Test Master Calendar (OCR)

Abstract 

Living systems offer a remarkable design principle: individual agents such as cells, insects, or microorganisms, can physically couple to form a solid material whose mechanical properties and internal organization emerge collectively from local interactions. In this seminar, I will explore the concept of the living solid, in which biological agents actively control the mechanics and morphogenesis of the material they form. A brief example from our previous work on fire-ant rafts will illustrate how collective mechanics can emerge from simple behavioral rules operating through mechanical coupling.

The seminar will then focus on monolayers of endothelial cells, the epithelial lining of blood vessels, as a model system for self-organization in a physiological context. Endothelial cells are self-propelling agents that collectively form flocks whose organization has profound consequences for vascular morphogenesis and cardiovascular disease. Using cell-resolved simulations validated against experimental data from collaborators, we propose that coherent laning patterns are governed by cell-cell viscosity, a dissipative interaction mediated by cadherin junction remodeling, rather than by active contractility, which is commonly assumed to be the primary driver. Treating cells as a shear-thinning fluid reproduces the stable, periodic laning patterns observed experimentally, with the shear-thinning response suppressing large-scale coarsening and selecting a finite lane width.

Finally, I will argue that cells are not passive force transmitters but computing units that sense mechanical signals, integrate information from their neighbors, and generate active responses, opening new avenues for understanding pattern selection and adaptability in living solids.

About the Speaker

Franck Vernerey is a professor in the Department of Mechanical Engineering at the University of Colorado, Boulder. He received his Ph.D. from Northwestern University in 2006 in the field of theoretical and applied mechanics. His interests are in developing statistical mechanics approaches to understand the emerging response of network-like materials in biology and their synthetic analog. These networks span several orders of magnitude, from the molecular scale (polymers) to the micron scale (cell networks) and the macroscale (insect aggregations and entangled filaments). Although theoretical, this research has applications in the mechanical characterization of living materials, the computational design of biopolymers for regenerative medicine as well as the development of bio-inspired functional soft materials. Dr. Vernerey is the author of more than 100 scientific publications in peer-reviewed journals and book chapters. He is also the recipient of the NSF career award in 2014 and the Presidential Early Career Award for Scientists and Engineers (PECASE) in 2017. 

Host: Professor Taher Saif