PLATELET/ENDOTHELIAL CELL INTERACTIONS

急性冠状动脉血栓形成机制的研究进展 综合征和动脉血管重建手术（例如，经皮 经腔冠状动脉成形术（transluminal coronary angioplasty; PTCA）表明， 在动脉壁血栓和纤维蛋白的生成中，TF因子（TF）起重要作用。 这种TF的来源包括软脂质核心、巨噬细胞， 平滑肌细胞（SMC）。 然而，最近的体外数据表明， 1例间质小泡来源于功能障碍的内皮细胞 细胞（EC）可能是局部扰动、缓慢流动的额外来源 以分支点和分叉为特征的区域。 这样的EC可以 也直接激活SMC产生TF，因为在体内至少一些 动脉粥样硬化病变的SMC表达TF。 因此，我们将测试 动脉粥样硬化中内皮细胞控制TF积累假说 斑块 这可能是真实的两种方式是EC释放TF到 内皮下，和EC激活下面的SMC表达TF。 具体目标1是通过以下方式表征TF的功能性表达： 在流动室中预处理至低水平剪切的猪主动脉EC 应力，无或有缺氧，无或有振荡剪切 压力，长达24小时。 具体目标2是扩大我们的 研究发现，共培养系统包括单层猪主动脉 EC覆盖SMC。 具体目标3是进行TF的平行研究 也在流动装置中用猪主动脉的节段表达。 这些 目标将包括因子Xa的产生和结合，TF的评估 抗原和基因表达，并且，在受控球囊损伤后， 体外共培养和主动脉节段，血小板定量 通过落射荧光视频显微镜和/或111-铟测定粘附/聚集 （托酚酮）标记的血小板和125-碘标记的纤维蛋白原。 一 更清楚地了解剪切应力条件下的内皮细胞可能是重要的 在TF或Xa因子的特异性抑制剂的开发中，以及在 经皮腔内冠状动脉成形术（PTCA）等手术引起的病变EC再增殖。

Recent research into the mechanisms of thrombosis during acute coronary syndromes and arterial revascularization procedures (e.g., percutaneous transluminal coronary angioplasty; PTCA) indicates a major role for tissue factor (TF) in the generation of arterial mural thrombi and fibrin. Sources of this TF include soft lipid core, macrophages, and possibly smooth muscle cells (SMCs). Recent in vitro data, however, make a strong case that interstitial vesicles derived from dysfunctional endothelial cells (ECs) may be an additional source in the local disturbed, slow flow regions characteristic of branch points and bifurcations. Such ECs may also directly activate SMCs to produce TF, since in vivo at least some SMCs of atherosclerotic lesions express TF. We will therefore test the hypothesis that ECs control the accumulation of TF in atherosclerotic plaques. Two ways in which this may be true are EC release of TF into subendothelium, and EC activation of underlying SMCs to express TF. Specific Aim 1 is to characterize the functional expression of TF by porcine aortic ECs preconditioned in a flow chamber to low levels of shear stress, without or with hypoxia, and without or with oscillatory shear stress, for periods up to 24 hours. Specific Aim 2 is to extend our findings to a coculture system comprised of a monolayer of porcine aortic ECs overlying SMCs. Specific Aim 3 is to perform parallel studies of TF expression with segments of porcine aorta, also in a flow device. These aims will incorporate factor Xa generation and binding, assessment of TF antigen and gene expression, and, following controlled balloon injury to cocultures and aortic segments in vitro, quantification of platelet adhesion/aggregation by epifluorescence videomicroscopy and/or 111-indium (tropolone)-labelled platelets and 125-iodine-labelled fibrinogen. A clearer understanding of shear stress-conditioned ECs may prove important in the development of specific inhibitors of TF or factor Xa, and in the EC repopulation of lesions induced by such procedures as PTCA.