Exogenous Hydrogen Sulfide Donors Suppress Neointimal Hyperplasia by Modulating Mitochondrial Dysfunction in Vascular...

Phenotypic switching of vascular smooth muscle cells (VSMCs) from the contractile to the synthetic is a key factor driving the formation of intracranial atherosclerotic stenosis (ICAS); however, the upstream mitochondrial mechanisms underlying this process and its therapeutic implications remain poorly defined. This study aims to investigate the role and underlying molecular mechanisms of the mitochondria-targeted hydrogen sulfide (H₂S) donor AP39 in regulating mitochondrial function during VSMCs phenotypic switching and neointimal hyperplasia. In a platelet-derived growth factor-BB (PDGF-BB)-induced synthetic VSMCs model, mitochondrial function and phenotypic changes were systematically assessed. In vivo, AP39 was locally administered in a mouse carotid artery ligation model to evaluate neointimal formation and vascular remodeling. PDGF-BB induced hypermethylation of the mtDNA D-loop region, ROS accumulation, and Drp1 activation, accompanied by enhanced mitochondrial fission, impaired energy metabolism, and VSMCs phenotypic switching. These alterations were differentially reversed by 5-Aza-dC, NAC, Mdivi-1, or Drp1 silencing. AP39 reduced D-loop methylation and mitochondrial DNMT1 expression, suppressed ROS accumulation and Drp1 activation, preserved mitochondrial structure and oxidative phosphorylation, and attenuated VSMCs phenotypic switching, while partially restoring cystathionine γ-lyase (CSE)-mediated endogenous H₂S production. Consistent with these findings, local AP39 administration in vivo significantly alleviated neointimal hyperplasia following carotid ligation. These results indicate that the mitochondria-targeted H₂S donor AP39 exerts robust vasculoprotective effects through multi-level modulation of D-loop hypermethylation-driven mitochondrial dysfunction, thereby ameliorating ICAS-associated VSMCs phenotypic switching and neointimal hyperplasia. This study provides a novel mechanistic framework and highlights a potential mitochondria-targeted therapeutic strategy for vascular remodeling in ICAS.