Experimental hematology
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Experimental hematology · May 2004
Human CD34(+) and CD34(+)CD38(-) hematopoietic progenitors in sickle cell disease differ phenotypically and functionally from normal and suggest distinct subpopulations that generate F cells.
Sickle cell disease (SCD) is remarkable for stress erythropoiesis. We investigated the progenitor populations contributing to erythroid stress. ⋯ Stress erythropoiesis in SCD has been postulated to accelerate erythropoiesis and production of F cells. Thus, CD34(+)CD38(-) expressing GlyA may represent the "stress progenitor" population. This is the first study characterizing CD34(+) and CD34(+)CD38(-) hematopoietic progenitor cells in sickle bone marrow, comparing them to sickle peripheral blood and normal bone marrow and using them to generate sickle red blood cells that recapitulate F cell production observed in vivo. We identified a unique population of GlyA(+)CD34(+) cells in SCD, which is in an accelerated erythroid differentiation pathway, has not down-regulated CD34 antigen expression, and predominantly generates F cells.
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Experimental hematology · Jan 2003
Comparative StudyLong-term marrow reconstitutive ability of autologous grafts in lymphoma patients using peripheral blood mobilized with granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor compared to bone marrow.
The aim of this study was designed to compare the in vivo long-term hematopoietic potential of bone marrow and peripheral blood grafts. ⋯ Marrow progenitor cell counts were decreased for several years with both bone marrow and peripheral blood grafts. They were not different according to the origin of the graft, despite the reduced duration of peripheral blood cell recovery observed after PBPCT. Granulocyte colony-stimulating factor (G-CSF) used for PB graft mobilization and after transplantation resulted in faster neutrophil recovery compared to granulocyte-macrophage colony-stimulating factor (GM-CSF) with no evidence of decreased marrow progenitor cell recoveries. On the other hand, postgraft administration of GM-CSF enhanced long-term colony-forming unit granulocyte-macrophage reconstitution only after BMT. Factors that influenced marrow progenitor cell reconstitution have been identified by univariate and multivariate analysis: age, gender, type of lymphoma, and postgraft administration of hematopoietic growth factors (HGF) for the whole patient group; gender, graft progenitor cell yields, and type of HGF (G-CSF vs GM-CSF) for the PBPCT group; and only type of HGF for the BMT group. Despite faster peripheral blood cell recovery, persistent deficiency of marrow progenitor cells was found several years after PBPCT, as observed after BMT. G-CSF-mobilized PBPCT resulted in faster neutrophil recovery compared to GM-CSF mobilization, with no difference in long-term hematopoietic reconstitution.
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Experimental hematology · Jul 2002
Comparative StudyIn vitro studies of the combination of imatinib mesylate (Gleevec) and arsenic trioxide (Trisenox) in chronic myelogenous leukemia.
The aim of this study was the preclinical evaluation of imatinib mesylate (Gleevec, formerly STI571) in conjunction with arsenic trioxide (As2O3, Trisenox) for the treatment of chronic myelogenous leukemia (CML). ⋯ Favorable cytotoxicity and proapoptotic activity of imatinib in conjunction with As2O3 and specific down-regulation of Bcr-Abl protein levels by As2O3 in K562 cells indicate that As2O3 in combination with imatinib might be useful for circumventing resistance to imatinib monotherapy.
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Experimental hematology · Jun 2002
Ex vivo expanded cord blood cells provide rapid engraftment in fetal sheep but lack long-term engrafting potential.
Cord blood (CB) products are becoming routinely used in unrelated allogeneic transplantation for smaller pediatric patients. Because of the low numbers of cells in CB compared to bone marrow or peripheral blood progenitor cells, their use is more limited in larger adults. Therefore, we developed ex vivo expansion conditions for CB and currently are transplanting ex vivo expanded CB products to patients receiving high-dose chemotherapy. As there is concern that ex vivo expansion may exhaust long-term engrafting cells, the current clinical protocols consist of both an expanded fraction and an unexpanded fraction. To determine the effect of expansion culture on long-term engrafting cells, we evaluated the short- and long-term engrafting potential of ex vivo expanded CB using a fetal sheep xenogeneic transplant model. ⋯ Ex vivo expansion of CB CD34(+) cells under the conditions described results in the generation of increased mature cells and progenitors that are capable of more rapid engraftment in fetal sheep compared to unexpanded CB CD34(+) cells. The expanded cells engrafted primary sheep but lacked secondary and tertiary engrafting potential. These studies demonstrate that although ex vivo expanded cells may be able to provide rapid short-term engraftment, the long-term potential of expanded grafts may be compromised. Therefore, clinical protocols may require transplantation of two fractions of cells, an expanded CB graft to provide rapid short-term engraftment and an unmanipulated fraction of CB graft to provide stem cells for long-term engraftment.
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Experimental hematology · Dec 2001
CD34(+) cell subsets and long-term culture colony-forming cells evaluated on both autologous and normal bone marrow stroma predict long-term hematopoietic engraftment in patients undergoing autologous peripheral blood stem cell transplantation.
The aim of this study was to evaluate which CD34(+) cell subset contained in leukapheresis products could be regarded as the most predictive of long-term hematopoietic recovery after autologous peripheral blood stem cell transplantation (auto-PBSCT). ⋯ These data further support the hypothesis that the type of stromal feeders influences the frequency of LTC-CFC, possibly because they differ in their ability to interact with distinct subsets of hematopoietic stem cells. Furthermore, as the use of AS in LTC assay can mimic in vitro the human bone marrow microenvironment, it can be speculated that this culture system could be a useful means to study the kinetics of recovery of bone marrow stroma following chemotherapy and PBSCT. From these results, it can be concluded that some CD34(+) cell subsets appear to be more reliable predictors of long-term hematopoietic recovery rates than total CD34(+) cell quantity.