Stem cells are unspecialized cells that can self-renew or differentiate into tissue-specific cells. Due to the unique properties of these cells, stem cell therapy can be used to regenerate damaged or diseased tissues and organs. Cancer patients with impaired bone marrow functions, such as those diagnosed with leukemia, lymphoma, and myeloma, are often candidates for stem cell therapy. Bone marrow, a spongy tissue found in the center of large bones, is the main source of hematopoietic or blood-forming stem cells. Without healthy bone marrow, a patient cannot produce blood cells. To start stem cell therapy, blood cancer patients are first exposed to high doses of radiation or chemotherapy to destroy cancerous cells — a conditioning therapy. This may also affect their original stem cells. Then, hematopoietic stem cells harvested from the patient — an autologous transplant — or a healthy matching donor — an allogeneic transplant — are infused intravenously into the patient. Over time, the transplanted stem cells proliferate in the bone marrow and restore the patient’s ability to produce healthy blood cells.