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

Complications in sickle syndromes are thought to result from regional disturbances of normal blood flow with subsequent ischemic damage. Adherence of sickle erythrocytes has been implicated in the pathophysiology of occlusive complications. Most previous studies have explored adherence of sickle erythrocytes to endothelial cells from large vessels, even though the majority of the pathophysiologic models implicate the microvascular system. To explore potential variation in endothelial interactions at low shear rates, adherence of sickle erythrocytes to large vessel umbilical vein endothelium and microvascular endothelium was compared under flow conditions in a parallel-plate flow chamber at a shear stress of 1.0 dyne/cm2. Autologous plasma promotes high levels of sickle red cell adherence to microvascular endothelial cells, but only low levels of adherence to human umbilical vein endothelium. On average, autologous plasma promotes sixfold more sickle cell red adherence to microvascular endothelial cells. In contrast to umbilical vein endothelium, high molecular von Willebrand factor does not elevate sickle cell adherence to microvascular endothelial cells, and the integrin receptor agonist peptide, RGD, does not inhibit adherence to microvascular endothelial cells. These results demonstrate that sickle erythrocyte adherence to large vessel and microvascular endothelium is quantitatively and qualitatively different and that plasma factors may have significant impact on sickle erythrocyte adherence to endothelium in the microvessels. Since microvascular occlusion has been suggested as an antecedent of ischemic damage in sickle syndromes, plasma enhanced adherence to microvascular endothelium may contribute to the pathophysiology of episodic occlusion in sickle cell anemia.
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PMID:Sickle erythrocyte adherence to large vessel and microvascular endothelium under physiologic flow is qualitatively different. 140 30

Yield stress is a sensitive index of blood fluidity at low shear stress. Using a method that measured the stress required to cause motion of a thin sedimenting layer of red cells, we found significant elevations of yield stress in patients with homozygous sickle cell anemia during clinical steady state. Mixing studies of sickle cells in normal plasma and buffered saline and of normal red cells in sickle plasma showed (1) that the increased yield stress of sickle blood was not due to differences between sickle and normal plasma factors and (2) that yield stress of sickle cells was not increased in the absence of plasma proteins. Multivariate regression analysis was performed to determine the dependence of sickle blood yield stress on several red cell and plasma factors. The yield stress measurements were normalized for differences in plasma fibrinogen concentration. Other factors studied included cell density, fetal hemoglobin concentration, alpha globin genotype, cell deformability as measured by high shear viscosity, and fibronectin and von Willebrand factor concentrations. Cell density was the primary determinant of yield stress. Measurements of yield stress on density fractionated sickle cells confirmed that the increased yield stress of sickle blood was due to the dense sickle erythrocyte. We conclude that the increased yield stress of sickle blood during clinical steady state was due to an abnormal interaction between the dense sickle cell membrane and plasma protein(s).
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PMID:Influence of plasma and red cell factors on the rheologic properties of oxygenated sickle blood during clinical steady state. 194 May 75

The interactions of normal erythrocytes and erythrocytes from patients having hemoglobin S hemoglobinopathies with normal human endothelial cells (EC) were investigated under flow conditions. When EC supernatant, containing 2.8-11.0 U/dl of von Willebrand factor (vWF) antigen and vWF multimeric forms larger than those present in normal plasma, was the red blood cell (RBC)-suspending medium instead of serum-free medium (SFM), the adhesion of sickle RBC, but not normal RBC, to endothelial cells was greatly increased (range of enhancement of sickle RBC adhesion, 2- to 27-fold). Adhesion of sickle RBC to endothelial cells was reduced to near serum-free levels when EC supernatant was immunologically depleted of vWF forms. Sickle RBC suspended in SFM containing 200 U/dl of purified vWF multimers of the type found in normal human plasma or 300 micrograms/ml human fibronectin were only slightly more adhesive to endothelial cells than sickle RBC suspended in SFM alone. These data indicate that unusually large vWF multimers produced by endothelial cells are potent mediators of the adhesion of sickle erythrocytes to endothelial cells. Vaso-occlusive crises in sickle cell anemia may be caused, at least in part, by adhesive interactions between the abnormal surfaces of sickle RBC and the endothelium after the release of unusually large vWF multimeric forms from stimulated or damaged endothelial cells.
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PMID:Unusually large von Willebrand factor multimers increase adhesion of sickle erythrocytes to human endothelial cells under controlled flow. 349 53

