Tumor-Targeted Delivery of Synthetic DNA Payloads By Engineered Bacteria

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Bacteria capable of invasion into human cells offer a promising technology for cell-based therapies and could also be used to provide a route for DNA delivery, potentially enabling these bacteria to be a vector for gene therapies, DNA-based vaccines and in vivo genome engineering. Past work has demonstrated how modular DNA constructs can be used to engineer E. coli and Salmonella to target and enter cancer cell lines and tumours and specifically deliver protein payloads (e.g. toxins). The proposed project will go beyond delivery of just proteins and develop a platform for using tumor-targeting bacteria for the controlled delivery of DNA payloads that are then expressed in the host cell. We anticipate that this can become a core technology for both bacterial cell-based therapies and for DNA transfer for mammalian synthetic biology and synthetic genomics.This interdisciplinary project will bring together the foundational synthetic biology methods of DNA-based engineering and design of synthetic expression (Tom Ellis) with cutting-edge biomedical research of intracellular host-microbe interactions (Teresa Thurston, Ramesh Wigneshweraraj). It is co-sponsored by an exciting London-based industrial partner, Prokarium, and leverages their expertise and commercial knowledge of bacterial cell therapies. The research will build on an existing synthetic biology project between the company and the London BioFoundry, but now take this in the new direction of DNA delivery.The planned experimental work will see the student design, construct and test modular DNA programs that trigger secretion mechanisms and conjugation in relevant E. coli and Salmonella strains when these bacteria enter target cells. A core aim of this project will be to use non-pathogenic Salmonella strains as a vehicle to inject DNA encoding a eukaryotic gene into a cancer cell line. This process will be optimised and measured by tracking DNA expression and location by fluorescent imaging and single-molecule microscopy. Further work will look to test the limit of the lengths of DNA that can be transferred. Conjugation between bacteria is regularly used to transfer millions of bases of DNA in one go, and so this offers promise as a route to transfer big sections of synthetic DNA into target cells.