Dissecting Lentivirus-Host Interactions to Improve Gene Transfer

Hematopoietic gene therapy has tremendous potential to treat human disease. For this purpose, lentiviral vectors (LV) are among the best performing gene transfer platforms available to date. Nevertheless, primary human myeloid cells can hardly be transduced and high vector doses as well as stimulation with growth-promoting cytokine cocktails are required to reach significant transduction levels of clinically relevant human hematopoietic stem and progenitor cells (HSPC). This remains an enormous drawback for the field as it implies cumbersome, costly and not always sustainable large-scale vector productions and compromised cell quality due to prolonged ex-vivo transduction protocols. Like for myeloid cells, one of the potential reasons behind poor HSPC permissiveness to transduction may reside in the viral origin on LV. While extensively modified, LVs still share common features with infectious HIV-1, potentially triggering inflammatory/innate immune responses in HSPC and remaining most likely vulnerable to specific host anti-viral responses leading to poor target cell permissivity. Nevertheless, no data regarding LV-induced signaling in HSPC is available to date and the role of host antiviral factors in poor transduction efficiency in HSPC remains unclear. On these premises, our proposal aims to investigate the mechanisms responsible for poor permissiveness of human HSPC to LV gene transfer, improve gene delivery platforms to overcome innate immune hurdles and to provide genome-wide insight into the signaling pathways triggered by LV in hematopoietic cells. Our final goal is to render gene transfer as inert as possible, while at the same time increasing efficiency. Overall, this project will deliver knew knowledge critical for the development of safer and more efficient gene transfer approaches with potentially broad range clinical impact, including the development of novel therapeutic strategies specifically targeting the myeloid compartment.