Perez-Pujol Sílvia, Marker Paul H, Key Nigel S
Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
Cytometry A. 2007 Jan;71(1):38-45. doi: 10.1002/cyto.a.20354.
Platelet-derived microparticles (MPs) are believed to play an important role in coagulation and inflammatory disorders. Unfortunately, MP size renders them difficult to study and analyze by conventional flow cytometry.
We analyzed and characterized platelet-derived MPs, using antibodies against the major surface glycoproteins (GP), the platelet activation antigen P-selectin (CD62P), and a marker of procoagulant activity (phosphatidylserine exposure). MPs were generated by exposure of platelets to thrombin receptor activating peptide (TRAP) or ionophore. Both agonists induced significant microvesiculation of platelets, and the resulting MPs were analyzed by a new digital flow cytometer: Becton-Dickinson FACSAria.
Membrane GPs were equally well represented in MPs generated by either reagent. In contrast, P-selectin was more intensely expressed in TRAP-MPs, while phosphatidylserine (PS) expression was markedly increased in ionophore-MPs. Two distinct populations of TRAP-MPs (one PS-positive and another PS-negative) were apparent. The latter characteristic facilitated sorting of MPs according to their PS exposure.
The data presented herein show a significant improvement in the methodology applied until now to the characterization of MPs. The ability to characterize and sort MP subpopulations may help to resolve their contributions to normal and pathological functions.
血小板衍生微粒（MPs）被认为在凝血和炎症性疾病中起重要作用。不幸的是，MPs的大小使其难以通过传统流式细胞术进行研究和分析。
我们使用针对主要表面糖蛋白（GP）、血小板活化抗原P-选择素（CD62P）和促凝血活性标志物（磷脂酰丝氨酸暴露）的抗体，对血小板衍生的MPs进行分析和表征。通过将血小板暴露于凝血酶受体激活肽（TRAP）或离子载体来生成MPs。两种激动剂均诱导血小板显著微泡化，并通过新型数字流式细胞仪：Becton-Dickinson FACSAria对产生的MPs进行分析。
两种试剂产生的MPs中膜GP的表达情况相同。相比之下，P-选择素在TRAP-MPs中表达更强烈，而磷脂酰丝氨酸（PS）在离子载体-MPs中的表达明显增加。明显存在两种不同的TRAP-MPs群体（一种PS阳性，另一种PS阴性）。后一特征有助于根据PS暴露情况对MPs进行分选。
本文提供的数据表明，目前用于MPs表征的方法有了显著改进。对MP亚群进行表征和分选的能力可能有助于明确它们对正常和病理功能的作用。