The high incidence of thrombosis in inflammatory states and previous reports of increased adhesion of erythrocytes to endothelial cells in diabetes mellitus and sickle cell anemia prompted us to study the effect of fibrinogen and fibronectin on erythrocyte-endothelial interactions. Purified human fibrinogen enhanced erythrocyte adhesion in a concentration-dependent fashion. Erythrocytes from normal subjects, diabetics, and patients with sickle cell anemia were studied. The ratio between the adhesion of normal red cells in a 4 gm/L fibrinogen to adhesion in buffer without fibrinogen was 3.6 (p less than 0.001). Fibronectin also increased red cell adhesion but the effect was less than that of fibrinogen. The addition of fibronectin to fibrinogen limited the enhancing effect of fibrinogen, although the effect of the mixture was greater than that of fibronectin alone (p less than 0.05). Anti-von Willebrand factor and antifibronectin, which react with endothelial cells, also produced an increase in erythrocyte adhesion. The potentiation of adhesion by fibrinogen was also seen in experiments using red cells from patients with sickle cell anemia or diabetes mellitus. These observations provide possible mechanisms for the involvement of plasma proteins in vascular occlusive diseases.
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PMID:Fibrinogen, a modulator of erythrocyte adhesion to vascular endothelium. 685 27

The abnormal adherence of red blood cells, especially circulating reticulocytes (erythrocyte precursors), to the endothelium is believed to contribute to vascular occlusion observed in patients with sickle cell disease. Although several plasma proteins including von Willebrand factor and fibronectin have been proposed to mediate this adhesion, the mechanism of sickle cell adhesion to the endothelium remains unknown. Using flow cytometry, we screened sickle red blood cells with monoclonal antibodies (MoAbs) against known adhesion receptors and detected integrin subunits alpha 4 and beta 1 and the nonintegrin glycoprotein IV on reticulocytes but not on erythrocytes. No reactivity was detected against integrin subunits alpha 2, alpha 3, alpha 5, alpha 6, alpha v, beta 2, beta 3, integrin alpha IIb beta 3, or the nonintegrin glycoprotein Ib. Immunoprecipitation of reticulocytes with either alpha 4- or beta 1-specific antibodies identified the alpha 4 beta 1 complex (alpha 4(70) and alpha 4(80) forms), a receptor for fibronectin and vascular cell adhesion molecule-1. An antibody against glycoprotein IV, a receptor reported to bind thrombospondin and collagen, immunoprecipitated an 88-kD protein consistent with its reported M(r). MoAbs against alpha 4 and glycoprotein IV bound to an average of 4,600 and 17,500 sites per reticulocyte, respectively. Identification of alpha 4 beta 1 and glycoprotein IV on reticulocytes suggests both plasma-dependent and independent mechanisms of reticulocyte adhesion to endothelium and exposed extracellular matrix.
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PMID:Integrin alpha 4 beta 1 and glycoprotein IV (CD36) are expressed on circulating reticulocytes in sickle cell anemia. 750 18

