References of "Experimental hematology"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailTelomere deregulations possess cytogenetic, phenotype, and prognostic specificities in acute leukemias.
CAPRARO, Valérie ULg; Zane, Linda; Poncet, Delphine et al

in Experimental Hematology (2011), 39(2), 195-2022

OBJECTIVE: Telomeres are protected by tightly regulated factors and elongated by telomerase. Short and/or deprotected chromosomes are recombinogenic and thereby cancer prone. MATERIALS AND METHODS ... [more ▼]

OBJECTIVE: Telomeres are protected by tightly regulated factors and elongated by telomerase. Short and/or deprotected chromosomes are recombinogenic and thereby cancer prone. MATERIALS AND METHODS: Together with the quantification of telomerase activity (TA), measuring telomere length (TL) and expression of the genes that govern telomere protection and elongation are useful for assessing telomere homeostasis. RESULTS: By these means we demonstrate that TL, hTERT, and TA are in the order acute myelogenous leukemia (AML) > T-cell acute lymphoblastic leukemia (T-ALL) > B-cell acute lymphoblastic leukemia (B-ALL) > T-ALL > AML, and B-ALL > AML > T-ALL. AML0 and AML3 display the lowest amounts of hTERT transcripts, and ALL and AML cells with cytogenetic abnormalities possess the shortest telomeres. hTERT expression includes phenotype-specific RNA maturation and correlates with TA but not with TL. A wide ratio of TA to hTERT expression between leukemia subtypes suggests phenotype-specific hTERT post-transcriptional deregulations. B- and T-ALL overexpress Ku70 and Pinx1, T-ALL PTOP and RAP1, and B-ALL TRF2, the expression of which is significantly higher in cases with abnormal karyotype. hTERT transcription and TL correlate with response to intensive chemotherapy, and hTERT and RAD50 are independent prognostic factors for survival. CONCLUSIONS: Each leukemia subtype possesses specific telomere dysregulations that rely on phenotype, karyotype, response to treatment, and survival. [less ▲]

Detailed reference viewed: 40 (9 ULg)
Full Text
Peer Reviewed
See detailInhibition of the Jagged-1/Notch pathway increases the hematopoiesis-supportive activity of mesenchymal stem cells
Briquet, Alexandra ULg; Dolhet, Marie; Beguin, Yves ULg et al

in Experimental Hematology (2009), 37(9), 77

Detailed reference viewed: 26 (10 ULg)
Full Text
Peer Reviewed
See detailThe hematopoiesis-supporting activity of mesenchymal stem cells increases with the number of passages
Briquet, Alexandra ULg; Beguin, Yves ULg; Gothot, André ULg

in Experimental Hematology (2007, September), 35(9, Suppl. 2), 125-125

Detailed reference viewed: 25 (11 ULg)
Full Text
Peer Reviewed
See detailValproic acid induces apoptosis in chronic lymphocytic leukemia cells through activation of the death receptor pathway and potentiates TRAIL response.
Lagneaux, Laurence; Gillet, Nicolas ULg; Stamatopoulos, Basile et al

in Experimental hematology (2007), 35(10), 1527-37

OBJECTIVE: Chronic lymphocytic leukemia (CLL) cells develop chemoresistance over time associated with defects in apoptosis pathway. Novel treatment strategies are required to overcome resistance of cells ... [more ▼]

