The potential impact of exosomal miR-484 on post-myocardial infarction angiogenesis using bioinformatics and experimental verification

This study aimed to investigate the effect of miRNAs differentially expressed in serum exosomes on endothelial cells after myocardial infarction. Specific pathogen-free male Sprague–Dawley rats with acute myocardial infarction (AMI) were established by ligating the anterior descending branch of the left coronary artery. Hematoxylin–eosin staining was used to detect myocardial histopathological changes during model evaluation. The differentially expressed miRNAs carried by the serum exosomes were detected using the Agilent Rat miRNA Gene Chip on the Illumina platform. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed using the Database for Annotation, Visualization, and Integrated Discovery. The culture supernatant of hypoxic H9c2 cells was collected and centrifuged to obtain exosomes. The expression of miR-484 was verified using real-time fluorescence quantitative PCR (qRT‒PCR). miR-484 mimics were transfected into human umbilical vein endothelial cells (HUVECs) to construct cell models of miR-484 overexpression. Cellular proliferation, scratch wound, and tube formation assays were conducted with HUVECs. A dual-luciferase reporter assay was used to validate the target gene of miR-484. Serum exosomes were sequenced on an Illumina sequencing platform, and 22 differentially expressed miRNAs between the model and sham groups were detected (P < 0.05). Among them, miR-484 was prioritized for further evaluation, and its downregulation in MI serum exosomes was confirmed through both gene chip analysis and animal experiments. miR-484 expression increased in HUVECs after culture with exosomes from hypoxia-exposed H9c2 cells. miR-484 expression upregulation suppressed proliferation, migration, and vascular formation in HUVECs, indicating that miR-484 plays an antiangiogenic role. Bioinformatics analyses showed that rno-miR-484 and the VEGFA 3’UTR possess base binding sites. The dual-luciferase reporter assay showed that rno-miR-484 could significantly downregulate the expression of luciferase in r-Vegfa-3UTR-WT (P < 0.01). VEGFA expression was downregulated after miR-484 mimic transfection in HUVECs. Our study revealed that miR-484 may inhibit angiogenesis after myocardial infarction by targeting VEGFA, providing a novel focal point for the diagnosis and treatment of this disease.