Figure 4.

Inhibition of metalloproteinases is required for platelet function mediated through integrin αIIbβ3 in ESPs. (A) (i) Representative flow cytometry dot plots showing three mM MnCl₂-stimulated or 0.1 U/ml thrombin-stimulated fibrinogen binding to integrin αIIbβ3 in ESPs after pretreatment with 1% DMSO as a vehicle or 100 μM GM6001. (ii) The graphs show specific fibrinogen binding to αIIbβ3 stimulated with 3 mM MnCl₂ (reference 40), 0.1 U/ml thrombin, or 500 μM adenosine diphosphate. The value of control (vehicle) is defined as 100%. Results are the mean ± SEM from three independent experiments. (B) On day 14 of culture, washed ESPs pretreated with 1% DMSO or 100 μM GM6001 were plated on fibrinogen-coated coverslips for 45 min. An aliquot of each preparation was assayed in the presence of 1 U/ml thrombin. Cells were fixed, permeabilized, and stained with Alexa 488–phalloidin to stain F-actin (green) and with an anti-αIIb antibody followed by Alexa 567 (red). Bar, 10 μm. The value of control (vehicle) is defined as 100%. The right graph summarizes three independent experiments (mean ± SEM).