Panayiotis Zavos, a fertility doctor who runs a clinic in the US, was due to have announced at a conference in London today that he created 'human-cow' embryos that survived in the laboratory for two weeks. In theory, according to an article reporting on the forthcoming announcement in the UK's Sunday Times newspaper yesterday, the embryos could have been implanted into a woman.
Zavos said that while he had no plans to implant the hybrid embryos - created by inserting human DNA into cow's eggs - they were 'theoretically viable'. But he was only experimenting in order to perfect cloning techniques, and used bovine eggs in order to overcome both ethical and practical problems with using human eggs: 'We are not creating monsters', he said.
Zavos claims that the embryos grew to more than 100 cells and appeared to be developing normally. He also claimed they had passed the stage of differentiation, which may be taken to show that the human DNA had been left intact by the process. But other scientists were unconvinced by the report. Professor Richard Gardner, chairman of the Royal Society working group on stem cells and cloning, said 'this claim should be treated with extreme scepticism without evidence'.
In April 2003, Zavos, who formerly worked with maverick Italian fertility doctor Severino Antinori, announced that he had cloned the first human embryo for reproductive purposes. Zavos claimed to have cloned the human embryo for an American couple, saying that it would be kept frozen until further tests on it had been performed. He said that he would only consider implantation of the embryo if he could be certain that it was free from abnormalities and is capable of healthy development.