This research is reported in the January issue of the scientific journal Nature Immunology . They found that some stem cells only functioned for the first month and then disappeared, while other stem cells only started to function after several months, but then persisted. Because the stem cells have different functions, the clinical use of these cells will also be different. Stem cells make up just one in a million bone marrow cells, and are the cells from which the entire blood system grows. Stem cell transplants, a form of bone marrow transplants, are used widely for treating different types of cancer, anemia and auto-immune disorders.
Most applications require that stem cells function for many years following transplantation.
Therefore, the long-term repopulating stem cells would be the ones researchers would want to target when permanent replacement is important, such as in the development of new treatments, like gene therapy and stem cell expansion. However, there may also be application for the short-term repopulating stem cells, which allow for a robust but temporary graft following a stem cell transplant. Cancer patients often have to undergo large doses of chemotherapy to eradicate tumours, however, this also wipes out the vast majority of the blood system, requiring a stem cell transplant to replace the damaged blood system as fast as possible. Future research will determine if a large number of these cells could be expanded in culture, leading possibly to more a more successful transplant. The discovery of two different types of stem cells has made it important to determine how manipulations done to stem cells before transplantation might alter them and make them more or less effective.