Alain Francina

Red blood cell generation from human induced pluripotent stem cells: perspectives for transfusion medicine

Background Ex vivo manufacture of red blood cells from stem cells is a potential means to ensure an adequate and safe supply of blood cell products. Advances in somatic cell reprogramming of human induced pluripotent stem cells have opened the door to generating specific cells for cell therapy. Human induced pluripotent stem cells represent a potentially unlimited source of stem cells for erythroid generation for transfusion medicine. Design and Methods We characterized the erythroid differentiation and maturation of human induced pluripotent stem cell lines obtained from human fetal (IMR90) and adult fibroblasts (FD-136) compared to those of a human embryonic stem cell line (H1). Our protocol comprises two steps: (i) differentiation of human induced pluripotent stem cells by formation of embryoid bodies with indispensable conditioning in the presence of cytokines and human plasma to obtain early erythroid commitment, and (ii) differentiation/maturation to the stage of cultured red blood cells in the presence of cytokines. The protocol dispenses with major constraints such as an obligatory passage through a hematopoietic progenitor, co-culture on a cellular stroma and use of proteins of animal origin. Results We report for the first time the complete differentiation of human induced pluripotent stem cells into definitive erythrocytes capable of maturation up to enucleated red blood cells containing fetal hemoglobin in a functional tetrameric form. Conclusions Red blood cells generated from human induced pluripotent stem cells pave the way for future development of allogeneic transfusion products. This could be done by banking a very limited number of red cell phenotype combinations enabling the safe transfusion of a great number of immunized patients.

Human induced pluripotent stem cells can reach complete terminal maturation: in vivo and in vitro evidence in the erythropoietic differentiation model

Background Human induced pluripotent stem cells offer perspectives for cell therapy and research models for diseases. We applied this approach to the normal and pathological erythroid differentiation model by establishing induced pluripotent stem cells from normal and homozygous sickle cell disease donors. Design and Methods We addressed the question as to whether these cells can reach complete erythroid terminal maturation notably with a complete switch from fetal to adult hemoglobin. Sickle cell disease induced pluripotent stem cells were differentiated in vitro into red blood cells and characterized for their terminal maturation in terms of hemoglobin content, oxygen transport capacity, deformability, sickling and adherence. Nucleated erythroblast populations generated from normal and pathological induced pluripotent stem cells were then injected into non-obese diabetic severe combined immunodeficiency mice to follow the in vivo hemoglobin maturation. Results We observed that in vitro erythroid differentiation results in predominance of fetal hemoglobin which rescues the functionality of red blood cells in the pathological model of sickle cell disease. We observed, in vivo, the switch from fetal to adult hemoglobin after infusion of nucleated erythroid precursors derived from either normal or pathological induced pluripotent stem cells into mice. Conclusions These results demonstrate that human induced pluripotent stem cells: i) can achieve complete terminal erythroid maturation, in vitro in terms of nucleus expulsion and in vivo in terms of hemoglobin maturation; and ii) open the way to generation of functionally corrected red blood cells from sickle cell disease induced pluripotent stem cells, without any genetic modification or drug treatment.

A new α chain variant Hb Sallanches [α2 104(G11) Cys→Tyr] associated with HbH disease in one homozygous patient

Summary. We identified a new α‐chain variant (αSal) associated with haemolytic anaemia and low level of HbH in one homozygous patient. This new mutation is located in codon 104 (TGC → TAC) of the a2 globin gene and results in a Cys→Tyr replacement. In vitro and in vivo biosynthetic studies suggest that the mechanism leading to HbH disease in this homozygous patient is mostly related to a significant instability of αSal:β dimers rather than to the hyper‐instability of the αSal chain itself only.

Variants in genetic modifiers of β-thalassemia can help to predict the major or intermedia type of the disease

A cohort of 106 patients included in the French National Registry for Thalassemia were genotyped for 5 genetic modifiers of severity: i) β-thalassemia mutations; (ii) the XmnI SNP; (iii) the −3.7 kb α-thal deletion; (iv) the tag-SNP rs 11886868 in BCL11A exon 2; and (v) the tag-SNP rs9399137 in the HBSB1L-cMYB inter-region. Multivariate analysis was performed to study the risk of thalassemia Intermedia phenotype associated with the different combinations of alleles. The presence or absence of the favorable alleles could accurately predict the type of thalassemia in 83.2% of the cases. The percentage of correct predictions made from the β-thalassemia mutations and the XmnI SNP alone were significantly improved by the adjustment with the 3 other modifiers; from 73.6% to 83.2% (P<0.001). In this study, we showed that predictions based on genetic modifiers can foresee the Major or Intermedia type of β-thalassemia, even in cohorts of patients with various β-globin genotypes.

