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

Abstract

Catechin (CH) exhibits protective effects on bone metabolism, but its underlying mechanism remains incompletely understood. 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. 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. 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.