Effect of honeycomb-patterned surface topography on the adhesion and signal transduction of porcine aortic endothelial cells

Surface topography has vital roles in cellular response. Here, to investigate the mechanism behind cellular response to surface topography, we prepared honeycomb (HC)-patterned films from poly(ε-caprolactone) (PCL) with micropatterned surface topography by casting a polymer solution of water-immiscible solvent under high humidity. We characterized the adsorption of fibronectin (Fn) on the film using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). The response of porcine aortic endothelial cells (PAECs) to adsorbed Fn molecules onto HC-patterned films was observed by immunofluorescence labeling of vinculin and the actin fiber of PAECs cultured for 1 and 72 h in serum-free medium. The expression of focal adhesion kinase autophosphorylated at the tyrosine residue (pFAK) at 1 h culture was determined using an immunoprecipitation method. Fn adsorbed selectively around the pore edges to form ring-shaped aggregates. The immunostaining results revealed that PAECs adhered to the HC-patterned films at focal contact points localized around pore peripheries. These points correspond to adsorption sites of Fn. The expression of pFAK after 1 h on the HC-patterned film was 3 times higher than that on a corresponding flat film, indicating that the signaling mediated by the binding between Fn and the integrin receptor was more highly activated on the HC-patterned film. These results suggest that the cellular response to HC-patterned films (e.g., adhesion pattern and phosphorylation of FAK) originates from the regularly aligned adsorption pattern of Fn determined by the pore structure of the film.