MicroRNA-384-5p Promotes Endothelial Progenitor Cell Proliferation and Angiogenesis in Cerebral Ischemic Stroke through the Delta-Likeligand 4-Mediated Notch Signaling Pathway.

BACKGROUND: MicroRNAs (miRs) have a crucial regulatory role in endothelial cell function and tumor angiogenesis by inhibiting the expressions of their target genes. The participation of microRNA-384-5p (miR-384-5p) has been prominently reported in various ischemia-induced diseases such as myocardial ischemia and atherosclerosis. Hence, the present study aimed at exploring the effect of miR-384-5p on proliferation, apoptosis, and angiogenesis of endothelial progenitor cells (EPCs) in cerebral ischemic stroke and investigating the associated underlying mechanism.

METHODS: A middle cerebral artery occlusion (MCAO) mouse model was established, with determination of the expression of cluster of differentiation 31 (CD31) and vascular endothelial growth factor (VEGF) proteins. Next, the MCAO mice and EPCs separated from MCAO mice were injected or transfected with mimics or inhibitors of miR-384-5p, or small interference RNA Delta-likeligand 4 (si-DLL4) in order to evaluate their effect on brain infarct size, cell proliferation, apoptosis, and angiogenesis. The relationship among miR-384-5p, DLL4, and the Notch signaling pathway was then verified by a series of experiments.

RESULTS: In MCAO mice, an increased brain infarct size and cell apoptosis in brain tissues were evident, with decreased expression of miR-384-5p, VEGF, and CD31, as well as increased DLL4 expression. After miR-384-5p mimic or si-DLL4 treatment, the brain infarct size and cell apoptosis in the brain tissues were reduced in compliance with an increased expression of VEGF and CD31. Our findings demonstrated that miR-384-5p negatively regulated the expression of DLL4, which further downregulated the Notch signaling pathway. When miR-384-5p was overexpressed or DLL4 silenced, the cell proliferation and angiogenesis of EPCs were promoted and cell apoptosis was inhibited.

CONCLUSIONS: Our study demonstrated that overexpressed miR-384-5p targeting DLL4 could stimulate proliferation and angiogenesis, while inhibiting apoptosis of EPCs in mice with cerebral ischemic stroke through the Notch signaling pathway.