Generation of a Bovine Primary Enteroid-Derived Two-Dimensional Monolayer Culture System for Applications in Translational Biomedical Research.

Organoid cell culture systems can recapitulate the complexity observed in tissues, making them useful in studying host-pathogen interactions, evaluating drug efficacy and toxicity, and tissue bioengineering. However, applying these models for the described reasons may be limited because of the three-dimensional (3D) nature of these models. For example, using 3D enteroid culture systems to study digestive diseases is challenging due to the inaccessibility of the intestinal lumen and its secreted substances. Indeed, stimulation of 3D organoids with pathogens requires either luminal microinjection, mechanical disruption of the 3D structure, or generation of apical-out enteroids. Moreover, these organoids cannot be co-cultured with immune and stromal cells, limiting in-depth mechanistic analysis into pathophysiological dynamics. To circumvent this, we optimized a bovine primary cell two-dimensional (2D) enteroid-derived monolayer culture system, allowing co-culture with other relevant cell types. Ileal crypts isolated from healthy adult cattle were cultured to generate 3D organoids that were cryopreserved for future use. A 2D monolayer was created using revived 3D enteroids that were passaged and disrupted to yield single cells, which were seeded on basement membrane extract-coated transwell cell culture inserts, thereby exposing their apical surface. The intestinal monolayer polarity, cellular differentiation, and barrier function were characterized using immunofluorescence microscopy and measuring transepithelial electrical resistance. Stimulation of the apical surface of the monolayer revealed the expected functionality of the monolayer, as demonstrated by cytokine secretion from both apical and basal compartments. The described 2D enteroid-derived monolayer model holds great promise in investigating host-pathogen interactions and intestinal physiology, drug development, and regenerative medicine.