Gene delivery using a pH-sensitive molecular tweezer to catch and release nucleic acids

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After a long period of latency, gene therapy has become a reality. Four gene-based products have been approved since 2015 and several are on the way. This acceleration of approvals shows that researchers have accumulated enough fundamental knowledge to support gene therapy and endorse its feasibility and clinical relevance. Currently targeting rare diseases, gene therapy products will, in the future, concern more common disease, such as cancer, and will be accessible for a larger number of patients. Nevertheless, the production and the price of this therapy is still a great challenge, and has recently conducted to the withdrawn of Glybera (1 million $/treatment). We believe that improvement could come from the delivery strategy of the therapeutic gene. Viral vectors have been commercialized, but their exorbitant production cost, biosafety issues, potential immunogenicity, limit their large-scale production. Up to now, synthetic vectors have failed in clinical trials due to insufficient efficacy and non-specific toxicity, often attributed to their positive charge. ***We have recently developed pH-sensitive molecular tweezers, inspired from the biomimetic host-guest chemistry. These structures are inspired from the molecular machine field awarded by the Nobel Price in 2016. We have shown that these tweezers are able to bind a drug at physiological pH and release it at acidic pH. We also incorporated the tweezers in a lipid structure to get pH-sensitive liposomes. These nanocarriers were able to drastically improve the cytosolic delivery of hydrophilic drugs and nucleic acids in vitro and in vivo. Nevertheless, their cationic charge still limited their in vivo efficacy. ***In this project, we want to develop molecular tweezers to catch and release DNA. In a first step, they will be designed for non-specific binding of nucleic acids, and will be used as a non-cationic delivery system for gene therapy products. They will be synthesized, characterized, and compared in vitro and in vivo to the latest cationic systems. In a second step, we will design DNA tweezers for the specific recognition of sequences, mismatches or trinucleotide repeats. These defects in genomic DNA are associated with a number of genetic disease such as Huntington disease or muscular dystrophy. The specificity of such tweezers will be optimized in vitro. Then, a chip-base biosensor will be developed and used as a diagnostic tool for DNA defects and genetic diseases.**