A stem cell transplant; also called a blood or marrow transplant; is the injection or infusion of healthy stem cells into your body to replace damaged or diseased stem cells.A stem cell transplant may be necessary if your bone marrow stops working and doesn't produce enough healthy stem cells.This procedure also may be performed if high-dose chemotherapy or radiation therapy is given in the treatment of blood disorders such as leukemia, lymphoma, multiple myeloma or sickle cell anemia.A stem cell transplant can help your body make enough healthy white blood cells, red blood cells or platelets, and reduce your risk of life-threatening infections, anemia and bleeding.Although the procedure to replenish your body's supply of healthy blood-forming cells is generally called a stem cell transplant, it's also known as a bone marrow transplant, peripheral blood stem cell transplant or an umbilical cord blood transplant, depending on the source of the stem cells.Stem cell transplants can use cells from your own body (autologous stem cell transplant), from a donor (allogeneic stem cell transplant) or from an identical twin (syngeneic transplant).