A team of Korean scientists has stunned the scientific world with its rapid progress towards therapeutic cloning. Woo-Suk Hwang and his colleagues have successfully created 11 lines of human embryonic stem cells using donated eggs and genetic material from unrelated people ranging in age from 10 to 56. Their work shows clearly that it is possible to clone humans, just as Dolly the sheep was cloned in 1996. For stem cell scientists around the world it was a confirmation of their conviction that revolutionary therapies will emerge from this work. "It's a breakthrough that I didn't think would happen for decades," commented developmental biologist Gerald Schatten, of the University of Pittsburgh, an adviser to the team.
One of the most significant advances was an enormous increase in efficiency. Last year Hwang reported that it had taken him 242 eggs to produce a single stem cell line. In just one year he achieved a ten-fold increase in efficiency, making a stem cell line with an average of fewer than 20 eggs. "People will have to rethink the argument that it's not efficient," says Rudolf Jaenisch, of the Massachusetts Institute of Technology. One reason for the technical improvement was Hwang's discovery that freshly harvested eggs from young fertile women are the ones best suited for cloning.
All observers -- whether or not they support therapeutic cloning --- agree that miracle cures are not around the corner. Professor Bob Williamson, a leading stem cell researcher in Australia, said that one of the most valuable outcomes of Hwang's work would be to provide cellular models of disease in order to screen drugs and to do genetic research.
Although the experiment was a technical tour de force, ethical questions remain, even apart from the contentious issue of whether human embryos should be created and destroyed at all. Hwang was widely criticised after his last experiment because he apparently used eggs donated by one of his post-graduate students. This time he tried hard to make the informed consent process transparent and rigorous. Unfortunately, two bioethicists from Stanford University gave him a what amounted to C-minus for his efforts.
They concluded that "Hwang and colleagues' discussion of the consent process and their consent forms reveal little attention to the risks of the procedure and instead focus on the research aspects of their contribution". The bioethicists highlighted an ethical difficulty inherent in the whole therapeutic cloning project: that the word "therapeutic" is misleading. "It is nearly certain that the clinical benefits of the research are years or maybe decades away," say Magnus and Cho. "This is a message that desperate families and patients will not want to hear."
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