In the elderly with atherosclerosis, hypertension and diabetes, vascular calcification and ageing are ubiquitous. Melatonin (MT) has been demonstrated to impact the cardiovascular system. In this study, we have shown that MT alleviates vascular calcification and ageing, and the underlying mechanism involved. We found that both osteogenic differentiation and senescence of vascular smooth muscle cells (VSMCs) were attenuated by MT in a MT membrane receptor-dependent manner. Moreover, exosomes isolated from VSMCs or calcifying vascular smooth muscle cells (CVSMCs) treated with MT could be uptaken by VSMCs and attenuated the osteogenic differentiation and senescence of VSMCs or CVSMCs, respectively. Moreover, we used conditional medium from MT-treated VSMCs and Transwell assay to confirm exosomes secreted by MT-treated VSMCs attenuated the osteogenic differentiation and senescence of VSMCs through paracrine mechanism. We also found exosomal miR-204/miR-211 mediated the paracrine effect of exosomes secreted by VSMCs. A potential target of these two miRs was revealed to be BMP2. Furthermore, treatment of MT alleviated vascular calcification and ageing in 5/6-nephrectomy plus high-phosphate diet-treated (5/6 NTP) mice, while these effects were partially reversed by GW4869. Exosomes derived from MT-treated VSMCs were internalised into mouse artery detected by in vivo fluorescence image, and these exosomes reduced vascular calcification and ageing of 5/6 NTP mice, but both effects were largely abolished by inhibition of exosomal miR-204 or miR-211. In summary, our present study revealed that exosomes from MT-treated VSMCs could attenuate vascular calcification and ageing in a paracrine manner through an exosomal miR-204/miR-211.

中文翻译：

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褪黑素通过旁分泌的方式通过外泌体miR-204 / miR-211簇减轻血管钙化和衰老。

在患有动脉粥样硬化，高血压和糖尿病的老年人中，血管钙化和衰老无处不在。褪黑素（MT）已被证明会影响心血管系统。在这项研究中，我们表明MT减轻了血管钙化和衰老，并涉及了其潜在机制。我们发现MT以MT膜受体依赖性方式减弱了血管平滑肌细胞（VSMC）的成骨分化和衰老。此外，从VSMC分离或经MT处理的钙化血管平滑肌细胞（CVSMC）分离的外泌体可能被VSMC摄取，并分别减弱VSMC或CVSMC的成骨分化和衰老。此外，我们使用MT处理过的VSMC的条件培养基和Transwell测定法来证实MT处理过的VSMC分泌的外泌体通过旁分泌机制减弱了VSMC的成骨分化和衰老。我们还发现外泌体miR-204 / miR-211介导了VSMC分泌的外泌体的旁分泌作用。这两个miR的潜在目标被发现是BMP2。此外，MT的治疗减轻了5/6肾切除术和高磷酸盐饮食治疗（5/6 NTP）小鼠的血管钙化和衰老，而GW4869可以部分逆转这些影响。通过体内荧光图像检测，将经MT处理的VSMC衍生的外泌体内化到小鼠动脉中，这些外泌体减少了5/6 NTP小鼠的血管钙化和衰老，但通过抑制外泌体miR-204或miR-，这两种作用在很大程度上被消除了。 211。