BLOOD FLOW EFFECTS ON SICKLE ERYTHROCYTES & ENDOTHELIUM

镰状细胞病中的一些分子缺陷已经被很好地定义，但 治疗在很大程度上仍然只是支持性的。进一步定义 红细胞和内皮细胞水平的异常， 确定哪些异常在生产中是重要的 这种疾病的血管闭塞作用，以及了解这些 异常情况的出现将允许设计更好的治疗方法。这个 本申请提出了三个方面的研究：理解 镰状细胞/内皮细胞黏附增加的分子机制 在生理流动条件下，镰刀灌流的效果 生理条件下细胞对内皮细胞黏附的影响 流动，以及剪应力暴露对镰刀的影响 红血球。在第一个区域，我们假设结合蛋白， 特别是大形式的von Willebrand因子(VWF)，但可能 其他黏附蛋白将被用来剖析分子。 涉及的机制。令人兴奋的初步数据表明，类似GPIB的 受体可能是一个重要的组成部分--而阻断GPIB VWF与金三羧酸(ATA)的结合结构域显著减少 静脉血流状态下的粘连。 在第二个领域，我们假设在流动下的相互作用 内皮铅异常黏附和僵硬的镰刀状红细胞 血管内皮细胞代谢和功能的改变。这些 变化可能包括过度伤害，但也可能引起水平变化。 合成具有血管活性和有丝分裂活性的化合物(包括 前列环素、内皮衍生松弛因子、内皮素、 血小板衍生生长因子、组织型纤溶酶原激活剂和 纤溶酶原激活物抑制物-1型)。增加或减少 这些化合物的分泌与Smooth随后的相互作用 肌肉细胞或凝血系统的组成部分可能在 血栓形成问题、血管闭塞和平滑肌细胞增生 常见于镰状细胞病。在第三个领域，研究将是 用镰刀状红细胞及其密度亚组分制成 确定不同水平的剪应力在 恒剪率旋转粘度计。有待研究的影响包括 溶血、溶血改变、渗透脆性、变形性、 密度分布，钙的吸收和释放。潜在的 假设SS RBC不仅对剪切异常敏感，而且 此外，体内的剪应力可能会产生一些异常。 在这些细胞中观察到。将对除氧效果进行评估。 对照研究将在密度分级的红细胞中进行。 从各种贫血状态恢复的患者，从脾功能减退 受试者和具有镰状细胞特征的个体。我们有 我的实验室开发了几个独特的系统来研究这三个系统 建议的研究领域。

Some molecular defects in sickle cell disease have been well-defined, but treatment is still largely only supportive. Further definition of the abnormalities at the level of the erythrocyte and endothelial cell, identification of which abnormalities are important in production of the vasooclusive effect of the disease, and understanding how these abnormalities arise will permit the design of better therapies. The present application proposes studies in three areas: understanding the molecular mechanisms of increased sickle cell/endothelial cell adhesion under physiological conditions of flow, the effect of perfusion of sickle cells on endothelial cell adhesion under physiological conditions of flow, and the consequences of shear stress exposure for the sickle erythrocyte. In the first area, we hypothesize that binding proteins, particularly large forms of von Willebrand factor (vWF) but possibly other adhesive proteins will be employed to dissect the molecular mechanisms involved. Exciting preliminary data indicate that a GPIb-like receptor may be an important component--and that blocking the GPIb binding domain on vWF with aurin tricarboxylic acid (ATA) greatly reduces adhesion under venular flow conditions. In the second area, we hypothesize that interactions under flow of abnormally adhesive and rigid sickle erythrocytes with endothelium lead to alterations of endothelial cell metabolism and function. These changes may include over damage, but also may give rise to altered levels of synthesis of vasoactive and mitogenic compounds (including prostacyclin, endothelial-derived relaxation factor, endothelin, platelet-derived growth factor, tissue plasminogen activator and plasminogen activator inhibitor-type 1). Increased or decreased secretion of these compounds with subsequent interactions with smooth muscle cells or components of the coagulation system may be important in thrombotic problems, vasoocclusion and smooth muscle cell hyperplasia often seen in sickle cell disease. In the third area, studies will be done with sickle erythrocytes and density subfractions thereof to determine effects of various levels of shear stress produced in a constant shear rate rotational viscometer. Effects to be studied include hemolysis, changes in hemolysis, osmotic fragility, deformability, density distribution, and calcium uptake and release. The underlying hypothesis is that not only are SS RBCs abnormally shear sensitive, but also that shear stress in vivo may produce some of he abnormalities observed in these cells. Effects of deoxygenation will be evaluated. Control studies will be carried out in density-fractionated red cells from patients recovering from various anemic states, from asplenic subjects, and from individuals with sickle cell trait. We have developed, i our laboratory, several unique systems to study all three of the proposed areas of research.