CCB Seminar: Collective cell mechanics of organoids and epithelial sheets

Presenter: Jan Rozman (Jožef Stefan Institute)

Topic: Collective cell mechanics of organoids and epithelial sheets 

The study of organoids, artificially grown cell aggregates with the functionality and small-scale anatomy of real organs, is one of the most active areas of research in biology and biophysics, yet the basic physical origins of their different morphologies remain poorly understood. Using a 3D surface tension-based vertex model of epithelial shells, we reproduce the characteristic shapes from branched and budded to invaginated structures. We find that the formation of branched morphologies relies strongly on junctional activity, resulting in aggregations of topological defects in cell packing. To test whether this reliance of branching on topological activity is a more universal mechanism or a consequence of the model organoids being a highly constrained systems with relatively few cells, we then compare their morphologies to those of unsupported epithelial monolayers, also subject to active junctional noise. Together, this work provides a generic interpretation of many observed epithelial tissue shapes, highlighting the role of physical factors such as differential surface tension, cell rearrangements, compression, and tissue growth.