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ScienceNOW: “Research Questions Hybrid Approach to Stem Cells” Experiments to produce hybrid human–animal embryos have been unsuccessful. Will that mean anything to advocates of embryonic stem cell research?
A technique known as somatic cell nuclear transfer—effectively a form of human cloning intended to produce embryonic stem cells—has hit a setback. In the procedure, human DNA is inserted in animal eggs (used because of a shortage of human eggs), which are allowed to divide and multiply. So far, only once has the technique produced actual stem cells, even though one lab alone has gone through “thousands of animal eggs” in the attempt.
Human DNA is inserted in animal eggs, which are allowed to divide and multiply.
Researchers at that lab, Advanced Cell Technology in Massachusetts, tried to understand their lack of success by looking closely at gene activation in hybrid embryos that use mouse, cow, and rabbit eggs. For an embryo to develop, the egg’s DNA must be “reprogrammed,” something that doesn’t happen when the human DNA is inside an animal egg. Thus, the researchers believe the technique “will not generate human embryonic stem cells, presumably because eggs have species-specific factors that reprogram DNA.” (The study was reported in Cloning and Stem Cells.)
Rather than quieting advocates of hybrid embryo research, the study has started a new debate, with many criticizing the Advanced Cell Technology scientists for not letting the hybrid embryos develop longer. ScienceNOW’s John Travis also reports that some wish Advanced Cell Technology would have used monkey eggs. “I don’t think they’ve definitively shown anything,” argued Stephen Minger of King’s College London.
Thus, the research likely will not stop further attempts to create human–animal hybrid embryos; besides, the researchers note that human clones should still be able to produce embryonic stem cells. Alas, the weakening of standards for human life continues.
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