Comparison of GPVI expression and P-selectin exposure in stroke patients at day-0 and at day-90 (n = 51).

A) Total GPVI expression is not different at day-90 compared to day-0 (P = 0.52). B) GPVI-dimer is significantly higher at day-90 compared to day-0 (P <0.0001). The error bars represent the mean MFI of each of the cohorts ± SD and P-values were calculated by a paired t-test. C) Resting P-selectin exposure (P <0.0001), P-selectin exposure induced by 0.5 μM ADP (P <0.0001), and P-selectin exposure induced by 4 μg/mL CRP-XL (P = 0.001) are all significantly lower at day-90. The error bars represent the median (Q1–Q3) %PP of each of the cohorts and P-values were calculated by the Wilcoxon signed-rank test for non-parametric data. ns = not significant. D) Comparison of P-selectin expressed on the platelet surface of stroke patients at day-0 and at day-90 after stroke and P-selectin of resting normal platelets. The P-selectin exposure on stroke patients at day-0 are strongly correlated to GPVI-dimer expression (P <0.0001) and higher than those of resting control platelets. By day-90, the stroke patients’ P-selectin exposure, albeit still correlated with GPVI-dimer level (P <0.0001), has decreased. Correlations were calculated using Spearman’s rank correlation coefficient and regression line is presented for each data set. MFI = mean fluorescent intensity, %PP = percentage of platelets positive.