scholarly journals Influence of hydroxyurea on fetal hemoglobin production in vitro

Blood ◽  
1987 ◽  
Vol 70 (6) ◽  
pp. 1824-1829 ◽  
Author(s):  
BA Miller ◽  
O Platt ◽  
S Hope ◽  
G Dover ◽  
DG Nathan
Keyword(s):  
Sickle Cell ◽  
Peripheral Blood ◽  
Fetal Hemoglobin ◽  
Erythroid Cells ◽  
Hemoglobin Content ◽  
Hemoglobin F ◽  
Hydroxyurea Treatment ◽  
Hemoglobin Production

Cytotoxic drugs increase circulating fetal hemoglobin levels. We examined the mechanism by measuring the fetal hemoglobin produced per BFU-E-derived erythroblast following hydroxyurea treatment in vivo and in vitro. Treatment of four sickle cell patients increased the percentage of circulating F reticulocytes. The frequencies of bone marrow or peripheral blood BFU-E or CFU-E-derived colonies and their fetal hemoglobin content were unaffected. In all cases, the number of erythroid cells/progenitor-derived colony increased. To explore further the effect of hydroxyurea on fetal hemoglobin production, we added 50 mumol/L hydroxyurea to cultures of peripheral blood BFU-E-derived erythroblasts on 1 of 9 days (day 5 through 13) to nine samples. These BFU-E were derived from the peripheral blood of normal donors, sickle trait donors, and sickle cell anemia patients and from the bone marrows of monkeys. This concentration of hydroxyurea was selected so that the frequency of BFU-E and their size was moderately decreased. Addition of hydroxyurea to these progenitor-derived erythroid cells had no effect on fetal hemoglobin content per cell. Neither did transient exposure of progenitors to hydroxyurea prior to culture in nontoxic concentrations (0 to 500 mumol/L) result in a significant increase in fetal hemoglobin content in progenitor-derived erythroblasts. These data suggest that hydroxyurea does not directly alter the HbF program expressed by progenitor-derived erythroid cells. Instead, it enhances hemoglobin F content secondarily, possibly by inducing alterations in erythropoiesis.

scholarly journals Influence of hydroxyurea on fetal hemoglobin production in vitro

Blood ◽  
1987 ◽  
Vol 70 (6) ◽  
pp. 1824-1829 ◽  
Author(s):  
BA Miller ◽  
O Platt ◽  
S Hope ◽  
G Dover ◽  
DG Nathan
Keyword(s):  
Sickle Cell ◽  
Peripheral Blood ◽  
Fetal Hemoglobin ◽  
Erythroid Cells ◽  
Hemoglobin Content ◽  
Hemoglobin F ◽  
Hydroxyurea Treatment ◽  
Hemoglobin Production

Abstract Cytotoxic drugs increase circulating fetal hemoglobin levels. We examined the mechanism by measuring the fetal hemoglobin produced per BFU-E-derived erythroblast following hydroxyurea treatment in vivo and in vitro. Treatment of four sickle cell patients increased the percentage of circulating F reticulocytes. The frequencies of bone marrow or peripheral blood BFU-E or CFU-E-derived colonies and their fetal hemoglobin content were unaffected. In all cases, the number of erythroid cells/progenitor-derived colony increased. To explore further the effect of hydroxyurea on fetal hemoglobin production, we added 50 mumol/L hydroxyurea to cultures of peripheral blood BFU-E-derived erythroblasts on 1 of 9 days (day 5 through 13) to nine samples. These BFU-E were derived from the peripheral blood of normal donors, sickle trait donors, and sickle cell anemia patients and from the bone marrows of monkeys. This concentration of hydroxyurea was selected so that the frequency of BFU-E and their size was moderately decreased. Addition of hydroxyurea to these progenitor-derived erythroid cells had no effect on fetal hemoglobin content per cell. Neither did transient exposure of progenitors to hydroxyurea prior to culture in nontoxic concentrations (0 to 500 mumol/L) result in a significant increase in fetal hemoglobin content in progenitor-derived erythroblasts. These data suggest that hydroxyurea does not directly alter the HbF program expressed by progenitor-derived erythroid cells. Instead, it enhances hemoglobin F content secondarily, possibly by inducing alterations in erythropoiesis.

