RESUMO
Objectives: To explore the modulating effects and related mechanisms of p53-miR-34a-SIRT1 feedback loop in the process of replication senescence of vascular endothelial progenitor cells (EPC). Methods: EPC derived from umbilical cord blood were cultured and identified. Differences on senescence, cell apoptosis, cell cycle and blood tube formation were observed in EPC of 3rdand 6thgeneration. Protein expression of p53, Acetyl-p53, and SIRT1 was also detected by Western blotting in EPC of 3rdand 6thgeneration. The miR-34a inhibitor lentiviral vector was constructed and used to identify whether miR-34a inhibitor can protect 6thgeneration EPC from apoptosis. Results: EPC derived from umbilical cord blood were successfully cultured. The cells senescence rate and apoptosis rate of the 6thgeneration EPC were significantly higher than those of the 3rdgeneration EPC. The cell cycle of 6thgeneration EPC was mainly arrested at G0/G1 phase. The protein expression level of p53 was significantly higher, while the protein expression of acetyl-p53 and SIRT1 was significantly lower in the 6thgeneration EPC than in the 3rdgeneration EPC, all P<0.05. The senescence was significantly attenuated, and late apoptotic cells were significantly reduced, while angiogenesis ability was significantly enhanced in the 6thgeneration EPC transfected with lentiviral vector carrying miR-34a inhibitor. Conclusions: p53-miR-34a-SIRT1 is an important feedback mechanism in the process of EPC replication senescence. The miR-34a inhibitor may be the potential target of delaying EPC senescence.