Circulating MicroRNAs as Novel Biomarkers for Platelet Activation. Circ Res 112: 595–600

Rationale—MicroRNA (miRNA) biomarkers are attract-ing considerable interest. Effects of medication, however, have not been investigated thus far. Objective—To analyze changes in plasma miRNAs in re-sponse to antiplatelet therapy. Methods and Results—Profiling for 377 miRNAs was per-formed in platelets, platelet microparticles, platelet-rich plasma, platelet-poor plasma, and serum. Platelet-rich plasma showed markedly higher levels of miRNAs than serum and platelet-poor plasma. Few abundant platelet miRNAs, such as miR-24, miR-197, miR-191, and miR-223, were also increased in serum com-pared with platelet-poor plasma. In contrast, antiplatelet therapy significantly reduced miRNA levels. Using custom-made quan-titative real-time polymerase chain reaction plates, 92 miRNAs were assessed in a dose-escalation study in healthy volunteers at 4 different time points: at baseline without therapy, at 1 wee