Fibroblasts remodeling of type IV collagen at a biomaterials interface

This paper describes the fate of adsorbed type IV collagen (Col IV) in contact with fibroblasts on model biomaterial surfaces, varying in wettability, chemistry and charge. We found that fibroblasts not only interact but also tend to remodel differently adsorbed Col IV employing two distinct mechanisms: mechanical reorganization and proteolytic degradation. Apart from the trend of adsorption -NH₂ > CH₃ > COOH > OH- the cells interact better with NH₂ and OH surfaces -i.e. independently of the amount of adsorbed Col IV - evident from the quantitative measurements of cell adhesion and spreading and the improved recruitment of alpha 1 and alpha 2 integrins as well as p-FAK in focal adhesions. The linearly arranged Col IV co-localize with FN fibrils formed from either secreted, or exogenously added protein, which confirms their interdependence during a reorganization process. We further found that this reorganization is better pronounced on hydrophilic OH and positively charged NH₂ surfaces correlating with the improved cellular interaction. Conversely, the fibroblasts tend to round on COOH and CH₃ surfaces in compliance with the altered integrin signaling and also the increased pericellular proteolysis activity quantified by the increased de-quenching of adsorbed FITC-Col IV and zymography. Taken together, these results show that remodeling of Col IV at a cell-biomaterial interface depends strongly on the surface properties of a material and affects significantly its biological performance.