Gene targeting in sheep raises new hopes and fears

PPL Therapeutics Ltd of Roslin, Edinburgh, showed today how they succeeded a year ago (the delay was to secure a patent) in targeting a gene to a chosen location in embryonic sheep fibroblasts. Then they transferred the nucleus to stem cells and created whole transformed, gene-targeted sheep (Nature paper 1 and paper 2).We have succeeded in cloning sheep, goats, cows, pigs and mice, and now we have gene targeting in sheep. But it is proving difficult to clone whole animals efficiently, as the science involved is obscure (see Science vol 288, 9 June 2000, p 1722). According to Science "out of some 100 attempts to clone an animal, typically just two or three live offspring result. Even when an embryo does successfully implant in the womb, pregnancies often end in miscarriage. A significant fraction of the animals that are born die shortly after birth. And some of those that survive have serious developmental abnormalities...". So there is still much work to do before this technology gives us, for example, fields of cows providing us with spare cells for our immune systems.Nevertheless this field seems to be moving like a torrent, and the media are already warning of genetic modification of humans. Clearly it is not impossible. Which makes meetings like tonight's (29 June) debate "Should Restrictions on Therapeutic Cloning be Lifted?" at the Institute of Physics of extreme importance. Not only does the public need to be aware of what's happening, in depth and accurately, but scientists need to be fully thoughtful of the implications and potential of their work, and government needs to be aware of the legislation that may be needed.The Forum tonight is a Science & Public Affairs Forum on stem cell therapy. Current UK law restricts work on embryonic stem cells to research into infertility anddiseases of new born babies, but according to the blurb about this British Association for the Advancement of Science meeting "Dr Austin Smith, of the University of Edinburgh will argue at the debate that the law should be relaxed. According to Dr Smith, who is the only UK scientist licensed to work on human embryonic stem cells, they have enormous untapped potential. He said: 'They are a wonderful natural resource as they can develop into almost any kind of human cell, such as brain, bone or heart. They offer a unique opportunity to replace tissues damaged by disease.'"An expert committee, chaired by the Chief Medical Officer, is currently consideringproposed amendments to the law that would allow stem cells derived from humanembryos to be used for research into treatments for human diseases and injuries.Professor Julia Polak of Hammersmith Hospital will also speak. "Her pioneering work has hinted at the tantalising promise of stem cell research and she is excited by the possibilities" says the BAAS release. "She said: 'We are beginning to see that stem cells will grow into the right cell types when they are transplanted into other tissues, for example, stem cells injected into bone will start making bone cells.' Dr Sandy Thomas, Director of the Nuffield Council on Bioethics, will address the ethical issues the research raises.Tonight's meeting is a Science and Public Affairs Forum sponsored by the Medical Research Council. It takes place on Thursday 29 June from 6.30-8.00pm at the Institute of Physics, 76 Portland Place, London W1N 3DH.For free tickets contact James Allport, the BA, 23 Saville Row, London, W1 2NB on 020 7973 3070 (e-mail:james.allport@britassoc.org.uk)

Gene targeting in sheep raises new hopes and fears

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