OTTAWA, Nov. 30 (Xinhua) -- Canadian scientists have made a breakthrough in the research of stem cell transplants by making possible the transplant of a mismatched donor, local media reported Monday.

    A transplant from a mismatched donor usually fail because patients reject and attack the foreign donor cells. The ensuing response can kill the patient, or lead to infections or relapses of the original disease but the technique pioneered in a Montreal lab by Dr. Denis-Claude Roy of the Maisonneuve-Rosemont Hospital could change that, the Canadian Television reported.

    Roy explained that his research team developed a new approach that preserves the cells that fight infection and leukemia while eliminating the cells that reject donor cells.

    The technique involves introducing donor cells to the patient cells in a lab, he said.

    "Those cells that recognize foreign patient cells become activated. The cells that are there to fight infections or viruses or even leukemia aren't activated, they don't see their target, sothey're actually sleeping. So we then kill those cells that are activated," he explained.

    To kill the activated cells, a specially-designed photo-sensitizing product is introduced that makes the cells vulnerable to photo therapy.

    "They accumulate the drug, and when we turn on the light, this energy transfer results in the killing of only the cells that recognize the patients. The cells that fight infection, that are dormant, don't accumulate the drug and are not killed," he said.

    The technique, while 10 years in the making, is still experimental. But it is now poised to enter Phase 3 trials.

    A 28-year-old man who has a form of leukemia called Ewing sarcoma is about to undergo such experiment, become the first person in North America to get a transplant from a mismatched donor.