LONDON — It's finally happened. A team from the United States reported this week (24 November 2001) that they have successfully carried out cell nuclear replacement in human cells, raising the issue of human cloning as a 'clear and present' reality rather than merely a future prospect.

"They were such tiny dots, yet they held such immense promise," explained one the research team led by Jose Cibelli, writing lyrically about the event in Scientific American. He reported what they had achieved: "After months of trying, on 13 October 2001, we came into our laboratory at Advanced Cell Technology to see under the microscope what we'd been striving for — little balls of dividing cells not even visible to the naked eye. Insignificant as they appeared, the specks were precious because they were, to our knowledge, the first human embryos produced using the technique of nuclear transplantation, otherwise known as cloning."

A more scientific version of events, published in e-biomed: The Journal of Regenerative medicine, revealed that the group had tested two methods of developing human stem cells. The first — parthenogenesis — activated egg cells without fertilization by sperm cells to form preimplantation embryos. The process occurs in insects and microbes, but not naturally in higher organisms. The second technique used somatic cell nuclear transfer (cloning) — adding DNA from human somatic (body) cells to human egg cells from which DNA had been removed — to form preimplantation embryos. Results showed that they parthenogenetically activated 22 human eggs and performed nuclear transfer in 17 metaphase II eggs. Cleavage beyond the eight-cell stage was obtained in the eggs and blastocoele cavities were observed in six. Three somatic cell-derived embryos developed beyond the pronuclear stage up to the six cell stage.

Cibelli and colleagues argued that they have no intention of using their techniques to develop a cloned human (reproductive cloning), but only to provide stem cells (therapeutic cloning). They commented: "The ability to create autologous embryos represents the first step towards generating immune-compatible stem cells that could be used to overcome the problem of immune rejection in regenerative medicine." Many human embryonic stem cell lines are already in existence but are of little value in human transplantation because they would be rejected by recipients as being foreign. Human therapeutic cloning — developing stem cells from a patient's own cells — would overcome this problem by providing cells that were a precise genetic match."

This failed to reassure members of the US government and policymakers opposed to human cloning. A White House spokesperson said: "The president has made it clear that he is 100% opposed to any type of cloning of human embryos. He supported the House legislation to ban human cloning, which passed overwhelmingly." The House of Representatives voted last summer to ban human cloning and set penalties of up to 10 years in prison and a $1 million fine for those convicted of attempting to clone human beings, although the measure was not taken up by the Senate so had not become law.

The first report of human cloning has reinforced the need for clear guidelines on what scientists can and cannot do. New legislation to ban human cloning is currently being debated by the UK government, after the High Court ruled that cloning based on cell nuclear replacement (CNR) is not covered by current regulations and so, could, in fact, be carried out without breaking the law as it stands.

The High Court ruling surprised the government and research bodies in the UK because they had thought that human cloning was already banned. But the Secretary of State for Health, Alan Milburn, responded quickly by announcing urgent legislation making human cloning a specific criminal offence, unless the ruling was overturned on appeal. The ruling upheld a claim by a political party 'campaigning for absolute respect for innocent human life', Prolife Alliance, that organisms created by cell nuclear replacement — the technique that resulted in the early human clones created in the US, and previously in Dolly the sheep — were not embryos, because they were not created by the fertilisation of an egg by a sperm. In CNR, the nucleus from one cell is transplanted into an unfertilised egg from which the nucleus has been removed. Prolife Alliance argued that this meant that human embryos created by cell nuclear replacement fell outside the protection of the Human Fertilisation and Embryology Act 1990.

Mr Justice Crane agreed that organisms created by cell nuclear replacement were not embryos as defined in the Act, so were not covered by its regulations. After taking scientific advice, he argued that, "CNR of the kind under consideration does not normally involve fertilisation. "In his ruling, he said: "It has become clear that CNR has potential for research purposes that was not known in 1990." Prolife Alliance warned that the ruling meant that human reproductive cloning based on CNR could potentially be carried out in the UK. Director of the organization Bruno Quinatavalle said: "The upshot of the judgment is that there are no safeguards to stop any form of cloning in this country." But, the Human Fertilisation and Embryology Authority reported that it had received no license applications for stem cell research using embryos created by cell nuclear replacement.

The Health Minister, Lord Hunt of Kings Heath, said: "We are totally opposed to human reproductive cloning and have said that we will introduce legislation to make this a specific criminal offence. The Judge granted leave to appeal against his decision and we intend to do so. "Scientific bodies supported this position. Vice-President of the Royal Society, Sir Brian Heap, said: "As we have stated previously, the Royal Society believes that the Government should ensure that the law explicitly prohibits human reproductive cloning in the UK."

The judgment has no effect on the provisions of the 1990 Act, which continue to regulate the use of embryos created by fertilisation using sperm and eggs. Stem cell and other research will also continue to be allowed and regulated by the HFEA. Sir Brian noted: "Both Houses of Parliament have signaled their approval for the principle of allowing licensed research into embryonic stem cells using cell nuclear replacement. This should be respected by any proposed new legislation."