Title: Characterizing the mechanical properties of epithelial monolayers through compression and fracture.

By : Jonathan Fouchard, G. Charras Lab, London, UK

Summary:

To date, much research has focused on how tissues build and repair themselves, as well as how their integrity is maintained. Yet, intriguingly, almost nothing is known about how living tissues crack and what the mechanical and biological conditions leading to this rupture are. Here I will present a systematic analysis of fracture tests performed on suspended epithelial monolayers. These monolayers are devoid of ECM and are a minimal model representative of many epithelia involved in early development. In our experiments, monolayers are cultured between two flexible rods which allow the monolayer to be stretched in a controlled manner. The formation of experimenter-induced or self-induced cracks is then monitored in the aim to identify the biological actors involved in tissue resistance.

Within the same assay, we also study the response of epithelia to compressive stress. We find that buckling of the tissue can spontaneously be reversed through cell shape changes controlled by the acto-myosin cytoskeleton. This lead us to the definition of a rheological model including visco-elasticity and contractility.