Micro-patterned endogenous stroma equivalent induces polarized crypt-villus architecture of human small intestinal epithelium.

The small intestine is the major site for digestion, drug and nutrient absorption, as well as a primary site for many diseases. Current in vitro gut models fail in reproducing the complex intestinal extracellular matrix (ECM) network of the lamina propria and the peculiar architecture of the crypt-villus axis. Here we proposed a novel in vitro human intestine model that mimics the intestinal stromal topography and composition and strictly reproduces the tissue polarity with the crypt-villus architecture. First we developed a 3D human intestinal stromal equivalent (3D-ISE) composed of human intestinal subepithelial myofibroblasts (ISEMFs) embedded in their own extracellular matrix. Then, we seeded human colon carcinoma-derived cells (Caco-2) onto flat or patterned cell-synthetized stromal equivalent structure and cultured them until the formation of a well-oriented epithelium. We demonstrated that the patterned stroma increases the absorbing surface area, the epithelial proliferation rate, and the density of microvilli. In addition it induces changes in the biological functions of the epithelial cells such as enzymes and mucus production, polarization and tightness showing a physiological cell-lineage compartmentalization along the crypt/villi axes with the undifferentiated phenotypes at the base. At last, we reproduced an inflamed intestinal tissue model in which we identified the contribution of the stromal microenvironment by molecular (cytokines release and MMPs production) and immunofluorescence analyses and the effects of the epithelial-stromal cross-talk in the intestinal innate immunity by multiphoton investigation that revealed differences in the collagen network architecture.

STATEMENT OF SIGNIFICANCE: The intestinal stroma morphology and composition has a fundamental role in crypt-villus development and appropriate epithelial cell-lineage compartmentalization. On this base, here we develop an engineered organotypic model of human intestine equivalent in which a functional epithelial/ECM crosstalk is recapitulated. Due to its accessible luminal surface it provides a new platform for preclinical studies of mucosal immunology and bowel inflammation as well as the assessment of pharmaco-toxicity studies.