Fibroblast cell behaviour on bound and adsorbed fibronectin onto hyaluronan and sulphated hyaluronan substrates

The effect of fibronectin protein (Fn) coating onto polysaccharide layers of hyaluronic acid (Hyal) and its sulfated derivative (HyalS) on fibroblast cell adhesion was analyzed. The Hyal or HyalS were coated and grafted on the glass substrate by a photolithographic method. The Fn coating was achieved by two different routes: the immobilization of Fn by covalent bond to the polysaccharide layers and the simple adsorption of Fn onto Hyal and HyalS surfaces. AFM, SEM, and ATR-FTIR techniques were used for the chemical and topographical characterization of the surfaces. According to AFM and SEM data, the surface topography was dependent on the method used to cover the polysaccharide layers with the protein. ATR-FTIR analysis supplied information about the rearrangement of Fn after the interaction (adsorption or binding) with the Hyal and the HyalS. The conformational changes of the Fn were minimal when it was simply adsorbed on HyalS surfaces and larger once bound, whereas on the Hyal layer the protein underwent a bigger conformational change once adsorbed and covalently grafted. Then, the biological characterization was carried out by analyzing the human diploid skin fibroblasts adhesion on these surfaces. The morphology of fibroblasts was evaluated by SEM, whereas the dynamics of fibroblasts movement were recorded by a time-lapse system. Cell variations in area, perimeter, and length were analyzed at 2, 4, and 6 h. It was found that the addition of Fn (covalently bound or merely adsorbed) was fundamental in the promotion of fibroblasts adhesion and spreading. The greatest adhesion occurred onto HyalS layers covered by the adsorbed Fn.