Staff member

The intestinal epithelium is formed by villi and crypts. Intestinalstem cells (ISCs) located at the crypt base divide giving rise toproliferative cells that migrate up along the villi while differentiating,ultimately dying at the tips of the villi. This homeostasis is tightlycontrolled by biomolecular gradients of EGF, Wnt and BMP sig-naling pathways along the crypt-villus axis1. Intestinal organoids,despite including many physiologically relevant features, are notvalid cultures when access to the lumen is required. Here we present aculture platform that overcomes this limitation while comprising allkey features of the intestinal epithelium: 3D architecture, prolifera-tive and differentiated cell domains, and gradients of ISCs nichebiomolecules.Employing a simple photolithographic technique2, we fabricatedpoly(ethylene) glycol diacrylate (PEGDA) 3D villus-like scaffolds.We developed in silico models to simulate gradients of ISCs nichebiomolecules, we created them through the hydrogels by free diffusionand we characterized them by Light-sheet fluorescence microscopy.Organoid-derived intestinal epithelial cells covered the wholescaffold surface. The gradients profile and composition, constantover time, impacted on cell behavior by modifying the proportionand positioning of the different intestinal epithelial cell types alongthe vertical axis of our scaffold, faithfully recreating in vivo cellcompartmentalization.We have developed an apically accessible and 3D in vitro intes-tinal epithelial model, which bears biomolecular ISC niche gradientsand all relevant epithelial cell types. Therefore, we believe our modelcan be employed in many applications, particularly in the study ofintestinal epithelium biology in physiological and pathologicalconditions.

JTD