Chemistry and topographic domains: micropatterned surfaces. Production, physical-chemical and biological characterisation

The presence of micro and nano-domains on a surface allows the manipulation of two fundamental external signals: cellsubstrate and cell-cell interaction, in order to create a pattern of highly oriented cells capable of arranging themselves in tissue. Cell guidance also depends on the different chemical and/or topographic domains present on a surface and on their geometry. Thus, structures are realised so that they also contain different chemical and geometrical domains. Among the many known methods for modifying surfaces, the photoimmobilisation process is a useful technique for creating microstructures with both chemical and topographic patterns. In most approaches, cells are localized to adhesive regions on a substrate, thus limiting their use to one cell type. More recently, approaches have been developed for patterning two or more cell types in spatially defined co-cultures. These approaches can be used to study the effects of cell shape, cell-matrix interactions, and heterotypic cell-cell contact on various cell functions. Many studies on patterned co-cultures have involved the selective adhesion of one cell type compared to the normal adhesion of the other. In this chapter, the results of our research on micro-topography and cell behaviour are reviewed and discussed. Patterns with different geometries have been obtained by photoimmobilisation of the polysaccharide hyaluronic acid (Hyal) on glass surfaces. The resulting surface patterns have been utilised to study the influence of microstructures as a function of chemical, topographic and dimensional properties on both primary and tumoral cell lines. Cell adhesion and distribution have been analysed as a function of the shape and area of the microdomains. Studies carried out with the aim to analyse heterotypic cell-cell interaction as a function of geometry and dimension domains are also reported. In particular, the possibility of obtaining co-cultured microstructured surfaces by seeding fibroblasts on patterned samples with already adhered endothelial cells has been investigated. The chapter ends with an outline of the results recently obtained by other authors studying the combined effect of topographic domains and mechanical/gravitational stress, a very promising topic in the field of cell microenvironment topography.