scholarly journals Truncated Erythropoietin Receptors Confer an In Vivo Selective Advantage in Gene-Modified Erythroid Cells Expressing Fetal Hemoglobin Due to BCL11A Interference

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2063-2063
Author(s):  
Naoya Uchida ◽  
Claire Drysdale ◽  
Morgan Yapundich ◽  
Jackson Gamer ◽  
Tina Nassehi ◽  
...  
Keyword(s):  
Rhesus Macaques ◽  
Fetal Hemoglobin ◽  
Selective Advantage ◽  
Erythroid Cells ◽  
Post Transplant ◽  
Human Cd34 ◽  
Cd34 Cells ◽  
Hbf Induction

Hematopoietic stem cell gene therapy for hemoglobin disorders, such as sickle cell disease, requires high-level gene marking and robust therapeutic globin expression in erythroid cells (>20% of γ- or β-globin production) for widespread successful clinical application. We previously demonstrated that lentiviral transduction of a truncated human erythropoietin receptor (thEpoR) gene allows for erythropoietin-dependent selective proliferation of gene-modified human erythroid cells during in vitro differentiation (ASH 2017). In this study, we sought to evaluate whether thEpoR can enhance the phenotypic effect of a therapeutic vector in erythroid cells in xenograft mouse and autologous non-human primate transplantation models. To investigate this hypothesis, we designed lentiviral vectors encoding both thEpoR and BCL11A-targeting micro RNA-adapted short hairpin RNA (shmiBCL11A), driven off an erythroid specific ankyrin 1 (ANK1) promoter. Both selective proliferation and high-level fetal hemoglobin (HbF) induction were observed in in vitro erythroid differentiation cultures using transduced human CD34+ cells. Healthy donor CD34+ cells were transduced with shmiBCL11A vector, thEpoR-shmiBCL11A vector, and GFP vector (control). Transduced cells were transplanted into immunodeficient NBSGW mice. Five months post-transplant, xenograft bone marrow cells were evaluated for human cell engraftment (human CD45+) and vector copy number (VCN) in both human CD34+ progenitor cells and glycophorin A+ (GPA+) erythroid cells. HbF production was also measured in GPA+ erythroid cells by reverse phase HPLC. We observed efficient transduction in transduced CD34+ cells in vitro (VCN 2.1-5.1) and similar human cell engraftment among all groups (84-89%). The VCN with thEpoR-shmiBCL11A transduction was 3-fold higher in human erythroid cells when compared to CD34+ cells (p<0.01), but not with shmiBCL11A or GFP vectors. HbF levels were significantly elevated in thEpoR-shmiBCL11A vector (43±6%, p<0.01) when compared to no transduction control (1±0%), but not for either shmiBCL11A vector (3±1%) or GFP vector (1±0%). These data demonstrate selective proliferation of gene-modified erythroid cells, as well as enhanced HbF induction with thEpoR-shmiBCL11A transduction. We then performed autologous rhesus CD34+ cell transplantation using either shmiBCL11A vector (142562 and RA0706, n=2, compared to a GPA promoter-derived shmiBCL11A vector) or thEpoR-shmiBCL11A vector (ZL50 and ZM24, n=2, compared to a Venus-encoding vector). Transduced CD34+ cells were transplanted into autologous rhesus macaques following 2x5Gy total body irradiation. Efficient transduction was observed in CD34+ cells in vitro among all 4 macaques (VCN 3.8-8.7) using a high-density culture protocol (Uchida N, Mol Ther Methods Clin Dev. 2019). In shmiBCL11A transduction animals, engraftment of gene-modified cells (VCN 0.2-1.0) and robust HbF induction (14-16%) were observed 1 month post-transplant. However, VCN and HbF levels were reduced down to VCN ~0.1 and HbF ~0.4% in both animals 6 months post-transplant. In contrast, a thEpoR-shmiBCL11A transduction animal (ZL50) resulted in engraftment of gene-modified cells (VCN 0.8-1.0) and robust HbF induction (~18%) 1 month post-transplant, with both gene marking and HbF levels remaining high at VCN 0.6-0.7 and HbF ~15% 4 months post-transplant. These data suggest that shmiBCL11A transduction results in transient HbF induction in gene-modified erythroid cells, while thEpoR-based selective advantage allows for sustained HbF induction with shmiBCL11A. In summary, we developed erythroid-specific thEpoR-shmiBCL11A expressing vectors, enhancing HbF induction in gene-modified erythroid cells in xenograft mice and rhesus macaques. While further in vivo studies are desirable, the use of thEpoR appears to provide a selective advantage for gene-modified erythroid cells in gene therapy strategies for hemoglobin disorders. Disclosures No relevant conflicts of interest to declare.

