Orderly process of sequential cytokine stimulation is required for activation and maximal proliferation of primitive human bone marrow CD34+ hematopoietic progenitor cells residing in G0.
; ; GOTHOT, André et al
in Blood (1997), 90(2), 658-68
Bone marrow (BM) CD34+ cells residing in the G0 phase of cell cycle may be the most suited candidates for the examination of cell cycle activation and proliferation of primitive hematopoietic progenitor ... [more ▼]
Bone marrow (BM) CD34+ cells residing in the G0 phase of cell cycle may be the most suited candidates for the examination of cell cycle activation and proliferation of primitive hematopoietic progenitor cells (HPCs). We designed a double simultaneous labeling technique using both DNA and RNA staining with Hoechst 33342 and Pyronin Y, respectively, to isolate CD34+ cells residing in G0(G0CD34+). Using long-term BM cultures and limiting dilution analysis, G0CD34+ cells were found to be enriched for primitive HPCs. In vitro proliferation of G0CD34+ cells in response to sequential cytokine stimulation was examined in a two-step assay. In the first step, cells received a primary stimulation consisting of either stem cell factor (SCF), Flt3-ligand (FL), interleukin-3 (IL-3), or IL-6 for 7 days. In the second step, cells from each group were washed and split into four or more groups, each of which was cultured again for another week with one of the four primary cytokines individually, or in combination. Tracking of progeny cells was accomplished by staining cells with PKH2 on day 0 and with PKH26 on day 7. Overall examination of proliferation patterns over 2 weeks showed that cells could progress into four phases of proliferation. Phase I contained cytokine nonresponsive cells that failed to proliferate. Phase II contained cells dividing up to three times within the first 7 days. Phases III and IV consisted of cells dividing up to five divisions and greater than six divisions, respectively, by the end of the 14-day period. Regardless of the cytokine used for primary stimulation, G0CD34+ cells moved only to phase II by day 7, whereas a substantial percentage of cells incubated with SCF or FL remained in phase I. Cells cultured in SCF or FL for the entire 14-day period did not progress beyond phase III but proliferated into phase IV (with <20% of cells remaining in phases I and II) if IL-3, but not IL-6, was substituted for either cytokine on day 7. G0CD34+ cells incubated with IL-3 for 14 days proliferated the most and progressed into phase IV; however, when SCF was substituted on day 7, cells failed to proliferate into phase IV. Most intriguing was a group of cells, many of which were CD34+, detected in cultures initially stimulated with IL-3, which remained as a distinct population, mostly in G0/G1, unable to progress out of phase II regardless of the nature of the second stimulus received on day 7. A small percentage of these cells expressed cyclin E, suggesting that their proliferation arrest may have been mediated by a cyclin-related disruption in cell cycle. These results suggest that a programmed response to sequential cytokine stimulation may be part of a control mechanism required for maintenance of proliferation of primitive HPCs and that unscheduled stimulation of CD34+ cells residing in G0 may result in disruption of cell-cycle regulation. [less ▲]Detailed reference viewed: 15 (1 ULg)
Functional heterogeneity of human CD34(+) cells isolated in subcompartments of the G0 /G1 phase of the cell cycle.
