CircRNA_0004468 promotes VEGFA-mediated neurovascular repair by sponging miR-1224 in remote ischemic postconditioning against cerebral ischemia-reperfusion injury.

BACKGROUND: Cerebral ischemia/reperfusion injury remains a major barrier to neurological recovery after recanalization therapy. Although remote ischemic postconditioning (RIPostC) has neuroprotective potential, its non-coding RNA mechanisms remain unclear. This study investigated whether the circular RNA 0004468 (circRNA_0004468)/microRNA-1224 (miR-1224)/vascular endothelial growth factor A (VEGFA) axis mediates RIPostC-induced protection against cerebral ischemia/reperfusion injury. METHODS: Oxygen-glucose deprivation/reoxygenation (OGD/R)-treated PC12 cells were used as an in vitro model of ischemia-reperfusion injury, whereas rats subjected to ischemia/reperfusion (I/R), with or without RIPostC, were used for in vivo validation. The expression of circRNA_0004468, miR-1224, VEGFA, and PI3K-related proteins was examined by reverse-transcription quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Cell viability, apoptosis, molecular interactions, infarct volume, histopathological injury, neurological deficits, and endothelial repair were evaluated using Cell Counting Kit-8 (CCK-8) assay, flow cytometry, fluorescence in situ hybridization, dual-luciferase reporter assay, 2,3,5-triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin staining, behavioral scoring, and immunofluorescence staining. RESULTS: OGD/R decreased circRNA_0004468 and VEGFA expression but increased miR-1224 expression in PC12 cells. CircRNA_0004468 overexpression or miR-1224 inhibition improved cell viability and reduced apoptosis after OGD/R. Mechanistically, circRNA_0004468 directly bound to miR-1224 and relieved miR-1224-mediated suppression of VEGFA. In MCAO/R rats, RIPostC upregulated circRNA_0004468 and VEGFA, downregulated miR-1224, reduced infarct volume, alleviated neuronal injury, enhanced CD31 and CD34 expression, and improved neurological outcomes. These protective effects were further strengthened by circRNA_0004468 overexpression, miR-1224 inhibition, or VEGFA overexpression. CONCLUSIONS: The circRNA_0004468/miR-1224/VEGFA axis contributes to RIPostC-mediated neurovascular protection and may represent a potential target for improving recovery after ischemic stroke.