A Novel Strategy to Produce CAR-γδ T Cells via Site-Directed Gene Integration by a Combination of CRISPR/Cas9 and AAV

Chimeric antigen receptor (CAR)-αβ T cells are commonly employed in tumor therapy but hindered by some limitations. γδ T cells are promising substrates for CAR therapy for their major histocompatibility complex (MHC)-unrestricted recognition manner and innate immune function. Here, we established a novel method for generating CAR-γδ T cells. We utilized the clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) (CRISPR/Cas9) method to interrupt the TCR delta chain constant region (TRDC) sequence, followed by the site-directed insertion of the CAR sequence into the TRDC locus via homologous complementation mediated by adeno-associated virus (AAV) gene delivery. We optimized electroporation parameters for Cas9/ribonucleoproteins (RNP) delivery and infection conditions for CAR-gene carrying AAV in γδ T cells. These optimizations facilitated efficient TCR knockout and site-directed CAR insertion, ultimately yielding functional CAR-γδ T cells. In vitro experiments demonstrated that these newly prepared CAR-γδ T cells could stimulate cytokine production, kill tumor cells as well as exhibit robust proliferative potential and memory-like phenotype. These state-of-the-art CAR-γδ T cells could reduce tumor burden and extend the survival period of tumor-bearing mice.