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Query: UMLS:C0002895 (sickle cell disease)
 11,747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to obtain a transgenic mouse model of sickle cell disease, we have synthesized a novel human beta-globin gene, beta SAD, designed to increase the polymerization of the transgenic human hemoglobin S (Hb S) in vivo. beta SAD (beta S-Antilles-D Punjab) includes the beta 6Val substitution of the beta S chain, as well as two other mutations, Antilles (beta 23Ile) and D Punjab (beta 121Gln) each of which promotes the polymerization of Hb S in human. The beta SAD gene and the human alpha 2-globin gene, each linked to the beta-globin locus control region (LCR) were co-introduced into the mouse germ line. In one of the five transgenic lines obtained, SAD-1, red blood cells contained 19% human Hb SAD (alpha 2 human 1 beta 2SAD) and mouse-human hybrids in addition to mouse hemoglobin. Adult SAD-1 transgenic mice were not anemic but had some abnormal features of erythrocytes and slightly enlarged spleens. Their erythrocytes displayed sickling upon deoxygenation in vitro. SAD-1 neonates were anemic and many did not survive. In order to generate adult mice with a more severe sickle cell syndrome, crosses between the SAD progeny and homozygous for beta-thalassemic mice were performed. Hemoglobin SAD was increased to 26% in beta-thal/SAD-1 mice which exhibited: (i) abnormal erythrocytes with regard to shape and density; (ii) an enlarged spleen and a high reticulocyte count indicating an increased erythropoiesis; (iii) mortality upon hypoxia; (iv) polymerization of hemolysate similar to that obtained in human homozygous sickle cell disease; and (v) anemia and mortality during development.
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PMID:Towards a transgenic mouse model of sickle cell disease: hemoglobin SAD. 191 88

Very recently a high expression of human hemoglobin S, which causes sickle cell disease, has been obtained in transgenic mice. We have constructed a modified beta S gene, beta SAD which carries two additional mutations in order to induce polymerization of transgenic hemoglobin when diluted by endogenous mouse Hb. The transgenic SAD mice are not anemic but exhibit a low percentage of irreversible sickle cells. Sickling is induced by deoxygenation of erythrocytes in vitro. In addition, the anemia of neonates and the low incidence of SAD animals in the progeny suggest a deleterious effect of SAD Hb during development. Finally, hypoxia induces a high mortality in SAD adults suggesting the induction of vaso-occlusive events.
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PMID:Towards a mouse model for sickle cell disease: HB SAD. 210 73

Prevention of red cell K+ and water loss is a therapeutic strategy for sickle cell disease. We have investigated in vitro and in vivo the effects of clotrimazole (CLT) and miconazole (MIC) on transgenic mice red cells expressing hemoglobin SAD. CLT blocked the Gardos channel (ID50 75 +/- 22 nM; n = 3) and the A23187-induced dehydration of Hbbs/Hbbthal SAD 1 mouse erythrocytes in vitro. Oral treatment with CLT (160 mg/kg per d) and MIC (100 mg/kg per d) inhibited the Gardos channel in both SAD 1 and control (Hbbs/Hbbthal) mice. In the SAD 1 mice only, cell K+ content increased, and mean corpuscular hemoglobin concentration and cell density decreased. After 7 d of treatment, the hematocrit of SAD 1, CLT-treated animals also increased. All changes were fully reversible. Long-term treatments of SAD 1 mice with oral CLT (80 mg/kg per d for 28 d) lead to sustained increases in cell K+ content and hematocrit and sustained decreases in mean corpuscular hemoglobin concentration and cell density, with no changes in animals treated with vehicle alone. Thus, CLT and MIC can reverse dehydration and K+ loss of SAD 1 mouse erythrocytes in vitro and in vivo, further supporting the potential utility of these drugs in the treatment of sickle cell anemia.
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PMID:Treatment with oral clotrimazole blocks Ca(2+)-activated K+ transport and reverses erythrocyte dehydration in transgenic SAD mice. A model for therapy of sickle cell disease. 751 89

The transgenic SAD mouse which expresses a modified sickle hemoglobin, Hb SAD, displays in vivo hemoglobin polymerization and erythrocyte sickling. In the presence study functional and morphological renal analyses were performed in SAD mice in order to compare the renal pathology of SAD mice with the human disease. The SAD mice display renal hemosiderosis, microvascular occlusions, vascular thrombosis, cortical infarcts and papillary necrosis. In the medulla, hemoglobin polymers could be observed with infrequent erythrocyte sickling, which may explain the absence of significant renal concentration defect, whereas in humans, the difference in the vascularization network leads to more extensive sickling. Most animals develop glomerular hypertrophy and mesangial sclerosis which increases in frequency and severity with age. The glomerular damage is associated with functional defects, including increased blood urea nitrogen levels and non-selective proteinuria. The glomerular lesions of SAD mice strikingly mimic sickle cell glomerulosclerosis, the most severe renal complication of sickle cell disease in humans. In summary, the SAD mouse is a valuable model of the thrombotic and glomerulosclerotic complications of human sickle cell glomerulopathy and can serve for pathophysiologic studies, and, eventually, for prevention and therapy investigation.
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PMID:The transgenic SAD mouse: a model of human sickle cell glomerulopathy. 785 92

