Enriching HDR edits for enhancing efficacy and precision of HSPC gene therapy

Hematopoietic stem and progenitor cell (HSPC) gene therapy involving viral vectors has shown remarkable promise in treating severe genetic disorders. The advent of gene editing technologies offers new possibilities for broadening the scope of HSPC gene therapy by enabling precise in situ gene correction or targeted transgene integration through homology-directed repair (HDR). However, HDR efficiency in HSPCs remains limited due to their cell cycle dynamics, suboptimal responses to the repair template, and the dominance of error-prone DNA repair pathways such as non-homologous end joining (NHEJ) and microhomology-mediated end joining (MMEJ), which negatively impact the engraftment of HDR-edited cells in vivo. This proposal aims to overcome these challenges by introducing an innovative ""purifying selection"" strategy. By using CRISPR/Cas9 to target essential genes that are haplo-insufficient in HSPCs, only cells undergoing HDR-mediated insertion of the gene of interest (GOI) will restore the function of the essential gene, while non-HDR edited cells will fail to recover, leading to their elimination. This selective enrichment of HDR-edited cells will dramatically enhance the precision and efficacy of gene editing. ENRICHING-HDR project will focus on identifying critical genes required for HSPC survival and maintenance through genome-wide CRISPR screening, selecting the most promising candidates for purifying selection, and evaluating the system's precision and platformability for clinical application. This project will establish a standardized platform for guide/nuclease reagents and template delivery, enabling reliable genomic integration and rapid adaptation of new therapeutic transgenes, streamlining the development of targeted therapies. The comprehensive training in advanced experimental techniques, research communication, and knowledge transfer will be instrumental in shaping my career trajectory, driving me toward my goal of becoming an independent researcher.""