Fig. 6.

THP-1 cells have greater adhesion to ECs exposed to reversing flow. A: THP-1 cells were perfused across ECs pretreated for 24 h with the indicated shear stress conditions. Flow was stopped for 30 s, allowing the THP-1 cells to interact, and, after a 5-min rinse, adherent cells were counted in 10 frames in each of 5–6 separate experiments. *P < 0.001 between RF and all three other conditions. B: ICAM-1 surface expression was significantly upregulated in ECs exposed to 15 dyn/cm² of shear stress or RF for 24 h compared with ECs exposed to 1 dyn/cm² of shear stress or static fluid (*P < 0.05). Data represent flow cytometry data of ICAM-1 fluorescent intensities normalized to the average ICAM-1 fluorescent intensity of ECs exposed to static conditions. C: VCAM-1 surface expression was not significantly changed under any shear stress condition. D: functional blocking of ICAM-1 significantly reduced monocyte adhesion in cells pretreated with RF compared with ECs blocked with either mouse control IgG or VCAM-1 antibody (*P < 0.05). E: surface heparan sulfate proteoglycan expression was elevated in cells exposed to reversing shear stress compared with the three other conditions. Scale bar = 50 μm. F: treatment of cells exposed to reversing shear stress with heparinase III significantly attenuated monocyte adhesion (*P < 0.05).