Contact guidance via heterogeneity of substrate elasticity

Contact guidance, the widely-known phenomenon of cell alignment, is an essential step in the organiza-tion of adherent cells. This guidance is known to occur by, amongst other things, anisotropic features in the environment including elastic heterogeneity. To understand the origins of this guidance we employed a novel statistical thermodynamics framework, which recognises the non-thermal fluctuations in the cel-lular response, for modelling the response of the cells seeded on substrates with alternating soft and stiff stripes. Consistent with observations, the modelling framework predicts the existence of three regimes of cell guidance: (i) in regime I for stripe widths much larger than the cell size guidance is primarily entropic; (ii) for stripe widths on the order of the cell size in regime II guidance is biochemically medi-ated and accompanied by changes to the cell morphology while (iii) in regime III for stripe widths much less than the cell size there is no guidance as cells cannot sense the substrate heterogeneity. Guidance in regimes I and II is due to molli-avoidance with cells primarily residing on the stiff stripes. While the molli-avoidance tendency is not lost with decreasing density of collagen coating the substrate, the reduced focal adhesion formation with decreasing collagen density tends to inhibit contact guidance. Our results provide clear physical insights into the interplay between cell mechano-sensitivity and substrate elastic heterogeneity that ultimately leads to the contact guidance of cells in heterogeneous tissues.

Automated summary

Cell alignment, known as contact guidance, is an important step in the organization of adherent cells. By modeling the response of cells on substrates with alternating soft and stiff stripes, researchers have identified three different mechanisms of cell guidance. Guidance towards stiff stripes is primarily due to molli-avoidance behavior, while decreased collagen density inhibits contact guidance.