Multicellular Synthetic Biology in Mammalian Systems

In multicellular organisms, different types of cells use intercellular signals to communicate and regulate population dynamics, and further coordinate complex behaviors. This presents a rarely tapped into potential for mammalian synthetic biology, which was largely restricted to engineering a single cell type in the past to mimic and use similar multicellular designs to achieve more functionalities. However, with current synthetic biology tools and designs, there are several major challenges to achieve a multicellular circuit. Challenges include precise and tunable control over cell type switching, having an orthogonal cell-cell communication signal, and robust control of cell populations. To address these challenges, this thesis presents a system for tunable regulating of gene expression with DNA methylation, an auxin-based module for mammalian cell-cell communication, and a robust circuit for population control in mammalian cells. I further applied these work to engineering immune cells to show the potential of multicellular circuits in immunotherapies. Together, these works demonstrated the possibility of constructing multicellular circuits in mammalian systems, and that multicellular circuit can further extend the scope of synthetic biology to achieve more complex functions.