scholarly journals Reticulocyte Survival in Sickle Cell Anemia: Effect of Cyanate

Blood ◽  
1972 ◽  
Vol 40 (5) ◽  
pp. 733-739 ◽  
Author(s):  
Blanche P. Alter ◽  
Yuet Wai Kan ◽  
David G. Nathan
Keyword(s):  
Cell Survival ◽  
Sickle Cell ◽  
Fetal Hemoglobin ◽  
Red Cells ◽  
Red Cell ◽  
Hemoglobin Molecule ◽  
Red Cell Survival ◽  
And Control

Abstract Cyanate prevents sickling in vitro and apparently prolongs the survival of 51Cr-tagged sickle erythrocytes in vivo. Cautious interpretation is required because the effects of cyanate on 51Cr binding to sickle and fetal hemoglobin-containing red cells are unknown, and comparison of the effect of cyanate on sickle red cell survival to control red cell survival must be performed sequentially. We have studied the survival of sickle reticulocytes utilizing radioactive amino acids that are incorporated into hemoglobin. Two informed adult patients with sickle cell disease were studied. In each study, two 50-ml samples of blood were incubated separately with 14C- and 3H-leucine for 2 hr, after which 50 mM cyanate was added to one aliquot for 1 hr. The cells were then washed and reinfused. Frequent venous samples were obtained, and the specific activities of 14C and 3H in the hemoglobin were followed. The t ½ of the carbamylated cells was tripled, but remained below normal. This method provides a generally useful measurement of the influence of drugs bound to red cells on reticulocyte lifespan. The labels are incorporated into the hemoglobin molecule of the reticulocyte, and simultaneous comparison of the survivals of the same cohort of drug-treated and control cells is achieved.

scholarly journals Relationship of erythropoietin, fetal hemoglobin, and hydroxyurea treatment to tricuspid regurgitation velocity in children with sickle cell disease

Blood ◽  
2009 ◽  
Vol 114 (21) ◽  
pp. 4639-4644 ◽  
Author(s):  
Victor R. Gordeuk ◽  
Andrew Campbell ◽  
Sohail Rana ◽  
Mehdi Nouraie ◽  
Xiaomei Niu ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Tricuspid Regurgitation ◽  
Fetal Hemoglobin ◽  
Hemoglobin Concentration ◽  
Systolic Pulmonary Artery Pressure ◽  
Cell Disease ◽  
Hemoglobin F ◽  
Hydroxyurea Treatment ◽  
Relationship Of

