Fig. 5

HG alone rapidly downregulates Sirtuin (SIRT) 1 expression and function to suppresses mitochondrial activity as well as MSC osteogenesis via NAD⁺ depletion. A & B Representative and pooled data for expression levels of SIRT1 protein in human BMMSCs cultured in LG-CM or HG-CM for 8 h as assessed by western blot, respectively (n = 4 for each group). C Pooled data of depolarized and polarized mitochondrial ΔΨm. as assessed in human BMMSCs treated with LG-CM in the absence or presence of sirtinol (S; 20 μM), or HG-CM in the absence or presence of NMN or NMN combined with S for 8 h (n = 3 for each group). D Pooled data for frequency analyses of low, intermediate and high mitochondrial activity as assessed in human BMMSCs treated with LG-CM in the absence or presence of S, or HG-CM in the absence or presence of NMN or NMN combined with S for 8 h (n = 3 for each group). (E and F) qPCR analyses of CEBPB and KLF5 (E) as well as RUNX2 and ALPL (F) as assessed in human BMMSCs treated with LG-CM in the absence or presence of S, or HG-CM in the absence or presence of NMN or NMN combined with S for 8 h (n = 4 for each group). G and H Representative and pooled data (n = 3 for each group), respectively, for oil drop accumulation in human BMMSCs as assessed with OR staining. Scale bar, 50 μm. I and J Representative and pooled data (n = 3 for each group), respectively, for calcium deposition in human BMMSCs as assessed with AR staining. Scale bar, 50 μm. Data are shown as mean ± SD. *, p < 0.05; **, p < 0.01; ***, p < 0.001. #, p < 0.05 for comparison excluding LG-OM (1.^st bar)