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Adult/Tissue Stem Cell Questions1. Where are adult/tissue stem cells found? 1. Where are adult/tissue stem cells found? Adult stem cells are found in tissues that have already developed. There are many different types of adult/tissue stem cells present in adults, children, infants, umbilical cords and developing fetuses. For example, adult stem cells are found in bone marrow, fat, umbilical cord blood, amniotic fluid, the brain, liver, skin, nervous system, gastrointestinal tract, muscle and even the dental pulp of the tooth. According to the NIH, stem cells are thought to reside in specific areas of tissue where they remain slowly dividing until they are activated by the body’s normal need for more cells or by disease or tissue injury. Because these are stem cells that are found in specific types of tissue, they are also sometimes referred to as tissue stem cells. Adult stem cells are more limited and specialized than embryonic stem cells. Although there are many different types of adult or tissue-specific stem cells, each is generally limited to producing only the cell types that are present in its tissue of origin. For example, blood-forming stem cells are able to make blood and immune system cells, but not cells of other tissues such as bone or muscle. Adult stem cells also have a more limited capacity to replace themselves than do embryonic stem cells, so there are often fewer cells for researchers to work with. Although they are less versatile than embryonic stem cells, they are also used to treat patients. 2. What purpose do adult stem cells serve in the body? The primary roles of adult stem cells in the body are to maintain and repair the tissues in which they are found. For example, when you injure your muscle, muscle stem cells would divide and form new muscle cells to replace damaged cells. Umbilical cord blood also contains adult stem cells and is a rich source of blood-forming stem cells. Additional umbilical cord stem cells may also be able to differentiate into bone cells as well as the cells lining the inside of blood vessels. 3. What is the most common type of adult stem cell used in treatments today? Blood-forming stem cells from bone marrow or umbilical cord blood are the most common type of stem cell used to treat human diseases today. For example, when cancer patients are given a bone marrow transplant, they receive blood-forming stem cells that rebuild their blood and immune systems. The first successful bone marrow transplant was conducted in 1970. For 40 years bone marrow stem cells have been used to treat cancer patients with conditions like leukemia and lymphoma. During chemotherapy, while most of the leukemia cells are killed, so are the blood-forming stem cells in the bone marrow that patients need to make new blood cells. As a result, many patients die from the toxic effects of chemotherapy against normal blood cells. However, if stem cells are removed from the patient before chemotherapy and then re-injected after treatment is completed, they can produce large amounts of red and white blood cells. This keeps the body healthy and helps fight infections. 4. Why not use only adult stem cells for research? Scientists are studying adult stem cells and this research is yielding important discoveries. However, embryonic stem cells have unique and important features that adult stem cells do not have.
Whether we are trying to generate cells that will be used for treatment, or cells that will be used to screen new drugs, the ability to make indefinite quantities of any cell type in the body is very important. The overwhelming majority of scientists and physicians believe that in order to make the most rapid progress against disease, research should proceed using both embryonic and adult stem cells. |
Basic Questions
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Copyright © 2006, 2009 Michigan Citizens For Stem Cell Research & Cures