The XmnI Gγ polymorphism influences hemoglobin F synthesis contrary to BCL11A and HBS1L-MYB SNPs in a cohort of 57 β-thalassemia intermedia patients

The HbF level is a quantitative trait influenced by many loci inside or outside the beta-globin gene cluster. The aim of this study was to analyze in 57 beta-thalassemia intermedia patients with very various genotypes the effects on fetal hemoglobin levels of SNPs lying in three genes or chromosome regions which include the XmnI (G)gamma polymorphism at position -158 of the HBG2 promoter (rs7482144), two SNPs located in the BCL11A region (rs4671393 and rs11886868) and three SNPs located in the HBS1L-MYB region (rs28384513, rs9399137 and rs4895441). Our study shows a strong correlation between the XmnI (G)gamma polymorphism and the fetal hemoglobin expression in this patient population (p=0.002). Unfortunately, although recent studies clearly showed a role of SNPs in BCL11A and a HBS1L-MYB region on either clinical expression or fetal hemoglobin levels of beta-hemoglobinopathies such as sickle cell disease and beta-thalassemia, SNPs in BCL11A and the HBS1L-MYB region did not show statistically significant correlations with fetal hemoglobin levels. This suggests that the BCL11A and HBS1L-MYB loci have a minor effect on HbF level compared to the XmnI QTL in beta-thalassemia intermedia patients.

Hemoglobin debrousse (β96[FG3]Leu → Pro): A new unstable hemoglobin with twofold increased oxygen affinity

Hemoglobin Debrousse (β96[FG3]Leu → Pro) is a new unstable variant, with high oxygen affinity responsible, in the steady state, for an apparently well‐compensated chronic hemolytic anemia. The functional properties of this variant are due to the replacement of a leucine residue which is involved in the hydrophobic environment of the proximal side of the heme. This electrophoretically neutral hemoglobin was found as a de novo case in a 6‐year‐old girl suffering from severe anemia with hemolysis and transient aplastic crisis, following infection by parvovirus B19.

The effects of high molecular weight- and low molecular weight-heparins on superoxide ion production and degranulation by human polymorphonuclear leukocytes

High molecular weight (HMW) and low molecular weight (LMW) heparins affected superoxide ion production and degranulation by polymorphonuclear leukocytes (PMNL) isolated from either chronic hemodialyzed patients or healthy controls. Low concentrations in HMW-heparin, below 1.76 aXa IU/ml for patients and 1.34 aXa IU/ml for controls, increased O2- production started by phorbol myristate acetate. High concentrations above these values decreased it. Increasing LMW-heparin concentrations constantly decreased O2- production using the same stimulus. Myeloperoxidase (MPO) released by PMNL was found to be significantly HMW- and LMW-heparins dose-dependent. The addition of calcium chloride significantly increased MPO release. Lactoferrin release was not dose-dependent of HMW- or LMW-heparins. However, an increase of the percentage of positive responses for lactoferrin release was observed in the simultaneous presence of HMW-heparin and CaCl2 compared to HMW-heparin alone. Lysozyme release was also not dose-dependent of HMW- or LMW-heparins. An increase of the percentage of positive responses for lysozyme release was observed in the presence of CaCl2 alone compared to HMW-heparin.

Habitual Physical Activity and Endothelial Activation in Sickle Cell Trait Carriers

PURPOSE It remains unclear whether habitual physical activity in sickle cell trait (SCT) carriers modulates the levels of resting and postexercise vascular adhesion and inflammatory molecules. METHODS Plasma levels of pro-inflammatory (interleukin (IL)-4, IL-5, IL-8, sCD40L, and tumor necrosis factor α) and anti-inflammatory (IL-10) cytokines and adhesion molecules (soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), sP-selectin, or sE-selectin) were assessed at rest and in response to an incremental exercise to exhaustion in untrained (UT: no regular physical activity) and trained (T: soccer players, 8 h·wk minimum) SCT and control (CON) subjects (n = 8 per group; age = 23.5 ± 0.35 yr). RESULTS sVCAM-1 levels were significantly higher in the UT-SCT group than that in T-SCT group (+43.5%) at rest, at the end, and at 1, 2, and 24 h after the end of the exercise. For the other molecules, no differences emerged among the groups at rest, but in response to exercise plasma, sICAM-1, sVCAM-1, sE-selectin, and sCD40L increased in all groups, and sP-selectin only increased in the UT group. All values that increased with the acute exercise returned to their respective baseline levels 1 h after the end of the exercise. CONCLUSIONS A physically active lifestyle in SCT carriers may decrease endothelial activation and may limit the risk for vascular adhesion events in the microcirculation of SCT subjects.