AbstractHydroxyurea and higher hemoglobin F improve the clinical course and survival in sickle cell disease, but their roles in protecting from pulmonary hypertension are not clear. We studied 399 children and adolescents with sickle cell disease at steady state; 38% were being treated with hydroxyurea. Patients on hydroxyurea had higher hemoglobin concentration and lower values for a hemolytic component derived from 4 markers of hemolysis (P ≤ .002) but no difference in tricuspid regurgitation velocity compared with those not receiving hydroxyurea; they also had higher hemoglobin F (P < .001) and erythropoietin (P = .012) levels. Hemoglobin F correlated positively with erythropoietin even after adjustment for hemoglobin concentration (P < .001). Greater hemoglobin F and erythropoietin each independently predicted higher regurgitation velocity in addition to the hemolytic component (P ≤ .023). In conclusion, increase in hemoglobin F in sickle cell disease may be associated with relatively lower tissue oxygen delivery as reflected in higher erythropoietin concentration. Greater levels of erythropoietin or hemoglobin F were independently associated with higher tricuspid regurgitation velocity after adjustment for degree of hemolysis, suggesting an independent relationship of hypoxia with higher systolic pulmonary artery pressure. The hemolysis-lowering and hemoglobin F–augmenting effects of hydroxyurea may exert countervailing influences on pulmonary blood pressure in sickle cell disease.

Induction of Fetal Hemoglobin by Inactivation of HDAC1 or HDAC2 without Altering Cellular Proliferation

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 354-354
Author(s):  
Erica B. Esrick ◽  
Jian Xu ◽  
Katherine Lin ◽  
Marie Ellen McConkey ◽  
Alyse Frisbee ◽  
...  
Keyword(s):  
Hdac Inhibitor ◽  
Cell Cycle Progression ◽  
Hdac Inhibitors ◽  
Fetal Hemoglobin ◽  
Fold Increase ◽  
Globin Mrna ◽  
Gamma Globin ◽  
Hydroxyurea Treatment

Abstract Abstract 354 Histone deacetylase (HDAC) inhibitors are effective inducers of fetal hemoglobin, and prior studies have shown that selective inactivation of HDAC1 or HDAC2 is sufficient to induce fetal hemoglobin in vitro. In our current work, we demonstrate that HDAC1 and HDAC2 are attractive targets for clinical translation for two reasons: 1) Selective inhibition will decrease off-target effects that currently limit the use of hydroxyurea and pan-HDAC inhibitors, and 2) HDAC inhibitors induce fetal hemoglobin in various preclinical models, and they can be combined with hydroxyurea to achieve further fetal hemoglobin induction. To investigate off-target effects, we selectively inactivated HDAC1, HDAC2 or HDAC3 in human erythroid progenitor cells, and examined the effect of each knockdown on cellular cytotoxicity and cell cycle progression. Although knockdown of HDAC3 negatively influenced growth, selective knockdown of HDAC1 or HDAC2 had no effect on expansion of erythroid progenitors. In addition, knockdown of HDAC2 does not block cell cycle progression. These data support the possibility that an HDAC1- or HDAC2-specific inhibitor may offer a therapeutic advantage by reducing side effects, while maintaining robust HbF induction. Armed with this knockdown data, we are now investigating HDAC inhibitor compounds of various selectivity in in vitro and in vivo models. To perform optimal clinical trials, and ultimately to benefit the most sickle cell disease patients, it would be ideal to combine HDAC inhibitor treatment with hydroxyurea. A combination treatment approach may ameliorate some of the limitations of hydroxyurea use, such as the unpredictable effect on fetal hemoglobin levels, and the lack of benefit in beta thalassemia patients. First, we combined HDAC2 inactivation with hydroxyurea treatment in vitro. Human bone marrow-derived CD34+ cells were infected with lentiviruses containing an shRNA targeting either HDAC2 or a luciferase control gene. The cells were then treated on day 4 of erythroid differentiation with hydroxyurea (10–20 uM dose). Compared to the untreated luciferase control samples, we observed a 7–9-fold increase in gamma-globin expression in the untreated HDAC2-knockdown samples, a 2.5-fold increase in the hydroxyurea-treated luciferase control samples, and a trend toward an additive effect on gamma-globin induction in the cells where HDAC2 knockdown was combined with hydroxyurea treatment. To investigate the effects of HDAC inhibitors in vivo, we administered compounds to BCL11A conditional knockout transgenic mice (by erythroid-selective EpoR-GFP Cre) containing the human beta-globin locus. As reported previously, BCL11A inactivation powerfully de-repressed gamma-globin expression, and administration of an HDAC inhibitor, SAHA, led to a further elevation of gamma-globin mRNA. We now demonstrate that administration of another pan-HDAC inhibitor, panobinostat (LBH589), results in an additional 1.5- to 2.5-fold increase in gamma-globin mRNA relative to pre-treatment baseline. We are currently evaluating the combination of panobinostat and hydroxyurea in these mice to confirm that the compounds have an additive effect in vivo as well as in vitro. Taken together, these experiments indicate that inhibiting HDAC1 or HDAC2 is a promising therapeutic approach to increasing fetal hemoglobin levels in patients with beta-hemoglobinopathies, both alone and in combination with hydroxyurea. Disclosures: Bradner: Acetylon: .

