Paeonol induces osteoblast differentiation of bone marrow-derived human mesenchymal stromal cells and inhibits adipocyte differentiation.

BACKGROUND: Osteoporosis is a metabolic bone disease characterized by reduced bone mass and increased fracture risk. In this study, we investigated the effects of paeonol on the osteogenic and adipogenic differentiation of human bone marrow-derived mesenchymal stromal/stem cells (hBM-MSCs) in vitro. METHODS: Differentiation was assessed using alkaline phosphatase (ALP), Alizarin Red S, and Oil Red O staining. Changes in osteogenic and adipogenic markers were evaluated by Western blot and quantitative PCR. The modulation of Wnt/β-catenin, bone morphogenetic protein 2 (BMP2), and AMP-activated protein kinase (AMPK) pathways was analyzed by Western blot, and pathway involvement was further validated using specific pharmacological inhibitors (ICG-001 and Compound C). RESULTS: Paeonol promoted cell proliferation, increased ALP staining and extracellular matrix mineralization, and upregulated the levels of key osteogenic markers (osterix, ALP, and Runx2) in hBM-MSCs. The pro-osteogenic effects of paeonol were associated with the activation of components within the Wnt and BMP2 signaling axes, and were attenuated by the Wnt/β-catenin inhibitor ICG-001, which also abolished paeonol-induced BMP2 upregulation and Smad1/5 phosphorylation. Conversely, paeonol suppressed adipogenic differentiation, downregulated peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and sterol regulatory element-binding protein 1c (SREBP1c), increased AMPK phosphorylation, and modulated downstream lipogenic targets including acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS). The anti-adipogenic effects of paeonol were reversed by the AMPK inhibitor Compound C. CONCLUSION: Our in vitro findings demonstrate that paeonol promotes osteoblast differentiation and inhibits adipocyte differentiation in hBM-MSCs. These effects are linked to the modulation of Wnt/BMP and AMPK signaling pathways, respectively.