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March 2007 STANFORD, Calif. - Researchers at Stanford University Medical Center have discovered a way to transplant kidneys without having the patient remain on a lifelong course of immune-suppressing drugs in order to prevent rejection. As an added bonus, the donor kidneys don't even need to come from a relative - a restriction that has severely limited kidney availability to sick people in need.

Research results from four patients in the groundbreaking study will be presented April 28 in Washington, DC, at the American Transplant Congress by Maria Millan, MD, transplant surgeon at Stanford Hospital & Clinics and assistant professor of surgery. The work is also scheduled to be published in the journal Transplantation May 15.

Organ rejection after transplantation occurs because the immune system scans for foreign cells. If the immune system in the transplant recipient weren't heavily suppressed, it would attack cells in the transplanted organ, leading to rejection.

Strober said so far, two of the four patients in the study are completely free of drugs, with another still tapering off. This new approach to kidney transplantation began in the usual way, with surgery followed by immune-suppressing drugs, which were needed to prevent organ rejection while the team completed the next step.

After the transplant, the kidney recipient received multiple small doses of radiation targeted to the immune system combined with a drug to reduce the number of cells capable of an immune attack. The team then injected blood stem cells from the kidney donor into the recipient. The stem cells made their way to the recipient's bone marrow where they produced new blood and immune cells that mixed with those of the recipient. After this procedure, the recipient's immune cells recognize the donor's organ as friend rather than foe.

The Stanford team monitored the recipient's new hybrid immune system looking for a mixture of cells from both the recipient and the donor. These cells were tested in the laboratory and did not attack cells taken from the donor. This told the team that the new hybrid immune system would not mount an attack against the transplanted organ. At this time, the team slowly weaned the patient away from the immune-suppressive drugs.

http://www.sciencedaily.com/releases/2002/04/020424072642.htm