scholarly journals Abnormal Cytokine Production By Mast Cell Cultures from Sickle Cell Anemia Patients in Response to Inflammatory Stimuli and to Co-Culture with Eosinophils

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3566-3566
Author(s):  
Myriam Salazar-Terreros ◽  
Kleber Yotsumoto Fertrin ◽  
Nicolas Moreno Reyes ◽  
Fernando Ferreira Costa ◽  
Carla F. Franco-Penteado
Keyword(s):  
Mast Cell ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Peripheral Blood ◽  
Cytokine Production ◽  
Fold Increase ◽  
Individual Response ◽  
Activated State

Mast cell function (MC) in pathologic states can be studied through their ability to secrete mediators in vitro depending on MC phenotype and the nature of the stimuli. Reports on MC mediators in sickle cell anemia (SCA) patients are scarce, but clinical signs of MC activation syndrome, such as increased plasma histamine in vaso‐occlusive crisis (VOC), and normal or slightly elevated serum tryptase have been reported. However, assessing the biological relevance of MC as a cytokine source is more challenging because it is unclear under which circumstances they secrete those products in vivo, or if the cytokines measured systemically stem from a different cell type. We aimed to investigate the profile of mediators involved in the inflammatory process produced by MC in SCA. Methods:The supernatant of 5-week old MC cultures (17 SCA, 8 HV) obtained from peripheral blood CD34+ cells from 29 SCA patients and 13 healthy volunteers (HV) was analyzed using a multiplex platform and colorimetric assays for endothelin-1 (ET-1) and substance P (SP) (10 SCA, 6 HV). A correlation matrix (Pearson correlations, R software, v. 3.6.1) was generated using laboratory and clinical data chosen based on their value as inflammatory or prognosis markers (hydroxyurea [HU] treatment, fetal hemoglobin [HbF], hemoglobin [Hb], vaso-occlusive crisis [VOC], percentage of peripheral blood neutrophils, eosinophils (Eos), basophils, erythroblasts, and reticulocytes), MC surface expression of CD117, CD48 and CD63, and the supernatant content of 11 cytokines. To investigate MC cytokine release, we tested the supernatants from Eos-MC co-cultures (3:1 ratio), and after stimulation with ET-1 (20 nM), SP (10 µM) and imatinib (20 µg/ml)(n=3 per treatment). Results: Out of 26 cytokines, we found elevated levels of the following in the supernatants of SCA-MC cultures (data represented as mean in pg/ml±SE): TNFα: SCA=88.7±18.4, HV=32.6±3.8; IFNγ: SCA=55.3±11.2, HV=15.7±1.8; MCP1: SCA=555.0±147.2, HV=145.3±35.2; RANTES: SCA=24.7±3.9, HV=10.7±1.8 (p&lt;0.05). However, SCA-MC from patients treated with HU (n = 11) showed higher values of IL-1b, IL-4, IL-5, IL-9, IL-15, and FGF than HV (n=8) and HU-free patients (n=6) (p&lt;0.05). Supernatants from SCA-MC had higher ET-1 production compared to HV-MC (SCA=16.3±1.2, HV=11.93±1.3, pg/ml, p=0.02) but SP production was similar (SCA=27.9±1.3; HV=31.49±0.7 pg/ml). ET-1 stimulation of MC cultures caused 2-fold increase in IL-1AR production on HV-MC, but failed to produce any effect on SCA-MC. Similarly, imatinib reduced FGF only in HV-MC samples (HV: 15.1±3.5, HV-HU: 4.0±1.6, pg/ml). No effect on cytokine production was observed with SP. Conversely, Eos-MC cocultures showed a 10- and 4-fold increase of IL-5 and IL-9, respectively, regardless of the origin of Eos (HV or SCA). SCA-MC/SCA-Eos co-cultures had elevated proinflammatory (IL-1b, IL-12, TNF-α) and angiogenic (FGF, VEGF) cytokines, RANTES, IL-7, IL-4, and IL1-RA compared with SCA-MC/HV-Eos and HV-MC/HV-Eos (p&lt;0.05). Preliminary multiparametric analysis on data from SCA patients showed a strong negative correlation between HU therapy and VGEF production, and between HbF levels and CD63 expression (MC activation marker).We also found a positive correlation between history of VOC and eotaxin-1 produced by SCA-MC. Conclusions: We found that MC responses depend both on the origin of the cultured cell and the stimuli utilized. Despite differences between in vitro and in vivo MC populations, our data show that cultured SCA-MC have a sustained activated state and produce a repertoire of mediators that could contribute to a perivascular microenvironment in favor of leukocyte and endothelium activation. In terms of cytokine production, cultured SCA-MC were more sensitive to stimulation by SCA-Eos than by HV-Eos, which may be relevant to the pathophysiology of airway inflammation in SCA patients with asthma. Differences in cytokine production between SCA-MC cultures from patients treated or not with HU may reflect the variability in adherence to treatment, individual response to each compound, or epigenetic modifications during the MC differentiation process that affect the phenotype of the mature MC. These results support that mediators produced by MC can contribute to the chronic inflammatory state and may be implicated in exacerbated responses to eosinophil activation in SCA. Disclosures Fertrin: Agios Pharmaceuticals, Inc.: Research Funding.

