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Sections Blog Scientists use 'biological alchemy' to convert one cell type into another | Scientists use 'biological alchemy' to convert one cell type into another |
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| Saturday, 21 June 2008 | |
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Biological alchemy has been used to convert one cell type into another kind that could be used to repair a body damaged by accident or disease, marking a new approach to regenerative medicine that does away with the use of stem cells and embryos. In the quest for new treatments, scientists have spent the last decade working on human embryonic stem cells, parent cells which have the potential to turn into any of the 200 plus types in the body, for a vast range of treatments, from heart disease to Parkinson's disease. Rather than use embryos, or obtain embryonic stem cells by the use of cloning or genetic modification, a new front has opened up in regenerative medicine: the direct conversion of one cell type, say a skin cell, into another, say a brain cell. Today, New Scientist reports new evidence that this approach should work based on research that, according to Dolly pioneer Sir Ian Wilmut of Edinburgh University, "should make us all reconsider our general strategy." Sir Ian said that pioneering work in Oxford University by Prof Tariq Enver showed it is possible, turning white blood cells into red cells, but now a new study by Prof Doug Melton of Harvard University "is a timely reminder" that this method is worth more study to find out the best way to create new cells and tissues for repair. Prof Melton told the annual meeting of the International Society for Stem Cell Research in Philadelphia how he took specialist "pancreatic exocrine cells" that secrete digestive enzymes, which make up to 95 per cent of the pancreas, and converted them directly into another cell type, called beta cells, which make the hormone insulin to control blood sugar levels. Although there is a long way to go to show that this could be used to help treat diabetes, it adds to the existing evidence that a cell's destiny is no longer fixed. The team achieved the feat by hunting for special genes that control how the genetic code is interpreted by cells to turn them into brain, bone, heart cells or whatever. They found nine of these so called transcription factor genes that seemed critical for beta cell development. Then Prof Melton's team used a standard method of genetic modification, where a virus is used to introduced a gene. They injected nine viruses, each carrying a different gene, into the pancreases of lab mice and found that some of the pancreatic exocrine cells seemed to turn into fully functional beta cells and started to make insulin. "If we look at every gene we know to be important for beta cell function, we find it turned on," Prof Melton tells New Scientist, adding that they have now managed to repeat the feat using only three genes. Scientists are wary about using viruses to genetically alter cells in the body because they are unable to control how new genes are introduced with enough precision to ensure there are no side effects, notably cancer. But the hope is that, in years to come, a cocktail of factors could reprogram one cell type, say a skin cell, to become another. Prof Melton's work offers another alternative to one now being pursued by Sir Ian and many other scientists: using genetic engineering, Prof Shinya Yamanaka at Kyoto University found a way to create human embryo stem cells without the need for human eggs, which are in short supply, and without the need to create and destroy human cloned embryos, which is bitterly opposed by the pro life movement. "Many more observations are needed, some with human cells, to confirm that the cells are able to function normally and to discover whether the Yamanaka or the Melton approaches are most effective," says Sir Ian. |
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