Physics-Biology interface seminar: Pascal Silberzan


11:00 - 12:00

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Confining and releasing cell monolayers

Pascal Silberzan (Institut Curie, Paris)

Cell monolayers routinely exhibit collective behaviors largely controlled by cell-cell interactions. In this context, confinement and boundary conditions play an important role in the organization and dynamics of these cell assemblies. Interestingly, many in vivo processes, including morphogenesis or tumor maturation, involve small populations of cells within a spatially restricted region.

We report experiments in which epithelial monolayers confined in circular disks exhibit low-frequency periodic radial displacement modes. When the boundary is removed, cells collectively migrate on the free surface. The essential characteristics of the collective dynamics in these two situations are well-accounted for by the same theoretical model in which cells are described as persistent random walkers which adapt their motion to that of their neighbors.

In contrast, elongated fibroblasts that do not develop significant cell-cell adhesions self-organize until reaching a perfect nematic order upon confinement in linear stripes. When the cells are confined within a disk, the number and charge of the topological defects characteristic of nematics can be controlled, emphasizing the role of friction in this active nematic system.

After days in culture, the confined epithelia develop a tridimensional structure in the form of a peripheral cell cord at the domain edge. Confinement by itself is therefore sufficient to induce morphogenetic-like processes including spontaneous collective pulsations, global orientation and transition from 2D to 3D.

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