Erythrocyte sickling on deoxygenation in vitro occurs in transgenic SAD mice, hemizygous for a modified human sickle hemoglobin, HbSAD [alpha 2 beta 2S(beta 6val)Antilles (beta 23 lle)D- Punjab (beta 121Gln)] (SAD-1, 19% HbSAD; beta-thal/SAD-1, 26% HbSAD). The present study examines the cellular defects in vivo and pathologic changes observed in SAD-1 mice at atmospheric oxygenation as well as the effect of acute hypoxia. The transgenic mice showed generalized congestion and microvascular occlusions, occasionally with thrombosis and infarctions of lung, kidneys, penis, and myocardium. The most prevalent chronic organ lesions were congestive splenomegaly (83% of animals) and renal glomerulopathy, which affected 75% of animals by 10 months of age. Further, SAD mice have a mean lifespan that was reduced by 40% when compared with nontransgenic littermates. Premature death of SAD mice was associated with acute vasoocclusive events or severe renal disease. SAD mice developed lethal vasoocclusive processes when exposed to reduced pO2 conditions, whereas control mice survived normally. The sensitivity to hypoxia appears to depend on the cellular level of HbSAD, because death occurred at pO2 of 42 mmHg for SAD mice and 49 mmHg for beta-thal/SAD. Administration of an antisickling agent that increases oxygen affinity (BW12C79) protected SAD and beta-thal/SAD mice from the lethal hypoxic stress. In conclusion, the transgenic SAD and beta-thal/SAD mice developed a pathophysiology that strongly resembles human sickle cell disease. Moreover, this animal model allows studies on the effect of antisickling agents.
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PMID:Sickle cell disease of transgenic SAD mice. 794 91

Prevention of erythrocyte dehydration is a potential therapeutic strategy for sickle cell disease. Increasing erythrocyte magnesium (Mg) could inhibit sickle cell dehydration by increasing chloride (CI) and water content and by inhibiting potassium chloride (K-CI) cotransport. In transgenic SAD 1 and (control) C57BL/6 normal mice, we investigated the effect of 2 weeks of diet with either low Mg (6 +/- 2 mg/kg body weight/d) or high Mg (1,000 +/- 20 mg/kg body weight/ d), in comparison with a diet of standard Mg (400 +/- 20 mg/ kg body weight/d). The high-Mg diet increased SAD 1 erythrocyte Mg and K contents and reduced K-CI cotransport activity, mean corpuscular hemoglobin concentration (MCHC), cell density, and reticulocyte count. SAD 1 mice treated with low-Mg diet showed a significant reduction in erythrocyte Mg and K contents and increases in K-CI cotransport, MCHC, cell density, and reticulocyte counts. In SAD 1 mice, hematocrit (Hct) and hemoglobin (Hb) decreased significantly with low Mg diet and increased significantly with high-Mg diet. The C57BL/6 controls showed significant changes only in erythrocyte Mg and K content, and K-CI cotransport activities, similar to those observed in SAD 1 mice. Thus, in the SAD 1 mouse, changes in dietary Mg modulate K-CI cotransport, modify erythrocyte dehydration, and ultimately affect Hb levels.
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PMID:Modulation of erythrocyte potassium chloride cotransport, potassium content, and density by dietary magnesium intake in transgenic SAD mouse. 883 70

An array of sickle cell syndromes has been obtained in transgenic mice, expressing HbS or super HbS, from the asymptomatic phenotype similar to the human A/S state to a syndrome more severe than the human homozygous S/S state, inducing 100% fetal death. Anemia was observed in SAD and SAD (beta th/ beta +) neonates and disappeared during postnatal development. In adults, many features of sickle cell disease are found in transgenic mice, especially in SAD and SAD (beta th/ beta +) mice, including abnormal hemolysis, vasoocclusion, microthrombosis, infarct, priapism, chronic organ defects, and death on hypoxia. These mouse models are relevant to the study of the pathophysiology of sickle cell disease and the induction of vasoocclusion and to evaluate new therapeutic approaches in vivo. Clotrimazole and Mg2+ restore hydration of sickle cells and 12 C79 protected SAD mice from lethal acute hypoxia.
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PMID:Transgenic mouse models of sickle cell disease. 937 66

