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Dose of marrow works wonder

A new system could replace drugs in transplant cases.

LOS ANGELES - In what's being called a major advance in organ transplants, doctors say they have developed a technique that could free many patients from having to take antirejection drugs for the rest of their lives.

The treatment involved weakening the patient's immune system, then giving the recipient bone marrow from the person who donated the organ. In one experiment, four of five kidney recipients were off immune-suppressing medicines up to five years later.

"There's reason to hope these patients will be off drugs for the rest of their lives," said Dr. David Sachs of Massachusetts General Hospital in Boston, who led the research published in today's New England Journal of Medicine.

Since the world's first transplant more than 50 years ago, scientists have searched for ways to trick the body into accepting a foreign organ as its own. Immune-suppressing drugs that prevent organ rejection came into wide use in the 1980s. But they raise the risk of cancer, kidney failure and many other problems. And they have unpleasant side effects such as excessive hair growth, bloating and tremors.

Eliminating the need for antirejection drugs is "a huge advance," said Dr. Suzanne Ildstad, a University of Louisville immunology specialist who had no role in the work.

"It still needs some fine-tuning so that everyone who gets treated gets the same consistent outcome. ... It's not the holy grail of tolerance yet," she cautioned.

Doctors have experimented with giving marrow before, during or after organ transplants, while also tinkering with patients' immune systems to prime them to accept the new organs.

The new study involved five people who got kidneys from parents or siblings who had slightly different tissue types from the patients. Since many kidney transplants are similarly mismatched, there is hope more people might one day be spared immune-suppressing drugs.

Sachs' treatment involved weakening each kidney patient's immune system before the transplant. After the transplant, the patient got an infusion of marrow from the donor to create a new immune system.

The stem cells from the marrow reprogram the body by allowing new immune cells to grow that don't try to attack the donated organ.

The patients took antirejection drugs but were weaned several months later.

Four of the five patients developed a hybrid immune system - where recipient and donor cells live together in the body - for a short time. They were able to stop taking antirejection drugs and had healthy kidney function two to five years later.

In the one case that failed, the patient had a second kidney transplant and has been on medications since.

The study was funded by the Immune Tolerance Network, an international consortium of federal and advocacy groups. Sachs plans a followup study involving 15 to 20 patients at Massachusetts General and other hospitals.

[Last modified January 24, 2008, 01:38:35]