GOTHOT, André ; ; et al
in Blood (1997), 90(11), 4384-93
Using simultaneous Hoechst 33342 (Hst) and Pyronin Y (PY) staining for determination of DNA and RNA content, respectively, human CD34(+) cells were isolated in subcompartments of the G0 /G1 phase of the ... [more ▼]
Using simultaneous Hoechst 33342 (Hst) and Pyronin Y (PY) staining for determination of DNA and RNA content, respectively, human CD34(+) cells were isolated in subcompartments of the G0 /G1 phase of the cell cycle by flow cytometric cell sorting. In both bone marrow (BM) and mobilized peripheral blood (MPB) CD34(+) cells, primitive long-term hematopoietic culture-initiating cell (LTHC-IC) activity was higher in CD34(+) cells isolated in G0 (G0CD34(+) cells) than in those residing in G1 (G1CD34(+) cells). However, as MPB CD34(+) cells displayed a more homogeneous cell-cycle status within the G0 /G1 phase and a relative absence of cells in late G1 , DNA/RNA fractionation was less effective in segregating LTHC-IC in MPB than in BM. BM CD34(+) cells belonging to four subcompartments of increasing RNA content within the G0 /G1 phase were evaluated in functional assays. The persistence of CD34 expression in suspension culture was inversely correlated with the initial RNA content of test cells. Multipotential progenitors were present in G0 or early G1 subcompartments, while lineage-restricted granulomonocytic progenitors were more abundant in late G1 . In vitro hematopoiesis was maintained for up to 6 weeks with G0CD34(+) cells, whereas production of clonogenic progenitors was more limited in cultures initiated with G1CD34(+) cells. To test the hypothesis that primitive LTHC-ICs would reenter a state of relative quiescence after in vitro division, BM CD34(+) cells proliferating in ex vivo cultures were identified from their quiescent counterparts by a relative loss of membrane intercalating dye PKH2, and were further fractionated with Hst and PY. The same functional hierarchy was documented within the PKH2(dim) population whereby LTHC-IC frequency was higher for CD34(+) cells reselected in G0 after in vitro division than for CD34(+) cells reisolated in G1 or in S/G2 + M. However, the highest LTHC-IC frequency was found in quiescent PKH2(bright) CD34(+) cells. Together, these results support the concept that cells with distinct hematopoietic capabilities follow different pathways during the G0 /G1 phase of the cell cycle both in vivo and during ex vivo culture. [less ▲]Detailed reference viewed: 16 (10 ULg)
Defective iron supply for erythropoiesis and adequate endogenous erythropoietin production in the anemia associated with systemic-onset juvenile chronic arthritis.
; ; et al
in Blood (1996), 87(11), 4824-30
Systemic-onset juvenile chronic arthritis (SoJCA) is associated with high levels of circulating interleukin-6 (IL-6) and is frequently complicated by severe microcytic anemia whose pathogenesis is unclear ... [more ▼]
Systemic-onset juvenile chronic arthritis (SoJCA) is associated with high levels of circulating interleukin-6 (IL-6) and is frequently complicated by severe microcytic anemia whose pathogenesis is unclear. Therefore, we studied 20 consecutive SoJCA patients with hemoglobin (Hb) levels <12 g/dL, evaluating erythroid progenitor proliferation, endogenous erythropoietin production, body iron status, and iron supply for erythropoiesis. Hb concentrations ranged from 6.5 to 11.9 g/dL. Hb level was directly related to mean corpuscular volume (r = .82, P < .001) and inversely related to circulating transferrin receptor (r = -.81, P < .001) suggesting that the severity of anemia was directly proportional to the degree of iron-deficient erythropoiesis. Serum ferritin ranged from 18 to 1,660 microgram/L and was unrelated to Hb level. Bone marrow iron stores wore markedly reduced in the three children investigated, and they also showed increased serum transferrin receptor and normal-to-high serum ferritin. All 20 patients had elevated IL-6 levels and normal in vitro growth of erythroid progenitors. Endogenous erythropoietin (epo) production was appropriate for the degree of anemia as judged by both the observed to predicted log (serum epo) ratio 10.95 +/- 0.12) and a comparison of the serum epo-Hb regression found in these subjects with that of thalassemia patients. Multiple regression analysis showed that serum transferrin receptor was the parameter most closely related to hemoglobin concentration: variation in circulating transferrin receptor explained 61% of the variation in Hb level (P < .001). In 10 severely anemic patients, amelioration of anemia following intravenous iron administration resulted in normalization of serum transferrin receptor. Defective iron supply to the erythron rather than blunted epo production is the major cause of the microcytic anemia associated with SoJCA. A true body-iron deficiency caused by decreased iron absorption likely complicates long-lasting inflammation in the most anemic children, and this can be recognized by high serum transferrin receptor levels. Although oral iron is of no benefit, intravenous iron saccharate is a safe and effective means for improving iron availability for erythropoiesis and correcting this anemia. Thus, while chronically high endogenous IL-6 levels do not appear to blunt epo production, they are probably responsible for the observed abnormalities in iron metabolism. Anemia of chronic disease encompasses a variety of anemic conditions whose peculiar features may specifically correlate with the type of cytokine(s) predominantly released. [less ▲]Detailed reference viewed: 20 (1 ULg)
Prognostic Significance of bcl-2 Protein Expression in Aggressive Non-Hodkin's Lymphoma
; ; et al
in Blood (1996)Detailed reference viewed: 22 (3 ULg)
Early prediction of response to recombinant human erythropoietin in patients with the anemia of renal failure by serum transferrin receptor and fibrinogen.
