Quercetin has been shown to have a wide range of beneficial effects, such as anti-inflammation, anti-oxidation and immunomodulation. The study was designed to explore the role and molecular mechanisms of quercetin on the protective effect of bone marrow-derived mesenchymal stem cells (BMSCs) under oxidative stress in vitro. BMSCs were isolated from 4-week-old male Sprague-Dawley rats. Upon H2O2 stimulation in vitro, the effects of quercetin on the proliferation, anti-oxidation and osteogenic differentiation of BMSCs were evaluated by Cell Counting Kit-8, reactive oxygen species analysis, Western blot (WB), real-time PCR (RT-PCR), alkaline phosphatase staining and alizarin red staining. Additionally, ferroptosis-related markers were examined by WB, RT-PCR and Mito-FerroGreen. Finally, PI3K/AKT/mTOR signaling pathway was explored in these processes. We found that quercetin significantly maintained BMSCs viability upon H2O2 stimulation. Quercetin upregulated protein (ALP, OPN and RUNX2) and mRNA (Alp, Opn, Ocn and Runx2) levels of osteogenic markers, downregulated ROS levels and upregulated antioxidative gene expressions (Nrf2, Cat, Sod-1 and Sod-2) compared with the H2O2 group. The ferroptosis in BMSCs was activated after H2O2 stimulation, and the phosphorylation level of PI3K, AKT and mTOR was upregulated in H2O2-stimulated BMSCs. More importantly, quercetin inhibited ferroptosis and the phosphorylation level of PI3K, AKT and mTOR were downregulated after quercetin treatment. We conclude that quercetin maintained the viability and the osteoblastic differentiation of BMSCs upon H2O2 stimulation, potentially via ferroptosis inhibition by PI3K/AKT/mTOR pathway.
Keywords: BMSCs; PI3K/Akt/mTOR pathway; ferroptosis; osteogenic differentiation; quercetin.