Word: miceli
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Dates: during 1980-1989
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After more than a year, the Stanford mice are still thriving. Their new immune systems, however, must be sustained by injections of fetal liver cells every eight to twelve weeks. In addition, researchers are not sure whether all the parts of the human system are functioning in the mice. "We'll find that out," says Weissman, "but we'll have to do every known test for human immune cells. These mice open ways of studying human systems, normal or diseased, under experimental circumstances that were impossible before...
...Jolla team also used SCID mice. By comparison, however, their approach was simple. Circulating white blood cells taken from human adults were injected into mice. Almost immediately, the mice began replicating the cells. Within three weeks they had human immune systems with nearly correct proportions of all the major types of white cells found in human blood. Moreover, when the researchers injected these mice with tetanus toxoid, most of the animals produced human antietanus antibodies, further proof that their new immune systems were functioning as though they were naturally human...
Because SCID mice lack immune systems, the scientists did not expect them to reject the transplanted human cells. Researchers also suspected that the human fetal cells, since they are too immature to distinguish themselves from foreign cells, would not reject the mice in a graft-vs.-host response. But, surprisingly, the adult human cells used in the La Jolla research did not reject the mice either. "That these human cells recirculate around in the mice without caring is astounding," said Dr. Donald Mosier, head of the La Jolla research team...
There was yet another unexpected consequence of the experiment. After being injected with human immune cells, many of the mice suddenly developed rapidly growing cancers, perhaps caused by a virus in the blood of some of the donors; mice injected with cells not exposed to this virus did not develop the tumors. The implications for cancer research could be enormous: the rapid growth -- in eight to 16 weeks -- would afford scientists a rare opportunity to track the emergence and spread of cancer. Said Mosier: "This is an extraordinary breakthrough. We may be able to dissect that tissue week by week...
...Stanford results a week early in order to coincide with the NIH meeting, strongly backed the scientists' right to continue their research. Said Koshland: "This is an excellent example of careful, scientifically controlled use of fetal tissue to attack major human disease." Moreover, the fetal-tissue transplants give the mice a more complete human immune system, which should provide a better model for studying the progression of AIDS and other diseases...