Siedlecki C A, Wang I W, Higashi J M, Kottke-Marchant K, Marchant R E
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
Biomaterials. 1999 Aug;20(16):1521-9. doi: 10.1016/s0142-9612(99)00065-4.
Platelet activation on a thrombogenic surface includes the release of membrane-derived microparticles that provide catalytic sites for blood coagulation factors. Here, we describe a quantitative investigation on the production and dimensions of platelet-derived microparticles observed on glass and polyethylene under aqueous conditions, using atomic force microscopy (AFM) and complementary fluorescence microscopy. The results show that contact-activated platelet microparticles are not evenly distributed over a thrombogenic surface, but in clusters in close proximity to adherent platelets. The microparticles are localized near the platelet periphery, and in some cases appear to emanate from platelet pseudopodia, suggesting that formation may result from vesiculation of the pseudopodia. The microparticles measured 125 +/- 21 nm (n = 73) in the x-y dimensions and 5.2 +/- 3.6 nm in height. The results compared closely with 125 +/- 22 nm width and 4.1 +/- 1.6 nm height obtained for control preparations of thrombin activated microparticles, that were filtered and deposited on glass. Large differences between the measured widths and heights of adsorbed microparticles suggest that platelet microparticles may undergo spreading after attachment to a surface. The adsorbed microparticles expressed platelet membrane receptor GPIIb/IIIa, and many expressed the platelet activation marker P-selectin as determined by fluorescence microscopy. The high number distribution of procoagulant microparticles per unit area of surface compared with platelets suggests that platelet-derived microparticles provide a mechanistic route for amplifying thrombus formation on a thrombogenic surface.
在致血栓形成表面上的血小板活化包括释放膜衍生的微粒，这些微粒为血液凝固因子提供催化位点。在此，我们描述了一项定量研究，该研究使用原子力显微镜（AFM）和互补荧光显微镜，在水性条件下观察玻璃和聚乙烯表面上血小板衍生微粒的产生和尺寸。结果表明，接触激活的血小板微粒并非均匀分布在致血栓形成表面上，而是聚集在贴壁血小板附近。微粒位于血小板周边附近，在某些情况下似乎源自血小板伪足，这表明其形成可能是伪足囊泡化的结果。微粒在x - y维度上测量为125±21 nm（n = 73），高度为5.2±3.6 nm。该结果与经过滤并沉积在玻璃上的凝血酶激活微粒对照制剂所获得的宽度125±22 nm和高度4.1±1.6 nm密切相关。吸附微粒的测量宽度和高度之间的巨大差异表明，血小板微粒在附着于表面后可能会发生铺展。通过荧光显微镜测定，吸附的微粒表达血小板膜受体GPIIb/IIIa，许多微粒还表达血小板活化标志物P - 选择素。与血小板相比，每单位面积表面上促凝血微粒的高数量分布表明，血小板衍生微粒为在致血栓形成表面上放大血栓形成提供了一种机制途径。
