Blowing Up the Immortal Strand Hypothesis
From PhysOrg.com: "How do adult stem cells protect themselves from accumulating genetic mutations that can lead to cancer? For more than three decades, many scientists have argued that the 'immortal strand hypothesis' - which states that adult stem cells segregate their DNA in a non-random manner during cell division -- explains it. ... [researchers] labeled DNA in blood-forming mouse stem cells and painstakingly tracked its movement through a series of cell divisions. In the end, they found no evidence that the cells use the immortal-strand mechanism to minimize potentially harmful genetic mutations. ... This immortal strand idea has been floating around for a long time without being tested in stem cells that could be definitively identified. This paper demonstrates that it is not a general property of all stem cells." The more we know about the changes that accumulate in cells with age - and the mechanisms by which those changes occur - the better armed we are work towards the repair of aging.