Effects of spermidine on osteogenic differentiation of bone-marrow mesenchymal stem cells in senescent rabbit and its related mechanisms

  Background  Osteogenic differentiation of senescent rabbit bone-marrow mesenchymal stem cells (BMSCs) are weakened with aging, and spermidine can attenuate age-associated diseases.

  Objective  To investigate the effects of spermidine on osteogenic differentiation of senescent rabbit BMSCs.

  Methods  BMSCs were divided into three groups: Vehicle, D-gal (D-galactose, 40 g/L D-gal), and Spermidine (40 g/L D-gal+3 μmol/L spermidine). NAD⁺/NADH kit was used to evaluate intracellular NAD⁺/NADH, and MTT method was used to detect cell viability. After cultured in osteogenic medium, western blotting assay was used to investigate the protein expression level of Sirt1, qPCR was used to detect osteogenic genes transcription.

  Results  Compared with the Vehicle group, NAD⁺/NADH level in D-gal group decreased and BMSCs growth was inhibited (P＜0.05); while NAD⁺/NADH level in spermidine group increased and BMSCs growth was promoted (P＜0.05). After cultured in osteogenic medium, D-gal decreased Sirt1 expression and down-regulated Runx2, Osx and ALP transcription (all P＜0.05); while spermidine up-regulated Runx2, Osx and ALP transcription (P＜0.05). However, when inhibiting Sirt1 using small interfering RNA, the effects of spermidine on promoting osteogenic genes transcription were blunted (P＜0.05).

  Conclusion  Spermidine can promote osteogenic differentiation of senescent rabbit BMSCs via activating Sirt1.