Individuals who suffer from bone or blood diseases that don't respond to other treatments may be candidates for a bone marrow transplant. In this procedure, healthy bone marrow stem cells from a donor are placed into the bones of the recipient, where they begin to manufacture healthy blood cells to circulate into the recipient's bloodstream.
Biology
Bone marrow is the soft, spongy tissue inside bones. The bone marrow makes stem cells that can produce all of the different types of blood cells in the body, including red blood cells, the white blood cells of the immune system and the platelets that help blood clot. Since stem cells are so versatile, defects in blood cells can be corrected by replacing these stem cells inside the bone marrow.
Reasons
Bone marrow transplants are sometimes necessary as a treatment for blood cancers such as leukemia, lymphoma, and multiple myeloma. Diseases that involve malformed or insufficient blood cell production, such as sickle cell anemia and thalassemia, may also be treated with a bone marrow transplant. In cancer patients, a transplant is sometimes necessary when bone marrow has been destroyed through chemotherapy or other treatments.
Types
The three types of bone marrow transplants are defined by the source of the stem cells. In an autologous bone marrow transplant, the stem cells are taken from the patient's own bone marrow to be later replaced after the patient undergoes chemotherapy or other damaging treatments. In an allogeneic bone marrow transplant, the source of the stem cells is another person. In an umbilical cord transplant, the stem cells are collected from the umbilical cord of a newborn baby and donated to the person who needs the transplant.
Donation
If the stem cells to be transplanted come from a donor, the person must first be screened to ensure his blood antigens sufficiently match those of the recipient's body so that the recipient won't reject the new marrow. The closest match comes from identical twins, but other close family members are also likely to have compatible marrow. For individuals who have no relatives with matching bone marrow, a national registry of people willing to donate marrow may provide a match. Donated marrow is removed from the bone of the hip.
Procedure
In order to perform a bone marrow transplant, the patient's original bone marrow must first be removed or destroyed through chemotherapy or radiation before attempting transplantation of new bone marrow. The bone marrow is given to the patient through an IV line, not a surgery. The infused bone marrow stem cells travel to the patient's bones and establish themselves there. If the transplant is a success, the new marrow will begin producing healthy blood cells.
