Metformin Rescues the Impaired Osteogenesis Differentiation Ability of Rat Adipose-derived Stem Cells in High Glucose by Activating Autophagy.

The incidence and morbidity of diabetes osteoporosis (DOP) are increasing with each passing year. Patients with DOP have a higher risk of bone fracture and poor healing of bone defects, which make a poor quality of their life. Bone tissue engineering based on autologous adipose-derived stem cells(ASCs) transplantation develops as an effective technique to achieve tissue regeneration for patients with bone defects. With the purpose of promoting auto-ASCs transplantation, this research project explored the effect of metformin on the osteogenic differentiation of ASCs under a high glucose culture environment. Here, we found that 40mM/L high glucose inhibited the physiological function of ASCs including cell proliferation, migration, and osteogenic differentiation. Indicators of osteogenic differentiation were all down-regulated by 40mM/L high glucose, including alkaline phosphatase(ALP) activity, runt-related transcription factor 2(RUNX2), and osteopontin(OPN) gene expression and Wnt signaling pathway. At the same time, the cell autophagy makers BECLIN1 and microtubule-associated protein 1 light chain 3(LC3 I/II) were decreased. While 0.1mM/L metformin upregulated the expression of BECLIN1 and LC3 I/II gene and inhibited the expression of mTOR and GSK3β, contribute to reverse the osteogenesis inhibition of ASCs caused by high glucose. While 3-MA was used to block the activity of metformin, metformin couldn't exert its protective effect on ASCs. All the findings elaborated the regulatory mechanism of metformin in the high glucose microenvironment to protect the osteogenic differentiation ability of ASCs. Metformin plays an active role in promoting the osteogenic differentiation of ASCs with DOP, and it may contribute to the application of ASCs transplantation for bone regeneration in DOP.