Asymmetric cell collisions on nanofibers: how do cell morphology and mechanics affect the outcomes?

The behavior of cells attached to and crawling along suspended nanofibers, like how cells migrate and interact in a fibrous environment mimicking the natural extracellular matrix, can be of interest for biophysical studies due to the relevance to collective cell migration in living systems. Previously, we numerically simulated symmetric collisions between identical cells moving on fibers, with outcomes similar to observations of fibroblasts such as cells sticking together or walking past each other. However, most collisions in experiments involve cells of distinct morphological and mechanical properties reflected by different sizes, shapes and speeds, which can determine the asymmetric collision outcomes. To test the effects of various cellular features, we simulate two-cell collisions on nanofibers with asymmetric morphologies (depending on cell sizes and number of fibers attached to) and velocities (controlled by active force strength) using a phase-field model for both cell shape and polarity. We show diverse outcomes (cells reversing, moving as a group, or walk-past) and focus on collisions on two parallel fibers where one cell keeps direction of motion and forces the other to turn around. To predict the winning cell (possibly the larger or faster one), we use logistic regression analysis to develop a data-driven statistical method based on cell shape parameters and speed contrast, as well as fiber geometry (e.g. distance between fibers), offering clues for further experimental investigations.