Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA.
Biomaterials. 2012 Feb;33(5):1255-60. doi: 10.1016/j.biomaterials.2011.10.074. Epub 2011 Nov 17.
Circulating activated platelets roll and make transient contacts before ultimately adhering to a substrate. However, despite the dynamic nature of platelet adhesion, most in vitro adhesion and activation studies have focused on establishing local cause and effect relationships. Here, we determined the effect of exposing platelets to immobilized upstream human fibrinogen on downstream adhesion and activation. Microcontact printing was used to prepare substrates that contained well defined fibrinogen priming regions. Washed platelets were perfused over the substrates and adhesion and activation in a downstream capture region were compared with samples that did not contain a fibrinogen priming region. It was found that samples containing an upstream priming region resulted in higher adhesion, platelet spreading areas and aggregation than samples that lacked the priming region. Also, when the priming region was selectively blocked with a polyclonal anti-fibrinogen antibody, the platelet response was attenuated. To characterize this phenomenon further, flow cytometry was used to assess bulk platelet activation following fibrinogen priming. The expression of two activation markers, PAC-1 and P-selectin were quantified. Expression of both activation markers was found to be higher after perfusion over fibrinogen versus albumin-coated substrates.
循环激活的血小板在最终黏附于基质之前会滚动并发生短暂接触。然而，尽管血小板黏附具有动态特性，但大多数体外黏附和激活研究都集中于建立局部因果关系。在这里，我们确定了将血小板暴露于固定化的上游人纤维蛋白原对上游下游黏附和激活的影响。微接触印刷用于制备包含明确定义的纤维蛋白原引发区域的底物。将洗涤后的血小板灌注到这些底物上，并将下游捕获区域中的黏附和激活与不含纤维蛋白原引发区域的样品进行比较。结果发现，与缺乏引发区域的样品相比，含有上游引发区域的样品会导致更高的黏附、血小板扩展面积和聚集。此外，当用多克隆抗纤维蛋白原抗体选择性阻断引发区域时，血小板反应会减弱。为了进一步描述这种现象，使用流式细胞术评估纤维蛋白原引发后的血小板整体激活情况。定量了两种激活标记物 PAC-1 和 P-选择素的表达。与白蛋白涂覆的底物相比，在纤维蛋白原上灌注后，两种激活标记物的表达都更高。
