Cloning experts in Britain have welcomed news that an American research team has cloned dozens of embryos from adult monkeys in a breakthrough that could lead to the efficient creation of cloned human embryos for research.
Scientists in the US said they had produced dozens of cloned embryos from a 10-year-old adult macaque monkey using a new technique that avoids damaging the egg cells. They also said they had extracted stem cells from some of the embryos and grown them in the test tube into the specialised cells of the nervous system and the heart.
Sir John Gurdon, of Cambridge University, who was the first scientist to clone an animal when he produced cloned tadpoles in the 1960s, said the scientists, from the Oregon National Primate Research Centre in Beaverton, had performed "marvellous work" that should provide the basis for attempts at cloning human embryos.
Sir Richard Gardner, a Royal Society professor at Oxford University, said it was hard to assess the true value of the work until it was formally published, but preliminary findings, as reported in The Independent yesterday, suggested that it was an important breakthrough.
"It certainly seems to discredit the claim that there is something fundamentally different about primates that makes cloning difficult in monkeys and humans," Sir Richard said.
Robin Lovell-Badge, a stem cell scientist at the National Institute for Medical Research in Mill Hill, near London, said: "Although this work has not been published yet, it is potentially significant because there has been a worry that primates may prove to be difficult in terms of cloning."
The Oregon team, led by Shoukhrat Mitalipov, has experimented in placing about 100 cloned macaque embryos into the wombs of about 50 surrogate mothers, but so far the scientists have not had any success in producing live offspring.
Professor Don Wolf, a leading member of the Oregon team, said that the breakthrough resulted from a new way of handling primate egg cells under a microscope using polarised light rather than ultraviolet light and dyes.
The work is scheduled to be published in Nature this month. A spokeswoman for the journal said she could not comment on any manuscript that may be in press.