Engineering platforms for human-microbe interaction studies in intestinal tract: materials approach

Steep oxygen gradient across the healthy epithelium and micro-to-anaerobic lumen is shaped by the cooperation of host and microbial metabolism. Spatial oxygen distribution in a GI tract with dysbiotic microbiome and tissue inflammation, drifts away from the homeostatic condition. However, current human-specific in vitro models miss some key physiologic features, and creating the characteristic intestinal oxygen microenvironment is challenging. The goal of this dissertation is to bridge the gap between in vitro GI-microbe models by reducing the complexity in experimental setup. First, we developed a host-free microscale bacterial culture method using aqueous two-phase system (ATPS) and characterized passive oxygen control using the materials properties of ATPS and polydimethyl siloxane. Next, we showed the ATPS microscale culture is capable of supporting a co-culture of facultative and obligate anaerobes without the use of anaerobic chambers. Escherichia coli O157:H7, a human enteric pathogen, co-cultured with Bacteroides thetaiotaomicron, a human commensal, in low glucose ATPS culture showed enhanced virulence, which was comparable to in vivo studies. Lastly, we explored various ways to interface ATPS culture with human intestinal organoids and maintain physiologic oxygen microenvironment. We believe this culture method will be particularly useful for researchers in gastroenterology with little engineering background and provide valuable insights. Moreover, the properties of microscale ATPS bacterial culture will be useful for developing high throughput assays.Ph.D