Most animals display one or more body axes, such as the head-to-tail axis, which usually form during early embryogenesis. Such axis formation can be studied in vitro, in stem cell aggregates called gastruloids. While initially isotropic, gastruloids break rotational symmetry over the course of roughly a day, reflected in an asymmetric distribution of cell fates.

We want to understand how cell fate dynamics interacts with cell motion and tissue dynamics.

On this project, we work together with the theory group of Simon Gsell and the experimental groups of Pierre-François Lenne (Marseille), Vikas Trivedi (Barcelona), and Verena Ruprecht (Innsbruck).

A key process during animal development is the anisotropic deformation of tissues. Often, such deformation is driven by tissue-internal active processes, which are controlled by some kind of orientational information present in the tissue (for instance cell polarity or cell shape anisotropy). Yet, generic theories for such active materials with orientational information predict inherent instabilities. How could such instabilities be prevented to during animal development? To address this question, we study the interplay between orientational information and tissue mechanics using both cell-based and hydrodynamic models for biological tissues.

Sheet-like biological tissues, called epithelia, are often curved during animal development. How does curvature affect the tissue dynamics? For instance, when tissues change their Gaussian curvature, then they need to deform tangentially. What are the consequences of this for tissue flow?

On this project, we work together with the experimental group of Thomas Lecuit (Marseille).

How do large-scale properties of disordered systems arise from the complex interplay of their microscopic constituents? This question is important to understand a large class of materials both living and non-living. Recently, we have shown analytically that the elastic properties of the broad class of under-constrained materials can be predicted by very generic relations. This is relevant to understand systems as diverse as semi-flexible polymer networks like collagen, cell-based vertex models for biological tissue, colloidal gels, and membranes.

On this project, we work together with the theory group of Daniel Sussman (Atlanta).

How does the rheology of cellular materials - like biological tissues, emulsions, and foams - arise from their cellular structure? Combining microscopic simulations, the development of mesoscopic models, and experimental collaborations, we systematically dissect the relation between structure and non-linear visco-elasto-plastic material rheology.

On this project, we work together with the theory group of Simon Gsell (Marseille) and the experimental group of Léa-Laëtitia Pontani (Paris).