The day scientists might be able to create a human baby through cloning moved closer this week, when South Korean scientists revealed that they had cloned some 30 human embryos, grown them for a week in a laboratory and extracted stem cells for more research. Although the experiments were not intended to produce a baby, and none of the embryos were implanted in a woman, the techniques described by the Koreans will probably make it easier for some scientist somewhere to clone a human. Clearly it is time for the United States and other nations to ban cloning for human reproduction. For now, the only legitimate use of cloning should be for research and medical therapies.
The Korean achievement in an area where limited American efforts have so far fizzled is a worrisome sign that restrictions on financing stem cell research and taboos against cloning may be undercutting American innovation. A small, underfinanced American biotechnology company claimed two years ago to have produced the world’s first cloned human embryos, but none developed beyond six cells and the results were disputed. By contrast, the Koreans reported growing cloned embryos to the blastocyst stage, where the embryo is a tiny ball of some 100 to 150 cells and stem cells first appear.
Stem cells have the ability to grow into virtually all cell types found in the body, making them potentially useful for repairing a wide range of diseased tissues. Stem cells from a cloned embryo are particularly prized because of their use in certain kinds of research, and because they could be used to derive tissue transplants that are genetically matched to a patient, lessening the risk of rejection by the immune system. Such medical uses are thought to be many years away, but if the Korean study can be replicated by other scientists, an important milestone will have been reached. The results gain credence from being published by Science, a distinguished peer-reviewed journal.
The worrisome element is that the blastocyst stage, needed to extract stem cells, is also the stage where fertility clinics typically implant embryos, with a 40 to 60 percent chance of producing a baby. Cloned embryos might not have that same success rate, but the Korean achievement in producing cloned blastocysts, the result of meticulous tweaking of laboratory methods, makes it more likely that some maverick scientist will try.
That would be irresponsibly risky. The Korean achievement in no way eases concerns that cloned fetuses or babies might suffer devastating defects. Cloning for reproduction ought to be banned. Unfortunately, the Bush administration and Congressional Republicans want to ban all cloning, even for research and therapy. Such an all-out ban will only ensure that the cutting edge of biomedicine migrates to other shores.