OBJECTIVE: Chronic lymphocytic leukemia (CLL) cells develop chemoresistance over time associated with defects in apoptosis pathway. Novel treatment strategies are required to overcome resistance of cells to commonly used agents. The effects of valproic acid (VPA), an antiepileptic drug with histone deacetylase inhibitory activity, on mononuclear cells isolated from 40 CLL patients were evaluated. METHODS: CLL cells were treated with increasing doses of VPA (0.5, 1, 2, and 5 mM). The mode of cytotoxic drug action was determined by annexin binding, DNA fragmentation, and caspase activation. RESULTS: Exposure of CLL cells to VPA resulted in dose-dependent cytotoxicity and apoptosis in the 40 CLL patients. VPA treatment induced apoptotic changes in CLL cells including phosphatidylserine externalization and DNA fragmentation. The mean apoptotic rates were similar between IgV(H) mutated and unmutated patients, the latter presenting a more aggressive clinical course. VPA induced apoptosis via the extrinsic pathway involving engagement of the caspase-8-dependent cascade. Although CLL cells are commonly resistant to death receptor-induced apoptosis, VPA significantly increased sensitivity of leukemic cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and led to downregulation of c-FLIP (L) expression. VPA caused no potentialization of TRAIL-induced apoptosis on normal B cells. In addition, VPA overcame the prosurvival effects of bone marrow stromal cells. CONCLUSION: These findings point out that the combination of TRAIL and VPA, at clinically relevant concentration, may be valuable in the treatment of CLL. [less ▲]

Detailed reference viewed: 50 (4 ULg)
Full Text
Peer Reviewed
See detailPegfilgrastim compared with Filgrastim after autologous hematopoietic peripheral blood stem cell transplantation.
Vanstraelen, Gaetan; Frere, Pascale ULg; Ngirabacu, Marie-Christine et al

in Experimental hematology (2006), 34(3), 382-8

In order to assess the effect of Pegfilgrastim on the duration of neutropenia and clinical outcome of patients after autologous peripheral blood stem cell (PBSC) transplantation, we compared 20 ... [more ▼]

In order to assess the effect of Pegfilgrastim on the duration of neutropenia and clinical outcome of patients after autologous peripheral blood stem cell (PBSC) transplantation, we compared 20 consecutive patients with lymphoma or multiple myeloma receiving a single 6-mg dose of Pegfilgrastim on day 1 posttransplant to an historical control group of 60 patients receiving daily Filgrastim 5 microg/kg starting on day 1 posttransplant. The duration of neutropenia was similar in the Pegfilgrastim group compared with the control group. There were no differences in time to neutrophil, erythroid, or platelet engraftment nor in the incidence of fever and infections. The duration of antibiotic therapy, transfusion support, and time to hospital discharge were similar in the two groups. However, after initial hematopoietic reconstitution, we observed significantly higher values of lymphocytes (e.g., 1,660+/-1,000 versus 970+/-460 on day 80, p=0.0002), neutrophils (e.g., 3,880+/-2,030 versus 2,420+/-1,500 on day 25, p=0.0004), reticulocytes (e.g., 148,160+/-90,590 versus 87,140+/-65,920 on day 25, p<0.0001), and platelets (e.g., 210,700+/-116,090 versus 150,240+/-58,230 on day 55, p=0.0052) up to day 100 in the Pegfilgrastim group compared with the Filgrastim group. These observations had no impact on clinical outcome of the patients after day 30 due to the low incidence of infectious events after engraftment in autologous PBSC transplantation. We conclude that the effect of Pegfilgrastim administrated on day 1 posttransplant is comparable to that of daily Filgrastim on initial hematopoietic reconstitution. The possibly superior effect of Pegfilgrastim on cell counts we observed after initial engraftment should be further tested in a prospective randomized trial. [less ▲]

Detailed reference viewed: 32 (1 ULg)
Full Text
Peer Reviewed
See detailRecombinant human erythropoietin therapy after allogeneic hematopoietic cell transplantation with a nonmyeloablative conditioning regimen: low donor chimerism predicts for poor response.
Vanstraelen, Gaëtan; Baron, Frédéric ULg; Willems, Evelyne ULg et al

in Experimental hematology (2006), 34(7), 841-50

PURPOSE: After allogeneic hematopoietic stem cell transplantation with nonmyeloablative conditioning (NMHCT), many patients experience prolonged anemia and require red blood cell (RBC) transfusions. We ... [more ▼]

