  The migratory dynamics of cells in physiological processes, ranging from
wound healing to cancer metastasis, rely on contact-mediated cell-cell
interactions. These interactions play a key role in shaping the stochastic
trajectories of migrating cells. While data-driven physical formalisms for the
stochastic migration dynamics of single cells have been developed, such a
framework for the behavioral dynamics of interacting cells still remains
elusive. Here, we monitor stochastic cell trajectories in a minimal
experimental cell collider: a dumbbell-shaped micropattern on which pairs of
cells perform repeated cellular collisions. We observe different characteristic
behaviors, including cells reversing, following and sliding past each other
upon collision. Capitalizing on this large experimental data set of coupled
cell trajectories, we infer an interacting stochastic equation of motion that
accurately predicts the observed interaction behaviors. Our approach reveals
that interacting non-cancerous MCF10A cells can be described by repulsion and
friction interactions. In contrast, cancerous MDA-MB-231 cells exhibit
attraction and anti-friction interactions, promoting the predominant relative
sliding behavior observed for these cells. Based on these experimentally
inferred interactions, we show how this framework may generalize to provide a
unifying theoretical description of the diverse cellular interaction behaviors
of distinct cell types.
