Publications

BackgroundCollective migration is the coordinated movement of a group of cells-a fundamental process in health and disease. Many models have been developed to study the molecular and physical mechanisms of collective migration. However, the aim of this study is to engineer a flexible in vitro framework that allows for mechanobiological quantification of the separate and combined contributions of individual cell mechanics to the directed migration of a collective. We utilised this framework to understand the role of juxtacrine Notch signalling during collective endothelial migration-an essential process during the formation of new blood vessels (known as angiogenesis).ResultsThis framework enables users to perform high spatiotemporal analysis of migrative behaviour, cell-matrix traction forces, and intercellular forces in different microenvironments. With this framework, we show that Notch inhibited collectives adopt a distinct regime of directed collective migration. Whereas the directionality of migration, traction forces and intercellular forces are not affected by Notch inhibition, we observed spatiotemporal differences in migration speed, traction force magnitude and normal and shear stresses within Notch-inhibited collectives.ConclusionsThe in vitro framework is a powerful approach for dissecting the mechanisms of collective migration. With this framework, we show that a potential link exists between the juxtacrine signalling of Notch and an increased mechanical cohesiveness among collective cells.

JTD Keywords: Angiogenesis, Cell-cell dynamics, Cell-matrix dynamics, Collective endothelial migration, Dynamics, Forces, In vitro framework, Juxtacrine notch signalling, Migration kinematics, Morphogenesis, Organization

Tissue morphogenesis occurs in a complex physicochemical microenvironment with limited experimental accessibility. This often prevents a clear identification of the processes that govern the formation of a given functional shape. By applying state-of-the-art methods to minimal tissue systems, synthetic morphogenesis aims to engineer the discrete events that are necessary and sufficient to build specific tissue shapes. Here, we review recent advances in synthetic morphogenesis, highlighting how a combination of microfabrication and mechanobiology is fostering our understanding of how tissues are built.Copyright © 2022 Elsevier Ltd. All rights reserved.

JTD Keywords: cell dynamics, elongation, endothelial-cells, epithelium, growth, lumen, mechanical tension, patterns, self-organization, synthetic morphogenesis, tissue folding, tissue mechanics, topological defects, Cell dynamics, Humans, Morphogenesis, Stem-cells, Synthetic morphogenesis, Tissue folding, Tissue mechanics, Tissue shape

Fluid deformable surfaces are ubiquitous in cell and tissue biology, including lipid bilayers, the actomyosin cortex or epithelial cell sheets. These interfaces exhibit a complex interplay between elasticity, low Reynolds number interfacial hydrodynamics, chemistry and geometry, and govern important biological processes such as cellular traffic, division, migration or tissue morphogenesis. To address the modelling challenges posed by this class of problems, in which interfacial phenomena tightly interact with the shape and dynamics of the surface, we develop a general continuum mechanics and computational framework for fluid deformable surfaces. The dual solid–fluid nature of fluid deformable surfaces challenges classical Lagrangian or Eulerian descriptions of deforming bodies. Here, we extend the notion of arbitrarily Lagrangian–Eulerian (ALE) formulations, well-established for bulk media, to deforming surfaces. To systematically develop models for fluid deformable surfaces, which consistently treat all couplings between fields and geometry, we follow a nonlinear Onsager formalism according to which the dynamics minimizes a Rayleighian functional where dissipation, power input and energy release rate compete. Finally, we propose new computational methods, which build on Onsager’s formalism and our ALE formulation, to deal with the resulting stiff system of higher-order partial differential equations. We apply our theoretical and computational methodology to classical models for lipid bilayers and the cell cortex. The methods developed here allow us to formulate/simulate these models in their full three-dimensional generality, accounting for finite curvatures and finite shape changes.

JTD Keywords: Capsule/cell dynamics, Computational methods, Membranes

Collective cell migration in tissues occurs throughout embryonic development, during wound healing, and in cancerous tumor invasion, yet most detailed knowledge of cell migration comes from single-cell studies. As single cells migrate, the shape of the cell body fluctuates dramatically through cyclic processes of extension, adhesion, and retraction, accompanied by erratic changes in migration direction. Within confluent cell layers, such subcellular motions must be coupled between neighbors, yet the influence of these subcellular motions on collective migration is not known. Here we study motion within a confluent epithelial cell sheet, simultaneously measuring collective migration and subcellular motions, covering a broad range of length scales, time scales, and cell densities. At large length scales and time scales collective migration slows as cell density rises, yet the fastest cells move in large, multicell groups whose scale grows with increasing cell density. This behavior has an intriguing analogy to dynamic heterogeneities found in particulate systems as they become more crowded and approach a glass transition. In addition we find a diminishing self-diffusivity of short-wavelength motions within the cell layer, and growing peaks in the vibrational density of states associated with cooperative cell-shape fluctuations. Both of these observations are also intriguingly reminiscent of a glass transition. Thus, these results provide a broad and suggestive analogy between cell motion within a confluent layer and the dynamics of supercooled colloidal and molecular fluids approaching a glass transition.

JTD Keywords: Active matter, Cell mechanics, Jamming, Collective cell dynamics, Nonequilibrium