Platelets spread on surfaces coated with collagen, anti–integrin β1 antibody, or integrin α2antibody.
(A) Washed platelets were seeded on surfaces coated with 1% fatty acid-free BSA, 50 μg/mL collagen, or 10 μg/mL anti–integrin β1 (TS2/16) or anti–integrin α2 antibody (7E10B) for 30 minutes at 30°C. After unbound platelets were removed, the platelets were fixed, then incubated with TRITC-conjugated phalloidin for actin fiber staining. (B) Washed platelets were seeded on surfaces coated with 50 μg/mL collagen or 10 μg/mL anti–integrin β1 (TS2/16) for the indicated time frames at 30°C. After unbound platelets were removed, the platelets were fixed, then incubated with TRITC-conjugated phalloidin for actin fiber staining. Platelets were photographed, and the extent of platelet spreading on collagen- (open circles) or TS2/16-coated (solid circles) surfaces was tentatively evaluated by the following scoring: a fully spread cell (2 points), a mildly spread cell (1 point), and a nonspread cell (0 point). After evaluating more than 25 platelets, the total points for 10 platelets were calculated (for the platelet spreading index); the data represent the mean of the total points. The extent of platelet adhesion on collagen- (open bars) or TS2/16-coated (hatched bars) surfaces was evaluated by counting the number of adhered platelets on 2 photographs (randomly taken) at a high-power field. The data represent the mean ± SD of the total numbers.
