Fibroblast Activation Protein‐Targeted CAR‐T Cells Induce Apoptosis in Murine Cardiac Myofibroblasts

Myocardial fibrosis is a common pathological feature in many cardiovascular diseases, yet effective targeted therapies remain elusive. Given the emerging potential of chimeric antigen receptor T (CAR-T) cell therapy in nononcological diseases and fibroblast activation protein (FAP) as a promising target, we engineered a second-generation FAP-targeted CAR construct incorporating the 4-1BB costimulatory domain to enhance therapeutic safety. Using two delivery approaches-lentiviral vectors and lipid nanoparticles (LNPs)-we generated FAP-CAR-engineered Jurkat cells as a preliminary screening model and evaluated their CAR expression, target recognition, and in vitro cytotoxic activity. These engineered cells selectively recognized and induced apoptosis in FAP-expressing cardiac myofibroblasts without triggering excessive IL-6 secretion, supporting their potential for fibrosis-selective cytotoxicity. Our findings provide key preliminary in vitro evidence supporting the design and target-specific functionality of FAP-targeted CAR constructs incorporating the 4-1BB domain, warranting further investigation in primary T cell models for cardiac fibrosis therapy.