Upregulation of circ‐IGF1R increased therapeutic effect of hypoxia‐pretreated ADSC‐derived extracellular vesicle by regulating miR‐503‐5p/HK2/VEGFA axis

Abstract Diabetes mellitus is a major cause of blindness and chronic ulcers in the working‐age population worldwide. Wound healing is deeply dependent on neovascularization to restore blood flow. Former research has found that differentially expressed circular RNAs (circRNAs) are associated with hyperglycaemia‐induced endothelial cell damage, and hypoxia‐pretreated adipose‐derived stem cells (ADSCs)‐extracellular vesicle (HEV) transplants have a more therapeutic effect to enhance wound healing in diabetic mice by delivery circRNA. The current investigation employed high‐throughput sequencing to identify circRNAs that are abnormally expressed between EV and HEV. The regulatory mechanism and predicted targets of one differentially expressed circRNA, circ‐IGF1R, were investigated utilizing bioinformatics analyses, luciferase reporter assays, angiogenic differentiation assays, flow cytometric apoptosis analysis and RT‐qPCR. Circ‐IGF1R expression increased in HEV, and downregulation of circ‐IGF1R suppressed and reversed the promotion effect of HEV on angiogenesis in ulcerated tissue. Bioinformatics analyses and luciferase reporter assays confirmed that miR‐503‐5p was the downstream target of circ‐IGF1R, and inhibiting miR‐503‐5p restored the promotion effect of HEV on angiogenesis after circ‐IGF1R silence. The study also found that miR‐503‐5p can interact with 3'‐UTR of both HK2 and VEGFA. Overexpression of HK2 or VEGFA restored the promotion effect of HExo on angiogenesis after circ‐IGF1R silence. Overexpression miR‐503‐5p or silence HK2/VEGFA reversed the protective effect of circ‐IGF1R to MLMECs angiogenic differentiation. Overexpression of circ‐IGF1R increased the protective effect of HEV on the promotion of wound healing in mice with diabetes. Circ‐IGF1R promotes HIF‐1α expression through miR‐503‐5p sponging. Our data demonstrate that circ‐IGF1R overexpression EVs from ADSCs suppress high glucose‐induced endothelial cell damage by regulating miR‐503‐5p/HK2/VEGFA axis.