BOSTON Injecting blood or bone marrow cells into people who have just received a donated kidney can reduce the need for drugs that suppress the immune system, researchers reported on Wednesday.
The stem cells in the blood and bone marrow helped trick the body into tolerating the transplants, two teams of researchers reported in the New England Journal of Medicine.
In one series of experiments, researchers at Massachusetts General Hospital and Harvard Medical School in Boston tested the technique on five volunteers who received a kidney from a relative. Four were eventually weaned off their anti-suppression drugs.
"While we need to study this approach in a larger group of patients before it is ready for broad clinical use, this is the first time that tolerance to a series of mismatched transplants has been intentionally and successfully induced," said Dr. David Sachs, who helped lead the study.
Doctors have long sought a permanent and reliable way to trick the body into thinking that a transplanted organ is not a foreign invader. The drugs currently in use can have onerous side effects, including cancer and kidney damage.
Bone marrow makes the body's immune system cells, and the donor's immune cells presumably took up residence in the transplant patient's body and helped create a welcoming reception for the kidney, the researchers said.
This technique has been tried before under different circumstances including on multiple myeloma patients.
The new study involved patients whose kidney failure was caused by other problems. Patients first had their bone marrow partially destroyed and then received a drug that kills off T cells -- immune cells that play a key role in rejecting transplanted organs.
The patients ended up with bone marrow that was a temporary mix of their own cells and the cells from the donor.
The first two patients did very well. After problems with a third patient, the researchers added a drug to also kill B cells, another element of the immune system.
All four of the successfully transplant patients continue to have functioning kidneys two to five years later, the researchers said.
In another Journal article, a research team from the Stanford University School of Medicine, led by John Scandling, reported that they were also able to eliminate the need for immunosuppressive drugs in a 47-year-old patient who received donated blood cells from his brother two weeks after getting one of his kidneys.
"My body thinks my brother's kidney is mine," patient Larry Kowalski said in a statement.
Six other patients given the same treatment have not been able to stop taking their immunosuppressive drugs, although their donated kidneys were not a perfect match the way Kowalski's was.
In a third study, a 9-year-old girl who got a liver transplant was able to stop taking immune-suppressing drugs after the donor liver apparently seeded stem cells into her bone marrow, creating a hybrid immune system and even changing her blood type.
(Editing by Maggie Fox and David Wiessler)