there are several stem cell therapies that are currently in use. One of the most common and well-known is bone marrow transplant. This procedure is used to treat leukemia, blood-diseases and other types of cancer. It involves replacing diseased and abnormal bone marrow and subsequent stem cells, with that of a healthy matching donor. Successful transplants enable donated stem cells to migrate into the patient’s bone marrow where they can begin producing healthy leukocytes (infection-fighting white blood cells) and replacing abnormal cells.
Another such procedure is the transplant of adult peripheral blood stem cells. Although most stem cells are present in bone marrow, limited quantities are available in the blood. These stem cells can be used just like bone marrow to tackle the same diseases. The collection of peripheral blood stem cells is much easier and less invasive than collecting bone marrow. However, it is more challenging to collect enough stem cells in this fashion because they are less concentrated in the bloodstream than in bone marrow.
Umbilical cord stem cell transplants can also treat leukemia, blood-diseases and certain cancers. The umbilical cord, which is normally discarded after the birth of a baby, can now be used to harvest stem cells. The stem cells that come from the cord are less likely to be rejected than either bone marrow or peripheral blood stem cells (The University of Utah)