WASHINGTON, Nov 15 (Reuters) US researchers have cloned monkeys and used the resulting embryos to get valued embryonic stem cells, an important step towards being able to do the same thing in humans, they reported.
Shoukhrat Mitalipov and colleagues at Oregon Health&Science University yesterday said they have 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 get stem cells from the embryos. But they said they only managed to create two batches, or lines, of stem cells, so the method is still very inefficient and difficult.
Embryonic stem cells are the source of every cell, tissue and organ in the body. Scientists study them to understand the biology not only of disease, but of life itself, 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. US President George W Bush has repeatedly blocked legislation that would expand federal funding of such research.
Mitalipov's team used classic somatic cell nuclear transfer to create their embryos. This method involved taking the nucleus from an adult cell, in this case a fibroblast, a type of skin cell.
Then an egg cell is hollowed out and the nucleus from the adult cell inserted. This process in effect programs the egg into behaving as if it had been fertilized and it can grow into a embryo.
A LOT MORE WORK It was not an easy process. The researchers said they used 304 eggs from 14 rhesus macaque monkeys, and ended up with just two stem cell lines.
This means a lot more work before this would be useful for humans they said -- especially given how hard human eggs are to come by.
It was important to confirm the work. A rival journal, Science, was forced to withdraw papers published by South Korean scientist Hwang Woo-suk in 2004 and 2005 after his claims to have cloned a human embryo proved false.
Other cloning experts welcomed the Oregon work.
''The ability to produce embryo stem cells from cloned human embryos would create entirely new opportunities to study inherited diseases,'' said Ian Wilmut, director of the Scottish Centre for Regenerative Medicine at the University of Edinburgh and a member of the team that cloned Dolly the sheep in 1997.
''Cloned cells produced with the genetic material of a patient who has inherited a disease would have the abnormalities associated with the disease,'' Wilmut added in a statement.
The paper ''provides the first convincing evidence that nuclear reprogramming is feasible in primates,'' said Alison Murdoch and Dr Mary Herbert of the North-East England Stem Cell Institute in Newcastle.
''This is a very exciting development which takes us several steps closer to the production of patient-specific stem cells to treat life-limiting conditions such as Parkinson's, motor neuron disease, Huntington's disease and cystic fibrosis.'' REUTERS AE BD1011