Word: stemness
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
...they don't grow very well, and were cultured using methods that are outdated. What's more, the chromosomes undergo subtle changes over time, compromising the cells' ability to remain "normal." Back in the late '90s, when the lines were created, "we didn't know much about growing stem cells," says Kevin Eggan, principal faculty member at the Harvard Stem Cell Institute. "They can't do what the newer cell lines can do." Curt Civin, a cancer researcher at Johns Hopkins, has spent the past several years trying to differentiate the presidential lines into blood cells that could be used...
...wake of Bush's original order, Harvard decided to use private funding to develop about 100 new cell lines from fertility-clinic embryos, which it shares with researchers around the world. Scientists, desperate for variety, snap them up. "Not all embryonic-stem-cell lines are created equal," says Dr. Arnold Kriegstein, who runs the Institute for Regeneration Medicine at the University of California, San Francisco. "Some are more readily driven down a certain lineage, such as heart cells, while others more easily become nerve. We don't understand how it happens, but it does mean we need diversity...
...cell lines through somatic cell nuclear transfer, or therapeutic cloning. In this process, a cell from a patient with diabetes, for instance, is inserted into an unfertilized egg whose nucleus has been removed; then it is prodded into growing in a petri dish for a few days until its stem cells can be harvested. Unlike fertility-clinic embryos, these cells would match the patient's DNA, so the body would be less likely to reject a transplant derived from them. Even more exciting for researchers, however, is that this technique can yield embryos that serve as the perfect disease...
...long-term promise is boundless, but the immediate barriers are high. The only people who claim to have succeeded in creating human-stem-cell lines through nuclear transfer were the South Korean researchers who turned out to be frauds. It will take much trial and error to master the process, but where do you get the human eggs needed for each attempt, particularly since researchers find it ethically inappropriate to reimburse donors for anything but expenses? And even if the technique for cloning embryos could be perfected, would Congress allow...
...less ethically troublesome, ideally one that involves no embryo destruction at all. One approach is "altered nuclear transfer," in which a gene, known as CDX2, would be removed before the cell is fused with the egg. That would ensure that the embryo lives only long enough to produce stem cells and then dies. That strategy, promoted by Dr. William Hurlbut, a member of the President's Council on Bioethics, has its critics. Dr. Robert Lanza of biotech firm Advanced Cell Technology considers it unethical to deliberately create a crippled human embryo "not for a scientific or medical reason, but purely...