Catechin promotes osteogenic differentiation via AMPK-mediated autophagy activation in bone marrow mesenchymal stem cells

BACKGROUND: Catechin (CH) exhibits protective effects on bone metabolism, but its underlying mechanism remains incompletely understood. METHODS: We investigated the osteogenic effects of CH and its molecular pathways using bone marrow mesenchymal stem cells and MC-3T3-E1 preosteoblasts. Cell viability was assessed after CH treatment (1-100 μg/mL). Osteogenic differentiation was evaluated by ALP activity, mineralization, and the expression of key markers (Runx2, Opn, Ocn, Sp7). Mechanistic studies involved examining autophagy markers (LC3-II, P62) and the AMPK pathway, using pharmacological inhibitors (compound C for AMPK; 3-methyladenine for autophagy). The protective role of CH under oxidative stress was tested in hydrogen peroxide-treated cells by measuring viability, ROS levels, NRF2 translocation, and osteogenic capacity. RESULTS: CH showed no significant cytotoxicity up to 100 μg/mL. At 10 μg/mL, it significantly enhanced osteogenic differentiation, increasing alkaline phosphatase activity (ALP), mineralization, and the gene/protein levels of osteogenic markers. CH activated autophagy (elevated LC3-II, decreased P62) and the AMPK pathway. Inhibition of AMPK or autophagy partially suppressed CH-induced osteogenesis, which was significantly rescued by CH co-treatment. Under oxidative stress, CH improved cell viability, reduced intracellular ROS, inhibited NRF2 nuclear translocation, and restored osteogenic differentiation. CONCLUSION: CH promotes osteogenesis primarily via the AMPK-autophagy axis and reverses oxidative stress-induced suppression of osteogenic differentiation through ROS clearance. These findings highlight its therapeutic potential for bone regeneration and related disorders.