PURPOSE: After allogeneic hematopoietic stem cell transplantation with nonmyeloablative conditioning (NMHCT), many patients experience prolonged anemia and require red blood cell (RBC) transfusions. We enrolled 60 consecutive patients undergoing NMHCT in a phase II trial to determine the optimal utilization of recombinant human erythropoietin (rHuEPO) therapy in this setting. PATIENTS AND METHODS: The first 14 NMHCT recipients did not receive rHuEPO (control group). Nineteen patients were scheduled to start rHuEPO on day 0 (EPO group 2) and 27 patients on day 28 after the transplant (EPO group 1). RHuEPO was administered subcutaneously once weekly at a dose of 500 U/kg/wk with the aim of achieving hemoglobin (Hb) levels of 13 g/dL. The 3 groups were well balanced for major characteristics. RESULTS: During the first month (p < 0.0001) as well as days 30 to 100 (p < 0.0001) and days 100 to 180 (p < 0.0001), Hb values were higher in patients receiving rHuEPO compared to those not receiving it. However, transfusion requirements were significantly decreased only in the first month in EPO group 2 (p = 0.0169). T-cell chimerism above 60% on day 42 was the best predictor of Hb response (p < 0.0001) or Hb correction (p = 0.0217), but myeloid chimerism above 90% also predicted for Hb response (p = 0.0069). Hb response was also decreased in patients receiving CD8-depleted grafts and increased in the few patients not receiving TBI, but only in univariate analysis. CONCLUSIONS: Anemia after NMHCT is sensitive to rHuEPO therapy, but less so than after conventional allogeneic HCT. RHuEPO decreases transfusion requirements only in the first 30 days posttransplant. T-cell chimerism below 60% on day 42 impaired Hb response, suggesting possible inhibition of donor erythropoiesis by residual recipient lymphocytes. A prospective randomized trial should be performed with rHuEPO starting on the day of transplantation to assess its clinical benefit in terms of transfusion requirements and quality of life. [less ▲]

Detailed reference viewed: 53 (4 ULg)
Full Text
Peer Reviewed
See detailOptimization of recombinant human erythropoietin therapy after allogeneic hematopoietic stem cell transplantation.
Baron, Frédéric ULg; Sautois, Brieuc ULg; Baudoux, Etienne ULg et al

in Experimental hematology (2002), 30(6), 546-54

OBJECTIVE: Allogeneic hematopoietic stem cell transplantation (HSCT) is associated with prolonged anemia caused by defective erythropoietin (Epo) production. We enrolled 34 recipients of an allogeneic ... [more ▼]

OBJECTIVE: Allogeneic hematopoietic stem cell transplantation (HSCT) is associated with prolonged anemia caused by defective erythropoietin (Epo) production. We enrolled 34 recipients of an allogeneic HSCT in three consecutive trials to determine the optimal utilization of recombinant human erythropoietin (rhEpo) therapy in this setting. MATERIALS AND METHODS: In the first trial (n = 7), rhEpo 1400 U/kg/week was given from day 1 until a hemoglobin (Hb) level of 10 g/dL was achieved, for a maximum of 60 days. In the second trial, rhEpo 500 U/kg/week was given to achieve Hb levels of 13 to 14 g/dL in 13 anemic patients with fatigue 56 to 1440 days after transplant. In the third trial, rhEpo was scheduled to start on day 35 in 14 patients at a dose of 500 U/kg/week with the aim of achieving Hb levels of 13 to 14 g/dL. RESULTS: In trial 1, erythroid recovery to 1% reticulocytes and red blood cell transfusion independence were faster, but the number of transfusions was not reduced compared to 10 controls. Responses were brisk in trial 2, with transfusion independence achieved after a median of 1 week in 12 of 13 patients, and 2-g Hb increments or Hb values of 11, 12, and 13 g/dL after 6, 7, 10, and 10 weeks, respectively. Transfusions were significantly reduced in the first month of rhEpo therapy. In trial 3, transfusion independence was obtained after a median of 1 week in 13 of 14 patients, and 2-g Hb increments or Hb values of 11, 12, and 13 g/dL after 3, 4, 6, and 8 weeks, respectively. Transfusions rates were considerably reduced compared to the previous month in the same patients or compared to controls undergoing peripheral blood or marrow transplant without rhEpo. CONCLUSIONS: Anemia after allogeneic HSCT is exquisitely sensitive to rhEpo. The benefit is minimal when it is given early post-transplant, as used in all trials to date. However, the rate of major response is greater than 90% when rhEpo is started after day 35. These data provide the basis on which to conduct a prospective, randomized, placebo-controlled trial of rhEpo therapy after allogeneic HSCT. [less ▲]

