Objective:To investigate the protective effect of nicotinamide phosphoribosyltransferase (NAMPT) on abdominal aortic aneurysm by delaying the senescence of aortic vascular smooth muscle cells (VSMC).Methods:The primary VSMC cells from normal and patients with abdominal aortic aneurysm were cultured by tissue adherence method. Cells were divided into normal human-derived VSMC group (Ctrl-VSMC group), abdominal aortic aneurysm patient-derived VSMC group (AAA-VSMC group), and angiotensinⅡ(AngⅡ) in vitro abdominal aortic aneurysm model group (AngⅡ-VSMC group, 100 nmol/L AngⅡ treated normal human-derived VSMC for 48 hours), AngⅡ+P7C3 group and AAA+P7C3 group after NAMPT agonist P7C3 intervention (adding 5 μmol/L P7C3 on the basis of AngⅡ-VSMC group and AAA-VSMC group, respectively). Immunofluorescence staining was used to identify VSMC; cell proliferation-associated antigen Ki67 staining was used to detect cell proliferation; senescence associated β-galactosidase (SA-β-gal) staining was used to detect cell senescence in each group; Western blotting was used to detect the protein expression levels of senescence-related proteins p21, p16 and NAMPT in each group. Results:Compared with the Ctrl-VSMC group, the positive rate of SA-β-gal staining and the expression levels of senescence-related proteins p21 and p16 in the AAA-VSMC group and AngⅡ-VSMC group were significantly increased [SA-β-gal staining positive rate: (74.1±4.4)%, (68.6±5.5)% vs. (36.8±10.3)%, p21/GAPDH: 0.61±0.07, 0.51±0.03 vs. 0.31±0.03, p16/GAPDH: 0.77±0.03, 0.72±0.06 vs. 0.33±0.26, all P < 0.01]. However, the expression of NAMPT was significantly decreased (NAMPT/GAPDH: 0.88±0.07, 0.79±0.14 vs. 1.29±0.02, both P < 0.01). Compared with the AngⅡ-VSMC group, the positive rate of SA-β-gal staining and the expressions levels of senescence-related proteins p21 and p16 in the AngⅡ+P7C3 group were significantly lower [SA-β-gal staining positive rate: (49.1±3.2)% vs. (68.6±5.5)%, p21/GAPDH: 0.35±0.06 vs. 0.51±0.03, p16/GAPDH: 0.47±0.08 vs. 0.72±0.06, all P < 0.05], while the expression of NAMPT was significantly increased (NAMPT/GAPDH: 1.15±0.06 vs. 0.79±0.14, P < 0.01). Compared with the AAA-VSMC group, the positive rate of SA-β-gal staining and the expression levels of senescence-related proteins p21 and p16 in the AAA+P7C3 group were significantly lower [SA-β-gal staining positive rate: (54.1±6.0)% vs. (74.1±4.4)%, p21/GAPDH: 0.38±0.02 vs. 0.61±0.07, p16/GAPDH: 0.50±0.13 vs. 0.77±0.03, all P < 0.05], but the expression of NAMPT was significantly increased (NAMPT/GAPDH: 1.25±0.28 vs. 0.88±0.07, P < 0.01). Conclusion:NAMPT agonist P7C3 can delay the senescence of VSMC and play a protective role in abdominal aortic aneurysm.