Hematopoietic stem cells are the precursors of mature blood cells that are defined by their ability to replace the bone marrow system following its obliteration (e.g., by gamma-irradiation) and can continue to produce mature blood cells. Hematopoietic stem cells give rise to red blood cells, white blood cells, and platelets and can be found both in the bone marrow and in the peripheral blood. Hematopoietic stem cells are often used in stem cell transplantation to rebuild a patient’s hematopoietic system following the destruction of the system as part of a medical treatment. Stem cell transplants have been found to be an effective option for patients suffering from diseases such as lymphoma, leukemia, sickle cell disease, some genetic disorders, and some autoimmune diseases. Hematopoietic stem cells may be harvested from donor blood marrow, donor peripheral blood, or donor umbilical cord blood and then transferred to the patient via infusion methods.