AGE-RELATED CIRCULATING ENDOTHELIAL EXTRACELLULAR VESICLES PROMOTE CEREBRAL MICROVASCULAR CELL DYSFUNCTION

The aim of this study was to determine, in vitro, the effect of endothelial cell-derived extracellular vesicles (EEVs) from older adults on brain microvascular endothelial cell oxidative stress, inflammation, nitric oxide (NO) and endothelin (ET)-1 production as well as tissue-type plasminogen activator (t-PA) release. Circulating EEVs (CD144+ extracellular vesicles) were enumerated and isolated (flow cytometry) from the plasma of 30 healthy, sedentary, non-obese, adults: 15 young (age: 21-35 yr; 7 M/8 F) and 15 older (55-80 yr; 7 M/8 F). Human cerebral microvascular endothelial cells (hCMECs) were cultured and treated with EEVs from either group. EEVs from older adults induced higher ROS (140±51 vs 99±16 % of control; P=0.02) production and lower expression of catalase (13.7±3.7 vs 23.2±7.4 AU; P<0.01) and SOD-1(147.6±41.1 vs 281.2±78.3; P<0.01) in hCMECs than EEVs from young adults. EEVs from older adults did not induce cellular inflammation. Expression of phosphorylated (p)-eNOS (Ser1177) was significantly lower (61.6±13.0 vs 77.7±17.6 AU), p-eNOS (Thr495) significantly higher (49.9±16.4 vs 38.0±10.9 AU) and NO production (5.9±1.6 vs 7.3±1.3 µmol/L)was significantly lower in hCMECs treated with EEVs from older adults. Big ET-1 (95.3±17.1 vs 69.4±20.6 AU; P<0.001) and ECE (164.8±26.0 vs 128.4±18.5 AU: P<0.001) expression as well as ET-1 production (27.3±9.1 vs 21.2±5.5 pg/mL; P=0.03) were significantly higher in hCMECs treated with EEVs from older adults. t-PA release in response to thrombin was significantly lower (~30%) in hCMECs treated with EEVs from older adults. Circulating EEVs represent a potential mechanistic factor contributing to increased stroke risk with aging.