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Stem cell shift may lead to infections, leukemia Aging of blood-producing stem cells could be responsible for the relatively high incidence of infections and myeloid leukemia in the elderly. Stem cell shift may lead to infections, leukemia Christen Brownlee Researchers have long wondered why elderly people suffer more infections and have a greater chance of developing myeloid leukemia, a type of blood cancer, than younger people do. Now, research in mice suggests that the aging of blood-producing stem cells could be responsible for both conditions. With age, the body of a person or other animal loses its capacity to sustain its tissues and organs. "Since we know the cells mediating this maintenance are stem cells, it doesn't take a great leap of faith to think that stem cells are at the heart of that failure," says Derrick Rossi of Stanford University. To examine whether the aging of stem cells contributes to infections and leukemia, Rossi and his colleagues irradiated young and old mice to kill off their blood-making stem cells. The scientists then transplanted such stem cells from young donor mice into elderly irradiated animals and from old donors into young irradiated animals. After several weeks, the researchers found that young animals' stem cells transplanted into the old mice produced the different types of blood cells in ratios much like those in young mice that haven't been irradiated. However, the young animals that received old animals' stem cells had significantly fewer new lymphoid blood cells-which make cells that battle infections-than normal young animals do. After examining gene activity in the stem cells transplanted from old animals, Rossi's team found a boost in activity among genes responsible for creating myeloid cells. These create red blood cells and some other blood components. Many myeloid-production genes have been associated with myeloid leukemia in people. The scientists conclude in the June 28 Proceedings of the National Academy of Sciences that a shift from lymphoid-cell production to myeloid-cell production could be responsible for the increases both in infections and in risk of leukemia that come with old age. References: Rossi, D.J., et al. 2005. Cell intrinsic alterations underlie hematopoietic stem cell aging. Proceedings of the National Academy of Sciences 102(June 28):9194-9199. Available at http://www.pnas.org/cgi/content/full/102/26/9194. Further Readings: Schlessinger, D., and G. Van Zant. 2001. Does functional depletion of stem cells drive aging? Mechanisms of Ageing and Development 122(Sept. 30):1537-1553. Abstract available at http://dx.doi.org/10.1016/S0047-6374(01)00299-8. Sources: Derrick J. Rossi Department of Pathology Stanford University School of Medicine 279 Campus Drive Stanford, CA 94305 New! Sign up for local CML support group meetings in your local community at http://cml.meetup.com Apply for Commercial Real Estate loans online and submit your deal to dozens of hungry lenders in just minutes. Loan programs for all types of business and commercial real estate. Apply anytime at http://realestatezoo.com CML (Chronic Myelogenous Leukemia Support List) --------------------------------- Part Of CMLHope.Com An International Community Of CML Patients For more information: http://cmlhope.com Post Message: [email protected] Subscribe: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] Change To No Mail/Web: [EMAIL PROTECTED] Change To Digest: [EMAIL PROTECTED] Change To Email: [EMAIL PROTECTED] List Help: [EMAIL PROTECTED] CML Group Web Site http://groups.yahoo.com/group/CML Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/CML/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
