Title: Surprising material properties of biological tissues
Abstract: Many tissues in your body are composed of tightly packed, or confluent, cells, and the mechanical properties and dynamical behavior of these “materials” help govern important processes such as embryonic development, wound healing, and cancer progression. Our goal has been to develop tractable models that make accurate predictions for these properties, and in the process we’ve discovered that these models exhibit rich and unexpected physics. For example, they exhibit a “jamming” transition governed by a purely geometric minimal surface criterion, which is qualitatively different from jamming in normal particulate matter. This prediction has been successfully validated in cells from the lungs of human patients. These models also have weird surface tension properties — when probed mechanically, interfaces between two tissue types behave just as predicted from equilibrium stat mech, but the interfaces are orders of magnitude sharper than expected from standard capillary wave arguments, due to the topological nature of cell-cell interactions. For biologists and bioengineers, these results lead to new tools for measuring mechanical properties of tissue, as well as new, testable hypotheses about mechanisms for tissue organization in cancer, asthma, wound healing, and morphogenesis.