Beguin, Yves ; ; R'Zik, Samir et al
in Blood (1993), 82(7), 2010-6
Recombinant human erythropoietin (rHuEpo) has been shown to be effective in correcting the anemia of chronic renal failure, but the dose needed may be variable. The reason for this variation is not known ... [more ▼]
Recombinant human erythropoietin (rHuEpo) has been shown to be effective in correcting the anemia of chronic renal failure, but the dose needed may be variable. The reason for this variation is not known, but several factors could be involved, such as iron deficiency, inflammation, aluminum intoxication, hyperparathyroidism, blood losses, or marrow dysfunction. Treatment with rHuEpo was given intravenously thrice weekly after hemodialysis to 64 consecutive unselected patients with the anemia of chronic renal failure. The starting dose was 50 U/kg/dose, which was increased to 75 and 100 U/kg/dose if no response was observed after 1 and 2 months of treatment. After a minimum follow-up of 6 months, response was evaluated as early (hematocrit [Hct] > or = 30% before 3 months) or late (Hct > or = 30% after 3 months) response, or failure (target Hct not attained). We examined the value of various laboratory parameters (baseline values and early changes) as predictors of response to rHuEpo. The best prediction by pretreatment parameters only was obtained with baseline serum transferrin receptor (TfR) (< or > or = 3,500 ng/mL) and fibrinogen (< or > or = 4 g/L): 100% response rate when both parameters were low, versus only 29% when they were both high, and versus 67% when one was low and the other high. When the 2-week TfR increment was greater than 20%, the response rate was 96%. When TfR increment was less than 20%, the response rate was 100% when baseline TfR and fibrinogen were low, 12% when fibrinogen was elevated, and 62% when fibrinogen was low but baseline TfR high. The predictive value of baseline TfR and fibrinogen and of the 2-week increment of TfR was confirmed by life table analysis and stepwise discriminant analysis. Major reasons for failure or late response were identified and included subclinical inflammation, iron deficiency, functional iron deficiency, marrow disorders, hemolysis, bleeding, and low Epo dose. We conclude that response to rHuEpo can be predicted early by pretreatment fibrinogen and TfR, together with early changes of TfR levels. These prognostic factors illustrate the importance of the early erythropoietic response, subclinical inflammation, and functional iron deficiency. Early recognition of a low probability of response in a given patient could help identify and correct specific causes of treatment failure to hasten clinical improvement and avoid prolonged ineffective use of an expensive medication. [less ▲]Detailed reference viewed: 19 (5 ULg)
Quantitative assessment of erythropoiesis and functional classification of anemia based on measurements of serum transferrin receptor and erythropoietin.
