Whole blood impedance aggregometry, single platelet aggregometry and vasodilator-stimulated phosphoprotein (VASP) platelet reactivity index, in healthy subjects and in patients with SCD before and after prasugrel treatment. Area under the aggregation curve (AU.min) as measured by impedance aggregometry in response to 6.5 μm ADP (A), platelet aggregation as measured by Plateletworks (B) and platelet reactivity index as measured by VASP phosphorylation assessed with flow cytometry and an enzyme-linked immunosorbent assay (ELISA) (C), at baseline before initiation of prasugrel treatment and following 12 days of prasugrel treatment in healthy subjects (n = 13) and in patients with SCD (n = 13). , baseline; , day 12