The In Vitro and In Vivo Antioxidant Effects of Erythropoietin in Thalassemia.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 573-573 ◽  
Author(s):  
Eitan Fibach ◽  
Johnny Amer
Keyword(s):  
Oxidative Stress ◽  
Fetal Hemoglobin ◽  
Membrane Lipid ◽  
Beta Thalassemia ◽  
Dialysis Patients ◽  
Erythroid Progenitors ◽  
High Exposure ◽  
Hemoglobin Production

Abstract Erythropoietin (EPO), a hormone produced on hypoxia mainly in the kidneys, enhances red blood cell (RBC) production (erythropoiesis) by stimulating the proliferation of erythroid progenitors and precursors in the bone marrow. This effect is mediated by the homodimeric EPO receptor, a class 1 cytokine receptor. Recombinant human EPO is widely used for the treatment of anemia, e.g., in patients on dialysis, patients with myelodysplastic syndrome and oncology patients undergoing chemotherapy. Treatment with EPO was also tried experimentally in patients with thalassemia. In these patients, in spite the state of chronic anemia, the levels of EPO is usually low relative to the degree of anemia. Administration of EPO to thalassemic patients have been shown to increase erythropoiesis and in some cases to elevate fetal hemoglobin production. In addition, EPO has been suggested to have cardio- and neuro-protecting effects and to increase RBC survival in dialysis patients. We have previously shown that RBC and platelets derived from patients with beta-thalassemia and sickle cell disease are under oxidative stress; they have elevated potential to generate reactive oxygen species (ROS) and membrane lipid peroxides, and have lower content of reduced glutathione (GSH) than normal RBC. This oxidative stress resulted in high exposure of phosphatidylserine (PS) that is considered a major factor in shortening the life span of thalassemic RBC, and in the tendency of platelets to undergo activation and thus contributes to the high incidence of thromboembolic complications in thalassemia. In the present study, we investigated the in vitro and in vivo effects of EPO as an antioxidant on RBC and platelets from beta-thalassemic patients and mice. Using flow-cytometry methodology, we showed that in vitro treatment of blood cells from beta-thalassemic patients with 1–4 U/ml of EPO for 2 hours increased the GSH content of RBC (2.1-fold) and platelets (1.7-fold) and reduced their ROS (1.5-fold), membrane lipid peroxidation and externalization of PS. Intraperitoneal injection of EPO to heterozygotes (Hbbth3/+) beta-thalassemic mice (3,000U/kg) significantly reduced ROS and increased GSH in their RBC within 3 hours. The in vitro effects of EPO on oxidative stress resulted in reduced sensitivity of thalassemic RBC to undergo hemolysis and phagocytosis by macrophages, and reduced tendency of platelets to undergo activation, as reflected by fewer platelets carrying external PS. Our results suggest that in addition to its effect on erythropoiesis and fetal hemoglobin production, EPO might alleviate symptoms in thalassemia and other hemolytic anemias as a potent antioxidant.

