Pinoresinol Diglucoside Relieves Osteoporosis Through Enhancing Osteogenic Differentiation via Activating Phosphatidylinositol-3-Kinase/Protein Kinase B Signaling Pathway

Background: The purpose of the current study was to explore whether Pinoresinol diglucoside (PD) could relieve osteoporosis through promoting osteogenic differentiation by activating phosphatidylinositol-3 kinase (PI3K)/AKT signaling pathway. Methods: Firstly, human bone marrow mesenchymal stem cells (hBMMSCs) and mouse embryo steoblast recursor cells (MC3T3-E1) were induced for osteogenic differentiation, and then the cells were subjected to 1 mu mol/l PD. Then, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot assay were used to detect the expression of osteogenic marker genes/proteins such as bone morphogenetic protein 2 (BMP2), runt-related transcription factor 2 (Runx2), and Osterix. The activity of alkaline phosphatase (ALP) in cells was also detected. Cell viability was further detected by Cell Count Kit-8 (CCK-8), and cell apoptosis was detected by flow cytometer. Finally, the protein expression of p-AKT and AKT was detected by Western blot assay. Results: The results showed that osteogenic differentiation of hBMMSCs and MC3T3-E1 cells were successfully induced, evidenced by increased BMP2, Runx2, Osterix mRNA expression and ALP activity enhancement. The osteogenic differentiation of MC3T3-E1 cells and hBMMSCs was enhanced by PD administration. At the same time, PD promoted the viability of MC3T3-E1 cells and reduced the MC3T3-E1 cell apoptosis. In addition, PD increased the protein expression of p-AKT and the ratio of p-AKT/AKT in MC3T3-E1 cells, suggesting PI3K/AKT pathway activation. Conclusion: PD promoted osteogenic differentiation of hBMMSCs and MC3T3-E1 cells, and it could promoted osteoblast proliferation and inhibit apoptosis, thereby playing a protective role in osteoporosis.