Engineering Bacterial Therapy in Multicellular Coculture Model

Engineering bacteria to locally supplant their natural niches and modify disease state is emerging area of synthetic biology. However, bacterial behavior in complex physiological environment remains largely uncharacterized due to lack of spatiotemporal information attained from animal models. We recently developed a coculture platform that stably grow various bacteria within the necrotic core of multicellular spheroids over days, recapitulating selective bacterial growth in solid tumor in vivo. Using time-lapse microscopy, we quantitatively measure dynamics of bacterial tumor colonization over time and space. We observed differential kinetics and spatial distribution of bacterial invasion in tumor mass among the bacterial species. Utilizing this system, we screened tumor-targeting bacteria that deliver a library of anticancer molecules via synthetic gene circuits and identified candidates exhibiting significant tumor reduction. We hope this approach will be useful as a starting point towards implementing engineered bacteria for in vivo therapeutic applications.