Title: Origin of fluidity, jamming and glassy behavior in biological tissues

Abstract: Cells must move through tissues in many important biological processes, including embryonic development, cancer metastasis, and wound healing. Often these tissues are dense and a cell’s motion is strongly constrained by its neighbors, leading to glassy dynamics. Although there is a density-driven jamming transition in particulate matter, these cannot explain liquid-to-solid transitions in tissues. I will demonstrate the existence of a new type of rigidity transition that occurs in confluent tissue monolayers at constant density. The onset of rigidity is governed by a model parameter that encodes single-cell properties such as cell-cell adhesion and cortical tension. I will also introduce a new model that simultaneously captures polarized cell motility and multicellular interactions in a confluent tissue and identify a glass transition line that originates at the critical point of the rigidity transition. This transition exhibits several hallmarks of a second-order phase transition, such as a growing correlation length and a universal critical scaling. I will elucidate the nature of rigidity transitions in dense biological tissues and other cellular structures using a generalized Maxwell constraint counting approach.

Host: Karen Daniels