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National Geographic : 2005 Jul
Contents
what are adult stem cells? where they've .. been found .. ® brain ® blood ® cornea ® retina ® heart ® fat ® skin ® dental pulp ® bone marrow ® blood vessels ® skeletal muscle ® intestines /4 neural stem cell 9. glial cells neurons a more grown-up cell The adult body has a small number of stem cells in mai sues and organs-where tl low until activated by illnes jury. Unlike embryonic stem adult stem cells haven't pro able to morph into every kir cell and may be limited to b ing cell types within their ti; of origin. An adult stem cell brain, for example, can bec a neuron or glial cell-both cells-but not a bone or liv ® umbilical cord cord blood platelets red blood white blood mesen cells cells chymal cells Similarly stem cells from a new ny tis- born's cord blood (considered hey lie adult cells because they aren't sorin- from embryos) produce only blood cells, cells. Recently, though, cord tissue ved has been found to contain mesen nd of chymal cells capable of generat ecom- ing bone and cartilage. ssue In general, adult stem cells are in the scarcer in the body and harder ome to culture than embryonic cells, Sneural yet large numbers are needed for er cell. therapies. hints of progress So far only adult stem cells have been tested in humans, though research on both adult and embryonic cells progresses apace as scientists seek treatments for myriad diseases. "This is the century of cells," says Harvard biologist Douglas Melton. Results are preliminary, but they hint at a transformation in medicine. Some disease updates: heart disease Adult bone marrow stem cells injected into heart arteries are believed to improve cardiac function in victims of heart attack or heart failure. leukemia and other cancers Invarious studies leukemia patients treated with stem cells from bone mar row and umbilical cord blood emerged free of disease; donor blood stem cells have also reduced non-Hodgkin's lymphoma and pancreatic and ovarian cancer in some patients. rheumatoid arthritis Adult stem cells may be helpful in jump starting repair of eroded cartilage. In human trials, joint pain lessened tempo rarily after donor stem cell therapy in some patients, and some then respond ed better to standard drug therapies. parkinson's disease Since fetal tissue implants had mixed success in reducing neurological symptoms, some researchers say the best hope is that a patient's own neural stem cells may eventually be coaxed to mature into the dopamine-producing cells needed to treat the disease. type I diabetes Basic research is focused on under standing how embryonic stem cells might be trained to become the type of pancreatic islet cells that secrete needed insulin. Recent developments using proteins to spur cell differentia tion may speed progress. NOT TOSCALENOM ART STEM CELLS 13 I NOT TO SCALE.NGMART STEM CELLS 13
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