What's Involved in a Bone Marrow Transplant
Bone marrow transplantation (hematopoietic stem cell transplantation) involves the infusion of hematopoietic stem cells into a patient after receiving high-dose chemotherapy (usually marrow-ablative) to re-establish normal blood cell production and immune function. 1
Core Components of the Transplant Process
Pre-Transplant Phase: Conditioning Regimen
- Most patients receive chemotherapy, serotherapy, and/or radiation therapy before the actual stem cell infusion to prepare the body for transplantation 1
- In allogeneic transplants, the conditioning regimen eradicates malignant cells in the bone marrow (if using myeloablative regimen) and induces immunosuppression to allow donor cell engraftment 1
- In autologous transplants, high-dose myeloablative chemotherapy treats the underlying malignancy, followed by rescue infusion of the patient's own previously harvested cells to restore blood cell production 1
Stem Cell Source Selection
The hematopoietic stem cells can be obtained from three sources 1:
- Peripheral blood stem cells (most common): Harvested after mobilization with growth factors (G-CSF or GM-CSF), avoiding general anesthesia and providing faster engraftment 1
- Bone marrow: Collected via aspiration under general anesthesia, preferred for certain conditions like severe aplastic anemia due to lower graft-versus-host disease (GVHD) risk 1
- Umbilical cord blood: Used primarily for pediatric allogeneic transplants, allows greater histoincompatibility tolerance 1
Transplant Type Classification
Allogeneic Transplantation (donor cells from another person):
- Requires HLA-matched donor, ideally an HLA-identical twin or matched sibling for best outcomes 1
- Alternative donors include matched unrelated donors (found through registries like the National Marrow Donor Program) or mismatched family members 1
- Most effective for severe aplastic anemia and offers the only curative therapy for chronic myelogenous leukemia 1
- Most commonly used for acute myeloid leukemia, acute lymphocytic leukemia, and myelodysplastic syndromes 1
Autologous Transplantation (patient's own cells):
- Preferred when patients require high-dose chemotherapy but have healthy, undiseased bone marrow 1
- Most frequently used for multiple myeloma, non-Hodgkin's lymphoma, and Hodgkin's disease 1
- Does not carry risk of chronic GVHD 1
Post-Transplant Management and Complications
Immunosuppression for Allogeneic Recipients:
- Cyclosporine or tacrolimus (FK506) is administered in combination with other immunosuppressive agents (methotrexate or corticosteroids) to prevent GVHD 1
- T-lymphocyte depletion techniques reduce GVHD but increase risks of graft rejection, CMV infection, invasive fungal infection, and EBV-associated lymphoproliferative disease 1
Key Risk Factors:
- Recipients of allogeneic grafts from non-HLA-matched siblings face substantially greater risk for GVHD, suboptimal graft function, and delayed immune recovery 1
- Allogeneic peripheral blood transplants carry increased GVHD risk compared to bone marrow grafts 1
Critical Pitfalls to Avoid
- Never use stem cell-toxic drugs (nitrosoureas, alkylating agents, especially melphalan) in potential transplant candidates before stem cell collection, as they damage the stem cell reserve 2
- Collect sufficient stem cells before starting treatment to allow for multiple transplants if needed, as long-term therapy may limit future collection 2
- For multiple sclerosis patients, autologous transplantation is not suitable for patients over 55 years old, with disease duration exceeding 20 years, or without focal inflammation 2
Outcomes and Success Factors
Transplant outcomes vary based on 1:
- Type and stage of disease being treated
- Overall health and age of the patient
- Degree of HLA-mismatch between donor and recipient (for allogeneic transplants)
- Source of hematopoietic cells used