Brain-Derived Cystathionine β-Synthase-Generated H2S Attenuates Cerebral Ischemia-Reperfusion Injury via VEGFR2-Mediated Angiogenesis in MCAO/R Rats

Ischemic stroke (IS) remains a major cause of global disability and mortality. While exogenous H₂S has demonstrated neuroprotective potential, the role of endogenous H₂S generated by cystathionine β-synthase (CBS) in cerebral ischemia-reperfusion injury (CIRI) remains incompletely elucidated. L-Cysteine (L-Cys), as a substrate for CBS, serves as a key precursor for endogenous H₂S. Using the established pre-clinical model of CIRI-middle cerebral artery occlusion/reperfusion (MCAO/R) in rats-we investigated the neuroprotective effects of brain-derived CBS-generated H₂S through neurological function scoring, 2,3,5-triphenylchlorotetrazole (TTC) staining, enzyme-linked immunosorbent assay (ELISA), and histopathological examination. Immunofluorescence, Western blot, and laser speckle contrast imaging were utilized to analyze the protein expression of ZO-1, claudin-5, CBS, vascular endothelial growth factor receptor-2 (VEGFR₂) and CD31, as well as cerebral blood flux changes. L-Cys treatment ameliorated neurological deficits, reduced cerebral infarct volume, decreased serum Lactate Dehydrogenase (LDH) and neuron-specific Enolase (NSE) levels, attenuated histopathological damage, alleviated cerebral edema, and restored blood-brain barrier integrity via upregulation of tight junction proteins ZO-1 and claudin-5. Additionally, L-Cys improved MCAO/R-induced cognitive impairment and behavioral deficits. Furthermore, L-Cys upregulated CBS and VEGFR₂ expression, enhanced endogenous H₂S production, promoted post-ischemic cerebral angiogenesis, and improved cerebral blood flux recovery. CBS-derived H₂S promoted post-ischemic angiogenesis mediated by VEGFR₂, enhances cerebral reperfusion flux, and consequently ameliorated MCAO/R-induced CIRI in rats, providing experimental evidence for clinical translation.