High glucose and free fatty acids induce endothelial progenitor cell senescence via PGC‐1α/SIRT1 signaling pathway

The objective of the research was to investigate the function of endothelial progenitor cells (EPCs) in the conditions of high glucose and lipids, which has been widely used to mimic the metabolic disorder that occurs in type 2 diabetic mellitus, and further to verify the role of PGC-1α and SIRT1, cellular energy metabolism regulators, in the process of senescence of EPCs with these combined stimuli. Circulating EPCs were incubated in absence or presence of high glucose (25 mM), FFA (200 µM) or both. EPCs senescence was assessed by β-galactosidase staining, EPCs telomerase activity was measured by telomeric repeat ampli-fication protocol assay, in vitro angiogenesis assay and MTT assays were performed to assess angiogenesis and proliferation ability of EPCs. The results showed that combined stimuli inhibited EPCs reendothelialization ability in vitro, accelerated EPCs senescence and decreased the telomerase activity. Meanwhile, with combined stimuli, the expression of PGC-1α increased whereas SIRT1 expression decreased in EPCs accompanied by activation of P53/P21 signaling pathway. Conversely, transfection of EPCs with PGC-1α-siRNA rescued EPCs premature senescence and up-regulated SIRT1 and decreased P53/P21 expression, correlating closely with the down-regulation of PGC-1α itself. In addition, the combined stimuli induced up-regulation of PGC-1α expression was partly mediated by ROS and P38 signaling pathway. Overall, the data presented here identify PGC-1α as a potent negative regulator of EPCs' senescence under combined stimuli, which is partly mediated by SIRT1/P53/P21 signaling pathway.