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Will cellular creations spin out of control?

发布时间:2019-03-08 08:08:09来源:未知点击:

BEING able to keep embryonic stem cells dividing in culture indefinitely may allow biologists to grow tissues for transplantation. But can we be sure that these cells will stop dividing once transplanted? The latest research suggests that such tissues might have changed in ways that make them more likely to become cancerous. Most of our cells divide only a few times before they die. Researchers believe that stem cells avoid this fate because they possess an enzyme called telomerase. This repairs the tips of chromosomes, which otherwise shorten each time a cell divides. Earlier this year, Californian researchers showed that normal cells can keep dividing if given active copies of the telomerase gene (In Brief, 24 January, p 23). But in a paper in last week’s Nature(vol 396, p 84), researchers in Seattle show that for telomerase to keep human skin cells dividing indefinitely, an anti-tumour protein called p16 must also be inactivated. Clearly, human stem cell lines grown in culture for long periods will have to be screened for dangerous changes before being used as tissue grafts. This will be a huge task, given the number of genes that must be screened. Tom Okarma of Geron, a company in Menlo Park, California, which is licensed to work with human stem cells,