Human cloning claims condemned by leading scientists

Attempts by Panayiotis Zavos to implant cloned embryos in women are unethical and dangerous, critics claim ahead of TV documentary

A maverick fertility expert who claims to be able to clone human beings has been condemned by other scientists for unethical practices that would be likely to lead to a damaged baby if they succeeded at all.

Panayiotis Zavos claims to have cloned 14 human embryos so far and implanted 11 of them into the wombs of four women, but none has survived. A documentary due to be screened tonight on the Discovery channel is expected to show the scientist carrying out his cloning procedures in an unnamed location, since the work is illegal in the UK and many other parts of the world.

Dr Stephen Minger, director of King's College London's stem cell biology laboratory, said Zavos had the necessary technical skills, "but the real problem is the safety issues associated with this". Cloning animals, famously successful with the birth of Dolly the sheep, has in reality been associated with huge problems. "This process has resulted in animals that have genetic abnormalities," he said. "The rate of spontaneous miscarriage is really huge, there is often no implantation, you get late miscarriage, which is unusual, and a lot of postnatal death."

Professor Peter Braude, director of the centre for preimplantation genetic diagnosis at Guy's and St Thomas' in London, said: "He's absolutely hellbent on trying to achieve this and he knows that there are significant risks.

"Who is the experiment here? It's the poor woman and the child involved."

Zavos, who has clinics in the USA and in Cyprus where he was born, claims to be helping people by attempting to recreate loved ones who have died. He is said to have engineered a hybrid embryo using the blood cells of a 10-year-old girl called Cady, who died in a car crash in the USA, and the egg of a cow that had its nucleus removed. Zavos said this was done to study the cloning process and that he would not put a hybrid embryo into a human womb. But he anticipated taking cells from it and inserting them into a human egg, which he said he believed would safely produce the clone of Cady that her parents wanted.

Justin St John, professor of reproductive biology at the University of Warwick, said this process would result in an embryo that still had both human and cow mitochondrial DNA (normally inherited from the mother). "Mitochondria are the generators of energy in our cells and mixing diverse populations of mitochondrial DNA would almost certainly result in the cells not functioning properly – a scenario that we definitely don't want," he said.

Others scientists dismissed the TV documentary as a further piece of attention-seeking by Zavos. "This whole affair shows a complete lack of responsibility," said Professor Azim Surani, Marshall-Walton professor of physiology and reproduction at the University of Cambridge.

"If true, Zavos has again failed to observe the universally accepted ban on human cloning, which was agreed because most of the resulting embryos from such animal experiments are abnormal. This is yet another episode designed to gain maximum publicity without performing rigorous animal experiments or presenting it for peer review in a scientific journal."

Professor Robert Winston, emeritus professor of fertility studies at Imperial College London, was blunter. "I do not know of any credible evidence that suggests Dr Zavos can clone a human being. This seems to be yet another one of his claims to get repeated publicity," he said.

Professor Wolf Reik, head of the epigenetics and chromatin programme at the Babraham Institute, Cambridge, said a successful clone would be no different from a naturally conceived identical twin. "But there are important ethical issues here that must be considered. For example, cloning a child who has died will create a genetically identical person; but it will not be the same child. This is most certainly not a way of bringing people back from the dead," he said.