Gene Therapy Targeting Pkp2 Deficiency Attenuates Cardiac Fibrosis: Insights From Single‐Cell Transcriptomics in Pkp2 ‐Knockout Rats

ABSTRACT Heart failure (HF), characterized by maladaptive cardiac fibrosis and progressive functional deterioration, remains a therapeutic challenge. In this study, we established a cardiac organoid HF model derived from human‐induced pluripotent stem cells (hiPSCs) and observed a significant downregulation of the desmosomal protein plakophilin‐2 (PKP2) in this model. Reduced PKP2 expression was detected in both HF rat and mouse. Subsequent in vivo studies on Pkp2‐ knockout ( Pkp2 ‐KO) rats demonstrated that adeno‐associated virus serotype 9 (AAV9)‐mediated restoration of PKP2 not only restored cardiac PKP2 expression but also attenuated the progression of fibrosis. Administration of AAV9‐PKP2 could also inhibit myocardial fibrosis and slow down disease progression in HF mouse. Single‐cell RNA sequencing analysis in rats revealed enriched pathological profibrotic cardiac fibroblasts (CFs) in PKP2‐deficient myocardium. Mechanistically, AAV9‐PKP2 administration induced the phenotypic conversion of activated CFs into quiescent antifibrotic states. Integrated bioinformatics identified that protein tyrosine phosphatase receptor type C ( Ptprc ) was a pivotal regulator orchestrating this cellular reprogramming. Our findings thus unveil PKP2 as a master regulator of fibroblast activation and propose AAV9‐PKP2 gene therapy as a promising novel therapeutic strategy targeting pathological fibrosis in HF.