Granulocyte-colony stimulating factor primed bone marrow and granulocyte-colony stimulating factor mobilized...

The first reported bone marrow transplant was published in 1939, although it was deemed unsuccessful. Between 1957 and 1965, numerous reports of bone marrow transplants, many of which were successful, were published for patients with irradiation injury, aplastic anemia, leukemia, lymphoma, and myeloma. Sources of marrow were autologous, isologous, and homologous (often unrelated, including cadaveric) donors. Bone marrow infusion was shown to be safe. It was also demonstrated that an aliquot of marrow, removed (harvested) from the ileum, had sufficient hematopoietic stem cells (SC) to repopulate the marrow and restore blood counts after myeloablation. For about 20 yr, bone marrow was the only source of hematopoietic stem cells (HSC) for transplantation. The first reported autologous peripheral blood HSC transplant was recorded in 1981 using chemotherapy 'mobilized' SC collected by leukapheresis. Mobilization is defined for these purposes to be any treatment that enhances the number of HSC in the blood such that the collection contains sufficient HSC to repopulate the marrow and restore blood counts after myeloablation. Since the early 1990s, SCT using blood-derived stem cells has become very popular and very common. The principal reason is that mobilized (whether by H growth factor or during recovery after chemotherapy) blood-derived stem cells engraft more rapidly than do marrow-derived stem cells. On the one hand, bone marrow was always harvested in the resting, unperturbed state (steady state). On the other hand, blood stem cells (BSC) were virtually always collected after mobilization, usually with granulocyte-colony stimulating factor (G-CSF). There is one report of collection of steady state BSC used for transplantation, and slow engraftment was documented. Bone marrow was never harvested after either chemotherapy or growth factor (priming). It is the mobilization (most often with G-CSF alone or after chemotherapy) of BSC that produces more rapid engraftment than for steady state marrow stem cells (MSC). This contribution shows the data that changes the old paradigm to a new paradigm which states bone MSC and BSC engraft identically if collected after the same pretreatment of the donor with growth factor.