BIOPHYSICS OF SICKLE CELL/ENDOTHELIAL CELL ADHERENCE

描述：调查人员建议继续研究 镰状细胞与血管内皮细胞黏附的机制 微血管系统，如他们的摘要进一步描述的： HbSS在低氧分压下的聚合被认为是 镰状细胞病理学中的主导因素。因为形态上的镰刀是 血红蛋白脱氧后延迟，使红细胞减慢的因素 微循环转运可能是微血管闭塞的先兆， 以镰状细胞为特征的缺血性组织损伤和疼痛发作 贫血。 我们假设镰刀状红细胞附着在微血管上 内皮细胞延迟红细胞微循环传递启动或 传播血管闭塞。我们的研究已经确定了血浆因子，红色 细胞受体和促进镰刀的内皮细胞黏附分子 流动状态下的细胞黏附。在体内，依从性必须发生在 动力条件和附着力必须足够强，以承受剪切 血流对闭塞的血管和组织进行再灌流所施加的力量。 因此，受体、细胞黏附分子和黏附蛋白 对于镰状细胞黏附和血管闭塞来说是必要的，但不是充分的。 我们假设，在活体内，附着生物物理学(主要是强度)将 调节镰状细胞黏附和血管闭塞的程度。条件 导致广泛和强有力的遵守将与 体内镰状细胞黏附和血管闭塞的病理生理学。至 为了解决这个问题，已经设计了以下具体的实验 目的：(1)证明流动状态下的镰状细胞黏附较强 在静态条件下的粘附性，而在流动条件下的粘附性选择 用于表达更多黏附受体的细胞；(2)量化 镰状细胞/内皮细胞对红细胞激动剂的反应， 内皮激活剂和细胞群体的粘附性血浆蛋白 单个细胞在0-10dynes/cm2剪应力范围内。 重点将特别放在调用多个 模拟可能导致疼痛的临床条件的黏附途径 体内发作，如血栓形成或感染；(3)形成血流通道 小静脉直径(20-50微米)，并证明镰状细胞 在受限的渠道中，粘附性很强。 镰状细胞与内皮细胞黏附的生物物理分析 模拟微循环的条件将提供洞察力 转化为促进广泛、快速和强大的生理条件 镰状细胞/内皮细胞黏附可能导致血管闭塞性疼痛 剧集。这些研究将确定最重要的参数和 靶向治疗药物发展的黏附途径 抑制或逆转黏附，以改善镰状细胞疼痛发作。

DESCRIPTION: The investigators propose to continue studies on the mechanisms of sickle cell adhesion to endothelial cells of the microvasculature, as further described by their abstract: "Polymerization of hemoglobin SS at low oxygen tension is assumed to be the dominant factor in sickle cell pathology. Since morphologic sickling is delayed after hemoglobin deoxygenation, factors which slow red cell microcirculatory transit are likely antecedents to microvascular occlusion, ischemic tissue damage, and pain episodes characteristic of sickle cell anemia. We hypothesize that sickle erythrocyte adherence to microvascular endothelium delays erythrocyte microcirculatory transit to initiate or propagate vaso-occlusion. Our studies have identified plasma factors, red cell receptors, and endothelial cell adhesion molecules which promote sickle cell adherence under flow. In vivo, adherence will have to occur under dynamic conditions and adhesion must be strong enough to withstand shear forces exerted by flowing blood to reperfuse occluded vessels and tissues. Thus, receptors, cell adhesion molecules, and adhesive proteins are necessary, but not sufficient for sickle cell adherence and vaso-occlusion. We hypothesize that in vivo, adherence biophysics (primarily strength) will regulate the extent of sickle cell adhesion and vaso-occlusion. Conditions which lead to extensive and strong adherence will be most relevant to the pathophysiology of sickle cell adherence and vaso-occlusion in vivo. To address this, experiments have been designed with the following specific aims: (1) Demonstrate that sickle cell adherence under flow is stronger than adherence under static conditions and that adherence under flow selects for cells expressing more adhesion receptors; (2) Quantify the strength of sickle-cell/endothelial adherence in response to red cell agonists, endothelial activators, and adhesive plasma proteins for cell populations and individual cells in the range of 0 - 10 dynes/cm2 shear stress. Particular emphasis will be placed on conditions which invoke multiple adherence pathways to mimic clinical conditions which may precipitate pain episodes in vivo, such as thrombosis or infection; (3) Develop flow channels with venular dimensions (20-50 micrometers) and demonstrate that sickle cell adherence in confined channels is strong. "Analysis of the biophysics of sickle cell adherence to endothelium under conditions which mimic those in the microcirculation will provide insights into the physiological conditions which promote extensive, rapid, and strong sickle cell/endothelial cell adherence likely leading to vaso-occlusive pain episodes. These studies will identify the most important parameters and adherence pathways to target for the development of therapeutic agents to inhibit or reverse adherence to ameliorate sickle cell pain episodes."