Mechanics and growth of tissues 
 

Speaker: Jean-Francois Joanny (Institut Curie, Paris)
Jean-Francois Joanny, Professor of Physics at the UMPC (University Pierre et Marie Curie) and  Director of the UMR (Curie Physico-Chemistry Unit), teaches physics, and although he belongs to the chemistry department, his current research concerns questions in cellular biology.

He started his scientific career with research on ’wetting’,  switched to ’polymers’ , and then to biology, studying problems at the scale of the cell, e.g. intercellular transport and the cytoskeleton. Because a good physical understanding requires quantitative comparison between theory and experiment, systematically varying controlled parameters, his group works in close collaboration with experimental groups (Institut Curie, UMR).

Besides several other prestigious awards in the past, in 2008 he was awarded the silver medal of Le Centre National de la Recherche Scientifique (CNRS).
In this talk, we present some recent results on the growth and mechanical properties of healthy and cancerous tissues.

We first show that because of the coupling between cell division and the local stress, a tissue can be considered as a visco-elastic liquid with a relaxation time smaller than the cell division time. We also discuss the role of the interstitial liquid between the cells. We give examples of the liquid behavior related to the competition for space between two tissues and discuss the stability of the interface between two tissues.

We present numerical simulations of tissues based on a dissipative particle dynamics algorithm. The simulations confirm the liquid-like behavior of the tissue and have been used to study the rheology of the tissue.

Finally, we discuss the steady state structure of villis which are the protrusions of the surface of the intestine or the colon. We describe the formation of villis as a buckling instability of a polar cell monolayer. The polarity of the layer does not seem to play a role in the intestine where the villis are arranged in a square array but it is important in the colon where they are organized in a hexagonal array.
 
Please keep the following dates free in your diary:
Thursday March 29th  2012 at 16.00 hrs., Cees Stam (VUmc)
Thursday April 26th  2012 at 16.00 hrs., Marcus Sauer (Bielefeld)
Thursday May 31st 2012 at 16.00 hrs., Florian Schiestl (Zurich)