But the Japanese group tried out all its promising drug candidates in rats, giving them skin transplants and seeing how long they survived after the resultant organ rejection.

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If pigs could be genetically modified to reduce the risk of organ rejection, it might be possible to use their organs for permanent transplants, not just temporary ones, many scientists believe.

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Additionally, years of dialysis can lead to a build-up of antibodies, which can cause rejection of the new organ.

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Because these cells would essentially be clones made from the patient's own cells, there would be no risk of the rejection problems typical with organ transplants, and therefore no need for the drugs that prevent the immune system from attacking a transplanted organ.

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However, she said, it might have no bearing on longer-term chronic rejection, which reduces the life of the transplanted organ.

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Marrocco is taking anti-rejection medication, which can lead to side effects like infection and organ damage.

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