Research pathologists in Imperial Cancer's Histopathology Unit analyzed female kidneys transplanted into male patients. Using a special DNA probe that identifies male cells, they checked the patient's new kidneys. They found male kidney cells in the donated female kidneys, meaning that the recipient's male bone marrow cells had transformed into kidney tissue.

Dr. Poulsom, a research pathologist at Imperial Cancer, added: "The potential for advances in medicine from using adult stem cells is enormous. They can give rise to many different types of cells so any organ may one day be repaired. Using adult stem cells also avoids the ethical dilemmas associated with embryonic stem cell work."

Commenting on the potential clinical impact, Professor Wright said: "Anti-rejection medication after a kidney transplant costs about £5,000 per patient a year, and each year the number of new patients needing kidney transplants increases by about 5 per cent. It would be fantastic to save kidney patients this trauma and save the NHS some money.

"Hopefully, we will come to understand how adult stem cells are triggered into regenerating specific tissues -- this would revolutionize the future of transplant medicine. Our next immediate challenge is to improve the efficiency with which the stem cells repopulate the damaged organ."

Sir Paul Nurse, Director General of Imperial Cancer Research Fund, said: "This is a great achievement and shows real progress by the team which, almost exactly a year ago, discovered that bone marrow stem cells are capable of turning into liver cells and repopulating damaged liver.

"Ultimately, this research may one day lead to regenerating a new kidney using the patient's own stem cells. This would solve the desperate shortage of available kidney transplants and avoid problems with rejection. The potential for therapies is enormous and very exciting."

(References: 1. Bone marrow contributes to renal parenchymal turnover and regeneration. Journal of Pathology online. The Journal of Pathology is an official journal of the Pathological Society and is published by John Wiley & Sons. 2. Hepatocytes from non-hepatic adult stem cells. Nature 2000;406: p257.)

25-Jul-2001