Stem cells are located in the blood and bone marrow, and they are used to generate other cells with specialized functions such as blood cells, muscle cells, or bone cells. Autologous stem cell transplants are performed when healthy stem cells are removed from a patient's own body and infused back into the patient to replace damaged bone marrow. Autologous stem cells are used to treat certain conditions including lymphomas and myeloma by harvesting stem cells prior to damaging treatment and then returning them to the patient.