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Generating an In Vitro Gut Model with Physiologically Relevant Biophysical Mucus Properties

Abstract

Introduction

Gastrointestinal (GI) in vitro models have received lasting attention as an effective tool to model drug and nutrient absorption, study GI diseases, and design new drug delivery vehicles. A complete model of the GI epithelium should at a minimum include the two key functional components of the GI tract: mucus and the underlying epithelium. Mucus plays a key role in protecting and lubricating the GI tract, poses a barrier to orally administered therapies and pathogens, and serves as the microenvironment for the GI microbiome. These functions are reliant on the biophysical material properties of the mucus produced, including viscosity and pore size.

Methods

In this study, we generated in vitro models containing Caco-2 enterocyte-like cells and HT29-MTX goblet-like cells and determined the effects of coculture and mucus layer on epithelial permeability and biophysical properties of mucus using multiple particle tracking (MPT).

Results

We found that mucus height increased as the amount of HT29-MTX goblet-like cells increased. Additionally, we found that increasing the amount of HT29-MTX goblet-like cells within culture corresponded to an increase in mucus pore size and mucus microviscosity, measured using MPT. When compared to ex vivo mucus samples from mice and pigs, we found that a 90:10 ratio of Caco-2:HT29-MTX coculture displayed similar mucus pore size to porcine jejunum and that the mucus produced from 90:10 and 80:20 ratios of cells shared mechanical properties to porcine jejunum and ileum mucus.

Conclusions

GI coculture models are valuable tools in simulating the mucus barrier and can be utilized for a variety of applications including the study of GI diseases, food absorption, or therapeutic development.

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Acknowledgments

We would like to thank the UMD Bioworkshop for core facility usage and Michele Kaluzienski for assisting with manuscript preparation. This work was funded by the University of Maryland New Directions Fund and Faculty-Student Research Award (KM) and the AHA Predoctoral Research Fellowship (JM).

Conflict of Interest

The authors (JM, AS, and KM) have no conflict of interest to declare.

Ethical Approval

No human studies were carried out by the authors for this article. No animal studies were carried out by the authors for this article.

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Correspondence to Katharina Maisel.

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McCright, J., Sinha, A. & Maisel, K. Generating an In Vitro Gut Model with Physiologically Relevant Biophysical Mucus Properties. Cel. Mol. Bioeng. 15, 479–491 (2022). https://doi.org/10.1007/s12195-022-00740-0

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Keywords

  • Gastrointestinal tract
  • Multiple particle tracking
  • Caco-2
  • HT29-MTX
  • Goblet cells
  • Enterocyte
  • Viscosity
  • Microrheology