A radical and remarkably easy way to make cells that can grow into any tissue in the body has been developed by scientists in Japan.
The feat has been hailed as a major discovery by researchers familiar with the work, and if it can be repeated in human tissue, could lead to cheap and simple procedures to make patient-matched stem cells that could repair damaged or diseased organs. In a series of elegant experiments, researchers showed that cells plucked from animals could be turned into all-powerful master cells simply by immersing them in a mildly acidic solution for half an hour.
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Haruko Obokata at the Riken lab in Kobe, Japan, told the Guardian that her team had created several dozen mice that had tissues grown from the cells, and had followed their health for one to two years. "So far they appear to be healthy, fertile, and normal," she said. The finding has stunned many researchers because previous attempts to make stem cells have been fraught with difficulties. One route is cloning, which is controversial because it involves the creation and destruction of embryos. A more recent method, called induced pluripotency, uses genetic manipulation to convert adult cells into a more flexible, immature state.
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His enthusiasm was shared by Chris Mason, a stem-cell expert at University College London. "If it works in man, this could be the game changer that ultimately makes a wide range of cell therapies available using the patient's own cells as starting material," he said. Obokata started work on the procedure five years ago while working at Harvard Medical School. The idea came to her after noticing by chance that cells that had been squeezed through a thin tube shrank to the size of stem cells. She went on to look more closely at what effects different kinds of stress – from heat, starvation and acidic conditions – had on cells.
After years of perfecting the experiments, Obokata showed that she could convert white blood cells taken from newborn mice into cells that behaved very much like stem cells. She went on to do the same with brain, skin, muscle, bone marrow, lung and liver cells. "It was very surprising to see that such a remarkable transformation could be triggered simply by stimuli from the outside," she said.
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Obokata calls the procedure "stimulus-triggered acquisition of pluripotency", and the resulting cells Stap cells. Immersion in a mild acidic solution, with a pH of 5.5, worked best. Squeezing cells had a similar effect but was less efficient.
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Austin Smith, director of the Wellcome Trust/MRC stem cell institute at Cambridge University, said the work looked sound, but that it was unclear whether it would work in humans and with adult tissue, such as skin cells taken from a patient. If scientists can get the procedure to work in people, it could quickly overcome regulatory hurdles that have held up the development of therapies based on induced pluripotent stem (iPS) cells. Therapies based on iPS cells face scrutiny because genes are added to the cells to convert them into stem cells. These genes probably need to be removed before they can be used safely in patients.
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Even if the procedure can be perfected in humans, Smith said major hurdles remain before patients could be treated with Stap cells. Any tissues grown from Stap cells would need to be proved safe in the body. Scientists would have to show they cannot turn into tumours, and demonstrate that they work with patients' healthy tissues without causing problems.
