Effect of VWF/FVIII complex on platelet adhesion under flow conditions using normal and platelet-reduced blood. PPACK- and mepacrine-treated whole (normal) blood (19 × 104 platelets/μL) and platelet-reduced blood (4-6 × 104 platelets/μL) were added with different amounts of FVIII/VWF complex and perfused to the flow chamber for 2 minutes at a shear rate of 1600 s–1 and the platelet adhesion was analyzed. (A) Platelet adhesion of normal blood containing 0, 1, 2, and 4 VWF:RCo U/mL exogenously added VWF/FVIII complex. Platelet adhesion was expressed as surface coverage at 2 minutes after the start of flow. Data are each a mean ± SEM (n = 5-6). (B) Photo images of the platelets adhered on the collagen surface in panel A. Those images correspond to the experiments using blood containing 0 to 4 VWF:RCo U/mL of exogenously added VWF/FVIII complex shown in panel A. (C) Platelet adhesion of platelet-reduced blood exogenously added with 0 (n = 15), 1 (n = 6), 2 (n = 9), and 4 (n = 8) VWF:RCo U/mL VWF/FVIII complex. Normal blood indicates the platelet adhesion of the original blood (n = 14). Data are each a mean ± SEM. *P < .05 as compared with no addition of VWF/FVIII complex. (D) Photo images of the platelets deposited on the collagen surface, corresponding to the experiments in panel C. These photoimages were captured at 2 minutes after start of the perfusion. Magnification, × 400.
