Cell migration is a crucial event in tissue development, wound healing, inflammation and tumor formation. In vivo, cells evolve in a complex environment and encounter narrow spaces that could favor or prevent migration. These interactions can be studied by incorporating micro- and nanotechnology-related tools. The design of substrates based on these technologies offers new possibilities to probe the cellular responses to changes in their physical environment. Here we developed and used micropillar substrates to study the influence of substrate confinement on cell migration and invasion propensity. To vary the topography and confinement, micropillar substrates were designed that contain ordered micron-sized pillars (~5-10 µm in diameter, from a few microns to tens of micrometers in height and edge-to-edge distances ranging from 2 microns up to around 10 µm) allowing cells to encounter flat surfaces and topographical features. Cells are thus allowed to transmigrate through confined spaces composed of micropillars. Thus, the goal of TOPOCELL is to develop in-plane micropillar substrates whose geometry can be easily tuned to control and analyze cell migration as well as a novel invasion assay. We develop a chip composed of micropatterned lines of extra-cellular matrix proteins to promote cell adhesion on which substrates of vertical micropillars were deposited. We used various materials to fabricate the micropillar substrates including polyDimethylSiloxane (PDMS) but also UV-curable elastomers whose refractive index matches that of the cell-culture medium to improve the imaging. We used various cell lines MDCK, MDA-MB-231, MDA-MB-468, MCF-7, MCF-10A, HeLa and HCT-116. We analyzed the transmigration efficiency of various cell lines in between the micropillars and determine conditions that enhance cell invasion and changes in cellular phenotypes.
