Development of Provisional Extracellular Matrix on Biomaterials Interface: Lessons from In Vitro Cell Culture

The initial cellular events that take place at the biomaterials interface mimic to a certain extent the natural interaction of cells with the extracellular matrix (ECM). The cells adhering to the adsorbed soluble matrix proteins, such as fibronectin (FN) and fibrinogen (FNG) tend to re-arrange them in fibril-like pattern. Using model surfaces we have demonstrated that this cellular activity is abundantly dependent on the surface properties of materials, such as wettability, surface chemistry, charge and topography. This raises the possibility that tissue compatibility of materials is connected with the allowance of cells to remodel substratum associated proteins presumably to form provisional ECM. We have further shown that antibodies which bind beta(1) and alpha(v), integrins (subunits of the FN and FNG receptors respectively) may induce their linear rearrangement on the dorsal surface of living cells - a phenomenon presumably related to the same early molecular events of fibrillar matrix assembly. Because the quantitative measurements revealed that this receptor dynamics is strongly altered on the low compatible (hydrophobic) substrata we hypothesized that in order to be biocompatible, materials need to adsorb matrix proteins loosely, i.e. in such a way that the cells can easily remove and organize them in matrix-like fibrils via coordinated functioning of integrins. More recent studies on the fate of FN on some real biomaterial surfaces, including different rough titanium (Ti) and hydroxyapatite (HA) cements and the surface of biosensors confirmed this point of view. They also show that quantitative measurements of adsorbed matrix proteins and their dynamic rearrangement at cell-material interface might provide insight to the biocompatibility of given material and even predict its tissue integration.