Experimental hematology
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Experimental hematology · May 2013
Diverse mechanisms of mTOR activation in chronic and blastic phase of chronic myelogenous leukemia.
Chronic myelogenous leukemia (CML) is a stem cell disorder, and leukemia stem cells (LSCs) can contribute to the relapse of the disease. Quiescent LSCs are BCR-ABL independent and resistant to imatinib; therefore, there is an unmet need to identify new therapeutic targets in LSCs. ⋯ Rapamycin effectively inhibits mTOR in all phases of CML, but does not reduce number of LSC-enriched CD34(+) blast crisis (BC) cells, neither alone nor in combination with imatinib in CML-BC cells. These results show that potential therapeutic benefits of mTOR inhibition may be the result of effects on differentiated leukemic cells and may be potentially achieved only in the chronic phase of the disease.
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Experimental hematology · Feb 2013
Multicenter Study Clinical TrialRituximab, fludarabine, and total body irradiation as conditioning regimen before allogeneic hematopoietic stem cell transplantation for advanced chronic lymphocytic leukemia: long-term prospective multicenter study.
To evaluate the efficacy and toxicity of reduced-intensity conditioning (RIC) combining fludarabine, low-dose total body irradiation (TBI) and rituximab before allogeneic hematopoietic stem cell transplantation (allo-HSCT) from human leucocyte antigen (HLA) identical siblings, we conducted a prospective study in patients ≤65 years old with advanced chronic lymphocytic leukemia (CLL) stage B or C in response after a salvage treatment. Conditioning included rituximab (375 mg/m² on day 5), fludarabine (30 mg/m² from day 4 to day 2), TBI (2 Gy on day 0), and rituximab (500 mg/m² on days 1 and 8). Forty patients were included, 34 (85%) were male with a median age of 54 years (range, 35-65 years), 38 (95%) were in B stage, and 2 were in stage C; only 7 patients (17%) were in complete response. ⋯ The median overall survival was not reached with 5-years probability of 55% (41-74). The multivariate analysis showed a positive effect of rituximab on overall survival and event-free survival (hazard ratio [HR] = 0.1 [0-0.6], p = 0.02; and HR = 0.1 [0-0.4], p = 0.035, respectively). The association of fludarabine, TBI, and rituximab is feasible, well tolerated, and allows better outcomes in advanced CLL.
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Experimental hematology · Nov 2010
HoxA cluster is haploinsufficient for activity of hematopoietic stem and progenitor cells.
Functional compensation between homeodomain proteins has hindered the ability to unravel their role in hematopoiesis using single gene knockouts. Because HoxB genes are dispensable for hematopoiesis, and most HoxA genes are expressed an order of magnitude higher than other cluster genes in hematopoietic stem cell (HSC)-enriched populations, we hypothesize that maintenance of HoxA cluster expression is important for adult hematopoiesis and that global decrease of HoxA gene expression levels affects steady-state hematopoiesis. ⋯ These results show for the first time that maintenance of adult HSCs and progenitors is particularly sensitive to HoxA gene levels, suggesting a specific role for the HoxA cluster in primary regulation of definitive hematopoiesis.
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Experimental hematology · Dec 2009
Mesenchymal stem cell-educated macrophages: a novel type of alternatively activated macrophages.
Mesenchymal stem cells (MSCs) are capable of modulating the immune system through interaction with a wide range of immune cells. This study investigates the hypothesis that interaction of MSCs with macrophages could play a significant role in their antiinflammatory/immune modulatory effects. ⋯ We describe a novel type of human macrophage generated in vitro after coculture with MSCs that assumes an immunophenotype defined as IL-10-high, IL-12-low, IL-6-high, and TNF-alpha-low secreting cells. These MSC-educated macrophages may be a unique and novel type of alternatively activated macrophage with a potentially significant role in tissue repair.
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Experimental hematology · Jan 2009
Podocalyxin selectively marks erythroid-committed progenitors during anemic stress but is dispensable for efficient recovery.
Podocalyxin expression on Ter119(+) erythroblasts is induced following administration of erythropoietin (Epo) or phenylhydrazine treatment, but is notably absent on committed erythroid progenitors during homeostatic red cell turnover. Following high-dose Epo administration in vivo, podocalyxin surface expression is upregulated, in part, via a signal transducers and activators of transcription 5-dependent pathway and this expression has been postulated to play a role in the release of reticulocytes from hematopoietic organs into the periphery under conditions of increased erythropoietic rate. Here we have thoroughly addressed this hypothesis and further examined the expression profile of podocalyxin during Epo-induced erythroblast expansion and stress erythropoiesis. ⋯ We demonstrate that podocalyxin is a highly specific marker of stress-induced blast-forming unit erythroid and colony-forming unit erythroid progenitors in mouse bone marrow and spleen. In addition, our findings suggest that podocalyxin is not necessary for efficient erythroblast expansion, erythroid differentiation, or reticulocyte release in response to Epo stimulation in vivo.