Design of liquid scaffolds based on aqueous multi-phase systems (AMPS) for co-culture of microbes and mammalian cells

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Microbes are found throughout nature and are involved in every facet of human lives, from agriculture, to food production and human health. The microbiome, which describes the microenvironment where commensal microbes coexist and interact with host organism, is a complex and dynamic ecosystem that is difficult to recreate in the laboratory. This is mostly due to the fact that microbes grow much faster than mammalian cells, which will quickly overwhelm the culture and negatively affect mammalian cell survival. The proposed research program will address this unmet technological gap in host-microbe research by creating a family of polymer-based culture systems that can control the growth of microbes in confined droplet arrays that are physically separated, but remains chemically connected to surrounding mammalian cells. In this project, we aim to develop aqueous multi-phase system (AMPS) formulations in a model consisting of bacteria colonies in direct contact with human epithelial cells. In previous studies, we have demonstrated that aqueous solutions containing polyethylene glycol (PEG) and dextran (DEX) form two separate immiscible phases. These phases support the establishment of bacterial colonies and biofilms over an epithelial cell layer, where bacteria cultures are trapped in droplets' of DEX-rich phase solution to prevent overgrowth into surrounding PEG-rich medium. However, this prototype formulation was not ideal and well understood, thus posing significant negatively effects on mammalian cell viability and its toxicity toward microbes is unknown. Here we aim to design a family of biocompatible AMPS formation. We will screen a wide range of polymers to select those that are biocompatible. The ideal AMPS composition should also minimize diffusion barrier towards a wide spectrum of secreted biomolecules, including signalling peptides, hormones, and metabolites. Partitioning coefficients of biomolecules in candidate AMPS formulations will be evaluated using advanced proteomic analysis. Finally, candidate formulation will be tuned using known signalling pathways to ensure the establishment of indirect, native-like cell-cell communications between bacteria colonies and mammalian cells. This project will build the foundation for our understanding of biocompatible phase separation systems and aid future designs of advance culture platforms.