Dynamic Shape Adaptation: Understanding the Relationship Between Cell Shape and Motion inCell Monolayers

Does cell shape determine motion or vice-versa? In addition, are there cell shapes that optimize

motion, and how do cell shapes differ for static packings versus the shapes of cells undergoing

continuous motion? We carry out discrete element method simulations of deformable particles

in two dimensions (2D) with active Brownian forces to induce motion and characterize the cell

shape distribution as a function of the driving using the shape parameter, S=P² /4πA, where P and

A are the perimeter and area of the cell. In our model, we can set preferred values for the

perimeter P₀ and area A₀ of each cell, which yield a preferred cell shape parameter S₀ . In cells

with preferred shape S₀ =1.15, active forces increase the observed shape parameter, S>S₀ . This

result shows that the optimal shape parameter for mobile systems is not the same as the

minimum shape parameter that occurs for confluent systems (S = 1.15). We find that in

simulations that mimic plasticity of the cell membrane, where P₀ is allowed to vary dynamically

based on local forces, a universal shape distribution emerges, independent of starting

conditions. We observe that the long-tailed shape of this distribution is similar to that for mobile

MDCK cell monolayers. These results suggest that living, mobile cells dynamically adjust their

perimeters (or surface area) to minimize resistive forces from their surrounding environment.