Area and Geometry Dependence of Cell Migration in Asymmetric Two-State Micropatterns
Micro-structured surfaces provide a unique framework to probe cell migration and cytoskeletal dynamics in a standardized manner. Here, we report on the steady-state occupancy probability of cells in asymmetric two-state microstructures that consist of two fibronectin-coated adhesion sites connected by a thin guidance cue. In these dumbbell-like structures, cells transition between the two sites in a repeated and stochastic manner and average dwell times in the respective microenvironments are determined from the cell trajectories. We study the dynamics of human breast carcinoma cells (MDA-MB-231) in these microstructures as a function of area, shape and orientation of the adhesion sites. On square adhesive sites with different areas, we find that the occupancy probability ratio is directly proportional to the ratio of corresponding adhesion site areas. Sites of equal area but different shape lead to equal occupancy, if shapes are isotropic, e.g. squared or circular. In contrast, an asymmetry in the occupancy is induced by anisotropic shapes like rhombi, triangles or rectangles that enable motion in the direction perpendicular to the transition axis. Analysis of the 2D motion of cells between two rectangles with orthogonal orientation suggests that cellular transition rates depend on the cell polarisation induced by anisotropic micropatterns. Taken together, our results illustrate how two-state-micropatterns provide a dynamic migration assay with distinct dwell times and relative cell occupancy as readouts, which may potentially be useful to probe cell-microenvironment interactions.