Dynamic flow and shear stress as key parameters for intestinal cells morphology and polarization in an organ-on-a-chip model

Chiara A M Fois,Peter Valtchev,Aaron Schindeler,Fariba Dehghani

doi:10.1007/s10544-021-00591-y

Abstract

Gut-on-a-chip microfluidic devices have emerged as versatile and practical systems for modeling the human intestine in vitro. Cells cultured under microfluidic conditions experience the effect of shear stress, used as a biomechanical cue to promote a faster cell polarization in Caco-2 cells when compared with static culture conditions. However, published systems to date have utilized a constant flow rate that fails to account for changes in cell shear stress ({tau }_{c}) resulting from changes in cell elongation that occur with differentiation. In this study, computational fluid dynamics (CFD) simulations predict that cells with villi-like morphology experience a {tau }_{c} higher than bulge-like cells at the initial growth stages. Therefore, we investigated the use of a dynamic flow rate to maintain a constant {tau }_{c} across the experiment. Microscopic assessment of cell morphology and dome formation confirmed the initiation of Caco-2 polarization within three days. Next, adopting our dynamic approach, we evaluated whether the following decreased flow could still contribute to complete cell differentiation if compared with the standard constant flow methodology. Caco-2 cells polarized under both conditions, secreted mucin-2 and villin and formed tight junctions and crypt-villi structures. Gene expression was not impacted using the dynamic flow rate. In conclusion, our dynamic flow approach still facilitates cell differentiation while enabling a reduced consumption of reagents.

Highlights

In the development of functional foods, pharmaceuticals, and nutraceuticals it is important to understand their absorption in the gastrointestinal tract (GIT)
This morphology is different from the one adopted in the bulge model theory, in which cells are considered as hemispherical bodies inside a microchannel, 1 3
Combining in silico computational fluid dynamics (CFD) simulations and in vitro microfluidic culture has given us unique insights into the relationship between cell differentiation and morphology and biomechanical cues such as shear stress

Summary

Introduction

In the development of functional foods, pharmaceuticals, and nutraceuticals it is important to understand their absorption in the gastrointestinal tract (GIT). Different approaches are used to estimate the absorption of active compounds in the GIT such as in silico simulations, in vitro models, in vivo testing on animal models, and clinical trials (Fois et al 2019). Clinical trials are the gold standard for measuring the absorption of active compounds and their functionality, yet they are neither a viable nor cost-effective approach for screening libraries of bioactive compounds. Various gut-on-a-chip have been developed during the last decade, incorporating different cell types. These range from patient-derived cells to other immortalized cell lines with different features of the human intestine (Beaurivage et al 2020; Gijzen et al 2020; Kasendra et al 2018; JaliliFiroozinezhad et al 2019). Colorectal carcinoma Caco-2 cells are widely used for studying the absorption and efficacy of active compounds in both standard and the

Methods

Results

Conclusion