Scientists for the first time were able to clone embryos from adult monkeys, a breakthrough that raises the possibility that human cloning might soon be possible, The Independent newspaper reported Monday.
A research team at the Oregon National Primate Research Center will report in the magazine Nature that they have been able to extract stem cells from some of the cloned embryos and that they have managed to grow these cells into mature heart cells and brain neurons.
Attempts to clone human embryos for research have been plagued by technical problems and controversies over fraudulent research and questionable ethics. But the new technique promises to revolutionise the efficiency by which scientists can turn human eggs into cloned embryos, The Independent reported.
The ONPRC team, led by Russian-born scientist Shoukhrat Mitalipov, reportedly developed a new way of handling primate eggs that involves fusing each egg with a nucleus taken from a skin cell of an adult primate.
The breakthrough is sure to heighten the cloning controversy.
Scientists in South Korea reported in 2004 that they had created the first cloned human embryo, but it was discovered in 2006 that the study's main author, Hwang Woo-suk, had committed fraud.
The Oregon team, working with a group in China, has so far produced about 100 cloned embryos that have been transferred into around 50 female macaques, but none has resulted in a full-term pregnancy, retired ONPRC director Don Wolf told The Independent.
"It's possible that we're still just having bad luck. We're producing may be one in 20 or one in 30 cloned blastocysts that are 'normal' and capable of producing a pregnancy and we just haven't got them into the animal recipient at the right time to allow implantation and pregnancy to occur," Wolf told the newspaper.
"The focus now is going to be on therapeutic cloning and using the non-human primate as a paradigm for therapeutic cloning for what you might be able to do clinically," he said.
"We're the first to do it, although it's a tainted subject because of the fraudulent research that came out of South Korea. One can never be sure but there may be some validity to what the South Koreans did. But this would now be the first documented therapeutic cloning in a primate," he added.