First 'proven' human cloned embryo
Friday, 18 January 2008
ABC/Reuters
No patient-specific stem cells yet: but the first documented and proven cloned human embryo, researchers say.
US scientists involved with a small company set up by an unnamed investor report they are the first to clone human embryos and prove it.
But some researchers are asking how much of a scientific development this really is.
Dr Andrew French of Stemagen Corporation of La Jolla in California and colleagues have published their findings online ahead of print publication in the journal Stem Cells.
The researchers used somatic cell nuclear transfer (SCNT) to clone five early-stage embryos, called blastocysts, from donated human eggs and skin cells from two men.
"This study demonstrates, for the first time, that SCNT can produce human blastocyst stage embryos using nuclei from a differentiated adult somatic cell," the researchers say.
They says the used eggs were "excess" and donated, free of charge by three young women involved in a fertility program.
The researchers' long term aim is to use SCNT to produce patient-specific stem cells for possible treatments, but this time around they did not actually produce stem cells from the cloned embryos.
Instead, they destroyed the embryos in the process of checking their DNA in order to prove they were clones.
French, who previously created animal clones while at Monash University in Australia, says the research team wants to make embryonic stem cells from donated embryos to perfect the technique before trying to use cloning methods again to make tailored cells.
"This field has faced a lot of controversy so we wanted to be clean," says French.
Excess eggs Stemagen Corporation's founder Dr Samuel Wood says his success at a large fertility clinic encouraged him to pursue cloning and stem cell research.
"We had this great excess of embryos in the tank that eventually were donated to research or to other couples. But what I also noticed was that we had a great excess of eggs," says Wood.
Human eggs are needed to use cloning techniques to make embryos, and that got Wood thinking. His mother had type-2 diabetes and died after a bad fall. He knew of an investor whose mother had died from a degenerative disease.
Wood says he made his pitch in 2005 to the investor, who wants to remain anonymous, "over a martini in a local restaurant." He then recruited French from Australia.
Wood says the cloning technique is only efficient if the egg is used within two hours of being taken from the woman.
A limited advance While some cloning experts support the new company's work, others are sceptical, including Dr Douglas Melton, who helped found Harvard University's stem cell research centre.
"The value, if any, will come from using the cells to discover drugs, i.e. using the cells as research tools," Melton says.
Others are also working on producing human embryos using SNCT but what many researchers really want to see are stem cells.
"This is the most successful description so far of the use of the cloning techniques with purely human material," says UK stem cell expert Professor Robin Lovell-Badge of the MRC National Institute for Medical Research.
"However, it is still a long way from achieving the goal of obtaining ES cells.
Lovell-Badge says in recent Rhesus monkey experiments only two embryonic stem cell lines were obtained from about 300 starting eggs.
"So it is likely that many more attempts will be necessary before anyone can calculate rates and claim real success in humans," he says.
"It still makes sense to explore the use of non-primate eggs first, until the methods can be improved, rather than using valuable human eggs."
Slippery slope? Opponents of cloning technology say it is a slippery slope to using cloning to make live babies.
Wood is mindful his work at a fertility clinic could raise suspicions. But he notes that cloned animals are often abnormal.
"To put any human through that just strikes me as inherently unethical," he says.
But federal funding for human embryonic stem cell research in the US is limited and the work is restricted to a few academic labs that can juggle the complex requirements of the federal limits, and private companies.
Other companies researching stem cells include Massachusetts-based Advanced Cell Technology, California-based International Stem Cell Corporation and Geron Corporation.
