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Transplant Procedure Increases Supply of Available Kidneys

Donor Pamela Paulk, 55, of Baltimore, Md., embraces transplant surgeon Dr. Robert Montgomery after sharing her transplant story during a press conference at Johns Hopkins Hospital in Baltimore, Maryland, July 7, 2009 (file photo)

Researchers say a new medical procedure has the potential to provide donor organs to thousands of transplant patients worldwide who are on waiting lists for available kidneys. The procedure makes it possible to transplant kidneys that might otherwise be rejected by the patients.

An estimated 85,000 people in the United States and tens of thousands of people internationally are on lists waiting for suitable kidneys for transplant. But experts say only about one-quarter of these patients receive a transplant each year in the United States, and as many as 5,000 others die waiting for a compatible donor kidney.

The deaths are usually related to complications of dialysis, a process that filters the blood, removing waste products normally cleansed by healthy kidneys. But dialysis is not a replacement for functioning kidneys and many patients succumb to cardiovascular disease.

Experts say that finding the matching kidneys is a challenge because many patients have antibodies in their systems that would destroy an organ that is not the right tissue or HLA type.

According to transplant surgeon Robert Montgomery of The Johns Hopkins University School of Medicine in Baltimore, Maryland, people usually develop antibodies following exposure to foreign tissue, such as a blood transfusion, or with pregnancy, when half of a baby’s DNA comes from the father.

“We usually think of antibodies as being a good thing," said Dr. Montgomery. "But this prevents people then after a pregnancy, some people who develop this antibody, from getting a transplant. And women indeed are disproportionately affected by this problem. Two-thirds of the patients who are in our study are women.”

Researchers at Johns Hopkins have developed a protocol to desensitize these individuals, so they can receive kidneys that normally would be rejected. The procedure, called plasmapheresis, removes the troublesome antibodies in patients who are scheduled to receive a kidney from an incompatible donor.

In a study conducted by Montgomery and his colleagues, 211 patients also were given a course of immunoglobulin proteins to further neutralize the antibodies.

Montgomery said plasmapheresis plus immunoglobulin therapy greatly increased survival of transplant patients compared to those on dialysis.

“What we’ve shown is that patients who are offered this therapy at the end of eight years double their survival rate compared to similar patients who stay on the list - similar patients who have a similar degree of sensitization who stay on the list waiting for a compatible organ,” said Montgomery.

Montgomery said the desensitizing procedure might result in 3,000 more live kidney donor transplants in the United States each year.

For now, he said, the protocol works only with patients receiving kidneys from living donors because it takes time to prepare them for surgery, which can be scheduled in advance. Montgomery said, though, transplant surgeons at Johns Hopkins are investigating plasmapheresis to increase the supply of other organs and tissue, including hearts and bone marrow.

An article on the desensitizing procedure for live kidney transplants is published in The New England Journal of Medicine.