Bone Marrow Transplant
Unlike solid organ transplants, the bone marrow transplant or BMT (sometimes called stem cell transplantation) procedure is relatively simple. Diagnostic tests are performed to confirm that the patient is medically eligible for BMT. Bone marrow or peripheral blood is collected via a needle inserted into the pelvic bone or a blood vessel, respectively.
Allogenic Bone Marrow Transplant:
An allogeneic donor is one other than the patient. Allogeneic transplants have the lowest risk of tumor relapse because of the GVL effect. However, GVHD (where the new transplanted immune system sees the patient as foreign), graft failure, and immune deficiency are potential problems. Allogeneic donors are chosen based on a blood test for human leukocyte antigens (HLA). HLA antigens are part of the biological process that allows each individual’s immune cells to differentiate between itself and the cells of other people or foreign organisms.
Autologous Bone Marrow Transplant:
The patient's own marrow or peripheral blood is used. Like syngeneic transplants, there is no risk of rejection or GVHD, and the GVL effect is absent. There is the additional concern of tumor contamination of the transplant. This may be a relatively minor concern for certain solid tumors but is a major problem for all blood cancers and some solid tumors.
Haploidentical Bone Marrow Transplant:
Many patients in need of a transplant will not have a matched family member or unrelated donor. A protocol has shown that half-identical, or haploidentical, related donors can be performed with similar outcomes to that seen with matched transplants. All parents and children, and about half of siblings, are half-matches. The ability to perform haploidentical transplants has revolutionized bone marrow transplant, so that almost everyone now needing a transplant can get one.
Syngeneic Bone Marrow Transplant:
The donor is an identical twin of the patient. This is the simplest source of stem cells. Syngeneic transplants are the least complicated transplants because there is no risk of rejection, graft-versus-host disease (GVHD), or tumor in the marrow. Blood cell recovery and return of immune system functioning is prompt. The only disadvantage of Syngeneic transplants is the lack of the graft versus leukemia (GVL) effect of allogeneic transplants that helps reduce tumor relapse.