High glucose mediates apoptosis and osteogenesis of MSCs via downregulation of AKT-Sirt1-TWIST

Background Mesenchymal stem cells have been widely used in the treatment of diabetes mellitus. However, hyperglycemia associated with DM promotes cell apoptosis and affects osteogenic differentiation of MSCs in varying degrees, leading to osteoporosis in DM patients. Therefore, in this paper, the effect of high glucose on apoptosis and osteogenesis of MSCs was investigated and underlying mechanism was further determined. Methods and results Intracellular ROS levels were determined using probe DCFH-DA. MMP was detected using JC-1 staining. Cell apoptosis was detected using Annexin V-FITC/PI and Flow Cytometer. The expression of genes and protein was detected by qRT-PCR and Western blot respectively. The results showed high glucose induced MSC apoptosis but promoted its osteogenesis. Western blot analysis revealed that high glucose downregulated AKT-Sirt1-TWIST pathway. Activation of Sirt1 via SRT1720 increased TWIST expression, alleviated MSC apoptosis and promoted osteogenesis of MSCs. TWIST knockdown studies demonstrated that inhibition of TWIST intensified high glucose-induced apoptosis but promoted osteogenesis differentiation of MSCs. TWIST is likely to be a new regulator for cross talk between Sirt1 and its downstream targets. Conclusion Our data demonstrates that high glucose induces MSC apoptosis and enhances osteogenesis differentiation via downregulation of AKT-Sirt1-TWIST.