Koreans Say they Cloned Embryos from Stem Cells
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 to replace failing tissues in those patients. The experiments mark a significant advance in therapeutic cloning, the fast-paced but controversial 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 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 almost 250 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 yesterday’s online version of the journal Science, the team needed only 17 eggs on average to make each batch of stem cells, which have the capacity to develop into any type of tissue. That means a single egg-retrieval procedure of the sort used routinely in fertility clinics is now adequate to produce a colony of personalized cells with the potential to treat a wide spectrum of diseases. If therapeutic cloning can indeed be achieved with the same efficiency as such a widely accepted medical procedure, it would deeply undercut one of the major ethics arguments against it: that it would require egg donations by countless women — at some risk — to make enough embryos and stem cells to be medically useful.
Fascinating. Of course, as any sci-fi fan knows, there are all manner of other ethical questions surrounding cloning beyond the number of egg donors.