Fetal Hemoglobin and F-Cell Responses to Long-Term Hydroxyurea Treatment in Young Sickle Cell Patients

Blood ◽  
1998 ◽  
Vol 91 (12) ◽  
pp. 4472-4479
Author(s):  
Micheline Maier-Redelsperger ◽  
Mariane de Montalembert ◽  
Antoine Flahault ◽  
Maria Grazia Neonato ◽  
Rolande Ducrocq ◽  
...  
Keyword(s):  
Sickle Cell ◽  
Young Patients ◽  
Fetal Hemoglobin ◽  
Maximal Response ◽  
Hemoglobin F ◽  
Hydroxyurea Treatment ◽  
F Cells ◽  
Group 2 ◽  
Group 1

We have studied the cellular and molecular responses to long-term hydroxyurea (HU) treatment in 29 severely affected young patients with sickle cell disease (mean age, 10.9 ± 4.1 years). Patients received HU at 20 mg/kg/d on 4 consecutive days per week initially, with a monthly escalated dose avoiding marrow-toxicity (mean steady-state dose, 34.2 ± 4.6 mg/kg/d) for 12 to 36 months (mean duration, 22 months). The studied parameters were hemoglobin F (HbF), F reticulocytes (F retics), F cells, the amount of HbF per F cell (F/F cell), polymer tendency at 40% and 70% oxygen saturation, and hemolysis. Initial HbF (Fi) was dispersed (from 0.85% to 13.9%). HbF increased in all patients but 1. HbF at maximal response (Fmax) reached a sustained level varying from a 1.5-fold to a 16-fold Fi after a variable delay (6 to 24 months). Fmax was not related to HU dosage, but ▵F (Fmax − Fi) was strongly correlated to ▵MCV (MCVmax − MCVi). HbF increase resulted from the increase of both F cells and F/F cell. In this rather short series, Fi and Fmax were not significantly associated with age, gender, or β-globin haplotype. Neither Fmax nor ▵F was related to bone marrow reserve, as measured by baseline reticulocyte or neutrophil counts. However, Fmax was highly dependent on Fi. When patients are individualized into three groups according to Fmax (group 1, Fmax >20% [12 patients]; group 2, 10% < Fmax < 20% [11 patients]; group 3, Fmax <10% [5 patients]), Fi is significantly different between groups, being the highest in group 1. In addition, the best responders (group 1) were significantly different from patients in the two other groups with higher levels of total hemoglobin, decreased bilirubin, and decreased polymer tendency.

