Endothelial barrier assay. (A) Real-time impedance measurement of endothelial barrier integrity after treatment with HCQ, MIX or combined treatment over time of CTR fpECAs from three independent experiments. Disruption of endothelial barrier was observed after challenge with MIX. (B.I–B.III) After quantification of cell index for specific time points, MIX treatment showed the strongest effect at 5 h (B.I), and a slow recovery over 10 h (B.II) and 15 h (B.III) of MIX-treated cells was detectable. Moreover, 1 µg/mL HCQ neither improved nor impaired endothelial barrier stability. Statistical analysis of differences between four conditions at specific time points (5, 10 and 15 h) was conducted with paired RM one-way ANOVA. N = 3; * p ≤ 0.05; ** p ≤ 0.01; ns, not significant.