Abstract 374: Small intestinal organoids to study the effects of tight junction modulators that may improve the absorption of orally-administered, anti-neoplastic drugs
Authors: Ubertini Valentina , French Stephanie , Wilson James , Ponthan Frida 
Published: June 2022

Abstract
Although oral dosing is the most convenient route of drug administration, most anti-neoplastic drugs are administered intravenously due to poor bioavailability because of the epithelial barriers. A major organ involved in oral drug absorption is the small intestine where enterocytes are linked together by tight junctions (TJs). TJs regulate paracellular transport by creating a selectively-permeable barrier to small molecules, ions and water, thereby restricting the uptake of drugs. Transient modulation of the TJs is considered a potential strategy to improve drug delivery. Human small intestinal (SI) organoids are 3D in vitro models of the epithelium which recapitulate the structure and function of the small intestine. However, their geometry prevents access to the apical compartment of the epithelium (the outer, or luminal, surface being located within the organoid with the basal surface on the outside), making them unsuitable for the study of orally-administered drugs. Here we describe methods to generate transwell cell monolayers and inverted or ‘apical-out’ organoids, both derived from normal human small intestine, that allow direct access to the apical surface. We demonstrate that both formats provide an in vivo-like cell composition, comprising of all the intestinal cellular types, including stem cells, Paneth cells, goblet cells, enteroendocrine cells and enterocytes, and respond to treatment with ‘tool drug’ TJ modulators such as sodium caprate, chitosan, EGTA and various cytokines. Briefly, for the generation of transwell-grown cell monolayers, SI organoids were dissociated into single cells and plated in matrix-coated transwell inserts. The monolayer formation was followed by live imaging and Trans-Epithelial Electrical Resistance (TEER) measurements. Treatments with TJ modulators were applied after TEER reached a plateau and effects on TJs were evaluated by TEER reduction, FITC-Dextran permeability increase and analysis of TJ proteins by immunofluorescence. For the generation of apical-out organoids, SI organoids were mechanically broken into fragments and seeded in low adhesion plates until the organoids switched polarity. Treatments with TJ modulators were applied and effects on TJs were evaluated by immunofluorescence. In conclusion, our models provide an innovative in vitro solution to study the effect of TJ modulators on increasing paracellular transport of orally-administered, anti-neoplastic drugs. Furthermore, as anti-neoplastic drugs can also have toxic effects on the intestinal epithelium by affecting TJs, thereby creating a leaky barrier, the models are useful to predict such effects and stratify drug candidates prior to in vivo studies.
Citation Format: Valentina Ubertini, Stephanie French, James Wilson, Frida Ponthan. Small intestinal organoids to study the effects of tight junction modulators that may improve the absorption of orally-administered, anti-neoplastic drugs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 374.