Dissecting and Overcoming Innate Immune Barriers for Therapeutically Efficient Hematopoietic Stem Cell Gene Engineering

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The low gene manipulation efficiency of human hematopoietic stem cells (HSC) remains a major hurdle for sustainable and broad clinical application of innovative therapies for a wide range of disorders. Indeed, high vector doses and prolonged ex vivo culture are still required for clinically relevant levels of gene transfer even with the most established lentiviral vector-based delivery platforms. Current and emerging gene transfer and editing technologies expose HSC to components potentially recognized by host antiviral factors and nucleic acid sensors that likely restrict their genetic engineering and contribute to broad individual variability in clinical outcomes observed in recent gene therapy trials. Nevertheless, specific effectors are yet to be identified in HSC. We have recently identified an antiviral factor that potently blocks gene transfer in HSC and have discovered small molecules that efficiently counteract it. This is the first example of how manipulating a single host factor can significantly impact gene transfer efficiencies in HSC but likely represents the mere tip of the iceberg of the plethora of innate sensing mechanisms potentially hampering genetic manipulation of this primitive cell compartment. This proposal aims to identify the antiviral factors and innate sensing pathways that prevent efficient modification of HSC and to mitigate their effects using methods developed through a thorough understanding of their mechanisms of action. My approach builds on the innovative concept that understanding the crosstalk between HSC and viral vectors will instruct us on which immune sensors and effectors to avoid and how, with direct implications for all gene engineering technologies. Successful completion of this project will deliver broadly exportable novel paradigms of innate pathogen recognition that will allow ground-breaking progress in the development of cutting-edge cell and gene therapies and to fight infectious and autoimmune diseases.