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. - See Marrow injections help kidney transplant success for the complete report.