In July the U.S. Senate passed H.R. 810, a bill that would have allowed federally funded research on any line of human embryonic stem cells for therapeutic purposes. The president vetoed the bill, and the vote to override the veto fell short. Thus, scientists who want federal research money must stick with lines developed before 9:00 p.m. Eastern time on August 9, 2001.
The challenge for scientists performing stem cell research remains finding new ways to grow and maintain stem-cell lines. Currently, one stem cell cannot be efficiently turned into many, and stem cells in culture tend to differentiate if conditions do not stay just right. As Peter Mountford of Stem Cell Sciences (Edinburgh, UK) says, "The single biggest obstacle to commercial and clinical applications of stem cells is the lack of a robust ex vivo cell-culture system." From a clinical perspective, scientists face an added issue: getting all animal products out of stem cell cultures.
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Going synthetic
Scientists must keep stem cells growing and undifferentiated. To do that, they generally follow a basic approach: put stem cells in a culture dish that has been coated with cells, usually mouse skin cells, and fill it with medium. Scientists call the cell coating a feeder layer, and it provides a surface for attachment and adds nutrients to the medium. The …
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