Beguin, Yves ; ; et al
in Blood (1993), 81(4), 1067-76
We evaluated the quantitative value of a simple model of erythropoiesis, based on the basic assumptions that the red blood cell (RBC) mass determines erythropoietin (Epo) production, which in turn ... [more ▼]
We evaluated the quantitative value of a simple model of erythropoiesis, based on the basic assumptions that the red blood cell (RBC) mass determines erythropoietin (Epo) production, which in turn stimulates erythropoietic activity. The RBC mass was quantitated by direct isotopic measurement (RCM), Epo production by serum Epo levels, and erythropoiesis by the ferrokinetic measurement of the erythron transferrin uptake (ETU), the serum transferrin receptor (TfR) level, and the reticulocyte (retic) index, and was completed by an evaluation of overall marrow erythron cellularity. We studied a total of 195 subjects, including 31 normal individuals, 38 patients with polycythemia, and 126 patients with various forms of anemia. Instead of only quantitating Epo and erythropoiesis in absolute terms, we also evaluated them in relation to the degree of anemia or polycythemia, and expressed the results as a ratio of observed values to values predicted from the regression equations between hematocrit (Hct) on the one hand, and Epo, TfR, and ETU on the other, obtained in a carefully selected subpopulation. The slope of the regression of TfR (as well as ETU) versus Hct was very similar to the slope of the regression of Epo versus Hct. Average EPO and TfR (as well as ETU) values predicted from the regression equations were quite comparable to observed values in most groups of subjects, with exceptions predictable from knowledge of the pathophysiology of these hematologic disorders. We identified four major patterns of erythropoiesis, ie, normal, hyperdestruction (with variants of hemolysis or ineffective erythropoiesis), intrinsic marrow hypoproliferation, and defective Epo production. Dissecting out groups of patients showed much greater heterogeneity than when patients were analyzed by group. This was particularly true in the case of a hypoproliferative component being combined with hyperdestruction, giving what we called a "mixed disorder of erythropoiesis." We conclude that the pathophysiology of anemia can be assessed by a simple measurement of Hct, retic index, Epo, and TfR levels, with Epo and TfR being more informative when expressed in relation to the degree of anemia. The model is particularly useful for detecting the presence of multiple mechanisms of anemia in the same patient. However, it has limitations inherent to the relative invalidity of TfR in iron deficiency, the imprecision of a retic count, and the difficulty in distinguishing hemolysis from ineffective erythropoiesis in some patients and in recognizing a component of hyperdestruction in hypoproliferative anemia. [less ▲]Detailed reference viewed: 34 (1 ULg)
Subcutaneous erythropoietin for treatment of refractory anemia in hematologic disorders. Results of a phase I/II clinical trial.
; ; Beguin, Yves et al
in Blood (1992), 79(1), 29-37
We have used recombinant human erythropoietin (rHuEPO) in a phase I/II clinical trial to evaluate its ability to reverse refractory anemia in hematologic disorders. rHuEPO was administered subcutaneously ... [more ▼]
We have used recombinant human erythropoietin (rHuEPO) in a phase I/II clinical trial to evaluate its ability to reverse refractory anemia in hematologic disorders. rHuEPO was administered subcutaneously 5 days per week at escalating doses (50 to 150 U/kg per day). The aim of treatment was a hemoglobin (Hb) level greater than or equal to 10 g/dL without blood transfusion. Of 25 patients treated, 17 were evaluable, most of them with a regular need for transfusion. Eight of these had lymphoproliferative disorders (three cases of malignant lymphoma and five of monoclonal gammopathy) and were exposed to cytotoxic therapy. The other nine patients had hematopoietic stem cell disorders (four cases of myelodysplastic syndrome, three of idiopathic myelofibrosis, and two of chronic myelogenous leukemia). All patients with lymphoproliferative disorder had serum EPO levels inappropriately low for the degree of anemia, while patients with stem cell disorder showed variable values. Erythroid marrow activity was inadequate in all cases. Seven of eight patients with lymphoproliferative disorder responded to treatment maintaining Hb above 10 g/dL without transfusion. The median dose of rHuEPO required for correction of anemia was 75 U/kg. In four cases response was maintained with 50 U/kg, three times per week. There was no complete response among patients with hematopoietic stem cell disorder, although transfusion requirement was eliminated or reduced in four cases. Four patients developed functional iron deficiency during rHuEPO treatment and required iron supplementation to obtain response. Aggravation of splenomegaly was observed in two cases of myeloproliferative disorder. We conclude that: (1) subcutaneous administration of rHuEPO can be effective and safe in patients with lymphoproliferative disorder exposed to chemotherapy and showing inappropriate EPO response to anemia; (2) this is less likely in hematopoietic stem cell disorders, although favorable responses may be observed in occasional patients; and (3) functional iron deficiency as a cause of nonresponse to rHuEPO is frequent also in nonrenal anemia. [less ▲]Detailed reference viewed: 21 (0 ULg)
Blunted erythropoietin production and decreased erythropoiesis in early pregnancy.
