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

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.