Migration of living droplets: a novel paradigm for chemotaxis of multicellular communities*

Collective cell migration is ubiquitous amongst multicellular communities and contributes to many phenomena, e.g., morphogenesis and cancer metastasis. Nonetheless, it is still poorly understood how cells coordinate to control the emergent collective motion of cell groups (or swarms). Recent experimental data suggests that physical interactions between cells within the swarms can result in emergent fluid-like properties. In this work, we propose a continuum, coarse-grained, active fluid model to study how physical interactions affect the complex spatiotemporal dynamics of cell swarms' collective chemotaxis in response to self-generated chemical gradients. Our results reveal that the interplay between physical interactions, cell proliferation and chemotaxis can lead to a new mode of pattern formation via self-organised shedding: as the swarms move collectively, they can periodically shed groups of cells at the rear. As such, our work offers a new perspective to the study of chemotaxis of multicellular communities revealing the role of physical interactions in mediating their collective dynamics.