In the small intestine, the complex interplay between the epithelium, lumen contents, and the underlying tissue works to maintain homeostasis. Breakdown of this homeostasis can cause chronic inflammation and diseases such as Inflammatory Bowel Disease. Populations of immune cells present in the intestinal lamina propria play key roles in differentiating between commensal bacteria and pathogens and between harmful and normal antigens; however, many in vitro models do not include immune cells despite their importance to the intestinal environment. This study aims to examine the complex crosstalk between immune cells, the epithelium, and lumen contents using an in vitro human intestinal model containing dendritic cells (DCs). Previous work in our laboratory developed a mesofluidic device incorporating a vertical hydrogel wall to enable visualization and analysis of the live intestinal mucosal barrier on a chip. This device includes central and side channels representing the intestinal lumen and circulatory flow, respectively. To incorporate DCs into the device, cells were seeded directly within the collagen hydrogel wall separating these channels or on the wall in the side channel. Organoid-derived primary duodenal cells were seeded on the hydrogel wall to represent the intestinal epithelial barrier. DCs were labeled with CellTracker and imaged via confocal microscopy over a period of 2 hours to assess their migration through the collagen gel wall. After 3 days, DCs were stained with Hoechst and Calcein AM to confirm their viability and migratory capabilities. DCs seeded in the side channel were observed to form dendrites and maintain their viability after 72 hours. To determine the factors that lead to differential responses to bacteria, DCs on chips were exposed to E. coli for 2 hours. Following exposure, DC migration was observed and media was collected for cytokine analysis. This study shows the feasibility of incorporating DCs into a mesofluidic in vitro intestinal model to better recapitulate intestinal biology essential in response to lumen antigens in a defined system. Ongoing work is exploring strategies for optimally seeding and stimulating DCs to allow direct visualization of their interactions with epithelium and lumen contents, including bacteria.