Fetal Hemoglobin and F-Cell Responses to Long-Term Hydroxyurea Treatment in Young Sickle Cell Patients

Blood ◽  
1998 ◽  
Vol 91 (12) ◽  
pp. 4472-4479 ◽  
Author(s):  
Micheline Maier-Redelsperger ◽  
Mariane de Montalembert ◽  
Antoine Flahault ◽  
Maria Grazia Neonato ◽  
Rolande Ducrocq ◽  
...  
Keyword(s):  
Sickle Cell ◽  
Young Patients ◽  
Fetal Hemoglobin ◽  
Maximal Response ◽  
Hemoglobin F ◽  
Hydroxyurea Treatment ◽  
F Cells ◽  
Group 2 ◽  
Group 1

Abstract We have studied the cellular and molecular responses to long-term hydroxyurea (HU) treatment in 29 severely affected young patients with sickle cell disease (mean age, 10.9 ± 4.1 years). Patients received HU at 20 mg/kg/d on 4 consecutive days per week initially, with a monthly escalated dose avoiding marrow-toxicity (mean steady-state dose, 34.2 ± 4.6 mg/kg/d) for 12 to 36 months (mean duration, 22 months). The studied parameters were hemoglobin F (HbF), F reticulocytes (F retics), F cells, the amount of HbF per F cell (F/F cell), polymer tendency at 40% and 70% oxygen saturation, and hemolysis. Initial HbF (Fi) was dispersed (from 0.85% to 13.9%). HbF increased in all patients but 1. HbF at maximal response (Fmax) reached a sustained level varying from a 1.5-fold to a 16-fold Fi after a variable delay (6 to 24 months). Fmax was not related to HU dosage, but ▵F (Fmax − Fi) was strongly correlated to ▵MCV (MCVmax − MCVi). HbF increase resulted from the increase of both F cells and F/F cell. In this rather short series, Fi and Fmax were not significantly associated with age, gender, or β-globin haplotype. Neither Fmax nor ▵F was related to bone marrow reserve, as measured by baseline reticulocyte or neutrophil counts. However, Fmax was highly dependent on Fi. When patients are individualized into three groups according to Fmax (group 1, Fmax &gt;20% [12 patients]; group 2, 10% &lt; Fmax &lt; 20% [11 patients]; group 3, Fmax &lt;10% [5 patients]), Fi is significantly different between groups, being the highest in group 1. In addition, the best responders (group 1) were significantly different from patients in the two other groups with higher levels of total hemoglobin, decreased bilirubin, and decreased polymer tendency.

scholarly journals Expression of embryonic globins by erythroid cells in juvenile chronic myelocytic leukemia

Blood ◽  
1991 ◽  
Vol 77 (12) ◽  
pp. 2569-2576 ◽  
Author(s):  
T Papayannopoulou ◽  
B Nakamoto ◽  
NP Anagnou ◽  
D Chui ◽  
L Dow ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Fetal Hemoglobin ◽  
Colony Growth ◽  
Leukemic Cells ◽  
Chronic Myelocytic Leukemia ◽  
Erythroid Cells ◽  
Myelocytic Leukemia ◽  
Synthetic Profile

Abstract Juvenile chronic myelocytic leukemia (JCML) is a rare hematopoietic neoplasia of early childhood with distinct hematologic and biochemical features. We studied the biologic properties and the globin synthetic profiles of JCML erythroid cells both in vivo and in vitro from a total of 24 patients. In these cases we observed the exuberant colony-forming unit-macrophage (CFU-M) colony growth, as reported previously. Furthermore, in contrast to previous reports, we found significant erythroid colony growth in most of our cases (average: 1,182 burst- forming unit-erythroid [BFUe] per 10(5) plated cells, range: 40 to 6,927). This growth was by and large erythropoietin-dependent and was not greatly influenced by other added cytokines. By several criteria all erythroid colony growth detected in vitro was derived from JCML progenitors. The globin synthetic profile of JCML erythroid cells showed high levels of fetal hemoglobin both in vivo and in vitro (gamma/gamma + beta: 53% to 94% in reticulocytes, 62% to 98% in BFUe- derived cells). In addition (in seven cases studied) we detected embryonic globins (epsilon and zeta) at the protein and messenger RNA level, a novel finding for primary leukemic cells. We speculate that the transformed erythroid cells in JCML harbor a trans environment supporting expression of developmentally earlier genes (fetal, embryonic). However, in contrast to other acute or subacute leukemias, JCML erythroid cells also have the ability to reach full maturation to the red cell level, thus allowing detection of this primitive program in vivo.

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