Exercise training blunts oxidative stress in sickle cell trait carriers

The aim of this study was to analyze the effects of exercise training on oxidative stress in sickle cell trait carriers. Plasma levels of oxidative stress [advanced oxidation protein products (AOPP), protein carbonyl, malondialdehyde (MDA), and nitrotyrosine], antioxidant markers [catalase, glutathione peroxidase (GPX), and superoxide dismutase (SOD)], and nitrite and nitrate (NOx) were assessed at baseline, immediately following a maximal exercise test (T(ex)), and during recovery (T(1h), T(2h), T(24h)) in trained (T: 8 h/wk minimum) and untrained (U: no regular physical activity) sickle cell trait (SCT) carriers or control (CON) subjects (T-SCT, n = 10; U-SCT, n = 8; T-CON, n = 11; and U-CON, n = 11; age: 23.5 ± 2.2 yr). The trained subjects had higher SOD activities (7.6 ± 5.4 vs. 5.2 ± 2.1 U/ml, P = 0.016) and lower levels of AOPP (142 ± 102 vs. 177 ± 102 μM, P = 0.028) and protein carbonyl (82.1 ± 26.0 vs. 107.3 ± 30.6 nm/ml, P = 0.010) than the untrained subjects in response to exercise. In response to exercise, U-SCT had a higher level of AOPP (224 ± 130 vs. 174 ± 121 μM, P = 0.012), nitrotyrosine (127 ± 29.1 vs.70.6 ± 46.6 nM, P = 0.003), and protein carbonyl (114 ± 34.0 vs. 86.9 ± 26.8 nm/ml, P = 0.006) compared with T-SCT. T-SCT had a higher SOD activity (8.50 ± 7.2 vs. 4.30 ± 2.5 U/ml, P = 0.002) and NOx (28.8 ± 11.4 vs. 14.6 ± 7.0 μmol·l(-1)·min(-1), P = 0.003) in response to exercise than U-SCT. Our data indicate that the overall oxidative stress and nitric oxide response is improved in exercise-trained SCT carriers compared with their untrained counterparts. These results suggest that physical activity could be a viable method of controlling the oxidative stress. This could have a beneficial impact because of its involvement in endothelial dysfunction and subsequent vascular impairment in hemoglobin S carriers.

Detection of a Thalassemic α-Chain Variant (Hemoglobin Groene Hart) by Reversed-Phase Liquid Chromatography

BACKGROUND Hemoglobin (Hb) Groene Hart [alpha119 (H2)Pro-->Ser (alpha1)], also known as Hb Bernalda, is a nondeletional alpha-thalassemic Hb variant that is frequent in southern Italy and North Africa. This variant is not supposed to be produced in the erythrocytes of carriers. The alpha-thalassemic behavior of this variant has been explained as an impaired interaction between the alpha-globin chain and the alpha-Hb-stabilizing protein. METHODS To separate globin chains, we developed a modified reversed-phase liquid chromatography (RPLC) procedure that uses acetonitrile-water solvents containing up to 3 mL/L trifluoroacetic acid. After RPLC, we characterized the isolated globin chains by electrospray ionization (ESI) mass spectrometry (MS) and analyzed their tryptic peptides with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS and nano-LC-ESI-MS/MS. RESULTS RPLC detected an abnormal peak with a retention time substantially greater than that of the wild-type alpha(A)-globin chain. We identified this variant as Hb Groene Hart and found it in the hemolysates of 11 unrelated patients (1 homozygote, 9 heterozygotes, and 1 heterozygote associated with the -alpha(3.7) deletion). These patients possessed abnormal hematologic features suggesting an alpha-thalassemia phenotype. Molecular modeling suggested that the increase in hydrophobicity was due to opening of the GH interhelical segment following replacement of amino acid residue 119 with a nonhelix breaker residue. CONCLUSIONS This method allows the detection of Hb variants at low concentrations, and adjusting the composition of the organic solvents enables the method to identify Hb variants with large changes in hydrophobicity.