中文摘要：

目的揭示血流剪应力对vWF—A1A2A3介导的循环血小板翻滚行为的调控机制。方法利用平行平板流动腔实验技术，在不同流体剪应力条件下，观察和分析血小板在铺有200μg/mL的A1A2A3流动腔底板上的翻滚黏附行为，提取细胞滚动特征参数。结果血小板在底板vWF—A1A2A3上的翻滚速度和时间、停留时间、停留频率和停留时间比率等参数均呈现双相力依赖的特性，剪应力阈值或拐点均发生在0．8Pa左右；在剪切阈值水平之下，剪应力的增加可降低细胞滚动速度并增加滚动的稳定性。结论流体壁面剪应力主要通过调节血小板在A1A2A3上的停留时间来影响其翻滚速度，提示相应的力学调节机制与GPIbα/A1A2A3黏附键从“逆锁键”向“滑移键”的转化过程相关。

英文摘要：

Objective To reveal the shear stress regulation mechanism on vWF-A1A2A3-mediated rolling of plate- lets in flows. Methods Platelets were perfused with various flow rates over 200μg/mL vWF A1A2A3 in parallel- plate flow chamber. The rolling events of platelets near the bottom of chamber were observed and analyzed to ob- tain the rolling characteristics. Results The mean rolling velocity and time, stop frequency and fractional stop time of platelets were all found to be biphasic dependent on wall shear stress, with all the threshold/inflection points occurring under the fluid stress of 0.8 Pa. Increasing shear stress below the threshold would slow and sta- bilize cell rolling in flows. Conclusions Wall shear stress regulates velocity of AlA2A3-mediated cell rolling by adjusting the cell stop time, suggesting that a catch- to slip-bond transition serves as a mechanical regulation mechanism for platelet rollinq throuqh A1A2A3-GPIbα interaction in flows.