Sickle red blood cell (RBC) adhesion to the blood vessel wall is hypothesized to be the initiating event in the periodic vaso-occlusive episodes that characterize sickle cell disease (SCD). Thrombospondin-1 (TSP) and von Willebrand factor (vWF) have each been implicated in the adhesion of sickle RBC to vascular endothelial cells (EC) and subendothelial matrices. To better understand the contributions of each of these adhesive glycoproteins, we examined the adhesion of sickle RBC to immobilized TSP and vWF using a parallel plate flow chamber. Under postcapillary venular shear stress (1 dyne/cm2), sickle RBC adhered preferentially to TSP. To explore potential interactive effects of vWF and TSP, we examined sickle RBC adhesion to mixtures of these proteins. Whether the proteins were first combined in solution or sequentially applied to the slide, the presence of vWF inhibited the binding of sickle RBC to TSP. The inhibition of adhesion by vWF was shown to be the result of specific and saturable binding of vWF to TSP. Furthermore, vWF in solution at normal plasma levels also inhibited RBC adhesion to immobilized TSP. These data indicate that sickle RBC adhesion in vivo may be significantly influenced by the relative concentrations of TSP and vWF in the vascular wall.
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PMID:Inhibition of sickle erythrocyte adhesion to immobilized thrombospondin by von Willebrand factor under dynamic flow conditions. 911 3

The abnormal adherence of sickle red blood cells (SS RBC) to endothelial cells has been thought to contribute to vascular occlusion, a major cause of morbidity in sickle cell disease (SCD). We determined whether the interaction of SS RBC with cultured endothelial cells induced cellular oxidant stress that would culminate in expression of cell adhesion molecules (CAMs) involved in the adhesion and diapedesis of monocytes and the adherence of SS reticulocytes. We showed that the interaction of SS RBC at 2% concentration in the presence of multimers of von Willebrand factor (vWf), derived from endothelial cell-derived conditioned medium (E-CM) with cultured human umbilical vein endothelial cells (HUVEC), resulted in a fivefold increased formation of thiobarbituric acid-reactive substances (TBARS) and activation of the transcription factor NF-kB, both indicators of cellular oxidant stress. Normal RBC show none of these phenomena. The oxidant stress-induced signaling resulted in an increased surface expression of a subset of CAMs, ICAM-1, E-selectin, and VCAM-1 in HUVEC. The addition of oxygen radical scavenger enzymes (catalase, superoxide dismutase) and antioxidant (probucol) inhibited these events. Additionally, preincubation of HUVEC with a synthetic peptide Arg-Gly-Asp (RGD) that prevents vWf-mediated adhesion of SS RBC reduced the surface expression of VCAM-1 and NF-kB activation. Furthermore, SS RBC-induced oxidant stress resulted in a twofold increase in the transendothelial migration of both monocyte-like HL-60 cells and human peripheral blood monocytes, and approximately a sixfold increase in platelet-endothelial cell adhesion molecule-1 (PECAM-1) phosphorylation, each of which was blocked by protein kinase C inhibitor and antioxidants. These results suggest that the adherence/contact of SS RBC to endothelial cells in large vessel can generate enhanced oxidant stress leading to increased adhesion and diapedesis of monocytes, as well as heightened adherence of SS reticulocytes, indicating that injury/activation of endothelium can contribute to vaso-occlusion in SCD.
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PMID:Interaction of sickle erythrocytes with endothelial cells in the presence of endothelial cell conditioned medium induces oxidant stress leading to transendothelial migration of monocytes. 980 86

The abnormal adherence of sickle red blood cells (SS RBC) to vascular endothelium may play an important role in vasoocclusion in sickle cell anemia. Thrombospondin (TSP), unusually large molecular weight forms of von Willebrand factor, and laminin are known to enhance adhesion of SS RBC. Also, these endothelial proteins bind to sulfated glycolipids and this binding is inhibited by anionic polysaccharides. Reversible sickling may expose normally cryptic membrane sulfatides that could mediate this adhesive interaction. In this study, we have investigated the effect of anionic polysaccharides, in the presence or absence of TSP, on SS RBC adhesion to the endothelium, using cultured human umbilical vein endothelial cells (HUVEC) (for the adhesion assay) and the ex vivo mesocecum of the rat (for hemodynamic evaluation). The baseline adhesion (ie, without added TSP) of SS RBC to HUVEC was most effectively inhibited by high molecular weight dextran sulfate (HDS), whereas low molecular weight dextran sulfate (LDS) and the glycosaminoglycan chondroitin sulfate A (CSA) also had significant inhibitory effects. Heparin was mildly effective whereas other glycosaminoglycans (chondroitin sulfates B and C, heparan sulfate, and fucoidan) were ineffective. Similarly, HDS and CSA resulted in an improved hemodynamic behavior of SS RBC. Soluble TSP caused significant increases in SS RBC adhesion and in the peripheral resistance. Both HDS and CSA prevented TSP-enhanced adhesion and hemodynamic abnormalities. Thus, anionic polysaccharides can inhibit SS RBC-endothelium interaction in the presence or absence of soluble TSP. These agents may interact with RBC membrane component(s) and prevent TSP-mediated adhesion of SS RBC to the endothelium.
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PMID:Anionic polysaccharides inhibit adhesion of sickle erythrocytes to the vascular endothelium and result in improved hemodynamic behavior. 994 87