Detailed reference viewed: 26 (2 ULg)
Full Text
Peer Reviewed
See detailGenesis of Clone Size Heterogeneity in Megakaryocytic and Other Hemopoietic Colonies: The Stochastic Model Revisited
Paulus, Jean-Michel ULg; Levin, J.; Debili, N. et al

in Experimental Hematology (2001), 29(11), 1256-69

OBJECTIVE: We previously showed that the distributions of the numbers of doublings (NbD) undergone by individual megakaryocyte progenitors before commitment to polyploidization are markedly skewed and can ... [more ▼]

OBJECTIVE: We previously showed that the distributions of the numbers of doublings (NbD) undergone by individual megakaryocyte progenitors before commitment to polyploidization are markedly skewed and can consistently be fitted to straight lines when plotted on semilogarithmic coordinates. The slope of such lines, which yields the probability of polyploidization per doubling, is made less steep by stimulators of megakaryocyte colony formation and is less steep in mixed erythroid-megakaryocyte than in pure megakaryocyte colonies. Therefore, megakaryocytopoiesis provides a unique model for the study of clonal heterogeneity in a hemopoietic lineage, which is the subject of this review. DATA SOURCES: Articles relevant to the interpretation of these data were selected from the authors' and public databases. DATA SYNTHESIS: Exponential NbD distributions were first explained by postulating that following the assembly of thrombopoiesis-specific regulators, megakaryocyte progenitors require only a single random event to arrest proliferation and commit to polyploidization. However, this stochastic model was refuted by data indicating that intrinsic properties of individual progenitors affect the NbD they achieve. We suggest that the unequal repartition of critical compounds (including receptors, signaling molecules, and gene regulators) inherent in the stem cell-progenitor transition causes a heritable heterogeneity in megakaryocyte progenitor responsiveness to polyploidization inducers. This model would be compatible with 1) the evidence for intraclonal synchronization in megakaryocyte and other hemopoietic clones generated by committed progenitors; 2) the low probability of polyploidization of the relatively insensitive bipotent megakaryocyte progenitors; and 3) the thesis that stimulators act in part by recruiting megakaryocyte progenitor cells endowed with lesser responsiveness to polyploidization inducers and higher proliferative potential. CONCLUSION: The responsiveness of individual megakaryocyte progenitors to polyploidization inducers may be a major determinant of the exponential shape of NbD distributions. [less ▲]

Detailed reference viewed: 17 (0 ULg)
Full Text
Peer Reviewed
See detailCell cycle activation of hematopoietic progenitor cells increases very late antigen-5-mediated adhesion to fibronectin.
Giet, Olivier ULg; Huygen, Sandra; Beguin, Yves ULg et al

in Experimental hematology (2001), 29(4), 515-24

Recent studies suggested that trafficking of hematopoietic progenitor cells is related to cell cycle status. We studied whether adhesion of progenitor cells to extracellular matrix proteins was modulated ... [more ▼]

