USA: Researchers obtain stem cells from cloned monkeys

In a report released on Wednesday (November 14) Shoukhrat Mitalipov and colleagues at Oregon Health & Science University said they used skin cells from monkeys to create cloned embryos, and then extracted embryonic stem cells from these days-old embryos. This had only been done in mice before, they reported in the journal Nature. Mitalipov had given sketchy details of his work at a conference in Australia in June, but the work has now been independently verified by another team of experts. They said their work shows it is possible, in principle, to clone humans and take stem cells from the embryos. Embryonic stem cells are the source of every cell, tissue and organ in the body. Scientists study them to understand the biology of disease and want to use them to transform medicine. The idea would be to take a small piece of skin from a patient and grow tissue or even organ transplants perfectly matched to the patient. But their use is controversial, with opponents saying it is wrong to use a human embryo in this way. U.S. President George W. Bush has repeatedly blocked legislation that would expand federal funding of such research. Many species of animals have been cloned, and experts have taken stem cells from a variety of embryos, including human embryos. But it has been very difficult to both clone and then get embryonic stem cells from any animal. Mitalipov's team overcame two barriers -- first cloning a primate, the group of mammals that includes monkeys, apes and humans, and then getting embryonic stem cells from the clone. Mitalipov said the dyes used in cloning some animals apparently are toxic to primate cells. They used somatic cell nuclear transfer, which involves taking the nucleus from an adult cell, in this case fibroblasts, a type of skin cell, taken from nine adult males. Then an egg cell is hollowed out and the nucleus from the adult cell inserted. This programs the egg into behaving as if it had been fertilised and it can grow into a embryo. It was not easy. The researchers used 304 eggs from 14 rhesus macaque monkeys and ended up with just two stem cell lines. The researchers said much more work was needed before it would be useful for humans.

ITN Source | November 15, 2007

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