Effect of shear-induced platelet activation on red blood cell aggregation.

Mechanical shear stress is one of the important factors for platelet activation. Although shear stress has been frequently utilized in many applications of diagnostic bio-equipment, there has been little consideration as to whether shear stress induces platelet activation and consequently alters hemorheological characteristics. Therefore, we investigated the effect of shear-induced platelet activation on red blood cell (RBC) aggregation. The hypothesis of the present research is as follows: Platelets activated by high shear stress secrete substances, which can affect hemorheological characteristics to promote RBC aggregation. In our study, an increase in RBC aggregation indices (critical shear stress (CSS) and aggregation index (AI)) by shear-induced platelet activation was observed. Significantly, an increase of 19% in CSS was observed. However, deformability remained unchanged. These phenomena could be a result of the increased cellular adhesion force on RBC membranes due to secreted substances from activated platelets. Therefore, since high shear application results in the unexpected effect on RBC aggregation, conditions for shear application in diagnostic bio-equipment are to be carefully determined.