Tanshinone <scp>IIA</scp> Reverses Osteogenic Differentiation of Bone Marrow Mesenchymal Stromal Cells Impaired by Glucocorticoids via the <scp>ERK1</scp>/2‐<scp>CREB</scp> Signaling Pathway

Glucocorticoids-induced osteoporosis poses a critical health issue due to its detrimental impact on bone marrow mesenchymal stem cells (BMSCs); Tanshinone IIA (TSA) emerges as a promising therapeutic intervention, demonstrating its capacity to reverse osteogenic differentiation impairment. The aim is to determine whether TSA enhances the osteogenic differentiation of BMSCs damaged by dexamethasone (DEX) through the ERK1/2 -CREB signaling pathway. BMSCs were treated with varying concentrations of DEX (0.1-30 μM) and TSA (0.04-5 μM) for 18 or 36 h. Cell viability was assessed using the MTT assay. Osteogenic differentiation was evaluated through Alizarin Red S staining and quantified by qRT-PCR for osteogenic markers such as Runx2 and ALP. Apoptosis was measured by Annexin V-FITC/PI staining and TUNEL/DAPI co-staining. The ERK1/2-CREB signaling pathway was examined using Western blot and immunofluorescence. TSA at 5 μM significantly bolstered BMSCs viability and osteogenic differentiation, reversing the deleterious effects of 30 μM DEX. TSA pre-treatment decreased apoptosis and ROS levels, and importantly, it enhanced the ERK1/2-CREB signaling pathway, as evidenced by increased phosphorylation of ERK1/2 and CREB. The ERK1/2 inhibitor PD98059 and siCREB abrogated TSA's protective effects, highlighting the pathway's significance. These findings indicate that TSA, through the ERK1/2-CREB axis, provides a protective strategy against DEX-induced impairment in BMSCs. TSA's modulation of the ERK1/2 -CREB pathway reverses DEX-induced osteogenic inhibition and apoptosis in BMSCs, suggesting its therapeutic efficacy against glucocorticoid-induced bone disorders.