Exosomal Notch3 from high glucose-stimulated endothelial cells regulates vascular smooth muscle cells calcification/aging

Aims: Vascular calcification/aging can cause different kind of serious diabetic vascular complications. High glucose could induce vascular smooth muscle cells (VSMCs) calcification/aging and then lead to diabetes-related vascular calcification/aging. In this study, we investigated how information in the blood is transmitted to VSMCs and the mechanisms of VSMCs calcification/aging under hyperglycaemic conditions. Materials and methods: Transmission electron microscopy and molecular size analysis were used to assess the morphology and size of exosomes. Alizarin Red S staining and senescence-associated beta galactosidase (SA-beta-gal) staining were carried out to detect calcification and senescence in VSMCs, respectively. Proteomics analysis was carried out to detect the different expression of exosomal proteins. Protein levels were measured by western blot analysis. Key findings: The results show that exosomes isolated from high glucose stimulated human umbilical vein endothelial cell (HG-HUVEC-Exo) exhibited a bilayer structure morphology with a mean diameter of 63.63 +/- 2.96 nm. The presence of exosome markers including CD9, CD63 and TSG101 were also detected in HG-HUVEC-Exo. High glucose could induce VSMCs calcification/aging by increasing the expression of osteo-calcin (OC) and p21 as well as the formation of mineralised nodules and SA-beta-gal positive cells. Fluorescence microscopy verified that the exosomes were taken up by VSMCs and Notch3 protein was enriched in HG-HUVECExo. Most importantly, mTOR signalling was closely related to Notch3 protein and was involved in regulating HG-HUVEC-Exo-induced VSMCs calcification/aging. Significance: The data demonstrate that Notch3 is required for HG-HUVEC-Exo promoted VSMCs calcification/aging and regulates VSMCs calcification/aging through the mTOR signalling pathway.