The drug works by tripping a cellular switch that was discovered serendipitously by scientists studying an unrelated drug--Rapamune, a Wyeth chemical used to suppress the immune systems of organ transplant patients.
Gene hunters have long focused on a mere 1.5% of the human genome, an estimated 25, 000 genes that code for proteins and thereby control the immune response, organ growth and brain activity, among other things.
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.
This means the patient won't have to take powerful drugs to prevent her immune system from rejecting the organ.
This happens when cells from the immune system gather around the foreign organ and try to destroy it.
The Kepners knew a double hand transplant meant Kepner would have to take drugs to suppress his immune system for the rest of his life (like any transplant, the recipient's immune system could attack the new organ as a foreign object).
Nor is it clear how the transplanted immune cells stop the existing ones from attacking the new organ.
Tissue cloned in this way from the patient's own cells would not, it is thought, be rejected by the body's immune system, which is currently a major obstacle to organ transplants and many other treatments.
ECONOMIST: To clone or not to clone, is that the question? | The
The immune-disease angle surfaced when doctors noticed that cancer patients who also had psoriasis found their skin improved when they took the immune suppressants methotrexate (for cancer) and cyclosporine (for organ transplants).
This combined treatment created a kind of "peacekeeping" immune cell, which appeared able to avert the attack on the foreign organ.
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