Marrow is a substance found inside bones.
It resembles blood and contains stem cells, which produce red blood cells, white blood cells and other blood components important for fighting infection, carrying oxygen and helping to control bleeding. There are several treatments that will dramatically increase the release of stem cells into the circulating blood so that enough stem cells for transplant can be collected directly from the bloodstream. Although some patients with aplastic anemia, leukemia or other cancers have a genetically matched family member who can donate, about 70 percent do not. These patients' lives depend on finding an unrelated individual with a compatible tissue type, often within their own ethnic group, who is willing to donate marrow. Also as of this date the National Registry has over 3.8 million volunteer donors.