Trigani Kevin T, DeCortin Michael E, Diamond Scott L
Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States.
TH Open. 2022 Jun 13;6(2):e135-e143. doi: 10.1055/a-1832-9293. eCollection 2022 Apr.
Platelet contractility drives clot contraction to enhance clot density and stability. Clot contraction is typically studied under static conditions, with fewer studies of wall-adherent platelet clots formed under flow. We tested the effect of inhibitors of ADP and/or thromboxane A2 (TXA2) signaling on clot contraction. Using an eight-channel microfluidic device, we perfused PPACK-treated whole blood (WB) ± acetylsalicylic acid (ASA), 2-methylthioAMP (2-MeSAMP), and/or MRS-2179 over collagen (100/s) for 7.5 min, then stopped flow to observe contraction for 7.5 minutes. Two automated imaging methods scored fluorescent platelet percent contraction over the no-flow observation period: (1) "global" measurement of clot length and (2) "local" changes in surface area coverage of the numerous platelet aggregates within the clot. Total platelet fluorescence intensity (FI) decreased with concomitant decrease in global aggregate contraction when ASA, 2-MeSAMP, and/or MRS-2179 were present. Total platelet FI and global aggregate contraction were highly correlated ( = 0.87). In contrast, local aggregate contraction was more pronounced than global aggregate contraction across all inhibition conditions. However, ASA significantly reduced local aggregate contraction relative to conditions without TXA2 inhibition. P-selectin display was significantly reduced by ADP and TXA2 inhibition, but there was limited detection of global or local aggregate contraction in P-selectin-positive platelets across all conditions, as expected for densely packed "core" platelets. Our results demonstrate that global aggregate contraction is inhibited by ASA, 2-MeSAMP, and MRS-2179, while ASA more potently inhibited local aggregate contraction. These results help resolve how different platelet antagonists affect global and local clot structure and function.
血小板收缩性驱动血凝块收缩，以提高血凝块密度和稳定性。血凝块收缩通常在静态条件下进行研究，而对在流动状态下形成的壁黏附血小板凝块的研究较少。我们测试了ADP和/或血栓素A2（TXA2）信号抑制剂对血凝块收缩的影响。使用八通道微流控装置，我们将经PPACK处理的全血（WB）±乙酰水杨酸（ASA）、2-甲硫基腺苷酸（2-MeSAMP）和/或MRS-2179以100/s的流速灌注在胶原蛋白上7.5分钟，然后停止流动以观察7.5分钟的收缩情况。两种自动成像方法对无流动观察期内荧光血小板的收缩百分比进行评分：（1）血凝块长度的“整体”测量；（2）血凝块内众多血小板聚集体表面积覆盖的“局部”变化。当存在ASA、2-MeSAMP和/或MRS-2179时，总血小板荧光强度（FI）下降，同时整体聚集体收缩也随之降低。总血小板FI与整体聚集体收缩高度相关（r = 0.87）。相比之下，在所有抑制条件下，局部聚集体收缩比整体聚集体收缩更明显。然而，相对于未抑制TXA2的条件，ASA显著降低了局部聚集体收缩。ADP和TXA2抑制显著降低了P-选择素的表达，但正如对紧密堆积的“核心”血小板所预期的那样，在所有条件下，P-选择素阳性血小板中整体或局部聚集体收缩的检测有限。我们的结果表明，ASA、2-MeSAMP和MRS-2179抑制了整体聚集体收缩，而ASA更有效地抑制了局部聚集体收缩。这些结果有助于阐明不同的血小板拮抗剂如何影响整体和局部血凝块的结构和功能。
