Organ-on-Chip Approaches for Intestinal 3D In Vitro Modeling

Abstract

The intestinal epithelium has one of the highest turnover rates in the human body, which is supported by intestinal stem cells. Culture models of intestinal physiology have been evolving to incorporate different tissue and microenvironmental elements. However, these models also display gaps that limit their similarity with native conditions. Microfluidics technology arose from the application of microfabrication techniques to fluid manipulation. Recently, microfluidic approaches have been coupled with cell culture, creating self-contained and modular in vitro models with easily controllable features named organs-on-chip. Intestine-on-chip models have enabled the recreation of the proliferative and differentiated compartments of the intestinal epithelium, the long-term maintenance of commensals, and the intraluminal perfusion of organoids. In addition, studies based on human primary intestinal cells have shown that these systems have a closer transcriptomic profile and functionality to the intestine in vivo, when compared with other in vitro models. The design flexibility inherent to microfluidic technology allows the simultaneous combination of components such as shear stress, peristalsis-like strain, 3-dimensional structure, oxygen gradient, and co-cultures with other important cell types involved in gut physiology. The versatility and complexity of the intestine-on-chip grants it the potential for applications in disease modeling, host-microbiota studies, stem cell biology, and, ultimately, the translation to the pharmaceutical industry and the clinic as a reliable high-throughput platform for drug testing and personalized medicine, respectively. This review focuses on the physiological importance of several components that have been incorporated into intestine-on-chip models and highlights interesting features developed in other types of in vitro models that might contribute to the refinement of these systems.

Quantifying the transport of biologics across intestinal barrier models in real-time by fluorescent imaging

“…Thus, the biological complexity of the model could potentially be increased by replacing the commonly used Caco-2 and HT29 cell lines with a more biological relevant cell pool, e.g. from intestinal organoids (Bein et al, 2018;Beaurivage et al, 2020;Naumovska et al, 2020;Pimenta et al, 2022). "…”

Perspective: Leveraging the Gut Microbiota to Predict Personalized Responses to Dietary, Prebiotic, and Probiotic Interventions

“…Direct contact with host tissues can be achieved in vitro in organoid or organ-on-a-chip models ( 59 , 60 ), which can be connected microfluidically with peristaltic pumps ( 61 ). Advances in coupling microfluidic and cell culture approaches with 3D organ-on-a-chip systems have allowed for novel experimental possibilities and have greatly increased in vitro model complexity ( 62 ).…”

“…Furthermore, the lack of complex multitissue interactions and the buildup of metabolites give rise to an artificial environment for the microbiota, which leads to “bottle effects” where the ecology of the in vitro community begins to diverge from what it would look like in vivo ( 64 ). Nonetheless, significant progress in culturing and isolation methods, host cell and tissue culturing, and the release of multiple gut microbiota strain banks that contain representative commensal strain diversity from large and diverse human populations, such as the Broad Institute-OpenBiome Microbiome Library ( 65 ) and the Global Microbiome Conservancy ( 66 ), in combination with the development of more robust experimental systems that include host tissues ( 60 , 61 ), continue to widen the scope of applicability of in vitro models.…”

Gut-on-a-chip for disease models

“…The digestive, absorption and barrier functions of the small intestine are closely related to its unique structural features, such as villi and microvilli structures, mucus layers and periodic peristalsis. 1 – 3 The large surface area of the villi enhances absorption in the small intestine. 4 The mucus layer is the first significant barrier between the small intestine and external world.…”

“… 3 , 21 , 22 Based on intestinal functions, gut-on-a-chip introduces modules with different parts, such as an injection pump for fluid flow and a pressure system for mechanical deformation. 1 , 23 – 25 Many modules, including the trans-epithelial electrical resistance (TEER) module, pH module and metabolite analysis module, have been introduced to detect cell growth on a chip in real-time. 26 Therefore, the concept of ‘multi-organs-on-a-chip’ can aid in providing new insights into diseases and has also been proposed to examine certain conditions involving multiple organs.…”