Control of lumen geometry and topology by the interplay between pressure and cell proliferation rate in pancreatic organoids

Many internal organs in multicellular organisms comprise epithelia which enclose fluid-filled cavities. These are referred to as lumens and their formation is regulated by a wide range of processes, including epithelial polarization, secretion, exocytosis and actomyosin contractility [1, 2]. While these mechanisms have shed light on lumen growth, what controls lumen morphology remains enigmatic. Here we use pancreas organoids to explore how lumens acquire either a spherical shape or a branched topology [3]. Combining computational simulations based on a phase field model with experimental measurements we reveal that lumen morphology arises from the balance between the cell cycle duration and lumen pressure, with more complex lumen at low pressure and fast proliferation rates. Moreover, the manipulation of proliferation and lumen pressure in silico and in vitro is sufficient to alter and reverse the morphological trajectories of the lumens. Increasing epithelial permeability of spherical lumens lead to lower lumen pressure and converts their morphology to complex lumen shapes, highlighting its crucial role. In summary, the study underscores the importance of balancing cell proliferation, lumen pressure, and epithelial permeability in determining lumen morphology, providing insights relevant to other organs, for tissue engineering and cystic disease understanding and treatment [4].