A proposed model of exosomes from melatonin-induced ECs in ameliorating vascular calcification and ageing. Melatonin triggered miR-302d-5p maturation through HNRNPA2B1/DGCR8 pathway in a m6A dependent manner and thereby promoted secretion of exosomes that enriched in miR-302d-5p. Subsequently, these exosomes were uptaken by adjacent VSMCs and miR-302d-5p was transferred into VSMCs. In VSMCs, miR-302d-5p alleviated vascular calcification and ageing by targeting Wnt3.