To provide quantitative information on the sites that promote polymerization of sickle hemoglobin (HbS) after formation of the initial hydrophobic bond involving Val-6(beta) [E6V(beta)] and also to provide hemoglobins with an enhanced polymerization that could be used in a mouse model for sickle cell anemia, we have expressed recombinant double, triple, and quadruple HbS mutants with substitutions on both the alpha- and beta-chains, E6V(beta)/E121R(beta), D75Y(alpha)/E6V(beta)/E121R(beta) and D6A(alpha)/D75Y(alpha)/E6V(beta)/E121R(beta). These recombinant hemoglobins were extensively characterized by high-performance liquid chromatography analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, isoelectric focusing, amino acid analysis, and mass spectroscopy. They retained the functional properties of the Hb tetramer and polymerized in a linear manner at progressively lower Hb concentration as a function of the degree of substitution, suggesting that these remote sites (alphaD6A, alphaD75Y, and betaE121R) on the alpha- and beta-chains exhibit additive, enhanced polymerization properties. The quadruple mutant has a polymerization concentration close to that of the purified SAD hemoglobin from transgenic mouse red blood cells consisting of HbS, Hb Antilles, and Hb D-Punjab. Normal mouse Hb increases the polymerization concentration of each mutant. Thus, the general approach of using recombinant Hbs as described here should prove useful in elucidating the quantitative aspects of the mechanism of HbS polymerization and in identifying the contribution of individual sites to the overall process. The strategy described here demonstrates the feasibility of a systematic approach to achieve future recombinant HbS mutants that could provide a new generation of the transgenic mouse model for sickle cell anemia.
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PMID:Systematic enhancement of polymerization of recombinant sickle hemoglobin mutants: implications for transgenic mouse model for sickle cell anemia. 937 74

We investigated the mechanisms of sickle cell disease (SCD) hematopoietic/erythropoietic defects using bone marrow, spleen, and/or peripheral blood from the transgenic SAD mouse model, which closely reproduces the biochemical and physiological disorders observed in human SCD. First, the erythropoietic lineage late precursors (polychromatophilic normoblasts to the intramedullary reticulocytes) of SAD mouse bone marrow were significantly altered morphologically. These anomalies resulted from high levels of hemoglobin polymers and were associated with increased cell fragmentation occurring during medullary endothelial migration of reticulocytes. Secondly, analysis of bone marrow erythropoiesis in earlier stages showed a marked depletion in SAD erythroid burst-forming units (BFU-E; of approximately 42%) and erythroid colony-forming units (CFU-E; of approximately 23%) progenitors, despite a significant increase in their proliferation, suggesting a compensatory mechanism. In contrast to the bone marrow progenitor depletion, we observed (1) a high mobilization/relocation of BFU-E early progenitors (approximately 4-fold increase) in peripheral blood of SAD mice as well as of colony-forming units-granulocyte-macrophage (CFU-GM) and (2) a 7-fold increase of SAD CFU-E in the spleen. Third, and most importantly, SAD bone marrow multipotent cells (spleen colony-forming units [CFU-S], granulocyte-erythroid-macrophage-megakaryocyte colony-forming units [CFU-GEMM], and Sca(+)Lin(-)) were highly mobilized to the peripheral blood (approximately 4-fold increase), suggesting that peripheral multipotent cells could serve as proliferative and autologous vehicles for gene therapy. Therefore, we conclude the following. (1) The abnormal differentiation and morphology of late nucleated erythroid precursors result in an ineffective sickle erythropoiesis and likely contribute to the pathophysiology of sickle cell disorders; this suggests that transfer of normal or modified SCD bone marrow cells may have a selective advantage in vivo. (2) A hematopoietic compensatory mechanism exists in SAD/SCD pathology and consists of mobilization of multipotent cells from the bone marrow to the peripheral blood and their subsequent uptake into the spleen, an extramedullary hematopoietic site for immediate differentiation. Altogether, these results corroborate the strong potential effectiveness of both autologous and allogeneic bone marrow transplantation for SCD hematopoietic therapy.
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PMID:Altered hematopoiesis in murine sickle cell disease. 1043 33

Sickle cell disease is a hereditary disorder characterized by erythrocyte deformity due to hemoglobin polymerization. We assessed in vivo the potential curative threshold of fetal hemoglobin in the SAD transgenic mouse model of sickle cell disease using mating with mice expressing the human fetal Agamma-globin gene. With increasing levels of HbF, AgammaSAD mice showed considerable improvement in all hematologic parameters, morphopathologic features and life span/survival. We established the direct therapeutic effect of fetal hemoglobin on sickle cell disease and demonstrated correction by increasing fetal hemoglobin to about 9-16% in this mouse model. This in vivo study emphasizes the potential of the SAD mouse models for quantitative analysis of gene therapy approaches.
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PMID:Genetic correction of sickle cell disease: insights using transgenic mouse models. 1065 6


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