Co-Delivery of Multiple RNAs via Lipid Nanoparticles Enables Precise Gene Editing of CAR-T Cells

Over the past decade, CAR-T cell therapy has achieved remarkable success in treating hematological malignancies. However, traditional CAR-T cell engineering employs viral vectors, which has several limitations. Additionally, the immunosuppressive tumor microenvironment, particularly mediated by the PD-1/PD-L1 pathway, significantly restricts CAR-T cell efficacy. CRISPR/Cas9-mediated PD-1 knockout can enhance CAR-T cell anti-tumor activity, but traditional electroporation (EP) method often damages T cells. Herein, a novel lipid nanoparticles (LNPs)-mediated delivery technology are introduced to engineer CAR-T cells. The LNPs platform enables the simultaneous expression of CAR cassette and CRISPR/Cas9 gene editor in T cells via co-delivery of multiplex RNAs (CD19 CAR mRNA+Cas9 mRNA+sgRNA targeting PD-1). Importantly, LNPs exhibit higher transfection efficiency and superior cell viability compared to traditional electroporation method. The engineered CAR-T cells with PD-1 knockout, which express anti-CD19 CAR, can specifically kill CD19+ Nalm-6 tumor cells in vitro and display enhanced anti-tumor activity in vivo. Furthermore, LNPs-mediated co-delivery of Cas9 mRNA and sgRNAs targeting PD-1, TRAC, and B2M enables triple-knockout of T cells with high editing efficiencies (76% for PD-1, 86% for TRAC, and 80% for B2M), highlighting the ability for multiplex gene editing. This LNP-mediated delivery strategy has great potentials for the development of safer and more efficacious CAR-T cells.