Recent studies suggested that trafficking of hematopoietic progenitor cells is related to cell cycle status. We studied whether adhesion of progenitor cells to extracellular matrix proteins was modulated by cell cycle transit.Mobilized peripheral blood CD34+ cells were stimulated ex vivo for 48 hours with stem cell factor, flt-3 ligand, and thrombopoietin and fractionated by adhesion to fibronectin or vascular cell adhesion molecule-1 (VCAM-1). Adherent and nonadherent cells were assayed for cell cycle status, long-term culture-initiating cell frequency, and integrin function. Binding to fibronectin, but not to VCAM-1, displayed a cell cycle selectivity as the adherent fraction to fibronectin was enriched in cycling CD34+ cells and in cycling long-term culture-initiating cells compared to the nonadherent fraction. Combined cell cycle and phenotypic analysis showed that the expression of VLA-5 was upregulated during S/G2+M but that of VLA-4 remained constant. The selective binding of cycling CD34+ cells to fibronectin was reverted by anti-VLA-5 but not by anti-VLA-4 blocking antibodies. Also, cycling CD34+ cells preferentially adhered to the VLA-5 binding domain but not to the VLA-4 binding domain of fibronectin. Adhesion of cycling CD34+ cells to fibronectin was a reversible process modulated by cell cycle progression, because adherent cells could exit the cell cycle and return to a nonadhesive state within an additional 48-hour culture period.The results indicate that the enhanced binding capacity of cycling progenitor cells to fibronectin is mediated by VLA-5. [less ▲]

Detailed reference viewed: 31 (1 ULg)
Full Text
Peer Reviewed
See detailSerum soluble transferrin receptor concentration is an accurate estimate of the mass of tissue receptors.
R'Zik, Samir ULg; Beguin, Yves ULg

in Experimental hematology (2001), 29(6), 677-85

OBJECTIVE: Serum levels of the soluble transferrin receptor (sTfR) vary depending on the erythropoietic activity and iron status. In vitro, sTfR shed in the incubation medium correlates well with cellular ... [more ▼]

OBJECTIVE: Serum levels of the soluble transferrin receptor (sTfR) vary depending on the erythropoietic activity and iron status. In vitro, sTfR shed in the incubation medium correlates well with cellular TfR, but this relationship has never been established in vivo. To determine the value of serum sTfR as a quantitative marker of the body mass of tissue TfR, we designed experiments to examine the correlation between serum sTfR and tissue TfR in rats with various degrees of erythropoietic activity or iron status. MATERIALS AND METHODS: We studied changes in erythropoietic activity in normal rats as well as in animals experiencing hemolysis, phlebotomy-induced iron deficiency, transfusion- or thiamphenicol-induced erythroid aplasia, or inflammation. At the end of follow-up, ferrokinetic studies were performed and animals were sacrificed. Organs were isolated and homogenized to determine the total mass of tissue TfR from the sum of tissue solubilized TfR in the bone marrow, spleen, liver, and blood cells (direct method). An indirect method was developed to derive the corporeal mass of tissue TfR from a representative marrow sample. RESULTS: As expected, serum sTfR and total mass of tissue TfR varied as a function of iron status and erythropoiesis. Relative erythroid expansion in the spleen was greater than in the bone marrow. With the exception of phlebotomized animals, the indirect method correlated very well with direct measurements of the total mass of tissue TfR (r = 0.97, p < 0.0001). There was a close relationship between the total mass of tissue TfR and the total mass of serum sTfR (r = 0.79, p < 0.0001). Serum sTfR represented approximately 5-6% of the total mass of tissue TfR in most experimental situations, but this ratio was twice as high during iron-restricted erythropoiesis. In addition, the ratio could be higher or lower in nonsteady-state situations, because changes in tissue TfR occurred faster than those of serum sTfR. CONCLUSIONS: Serum sTfR represents a constant proportion of the total mass of tissue TfR over a wide range of erythropoietic activity. However, iron deficiency results in a higher proportion of serum sTfR, and the pace of change in serum sTfR levels is slower than that of tissue TfR mass. [less ▲]

Detailed reference viewed: 133 (7 ULg)
Full Text
Peer Reviewed
See detailAssessment of proliferative and colony-forming capacity after successive in vitro divisions of single human CD34+ cells initially isolated in G0.
GOTHOT, André ULg; Pyatt, R.; McMahel, J. et al

in Experimental hematology (1998), 26(7), 562-70

Exit of primitive hematopoietic progenitor cells (HPCs) from the G0 phase of the cell cycle in response to in vitro cytokine stimulation is a limiting step in successful ex vivo expansion. Simultaneous ... [more ▼]

