CCB Seminar: From single cells to collective response in jammed model tissues

Presenter: John Treado (Yale University)

Topic: From single cells to collective response in jammed model tissues

The mechanical, structural, and ultimately functional properties of tissues depend heavily on the mechanical properties of individual constituent cells. A key challenge to modeling and predicting the behavior of tissues is due to the complexity of cell mechanical behavior; for example, how can floppy, deformable cells come together to construct a solid-like tissue? We address this question using simulations of jammed, two-dimensional, purely-repulsive deformable particles. We study the vibrational properties of both single cells and jammed packings of cells, and elucidate the conditions necessary for the onset of rigidity. We find that floppy cells form jammed structures through exotic, “quartic” vibrational modes that can stabilize multiple degrees of freedom simultaneously, while packings of more rigid cells do not contain such modes. Quartic modes in packings of floppy cells are found to have non-trivial dependence on cell shape, and contribute to significant shape deformation during linear response. Our results demonstrate that deformable cells construct jammed solids that fundamentally differ from jammed solids made of rigid cells, indicating the importance of modeling explicit particle shape change in biological contexts and beyond.