Figure 1.

Effects of STA21 on platelet aggregation: PRP was incubated with STA21 or DMSO vehicle control (0.1%) for 10 min at 37°C and then induced to aggregate with various concentrations of collagen (A, Univariate Repeated Measures for each collagen dose compared to baseline, n = 9, *p < 0.001) or CRP (B, compared to baseline, n = 3, *p < 0.001). Secretion from α-granule was measured by detecting surface expression of CD62P by flow cytometry after platelets were stimulated with 2 μg/ml of collagen for 10 min (C, Univariate Repeated Measures for each CRP dose compared to baseline, n = 6, *p < 0.001). ATP (D, n = 6) and serotonin (E, n = 3) released from dense granules were measured by whole blood aggregometry and ELISA, respectively, in the supernatant of platelets stimulated with 2 μg/ml of collagen. The data for the panels A-C are also presented as box blots in Supplemental Figure 5. Thrombus formation in vitro was induced by perfusing STA21-treated (20 μm, 10 min at 37°C) blood over immobilized collagen for 1 min at a flow rate of 1 ml/min. Representative images show platelet thrombi in the presence (F) and absence (G) of STA21 (Bar = 200 μm). The areas covered by thrombi were quantified in 6 random images from each experiment (H, n = 3 separate sets of experiments, *p < 0.001). For mouse assay, C57BL/6J mice were daily injected with 4 or 8 mg/kg body weight of STA21 or vehicle control through tail veins for 3 days and collagen-induced platelet aggregation was measured on the third day on an optical aggregomater (I, n = 8, *p < 0.01).