Show IN THE WORLD Koreans say they cloned embryos for stem cells Rick Weiss The Washington Post Scientists in South Korea reported making nearly a dozen cloned human embryos that are genetic twins of patients with various medical problems and have isolated from those embryos batches of stem cells with the potential potential poten poten- potential to replace failing tissues in those patients The experiments mark a significant advance in therapeutic cloning the paced fast-paced but controversial controversial controversial con con- field that aims to make customized heart tissues for heart attack patients nerves for patients with spinal cord injuries and a host of other laboratory-grown laboratory spare parts genetically tailored to the patients who need them The single previous claim that stem cells had been derived from a cloned human embryo reported last year by the same team at Seoul National University's College of Veterinary Medicine left some scientists doubting the results Moreover the process appeared to be hopelessly inefficient requiring requiring ing almost human eggs extracted from female donors to get just one cloned embryo with its precious cache of stem cells In the new experiments described in |