Abstract
OBJECTIVE: To investigate the effects of sodium valproate (VPA) in inhibiting Erastin-induced ferroptosis in bone marrow mesenchymal stem cells (BMSCs) and its underlying mechanisms. METHODS: BMSCs were isolated from bone marrow of 8-week-old Spragur Dawley rats and identified [cell surface antigens CD90, CD44, and CD45 were analyzed by flow cytometry, and osteogenic and adipogenic differentiation abilities were assessed by alizarin red S (ARS) and oil red O staining, respectively]. Cells of passage 3 were used for the Erastin-induced ferroptosis model, with different concentrations of VPA for intervention. The optimal drug concentration was determined using the cell counting kit 8 assay. The experiment was divided into 4 groups: group A, cells were cultured in osteogenic induction medium for 24 hours; group B, cells were cultured in osteogenic induction medium containing optimal concentration Erastin for 24 hours; group C, cells were cultured in osteogenic induction medium containing optimal concentration Erastin and VPA for 24 hours; group D, cells were cultured in osteogenic induction medium containing optimal concentration Erastin and VPA, and 8 μmol/L EX527 for 24 hours. The mitochondrial state of the cells was evaluated, including the levels of malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species (ROS). Osteogenic capacity was assessed by alkaline phosphatase (ALP) activity and ARS staining. Western blot analysis was performed to detect the expressions of osteogenic-related proteins [Runt-related transcription factor 2 (RUNX2) and osteopontin (OPN)], ferroptosis-related proteins [glutathione peroxidase 4 (GPX4), ferritin heavy chain 1 (FTH1), and solute carrier family 7 member 11 (SLC7A11)], and pathway-related proteins [adenosine monophosphate-activated protein kinase (AMPK) and Sirtuin 1 (SIRT1)]. RESULTS: The cultured cells were identified as BMSCs. VPA inhibited Erastin-induced ferroptosis and the decline of osteogenic ability in BMSCs, acting through the activation of the AMPK/SIRT1 pathway. VPA significantly reduced the levels of ROS and MDA in Erastin-treated BMSCs and significantly increased GSH levels. Additionally, the expression levels of ferroptosis-related proteins (GPX4, FTH1, and SLC7A11) significantly decreased. VPA also upregulated the expressions of osteogenic-related proteins (RUNX2 and OPN), enhanced mineralization and osteogenic differentiation, and increased the expressions of pathway-related proteins (AMPK and SIRT1). These effects could be reversed by the SIRT1 inhibitor EX527. CONCLUSION: VPA inhibits ferroptosis in BMSCs through the AMPK/SIRT1 axis and promotes osteogenesis.