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The discovery of versatile stem cells in the amniotic fluid surrounding babies in the womb could make it possible for all mothers to save the cells as "spares" for baby. If the child suffers tissue or organ damage later in life, the cells could be retrieved and grown into the perfect graft, with no problems of tissue rejection by the immune system. Alternatively, the cells could be stored en masse from many babies in a public tissue bank, so that "off-the-peg" tissues would be available matching that of almost any patient. Doctors could extract the cells either from amniotic fluid withdrawn from the womb for prenatal testing, or directly from the placenta once the women had given birth. The cells could then be stored in liquid nitrogen, preserving them for rest of the babies' life. At least that is the theory, now that new research has demonstrated for the first time that amniotic fluid-derived stem (AFS) cells can be extracted and turned into many tissue types. "We've shown the cells can grow into nerve, blood vessels, liver cells, cartilage, bone and cardiac muscle," says Anthony Atala, head of the team which isolated and tested the cells at Wake Forest University School of Medicine in Winston-Salem, North Carolina, US. Halfway houses Atala says the AFS cells are "halfway houses" between embryonic stem cells - the primitive cells in embryos capable of forming every cell in the body - and adult stem cells, which are dispersed round the body and which replenish and repair tissue during life. "AFC cells have properties of both," says Atala. As well as growing into almost as many types of tissue as their embryonic counterparts, AFS cells also grow just as fast, doubling in number within 36 hours. Equally encouraging, nerve cells created from the amniotic stem cells successfully amalgamated with brain cells in mice, suggesting they may also be able to repair tissue in humans. Unlike embryonic stem cells (ESCs), AFC cells do not form tumours. Nor are there any ethical problems with saving amniotic cells, whereas ESCs have to be extracted from spare human embryos which perish in the process. This ESC procedure attracts passionate opposition from some groups. Atala would not comment on whether this made the amniotic cells more ethically acceptable, but he stressed that in his view, all avenues of stem cell research should continue to be pursued. Hybrid clones Other researchers welcome the findings. "If the cells can be extracted from the placenta, it's a very convenient way of getting large numbers of cell lines that repair all types of cells," says Ian Wilmut of the University of Edinburgh, UK. Lyle Armstrong, of the University of Newcastle-upon-Tyne, UK, says: "It's likely that therapies will arise from cells like these way before they're available from ESCs." They insist that ESCs will be invaluable for other applications, however, especially for research to understand disease and test new drugs. Wilmut, Armstrong, and a third team led by Stephen Minger of King's College London, UK, have each applied for permission to try and produce human ESCs from cloned "cow-human" or "rabbit-human" hybrid embryos. Their plan is to use animal eggs emptied of their own chromosomes to trick human cells back into an embryonic state from which the ESCs could be extracted and then studied to unravel the causes of disease. This week, the UK Human Fertilisation and Embryology Authority will rule on whether the three teams are to be permitted to proceed with this avenue of research. See our latest Short Sharp Science blog on this contentious issue, and give us your views. Journal reference: Nature Biotechnology (DOI: 10.1038/nbt1274) ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn