Atherosclerotic plaque-derived extracellular vesicles mediate smooth muscle cell phenotypic switching and promote vascular remodeling

Despite the use of lipid-lowering and anti-inflammatory treatments, the progression of atherosclerosis is relentless in most patients. This suggests the presence of in situ pathological factors that continuously exacerbate lesions. We hypothesized that extracellular vesicles (EVs) within the atherosclerotic microenvironment might act as in situ stimulatory factors on vascular smooth muscle cells (VSMCs), thereby exacerbating atherosclerosis. A local atherosclerosis model was induced using Ldlr knockout (Ldlr KO) rats fed a high-cholesterol diet and subjected to partial carotid ligation. Immunofluorescence, Western blot (WB), and single-cell sequencing confirmed the phenotypic switching of VSMCs in atherosclerotic plaques from both rats and humans. The phenotypic switching of VSMCs in atherosclerotic rats was characterized by reduced expression of VSMC contraction markers and increased expression of LGALS3, PDGFRB, and SCA1. GW4869 inhibited the phenotypic switching of VSMCs in atherosclerotic plaques in a rat model. EVs were extracted from atherosclerotic carotid tissues using differential centrifugation. Chitosan thermosensitive hydrogels were used for in situ delivery of EVs into the arterial wall of the carotid artery. Immunofluorescence staining revealed that atherosclerotic plaque-derived EVs (AS-EVs) promoted VSMC phenotypic switching and downregulated the expression of VSMC contractile markers in vitro. miRNA analysis of EVs derived from atherosclerotic plaques of rats identified miR-23a-3p and its target gene Myl12b. To investigate the underlying mechanisms, engineered EVs loaded with miR-23a-3p were used to mimic AS-EVs. AS-EVs potentially regulate MRTFA nuclear translocation via miR-23a-3p/Myl12b, inhibit contractile marker expression, promote VSMC phenotypic switching, and further promote carotid artery remodelling. We conclude that AS-EVs promote VSMC phenotypic switching and exacerbate atherosclerosis.