Primary exploration of host–microorganism interaction and enteritis treatment with an embedded membrane microfluidic chip of the human intestinal–vascular microsystem

Abstract

Intestinal flora plays a crucial role in the host’s intestinal health. Imbalances in the intestinal flora, when accompanied by inflammation, affect the host’s intestinal barrier function. Understanding it requires studying how living cells and tissues work in the context of living organs, but it is difficult to form the three-dimensional microstructure intestinal–vascular system by monolayer cell or co-culture cell models, and animal models are costly and slow. The use of microfluidic-based organ chips is a fast, simple, and high-throughput method that not only solves the affinity problem of animal models but the lack of microstructure problem of monolayer cells. In this study, we designed an embedded membrane chip to generate an in vitro gut-on-a-chip model. Human umbilical vein endothelial cells and Caco-2 were cultured in the upper and lower layers of the culture chambers in the microfluidic chip, respectively. The human peripheral blood mononuclear cells were infused into the capillary side at a constant rate using an external pump to simulate the in vitro immune system and the shear stress of blood in vivo. The model exhibited intestine morphology and function after only 5 days of culture, which is significantly less than the 21 days required for static culture in the Transwell® chamber. Furthermore, it was observed that drug-resistant bacteria triggered barrier function impairment and inflammation, resulting in enteritis, whereas probiotics (Lactobacillus rhamnosus GG) improved only partially. The use of Amikacin for enteritis is effective, whereas other antibiotic therapies do not work, which are consistent with clinical test results. This model may be used to explore intestinal ecology, host and intestinal flora interactions, and medication assessment.

Lab-on-chip technologies for exploring the gut–immune axis in metabolic disease

“…As introduced in section 2, mucus plays an important role in intestinal homeostasis, 55,182 yet it has not been an area of focus thus far in gut–immune lab-on-chip models. Given that Caco2 cells were shown to differentiate into all four major epithelial cell types, presence of mucus production was confirmed in Caco2 only models 22,31,32,161 and some limited mucus-focused studies were noted. For example, Jing et al (2022) investigated dextran sodium sulfate (DSS) induced mucus layer injury together with the ability of chitosan oligosaccharides (COS) to regulate mucus secretion and reduce injury; 32 while De gregorio et al (2022) monitored bacterial localisation within the mucus layer.…”

“…As introduced in section 2, mucus plays an important role in intestinal homeostasis, 55,182 yet it has not been an area of focus thus far in gut-immune lab-on-chip models. Given that Caco2 cells were shown to differentiate into all four major epithelial cell types, presence of mucus production was confirmed in Caco2 only models 22,31,32,161 and some limited mucus-focused studies were noted. For example, Jing et al…”

“…Zhao et al (2022) 161 therefore set out to overcome this challenge with a sealing channel design. 161 Their device comprised a PDMS chip with sealing channels into which liquid PDMS was injected to embed a collagen-coated porous PC membrane (Fig. 3F).…”

“…179 Organoid dissociation and subsequent growth as monolayers or within microfluidic lab-on-chip platforms overcomes some of these challenge. 23,161 Organoids are however still limited in that they generally do not include other physiological components such as the immune system. Tissue explants offer enhanced tissue-like features 180 and recent studies have demonstrated incorporation thereof in microfluidic models, such as Richardson et al (2020), Martinez et al (2022) and Cherwin et al (2023) which, using mouse explants, showed the presence of microbiota, 166 studied SCFA profiles as a function of oxygen conditions 181 and showed presence of immune (mast) cells 162 respectively.…”

“…In terms of the intestinal epithelial components of the nonexplant lab-on-chip studies in this review (Table 3) which incorporate intestinal epithelial and immune components, many of the studies, especially the earlier ones, have relied on commercially available cell lines (Caco2, HT-29). Caco2 are known to differentiate into enterocyte-like cells over a period of 21 days in conventional static culture, however lab-on-chip studies have more recently shown accelerated growth and differentiation, with three to seven, but most commonly five, days reported 28,31,32,149,151,155,160,161,175 Further, microfluidic conditions have also been shown in multiple studies to improve polarization, three-dimensional crypt-villi morphology 149,155 and differentiation. Under perfusion and strain conditions, Caco2 cells have further been shown to differentiate into the four major intestinal epithelial cell types namely, absorptive, mucussecretory, enteroendocrine, and Paneth cells, which had not previously been seen in static cultures, 28,33,163 while also exhibiting improved glucose reuptake and mucus production.…”