ROLE OF MATERIAL-SURFACES IN REGULATING BONE AND CARTILAGE CELL RESPONSE

Tissue engineering in vitro and in vivo involves the interaction of ce lls with a material surface. The nature of the surface can directly in fluence cellular response, ultimately affecting the rate and quality o f new tissue formation. Initial events at the surface include the orie ntated adsorption of molecules from the surrounding fluid, creating a conditioned interface to which the cell responds. The gross morphology , as well as the microtopography and chemistry of the surface, determi ne which molecules can adsorb and how cells will attach and align them selves. The focal attachments made by the cells with their substrate d etermine cell shape which, when transduced via the cytoskeleton to the nucleus, result in expression of specific phenotypes. Osteoblasts and chondrocytes are sensitive to subtle differences in surface roughness and surface chemistry. Studies comparing chondrocyte response to TiO2 of differing crystallinities show that cells can discriminate between surfaces at this level as well. Cellular response also depends on the local environmental and state of maturation of the responding cells. Optimizing surface structure for site-specific tissue engineering is o ne option; modifying surfaces with biologicals is another.