Figure 6. Exogenous intermediates participated in NAD+ biosynthesis ameliorates MSC replicative senescence. (A) SA-β-gal staining and p16INK4A mRNA expression of senescent LP MSCs in the presence of Vehicle (DMSO treated), 100 μM NAM, 100 μM NMN, 100 μM NAD, and 5 μM resveratrol (RSV) (scale bar = 50 μm) and quantification. (B, C, D) Effect of NAD intermediates treatment on NAD+ content (B) and NAD+/ NADH ratio (C), as well as Sirt1 deacetylase activity (D); n = 3 independent experiments. *P < 0.05, **P < 0.01.