In vitro demonstration of intestinal absorption mechanisms of different sugars using 3D organotypic tissues in a fluidic device.

Alessandra Marrella

doi:10.14573/altex.1908311

Abstract

Intestinal permeability is crucial in regulating the bioavailability and, consequently, the biological effects of drugs and compounds. However, systematic and quantitative studies of the absorption of molecules are quite limited due to a lack of reliable experimental models able to mimic human in vivo responses. In this work, we present an in vitro perfused model of the small intestinal barrier using a 3D reconstructed intestinal epithelium integrated into a fluid-dynamic bioreactor (MIVO®) resembling the physiological stimuli of the intestinal environment. This platform was investigated in both healthy and induced pathological conditions by monitoring the absorption of two non-metabolized sugars, lactulose and mannitol, frequently used as indicators of intestinal barrier dysfunctions. In healthy conditions, an in vivo-like plateau of the percentage of absorbed sugars was reached, where mannitol absorption was much greater than lactulose absorption. Moreover, a model of pathologically altered intestinal permeability was generated by depleting extracellular Ca2+, using a calcium-specific chelator. After calcium depletion, the pattern of sugar passage observed under pathological conditions was reversed only in dynamic conditions in the MIVO® chamber, due to the dynamic fluid flow beneath the membrane, but not in static conditions. Therefore, the combination of the MIVO® with the EpiIntestinal™ platform can represent a reliable in vitro model to study the passage of molecules across the healthy or pathological small intestinal barrier by discriminating the two main mechanisms of intestinal absorption.

Highlights

The intestinal epithelium is the main access point of nutrients and orally administered drugs to the systemic circulation (Ganapathy, 2012)
Animal-based tests reproduce the dynamic stimuli of the intestinal environment mediated by the systemic blood circulation, it is impossible to selectively distinguish and decouple all the variables involved in the passage of molecules through the intestinal barrier in human intestinal tissues (Cao et al, 2006)
Cells were obtained from commercial sources or isolated from tissues obtained from the International Institute for the Advancement of Medicine (IIAM; Scranton, PA) through the Organ Procurement Organization (OPO)

Summary

Introduction

The intestinal epithelium is the main access point of nutrients and orally administered drugs to the systemic circulation (Ganapathy, 2012). Animal-based tests reproduce the dynamic stimuli of the intestinal environment mediated by the systemic blood circulation, it is impossible to selectively distinguish and decouple all the variables involved in the passage of molecules through the intestinal barrier in human intestinal tissues (Cao et al, 2006). For these reasons, there is a growing interest to develop advanced, human-relevant in vitro models, where key parameters such as intestinal permeability and tissue barrier properties can be controlled and monitored at low cost and reduced time

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Results

Conclusion