The Progress of Intestinal Epithelial Models from Cell Lines to Gut-On-Chip

Abstract

Over the past years, several preclinical in vitro and ex vivo models have been developed that helped to understand some of the critical aspects of intestinal functions in health and disease such as inflammatory bowel disease (IBD). However, the translation to the human in vivo situation remains problematic. The main reason for this is that these approaches fail to fully reflect the multifactorial and complex in vivo environment (e.g., including microbiota, nutrition, and immune response) in the gut system. Although conventional models such as cell lines, Ussing chamber, and the everted sac are still used, increasingly more sophisticated intestinal models have been developed over the past years including organoids, InTESTine™ and microfluidic gut-on-chip. In this review, we gathered the most recent insights on the setup, advantages, limitations, and future perspectives of most frequently used in vitro and ex vivo models to study intestinal physiology and functions in health and disease.

Keywords: ex vivo; gut-on-chip; in vitro; inflammation; intestine; organoids.

Figure 1

Illustration of in vitro and ex vivo models. Panel (a) schematic representation of a Transwell system, where epithelial cells, immune cells such as peripheral blood mononuclear cells (PBMCs), microbes, and other features can be co-cultured together. Panel (b) schematic representation of intestinal organoids highlighting the different cell types. Panel (c) shows the setup of Ussing chamber system where the temperature is maintained at 37 °C in the reservoir. Panel (d) is a representation of the everted gut sac system. The everted gut sac is transferred to the incubation flask containing oxygenated media. Panel (e) illustrates the designed system InTESTine^TM from TNO with apical and basolateral compartments [40]. Panel (a–d) illustrations were created with BioRender.com and permission of the authors were taken for using the illustration in panel (e).

Figure 2

This illustration describes an example of gut-on-chip system. Epithelial cells on the chip differentiate to form villi, and polarize to form microvilli on the apical side. In this system, epithelial cells can be cultured in direct exposure with intestinal microorganisms, nutrients, drugs, or metabolites. In some systems, endothelial cells are grown on the basolateral side of the ECM-coated membrane. This system guarantees a continuous flow of oxygen on the basolateral side by using oxygenated mammalian-cell culture medium, whereas it is possible to use other types of (anaerobic) culture media on the apical side of the system. Immune cells, metabolites and other features can be introduced in the model to mimic, for instance, specific disease situations. This illustration was created with BioRender.com.