Hematopoietic cell transplantation, also known as bone marrow transplantation, is a procedure in which hematopoietic stem cells are transplanted from a donor into a patient in order to restore the body's ability to produce blood cells. This type of transplantation is used to treat a variety of conditions, including leukemia, lymphoma, and certain types of immune system disorders. The donor cells can be obtained from the patient themselves (autologous transplantation) or from a matched donor (allogeneic transplantation). The procedure involves first destroying the patient's existing bone marrow through chemotherapy or radiation, and then infusing the donor cells into the patient's bloodstream. The transplanted cells migrate to the patient's bone marrow and begin to produce healthy blood cells. Hematopoietic cell transplantation can be a potentially curative treatment for certain blood cancers and diseases, but it also carries risks of complications such as infection, organ damage, and graft-versus-host disease (in allogeneic transplantations). Advances in technology and research continue to improve the success and safety of hematopoietic cell transplantation.