A controversial fertility doctor today told British reporters that he has cloned 14 human embryos and transferred 11 of them into the uteruses of four women. The physician, Panayiotis Zavos, who operates fertility clinics in Kentucky and Cyprus, says none of the embryos gave rise to successful pregnancies, but he is confident that baby cloning is just around the corner, The Independent reports.
"There is absolutely no doubt about it, and I may not be the one that does it, but the cloned child is coming," Zavos told The Independent, adding, "If we intensify our efforts we can have a cloned baby within a year or two."
Fertility experts are relatively confident Zavos is capable of cloning embryos in the lab. (After all, scientists have been cloning animals using adult cells since the mid-1990's, when Dolly the sheep was born.) "Someone with Dr. Zavos' expertise could probably do it," says Oleg Verlinsky, a molecular geneticist at the Reproductive Genetics Institute in Chicago.
The method he uses is probably somatic cell nuclear transfer, which entails removing the nucleus from a woman's egg and replacing it with the nucleus of an adult "somatic" cell (a body cell as opposed to a gamete) of the person who is to be cloned, Verlinsky says, but notes that he is not familiar with Zavos' techniques.
Cloning embryos is one thing, but turning them into healthy babies is another, says Denny Sakkas, who directs the Assisted Reproduction Laboratories at Yale University School of Medicine in New Haven, Conn. In order for the process to work, the transplanted adult nucleus has to revert to the totipotent state of the early embryo, he says. "This means you have to wipe the slate clean [with] respect to gene expression in the somatic nucleus and then reestablish a new sequence of gene expression." And given the many genes involved in all these processes, he adds, there is a good chance something will go wrong.
This afternoon, the American Society for Reproductive Medicine (ASRM) blasted Zavos' claims, calling human reproductive cloning unacceptably dangerous. "We have yet to see any evidence that these safety concerns have been addressed," the org said in a statement, "and we have also yet to see any evidence as to the veracity of the claims themselves.” According to ASRM Scientific Director Andrew La Barbera, researchers have observed that cloned animals age prematurely and have inferior brains, and there is no evidence these same effects would not be seen in humans as well.
This is not the first time Zavos has stirred controversy with his cloning research. In 2004, he claimed to have transferred a cloned embryo into a woman's womb, but scientists said he had no evidence to prove it. Later that year, the editor of the Journal of Assisted Reproduction and Genetics withdrew a cloning study by Zavos' and his colleagues after Zavos allegedly misrepresented some of details of the research to reporters.
You can see Zavos at work with his cloned embryos here.
Image © iStockphoto/DrGrounds