Bone marrow transplant

Bone marrow transplant - The technique of using normal red bone marrow to replace cancerous or defective marrow in a patient. In allogeneic bone marrow transplantation (BMT), healthy bone marrow is taken from a donor who has a very similar tissue-type to the recipient’s (usually a brother or sister).

In autologous BMT, the patient’s own healthy bone marrow is harvested while his or her disease is in remission and is reinfused later. BMT is used only in the treatment of serious, mostly potentially fatal, blood and immune system disorders, including severe aplastic anaemia (see anaemia, aplastic), sickle cell anaemia,
and leukaemia.

An alternative treatment is stem-cell transplantation, in which cells from the umbilical cord of a newborn baby or bloodstream of an adult are used instead of bone marrow.

Before transplantation, all of the recipient’s marrow is destroyed by cytotoxic drugs or radiation in order to prevent rejection of the donated cells and to kill any cancer cells present. The donor bone marrow is transfused into the circulation from where cells find their way to the bone marrow cavities and start to
grow.

In autologous BMT, the patient’s bone marrow is stored by cryopreservation. Before being frozen, the marrow is usually treated to eliminate any undetected cancerous cells. If the patient’s disease recurs, the stored marrow can then be reinfused.

The major risks with BMT are infection during the recovery period and rejection (known as graft-versus-host disease, or GVHD). Immunosuppressant drugs are used to prevent and treat rejection.

The risk of GVHD may be reduced by removing the T-cells from the bone marrow using monoclonal antibodies (see antibody, monoclonal) before reinfusion. GVHD does not occur with allogeneic BMT or stem-cell transplantation.