How to harvest bone marrow for transplantation

Introduction Over the past decade bone marrow transplantation (BMT) has graduated from being an experimental treatment to having an established role in the first line management of patients with life threatening haematological disorders. The therapeutic principle involved is that the administration of myelotoxic treatment (preparative protocol), at doses beyond the threshold normally set to guarantee haematological recovery, will be effective in eradicating the abnormal pathology in the patient. A second requirement is that, where an allogeneic donor is the source of marrow, the preparative protocol will immunosuppress the host sufficiently to ensure that the marrow will successfully graft. There are preclinical data,' and some circumstantial evidence in man to suggest that the mechanisms by which the underlying disease in the host is eliminated, may not be solely due to the intensity of the preparative protocol but augmented by an immunologically mediated effect from the donated marrow, referred to as the "allogeneic effect".2 3 There are now several conditions to which bone marrow transplantation has been successfully applied (table). The bulk of this experience has been of transplantation from an HLA matched, mixed lymphocytic culture (MLC), non-reactive sibling donor. The capacity of this form of treatment to eradicate the underlying disease more effectively than conventional approaches is clear and has encouraged investigators to explore means by which transplantation can be made available to those who lack a suitable matched sibling. This has led to the use of the patients' own marrow collected earlier when in remission and, following storage, used as the source of haematological rescue to support high dose treatment (autologous BMT). More recently the organisation of registries of sufficient size has permitted a more systematic approach to using HLA phenotypically matched but unrelated donors as a source of stem cells.