Word: fetal
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Dates: during 1990-1999
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...stubs. Because any further divisions would fray the chromosomes, the cells settle into a twilight stage and eventually die. Only an enzyme called telomerase, first discovered in 1984, can repair the damaged telomeres. However, most human cells, with the exception of reproductive cells, stop making the compound during fetal development...
...thinnest possible slivers of fibrinogen. Checking on her samples one morning, she found that some of the slivers had curled up into spheres, each the size of a coarsely ground speck of pepper. Gabrielian added several of these odd-looking constructs to a culture dish that also contained fetal RPE cells. Within 24 hours, the cells attached themselves to these motes of material and started to grow. Then the researchers transplanted the spheres into the eyes of rabbits, positioning them just beneath the retina. The RPE cells did not stay put; instead they migrated throughout the eye. This suggested that...
...team made progress on one front, Ernest grew increasingly worried about the immune system's response to the transplants. Contrary to what many had supposed, fetal RPE cells did not behave as if they were immunologically neutral. In experiments in Sweden, for example, transplanted cells were rejected. And Ernest's team found that adding fetal RPE cells to laboratory cultures sent white blood cells, which attack transplanted tissue, into overdrive. Curiously, however, adding even greater numbers of RPE cells to the culture appeared to force the white blood cells into a quiescent state, thus lowering the chances of rejection. Pearl...
...knows yet whether this hunch is right. Gouras and his Swedish colleagues have found that rejection of fetal RPE cells can occur months down the road. Moreover, slight differences in approach between Gouras' team and Ernest's may or may not prove to be significant. "It's an experiment," says surgeon Patel. "That's all it is. What we're trying to find out is whether there's a rationale for going to a larger study...
From the beginning, Ernest and his colleagues were also worried about the explosive ethical questions raised by the use of fetal tissue. Very early on, Ernest approached Dr. Mark Siegler, director of the University of Chicago's MacLean Center for Clinical Medical Ethics, for advice. As Siegler and many others saw it, there were no insurmountable barriers to the use of fetal tissue for medical purposes. After all, organs and tissue from brain-dead children and adults are donated for transplantation all the time. And while such deaths are tragic, they are caused not in order to obtain the organs...