Fig. 1.

Differential platelet adhesion and spreading on immobilized fibrinogen is mediated by substrate stiffness. (A) Experimental setup illustrating how human platelets were incubated on polyacrylamide (PA) gels of varied stiffnesses but conjugated with the same fibrinogen concentration on the top surface. This creates a microenvironment in which the mechanical properties are uncoupled from the biochemical properties. (B) Confocal microscopy images of adherent platelets, stained with a fluorescent membrane dye, on PA gels with stiffnesses ranging from 0.25 to 100 kPa and glass. (C) The number of platelets adhered on PA gels of different stiffness and glass. (D) The spread surface area of adherent platelets on PA gels of different stiffness and glass. (E) Cumulative frequency of spread platelet surface area on substrates of different stiffnesses. (Scale bar: 10 μm.) (P < 0.05; n = 3 experiments; error bars indicate SD.)