ABSTRACT
Most mammalian cells require a surface for attachment, growth, and proliferation. Ongoing research suggests that cells respond and develop in a surface-specific manner depending on extracellular matrix (ECM) composition, elasticity and topology. The ECM, to which cells attach, is a porous, viscoelastic composite that comprises semiflexible and stiff elastic fibers of cell-secreted proteins embedded in a polysaccharide hydrogel. In addition to the chemical cues provided by these proteins, the cell also acts on the mechanical properties of the matrix. The influence of rigidity and surface topography on cellular responses, and the investigation of
mechanical interactions between cells and their growth substrates, is therefore of great interest [1, 2]. Depending on the cell type, surface properties influence cell polarity, motility, morphology, proliferation rate, and attachment strength. Mechanical signals play a significant role in the signaling system regulating cell and tissue development as well as physiology. Surface stimuli encompass the viscoelasticity of the substrate, surface patterning, wettability, roughness, and porosity [1-16]. So far, model substrates with defined pore geometry and distribution have rarely been used to obtain quantitative data on cell spreading and morphological details such as cytoskeleton development and elastic properties of the cell body [11, 12]. Lee and coworkers [13, 14] reported on fibroblasts cultured on track-etched micropores (0.2-8.0 µm) and found that cell adhesion and growth rate decreased gradually with increasing pore size, while Gold and coworkers introduced a model system based on microfabricated cell culture substrates consisting of interconnected channels [11, 12]. They found that fibroblasts bridge 0.8-1.8 µm wide channels and that channel periodicity alters fibroblasts’ morphology and attachment density. Highest cell density was found on flat unstructured surfaces. Even pores as large as 5 µm are spanned by fibroblasts as reported by Richter et al. [15]. Yamamoto and coworkers report that porcine aortic endothelial cells adhere to honeycomb patterned films with pore sizes larger than 1-2 µm by activating integrins preferably on the rim [16].
