Characterization of Hyaluronan-Protein Microstructures and Polymer Solutions

Evidence is mounting that mechanical and topographical features of biomaterials can be as critical for cellular behavior as chemical properties. A case in point is hyaluronan (HA), a large polysaccharide with unique mechanical and hydrodynamic properties, found in many tissues and bodily fluids. Thanks to a large variety of accessible conformations and aggregation states, this remarkable polymer can impart on its biological environment a diverse range of structural and viscoelastic properties with far-reaching consequences for cell physiology (migration, inflammation, cancer). Supramolecular assembly of HA is typically mediated by HA-binding proteins. These specialized molecules are known to assist the formation of organized structures, such as cross-linked bundles, gels, or the all-important pericellular coat, a polymer network anchored to many cell surfaces. Precisely how the material properties of HA-rich matrices and aggregates are modified by the associated proteins, however, is largely a matter of speculation. We will present new insights concerning the cell coat and HA-protein solutions characterized using passive microrheology, fluorescence recovery after photobleaching (FRAP), and optical force probe microscopy.