Visfatin increases NADPH consumption and induces telomere damage. Human dental pulp cells (hDPCs) were pretreated with FK866 (10 µM) for 2 h and then incubated with visfatin (500 ng/mL) for 24 h. (a) Measurement of the NADP/NADPH ratio in visfatin-treated hDPCs with or without FK866 pre-treatment. Nicotinamide mononucleotide (NMN, 100 µM), the product of the visfatin/Nampt enzymatic reaction, was used to compare its activity in NADPH consumption. (b) Immunofluorescence analysis of TRF-1 (Alexa fluoro (AF)-488, green) and γH2AX (AF-594, red) in hDPCs. The cells were analyzed using a confocal microscope. Nuclei were counterstained with DAPI (blue). Scale bar: 50 μm. (c) Quantification of the percentage of γH2AX-positive cells. (d) hDPCs were transiently transfected with a vector mediating the overexpression of visfatin (pCI-Visfatin-Myc) for 48 h and subjected to immunocytochemical analysis. Cells were stained using anti-Myc antibody (green) and anti-γH2AX (red). Nuclei were counterstained with DAPI (blue). Scale bar: 50 μm. * p < 0.1, ** p < 0.01, *** p < 0.001.