One of the most striking features of animal cells is their ability to change shape and migrate in response to environmental cues. At the tissue scale, cells behave and respond collectively to chemical and mechanical signals, giving rise to complex orchestrated processes such as morphogenesis or tumor growth. Developing a quantitative description of tissue dynamics is crucial not only for our fundamental understanding of key developmental and physiological processes but also for our very practical strategies in dealing with a variety of pathologies. 

In the past decade, progress in this field was made on many fronts and many levels of complexity including: (1) in vivo and in vitro experiments by cell biologists and biophysicists which retain the complexity of tissues [1-3], (2) the development of biomimetic experiments retaining only key aspects of the underlying system, offering a well-controlled experimental platform for soft matter physicists [4,5] and (3) an explosion of theoretical and in silico models which are minimal physical models and often retain only universal features (including continuum models, vertex models, deformable particles models, phase field models) [6-8]. 

While very active internationally, this field is nonetheless scattered across diverse specialist communities and lacks unifying principles. This mini-colloquium aims at bringing together both advanced and early career scientists from these diverse communities to foster discussions at the interface of (1) theory and experiments and (2) soft condensed matter physics and cell biology. By highlighting the complementarity of these different approaches, our goal is to find universal features in tissue dynamics (e.g. including pattern formation, collective migration, …). In doing so, we will also raise emerging questions in the field. For instance, a large body of literature is still devoted to two dimensional tissues both experimentally and in terms of models while recent progress in microscopy has brought 3D in vivo experiments into reach with applications including the folding process of drosophila wing during morphogenesis or the dynamics of the bone marrow during leukemia. Proper 3D in silico models are on the other hand still rare and we hope to trigger conversations and potential collaborations in these emerging areas.

Figure 1: (a) Deformation field of a migrating epithelial monolayer around an obstacle (Adapted from [3]); (b) Oil-water biomimetic emulsion functionalized to exhibit specific droplet–droplet adhesion flowing through a constriction (Adapted from [5]); (c) Displacement field in a self-propelled Voronoi model of epithelial tissues close to the glassy transition (Adapted from [6]).

References

[1] B. Ladoux and R.-M. Mège. Mechanobiology of collective cell behaviours. Nature Reviews Molecular Cell Biology, 18(12):743–757, 2017.

[2] M. Gómez-González, E. Latorre, M. Arroyo, and X. Trepat. Measuring mechanical stress in living tissues. Nature Reviews Physics, 2(6):300–317, 2020.

[3] S. Tlili, M. Durande, C. Gay, B. Ladoux, F. Graner, and H. Delanoë-Ayari. Migrating epithelial monolayer flows like a maxwell viscoelastic liquid. Phys. Rev. Lett., 125:088102, 2020.

[4] L.-L. Pontani, I. Jorjadze, V. Viasnoff, and J. Brujic. Biomimetic emulsions reveal the effect of mechanical forces on cell–cell adhesion. Proceedings of the National Academy of Sciences, 109(25):9839–9844, 2012.

[5] I. Golovkova, L. Montel, F. Pan, E. Wandersman, A. M. Prevost, T. Bertrand, and L.-L. Pontani. Adhesion as a trigger of droplet polarization in flowing emulsions. Soft Matter, 17:3820–3828, 2021.

[6] D. Bi, X. Yang, M. C. Marchetti, and M. L. Manning. Motility-driven glass and jamming transitions in biological tissues. Phys. Rev. X, 6:021011, 2016.

[7] R. Alert and X. Trepat. Physical models of collective cell migration. Annual Review of Condensed Matter Physics, 11(1):77–101, 2020.

[8] M. R. Shaebani, A. Wysocki, R. G. Winkler, G. Gompper, and H. Rieger. Computational models for active matter. Nature Reviews Physics, 2(4):181–199, 2020.