Figure 5.

Anti–P-selectin aptamer ARC5690 decreases leukocyte rolling flux and leukocyte adhesion. (A) ARC5690 decreases leukocyte rolling flux. Leukocyte rolling flux was determined by the number of cells rolling through a fixed point per minute (cells/min). Compared with saline-treated mice, pretreatment of SCD mice with ARC5690 (P < .001), but not with ARC5694 (P = .06), decreased leukocyte rolling flux under hypoxia/normoxia stress. (B) ARC5690 decreases leukocyte adhesion to endothelial cells. Leukocyte adhesion was quantified by counting the number of adherent cells (stationary for > 30 seconds) in a 100-μm length of the vessel. Pretreatment with ARC5690 before hypoxia/normoxia stress reduced the number of adherent leukocytes compared with saline-treated mice (P < .001). Scrambled aptamer ARC5694 showed some inhibition of leukocyte adhesion (P < .05; see “Discussion”). (C-D) Frame-captured images from videotaped intravital microscopy of bone marrow venules in SCD mice injected with saline (C) and ARC5690 (D) after infusion of PE rat anti–mouse CD45. Saline-treated mice show a higher number of adherent (white arrows) and rolling (open arrowheads) leukocytes. (E) ARC5690 improves velocities of free-flowing leukocytes. Velocities of free-flowing leukocytes were determined using Image Pro-Plus 5.0 software. Five to 8 velocity measurements were performed along the centerline of the vessel and used to calculate hemodynamic parameters. Velocity of free-flowing leukocytes increased after treatment with ARC5690 but not with the scrambled aptamer ARC5694 compared with saline treated mice. Values were mean ± SE obtained from 4 to 5 mice in each group. The number of venules in experimental groups ranged from 18 to 21. P values for statistical analyses are shown on top of the figures.