Background: Activation of platelets tends to cause adhesion and aggregation of platelets to the vascular wall. In circulatory environment, activation and adhesion may not occur at the same site since platelet activation requires time.

Aims: Thus, we hypothesize that platelet activation at upstream and adhesion at downstream would be relevant in assessing the increased thrombotic risk associated with hyper-responsive vulnerable blood.

Methods: In this study, we designed a highly integrated microfluidic flow system to mimic the hemodynamic environment of vasculature with an upstream activation of platelets and downstream adhesion of platelets. Platelets can be activated by either agonists or shear stress generated with a rotational disk. Degree platelet adhesion was monitored by the migration distance (MD) of blood through the microchannel until it is blocked.

Results: Degree of pre-activation was widely varied with incubation time, agonist concentration and shear stress levels, which directly affected downstream adhesion of pre-activated platelets. There were linear relation between degree of activation and that of adhesion. However, excessive activation, rather, degraded downstream adhesion of platelets due to upstream aggregation and platelet lysis.

Conclusions: The results suggested that platelet adhesion was strongly dependent on the general conditions of upstream activation of platelets. This study implicates that downstream thrombus formation may be caused by upstream platelet activation rather than on-site activation.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/thrombus-formation-study-of-upstream-activation-and-downstream-adhesion-of-platelets-in-a-highly-integrated-microfluidic-system/