Beguin, Yves ; ; et al
in Blood (1991), 78(1), 89-93
After decreasing in the first trimester of pregnancy, the total red blood cell mass increases in the second and third trimesters to peak at term at about 120% to 125% of nonpregnant values, but how this ... [more ▼]
After decreasing in the first trimester of pregnancy, the total red blood cell mass increases in the second and third trimesters to peak at term at about 120% to 125% of nonpregnant values, but how this is brought about by changes in the rate of erythropoiesis is not known. We evaluated erythropoiesis by measuring serum transferrin receptor (TfR) levels in 406 women during normal pregnancy (N = 317), at delivery (N = 63), or in the early postpartum (N = 27). Despite the presence of the placenta and the frequent occurrence of iron deficiency, TfR levels remained low in the first two trimesters and increased in the third trimester and at delivery. To explain why erythropoiesic activity was relatively low in early pregnancy, we also measured serum immunoreactive erythropoietin (Epo) in relation to the degree of anemia. There was a very strong correlation between serum TfR and Epo levels in the entire group (r = .59, P less than .0001) as well as in each period of pregnancy. Epo levels remained low for the degree of anemia and did not correlate with hematocrit in the first two trimesters, but recovered afterwards. In the early postpartum, Epo production and erythropoiesis were normal. We conclude that: (1) erythropoiesis is decreased in the first part of pregnancy but increases afterwards; and (2) blunted Epo production in early pregnancy could be responsible for that observation. [less ▲]Detailed reference viewed: 22 (0 ULg)
Circulating erythropoietin levels after bone marrow transplantation: inappropriate response to anemia in allogeneic transplants.
Beguin, Yves ; ; Oris, Renée et al
in Blood (1991), 77(4), 868-73
We studied 24 recipients of autologous bone marrow transplantation (ABMT) or allogeneic BMT (BMT) to determine whether impaired erythropoietin (Epo) response to anemia could delay full erythropoietic ... [more ▼]
We studied 24 recipients of autologous bone marrow transplantation (ABMT) or allogeneic BMT (BMT) to determine whether impaired erythropoietin (Epo) response to anemia could delay full erythropoietic recovery. Observed Epo levels were compared with predicted levels based on the relationship between Epo and hematocrit in 125 control subjects. Circulating Epo levels were normal during conditioning and the early posttransplant period. Between days 21 and 180, Epo levels remained normal in ABMT patients but were inappropriately low for the degree of anemia in BMT patients. Median time to full erythropoietic engraftment was longer in BMT than in ABMT recipients. Circulating Epo returned to appropriate levels after day 180, except in patients with active cytomegalovirus infection. We conclude that impaired Epo response to anemia can contribute to delayed erythropoietic recovery after allogenic BMT. Renal toxicity of ciclosporin, interaction between host and donor marrow, and cytomegalovirus infection might play a role. This study could support the use of recombinant human Epo to accelerate erythropoietic engraftment after BMT. [less ▲]Detailed reference viewed: 17 (3 ULg)
Intact transferrin receptors in human plasma and their relation to erythropoiesis.
; Beguin, Yves ; et al
in Blood (1990), 75(1), 102-7
Intact transferrin receptor molecules complexed with transferrin were found in human plasma. The concentration of receptors was determined by an enzyme-linked immunosorbent assay that uses polyclonal ... [more ▼]
Intact transferrin receptor molecules complexed with transferrin were found in human plasma. The concentration of receptors was determined by an enzyme-linked immunosorbent assay that uses polyclonal antibodies. The mean concentration of 8,279 micrograms/L in 56 normal adults appears to be unrelated to age or sex. Additional receptor measurements were performed on plasmas from 260 subjects with erythropoietic disorders. Decreased concentration of plasma receptors was found in patients with erythroid hypoplasia and increased numbers in those with erythroid hyperplasia. Ferrokinetic measurements of erythropoiesis were compared with numbers of receptors in 148 subjects, and a close correlation was found (r = .86). Both sets of values, measured in different conditions and expressed in relation to normal, were consistent with expected values. Receptor values were unproportionally increased only in conditions of iron deficiency. It is concluded that plasma receptors have a constant relationship to tissue receptors, and their number in most instances reflects the rate of erythropoiesis. [less ▲]Detailed reference viewed: 15 (3 ULg)
Model of reticuloendothelial iron metabolism in humans: abnormal behavior in idiopathic hemochromatosis and in inflammation.
