Antithrombin targeting to HSPG & heparin coated surfaces

描述(申请人提供)：凝血酶和凝血因子Xa(FXA)的激活发生在血管和生物材料表面，并启动凝血、血小板、信号和细胞增殖反应，从而可能促进自然循环系统和植入血管移植物、支架、血液透析通路移植物和心室辅助装置表面的病理性血栓形成、闭塞和再狭窄。通过中和凝血酶/FXA分子在血液-表面界面产生的早期干预将是减少凝血酶/FXA介导的病理的一种广泛适用的策略。这一方法的实施将需要血液携带的抑制剂靶向血管和生物材料表面，并在局部和全身炎症条件下保持稳定。本实验室研制的重组人抗凝血酶病(ATLLS)抑制凝血酶和FXA的效果与内源性ATIII相当，但与肝素的亲和力提高了50倍，对中性粒细胞弹性蛋白酶的裂解耐受性提高了10倍。这些“超β-ATIN”分子还可以靶向体外流动模型中肝素涂层的表面，其效率至少是血浆ATIII的9倍。因此，通过超β-ATIII将凝血酶/FXA抑制活性负载到天然血管和肝素涂层的生物材料表面的早期干预可能被证明对阻断表面催化的血栓形成、闭塞和再狭窄事件通常是有用的。随着这些病变在不同的流变学条件下发展，调节ATIII表面负荷的流动相关因素必须在不同的血管和植入物应用中得到阐明。R21的目标是获得流变学和剂量数据，以支持临床翻译工作。目的1通过模拟、体外流动模型和兔血管管腔表面分析，研究在低流与高流和稳流与脉动流条件下，超β-血管紧张素转换酶Ⅲ表面给药的质量传输效应。目的2评价超β-ATIII对兔颈动脉分流和狭窄模型血栓形成的预防作用。

DESCRIPTION (provided by applicant): Activation of thrombin and factor Xa (fXa) occurs on vascular and biomaterial surfaces and initiates coagulation, platelet, signaling and cell proliferation reactions, which may then promote pathological thrombosis, occlusion and restenosis in the native circulatory system and on surfaces of implanted vascular grafts, stents, hemodialysis access grafts and ventricular assist devices. Early intervention via the neutralization of thrombin/fXa molecules as they are generated at blood-surface interfaces would be a widely applicable strategy for reducing thrombin/fXa mediated pathologies. Implementation of this approach will require blood-borne inhibitors to target vascular and biomaterial surfaces and to remain stable under focal and systemic inflammatory conditions. Recombinant human antithrombin Ills (ATllls) developed in our lab inhibit thrombin and fXa with comparable efficiency to endogenous ATIII, but bind heparin with 50x greater affinity and are 10x more resistant to neutrophil elastase cleavage. These "super-beta-ATIN" molecules also target heparin-coated surfaces of an in vitro flow model at least 9x more efficiently than does plasma ATIII. Therefore, early intervention via super-beta-ATIII loading of thrombin/fXa inhibitory activity onto native vascular and heparin-coated biomaterial surfaces may prove generally useful for blocking surface-catalyzed thrombotic, occlusion and restenosis events. As these pathologies develop under widely varying rheological conditions, flow-related factors modulating ATIII surface loading in different vessels and implant applications must be elucidated. Goals of this R21 are to obtain rheological and dosing data to support clinical translation efforts. Aim 1 will investigate mass transport effects on super-beta-ATIII surface delivery under low-vs-high and steady-vs-pulsatile flow, using simulations, an in vitro flow model, and lumenal surface analysis of rabbit blood vessels. Aim 2 will evaluate the ability of super-beta-ATIII to prevent thrombosis in rabbit carotid shunt and stenosis models.