Viable embryos have been created from dead people by fusing their cells with empty cow eggs, a controversial fertility scientist claimed on Tuesday.
Panayiotis Zavos, of the Kentucky Center for Reproductive Medicine, Lexington, US, say his team has shown that cells taken from humans after death could be used for cloning. This latest work is purely experimental and no embryos were implanted for cloning, said Zavos, announcing the results at his own press conference in London, UK.
However, the claims were immediately met with both revulsion and scepticism from the UK scientific community.
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The work is 鈥渂oth scientifically questionable and ethically unacceptable鈥�, says Richard Gardner of the UK Royal Society鈥檚 working group on stem cell research and cloning. 鈥淚t is grossly misleading to suggest that you can replicate a loved one by producing a cloned person with the same genetic material.鈥�
鈥淭his man preys on the strong desires of the most vulnerable people in society 鈥� giving them false hopes,鈥� says Robin Lovell-Badge, head of developmental genetics at the UK鈥檚 National Institute for Medical Research. Other scientists argue that, even if cloning a person were possible, the risk of major birth defects is huge.
Peer review
鈥淲e have yet to see any proper description of any of the procedures that Dr Zavos claims to be able to use. He should publish his research in a recognised journal to prove that he is not a charlatan,鈥� says Lovell-Badge.
The UK鈥檚 regulatory body, the Human Embryology and Fertilisation Authority, refused to comment on Zavos鈥檚 latest work without it being peer-reviewed. Zavos says he has published a paper on earlier work in Reproductive Bio Medicine Online and that other papers are currently being reviewed.
In the latest work, Zavos claims to have taken live cells from the tissues of three dead people, injected them into cow eggs stripped of their nuclei and then fused them using electrical stimulation.
The successfully fused embryos begin to cleave after 48 hours, says Zavos, dividing into a small ball of cells. Two of the three human cells produced 鈥渧iable embryos鈥� which could have been implanted in an attempt to produce a pregnancy, he says. Several other groups have already created cloned embryos by fusing human cells with empty animal eggs, starting in 1996.
Car crash
Zavos used blood and other tissues from an 11-year-old girl who was killed in a car crash. Her parents kept the tissues in their home refrigerator until they were delivered in dry ice to Zavos鈥� group three days later.
Cells were also used from a dead 18-month-old boy, but the embryos produced survived until the four-cell stage only, Zavos says, and so were not viable.
The third case was that of a 33-year-old man. His tissues were harvested in the mortuary immediately after death, so the team was able to culture them 鈥渏ust like fresh cells鈥�. These cells produced embryos which grew to the 64-cell stage 鈥� 鈥渄efinitely transferable embryos which can yield a viable pregnancy鈥�, says Zavos.
But both Gardner and Simon Fishel, director of fertility centre CARE in Nottingham, UK, say the results add little to research. Fishel told New 杏吧原创: 鈥淥ne can鈥檛 conceive of any useful information that could come out of this at research level, let alone clinically.鈥�
Gardner notes that merely culturing healthy cells would demonstrate their viability. And he adds that bovine eggs are particularly good for cloning techniques: 鈥淚nterspecific combination may well work because it鈥檚 an egg recipient in which we know cloning works 鈥� it won鈥檛 inform you as to whether it works in humans.鈥