Professor SUNY Binghamton, New York, United States
Introduction:: The intestinal microbiome population varies with diet, age, and disease conditions. Generating a mock community from samples such as a stool specimen lacks reproducibility and also does not replicate the microbiome of different regions in the intestine. In the current work, we have developed a small intestine on a chip with both mammalian cells and a community of commensal bacteria. The bacteria used in our work are four of the six common genera found in the duodenum. Furthermore, the use of mechanical stimulation generated a close to in vivo environment on the chip.
Materials and Methods:: The microfluidic device was fabricated by polycarbonate machining and consists of two chambers separated by a porous polyester membrane. The apical chamber was seeded with Caco-2 and HT29-MTXE12 at a ratio of 3:1 to mimic the intestinal epithelium. To mimic the microbiota a biofilm composed of four species of bacteria, specifically Bifidobacterium bifidum, Enterococcus faecalis, Lacticaseibacillus rhamnosus, and Streptococcus salivarius1 was seeded on top of the in vitro gut epithelium. The gut on a chip was cultured under dynamic conditions at various flow rates and durations. A Lucifer yellow permeability assay and confocal microscopy were used after various time points to determine the robustness of the in vitro intestinal barrier.
Results, Conclusions, and Discussions:: The epithelial barrier showed the formation of tight junctions as early as 5 days of flow with a shear stress of 3.3 mdyn/cm2 (Figure 1(a)). We could also discern villi-like structure formation in the presence of dynamic condition. Successful culture of mammalian cells along with the 4 species microbiota mixture was achieved in our microfluidic device for more than 4 days. The mammalian cell layer maintained tight junctions even in the presence of commensal such as L. rhamnosus and opportunistic bacteria such as E. faecalis2 (Figure 1(b)). The barrier permeability was comparable to the control after 2 days of co-culture as seen from the Lucifer yellow assay (Figure 1(c)). We designed and validated a microfluidic device that replicates the human small intestine by mimicking the human intestinal epithelium, microbiota, and dynamic conditions. Stable barrier integrity for a longer period will enable us to carry out long-term studies on the gut on a chip. Our small intestine on a chip can be used to study interactions of various food additives and medications with the small intestinal cells and the microbiome effectively.
Acknowledgements (Optional): : This work was funded by the National Institutes of Health (R01ES028788)
