Haemopoietic stem cell transplantation

Haemopoietic stem cells (HSCs) give rise to the blood cell lineages and the cells of the immune system, and their transplantation may be an appropriate part of the management of conditions including (1) malignant haematological disorders (e.g. leukaemia, lymphoma, myeloma); (2) bone marrow failure syndromes (e.g. aplastic anaemia); and (3) congenital disorders—(a) haematological (e.g. Fanconi’s anaemia); (b) immunological—inherited immunodeficiency syndromes; and (c) metabolic (e.g. lysosomal storage diseases). Transplantation of HSCs uses either autologous HSCs (patient’s own stem cells) or allogeneic HSCs (harvested from an appropriately matched sibling or unrelated healthy donor). Successful engraftment of allogeneic HSCs depends upon (1) overcoming immune rejection by the recipient; (2) preventing or suppressing graft-versus-host disease (GVHD), in which donor cells mount an immune attack against recipient tissues; and (3) supporting the patient through periods of profound cytopenias and immune deficiency with susceptibility to infection. Identification and sources of HSCs—HSCs are principally identified by expression of the surface antigen CD34. Sources include (1) bone marrow; (2) peripheral blood—following stimulation by cytokines (e.g. granulocyte colony-stimulating factor); and (3) umbilical cord blood.