Characterization of a microfluidics-based in vitro model of the gastrointestinal human-microbe interface
Homeostasis within the human intestinal microbiome has been found to be related to the body’s maintenance of health and development of diseases. The University of Arizona’s Center for Applied NanoBioscience and Medicine (ANBM) has developed the in vitro HuMiX (human-microbial crosstalk) device to analyze human-host interactions with gastrointestinal microbiota. During testing at the University of Luxembourg’s Center for Systems Biomedicine (LUX), fewer than half of the originally inoculated cells were harvested, leading researchers to suspect problems with the device design or methodology in removing the cells. In establishing the HuMiX system at ANBM, systematic evaluation and characterization of each component of the device was performed to optimize the cell growth conditions and improve the device’s ability to recapitulate in vivo responses during co-culture of human epithelial (Caco-2) cells, bacteria (Lactobacillus rhamnosus GG/LGG) cells, and immune (CD4+) T cells. To understand where and how cells were lost in the culture device, we (1) evaluated optimal cell seeding densities, (2) applied coatings of different hydrophobic substances to prevent cells adherence with gasket, and (3) collected output medium from the device to analyze cell counts. Results showed that for confluency on the device’s gasket-membrane in a 7-day culture, the initial cell seeding density must be greater than 6*105 cells or that concentration of cells must be in culture for greater than seven days. Coatings did not significantly affect cell recovery. The closed one-chamber study indicated that low cell recovery was not simply due to cells sticking to the gasket surface. Insufficient cell harvest, inadvertent cell loss during medium change, and cell death after seeding in the confined environment could have contributed to low recovery rate observed at LUX. We are now advancing to evaluate a two-chamber co-culture set up followed by a three-chamber co-culture device with continuous perfusion in a complete HuMiX system.