Figure 2: Migration of straight edge patterned cells on flat and nanogroove-patterned PDMS substrate.

MCF10A wild type cells (A,B) and their mutant PIK3CA knockin cells (C,D) were patterned with a stencil after surface coating with type I collagen (50 μg/ml) on flat (A,C) and nanogrooved PDMS substrates (B,D). Scale bars = 100 μm, and an insert image (B) shows the direction of nanogrooves. Two images of straight-edged monolayers at 0 hr and 18 hrs respectively taken at the same positions combined into a single image. Yellow dot lines indicate the initial front edges of patterned cells and blue dot lines indicates the terminal front edges of migrated cells. Yellow arrows indicate a total migration distance over 18 hrs. The paths of individual migrating MCF-10A cells on flat (E) and nanogrooved (F) PDMS substrates were analyzed using custom MATLAB code. Individual migration paths of MCF-10A cells, defined as the angular deviation from the direction of nanotopography measured on both flat (G) and nanogrooved (H) substrates to assess migratory contact guidance. The portion of migration direction within ±15 degree from the nanogrooves representing straight directionality is highlighted in each graph. Migration speed (I) and persistence time (J) characterizing migratory responses of MCF-10A wild type and oncogenic PIK3CA knockin cells to substrate topography analyzed by fitting the mean-squared displacement of the cell path data to the persistent random walk model. Error bars represent standard deviations of three technical replicates with 80–100 cells per each experiment (*p < 0.01, **p < 0.001).