Fillet, Georges ; ; BEGUIN, Yves
in Blood (1989), 74(2), 844-51
Iron transport in the reticuloendothelial (RE) system plays a central role in iron metabolism, but its regulation has not been characterized physiologically in vivo in humans. In particular, why serum ... [more ▼]
Iron transport in the reticuloendothelial (RE) system plays a central role in iron metabolism, but its regulation has not been characterized physiologically in vivo in humans. In particular, why serum iron is elevated and RE cells are much less iron-loaded than parenchymal cells in idiopathic hemochromatosis is not known. The processing of erythrocyte iron by the RE system was studied after intravenous (IV) injection of 59Fe heat-damaged RBCs (HDRBCs) and 55Fe transferrin in normal subjects and in patients with iron deficiency, idiopathic hemochromatosis, inflammation, marrow aplasia, or hyperplastic erythropoiesis. Early release of 59Fe by the RE system was calculated from the plasma iron turnover and the 59Fe plasma reappearance curve. Late release was calculated from the ratio of 59Fe/55Fe RBC utilization in 2 weeks. The partitioning of iron between the early (release from heme catabolism) and late (release from RE stores) phases depended on the size of RE iron stores, as illustrated by the inverse relationship observed between early release and plasma ferritin (P less than .001). There was a strong correlation between early release and the rate of change of serum iron levels during the first three hours in normal subjects (r = .85, P less than .001). Inflammation produced a blockade of the early release phase, whereas in idiopathic hemochromatosis early release was considerably increased as compared with subjects with similar iron stores. Based on these results, we describe a model of RE iron metabolism in humans. We conclude that the RE system appears to determine the diurnal fluctuations in serum iron levels through variations in the immediate output of heme iron. In idiopathic hemochromatosis, a defect of the RE cell in withholding iron freed from hemoglobin could be responsible for the high serum iron levels and low RE iron stores. [less ▲]Detailed reference viewed: 44 (3 ULg)
Some properties of marrow derived adherent cells in tissue culture.
; Foidart, Jean-Michel
in Blood (1980), 56(6), 1006-12
It has previously been shown that monolayer cultures derived adherent cells (MDAC), apparently consisting of fibroblasts, macrophages, epithelioid cells, and fat cells, can support long-term stem cell ... [more ▼]
It has previously been shown that monolayer cultures derived adherent cells (MDAC), apparently consisting of fibroblasts, macrophages, epithelioid cells, and fat cells, can support long-term stem cell proliferation in vitro. In the present study, the hematopoietic support capability of murine MDAC monolayers was confirmed and the cultured cells further characterized with respect to the following properties: esterase I activity, complement (C3) receptors, IgG (Fc) receptors, colony stimulating activity (csa) production, and collagen synthesis. The cultures were also examined immunohistochemically to localize fibronectin, laminin, and collagen synthesis and to identify the collagen subtypes synthesized. MDAC morphology was as described in previous studies, although fat cells were few in number. It was found that MDAC included some cells with esterase I activity and C3 receptors. Fc receptors were not, however, detected, nor did the cultures produce csa, indicating that mononuclear phagocytes were not present. MDAC synthesized collagen types I and III and also fibronectin. Staining for epithelial basement membrane proteins (collagen types IV and V and laminin) was negative. The results indicate that the vast majority of these cultured MDAC were fibroblasts. [less ▲]Detailed reference viewed: 1 (0 ULg)