Exit of primitive hematopoietic progenitor cells (HPCs) from the G0 phase of the cell cycle in response to in vitro cytokine stimulation is a limiting step in successful ex vivo expansion. Simultaneous DNA/RNA staining with Hoechst 33342 and pyronin Y was used to separate human bone marrow CD34+ cells residing in G0 (G0CD34+) from those cycling in G1 and S/G2+M. Compared with CD34+ cells isolated in G1, G0CD34+ cells were characterized by a delayed response to cytokine stimulation and were enriched for long-term hematopoietic culture-initiating cells. We next compared the activation kinetics of individually sorted G0CD34+ cells stimulated with stem cell factor (SCF), flt3-ligand (FL), or interleukin-3 (IL-3) as single factors. In a novel clonal proliferation assay, the functional status of cells that had remained quiescent after an initial 7-day period and of those that had completed successive division cycles under each of these three factors was evaluated by assessment of subsequent proliferative capacity and maintenance of colony-forming cell precursor (pre-CFC) activity. All three cytokines were equally able to support the survival of primitive HPCs in the absence of cell division. Cells that did not respond to any cytokine stimulation for 7 days retained higher proliferative and pre-CFC activities than dividing cells. The hematopoietic function of cells that divided in response to SCF, FL, or IL-3 decreased after each division cycle. However, G0CD34+ cells displayed a heterogeneous response pattern to cytokine stimulation whereby SCF appeared to have a superior ability to promote the cycling of cells with high proliferative and pre-CFC activities. These results indicate that HPCs reside in opposing hierarchies of hematopoietic potential and responsiveness to cytokine stimulation. The data also begin to indicate relationships between cellular division in response to different stimuli and maintenance of hematopoietic function. [less ▲]

Detailed reference viewed: 12 (0 ULg)
Full Text
Peer Reviewed
See detailComparative cytokine production by in vitro stimulated mononucleated cells from cord blood and adult blood.
Sautois, Brieuc ULg; Fillet, Georges ULg; Beguin, Yves ULg

in Experimental hematology (1997), 25(2), 103-8

Cord blood transplantations successfully reconstituted hemopoiesis in patients treated with myeloablative therapies. These transplantations were associated with a low rate of acute graft-versus-host ... [more ▼]

Cord blood transplantations successfully reconstituted hemopoiesis in patients treated with myeloablative therapies. These transplantations were associated with a low rate of acute graft-versus-host disease (aGVHD), a major life-threatening complication of allo-transplantation. The physiopathology of aGVHD implies the recognition of host alloantigens by donor T cells but also involves a cytokine cascade. In this cascade, interleukin (IL)-1, IL-2, IL-6, tumor necrosis factor alpha (TNF-alpha), and interferon gamma (IFN-gamma) produced by donor T cells and monocytes/macrophages play a major effector role. Therefore, we investigated whether the lower percentage of aGVHD in cord blood transplants could be related to a lower ability to produce these cytokines in vitro compared with adult blood. Mononucleated cells (MNCs) isolated from term cord blood and adult peripheral blood were stimulated with a combination of lipopolysaccharide and phytohemaglutinin and incubated for 96 hours. Levels of IL-1beta, IL-2, IL-3, IL-4, IL-6, TNF-alpha, IFN-gamma, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were measured in the supernatants after various times of incubation. The productions of IL-1beta, IL-6, and GM-CSF were similar in stimulated cord and adult blood and IL-3 levels, though lower and delayed in cord blood, were not statistically different. On the other hand, we found markedly lower levels of IFN-gamma, TNF-alpha, and IL-4 in cord blood throughout the incubation period. The stimulated levels of IL-2 were similar in cord and adult samples throughout the first 48 hours of incubation but became significantly lower in cord blood after 72 and 96 hours. We suggest that the cytokine production pattern that characterizes cord blood could provide an explanation for the lower occurence of aGVHD following cord blood transplants. [less ▲]

Detailed reference viewed: 68 (3 ULg)