Abnormal interaction of sickle red blood cells (SS RBC) with the vascular endothelium has been implicated as a factor in the initiation of vasoocclusion in sickle cell anemia. Both von Willebrand factor (vWf) and thrombospondin (TSP) play important roles in mediating SS RBC-endothelium interaction and can bind to the endothelium via alphaVbeta3 receptors. We have used monoclonal antibodies (MoAb) directed against alphaVbeta3 and alphaIIbbeta3 (GPIIb/IIIa) integrins to dissect the role of these integrins in SS RBC adhesion. The murine MoAb 7E3 inhibits both alphaVbeta3 and alphaIIbbeta3 (GPIIb/IIIa), whereas MoAb LM609 selectively inhibits alphaVbeta3, and MoAb 10E5 binds only to alphaIIbbeta3. In this study, we have tested the capacity of these MoAbs to block platelet-activating factor (PAF)-induced SS RBC adhesion in the ex vivo mesocecum vasculature of the rat. Infusion of washed SS RBC in preparations treated with PAF (200 pg/mL), with or without a control antibody, resulted in extensive adhesion of these cells in venules, accompanied by frequent postcapillary blockage and increased peripheral resistance units (PRU). PAF also caused increased endothelial surface and interendothelial expression of endothelial vWf. Importantly, pretreatment ofthe vasculature with either MoAb 7E3 F(ab')(2) or LM609, but not 10E5 F(ab')(2), after PAF almost completely inhibited SS RBC adhesion in postcapillary venules, the sites of maximal adhesion and frequent blockage. The inhibition of adhesion with 7E3 or LM609 was accompanied by smaller increases in PRU and shorter pressure-flow recovery times. Thus, blockade of alphaVbeta3 may constitute a potential therapeutic approach to prevent SS RBC-endothelium interactions under flow conditions. (Blood. 2000;95:368-374)
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PMID:Monoclonal antibodies to alphaVbeta3 (7E3 and LM609) inhibit sickle red blood cell-endothelium interactions induced by platelet-activating factor. 1062 35

In this study, protein C (PC), protein S (PS), heparin cofactor II (HCFII), prothrombin fragment 1+2(PF1,2), thrombin-antithrombin III complex (TAT), von Willebrand factor (vWF) and thrombomodulin (TM) were investigated in 13 patients with beta thalassemia intermedia (TI) not requiring transfusion, six patients with sickle cell disease (SCD), and seven patients with HbS-beta thalassemia (S-BT) who were not in crisis. These hemostatic parameters were also studied in 12 healthy children assigned as a control group. Protein C and Protein S (PC-PS) were found to be decreased in TI patients and normal in S-BT patients. PC was decreased in SCD patients. In the patients with TI and SCD, the mean PF1,2 level was elevated, whereas the TAT level was not statistically different from that of the control group. These results suggested that in patients with hemoglobinopathies: a) decreased natural anticoagulants and b) enhanced procoagulant activation have been encountered. Other unexpected and interesting results of this study are the decreased vWF and elevated HCFII levels in all three patient groups.
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PMID:Changes of hemostatic factors in patients with hemoglobinopathies. 1077 92


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