To enhance the ex vivo expansion of CAR-NK-92 cells by regulating intracellular redox status

Abstract

Chimeric antigen receptor-Natural Killer-92 (CAR-NK-92) cell therapy has broad prospects as an effective cellular immunotherapy. Efficient CAR-NK-92 cell expansion ex vivo is crucial for its development and wide use. Unlike NK-92 cells, CAR-NK-92 cells need to maintain the stability of CAR expression during culture, besides keeping cell function. This work compared the growth and metabolism between NK-92 cells and CAR-NK-92 cells and found that the expansion efficiency of CAR-NK-92 cells was significantly lower than that of NK-92 cells. Meanwhile, the amino acid metabolism related to reducing agent production in CAR-NK-92 cells was weaker than in NK-92 cells, resulting in higher intracellular oxidation levels. The antioxidant N-acetylcysteine (NAC) was used to regulate the intracellular redox status of CAR-NK-92 cells. Under 1 mM NAC, the intracellular reactive oxygen species (ROS) level of CAR-NK-92 cells was down-regulated, and the cell expansion ability was improved. Furthermore, the addition of NAC has increased the levels of GSH and NADPH in CAR-NK-92 cells, elevated GSH/GSSG ratio and NADPH/NADP⁺ ratio, enhanced the antioxidant capacity and mitochondrial function of cells, and promoted cell expansion. This study aims to promote CAR-NK-92 cell expansion ex vivo by regulating intracellular redox levels to facilitate its clinical application.