Glucocorticoids Inhibit Osteogenic Differentiation Of Bone Marrow Mesenchymal Stem Cells By Upregulate FOXO1 And FOXO3a Expression

Objective:Glucocorticoids are widely applied for clinical treatment of non-infectious inflammation,cancer,and autoimmune diseases.However,a long-term application of high dosage of glucocorticoid can lead to secondary femoral head necrosis,and there is still no effective treatments at now.Studies have shown that glucocorticoids break the bone metabolism balance by altering the osteogenic and adipogenic differentiation capacity of bone marrow mesenchymal stem cells(BMSCs),and eventually induce femoral head necrosis.However,it is still unclear which molecules are involved in hormone-induced changes in BMSCs differentiation ability.Bone homeostasis depends on the dynamic balance of osteogenesis and adipogenesis of BMSCs.The osteogenic differentiation of BMSCs is accompanied by functional changes in the oxidative respiratory chain,resulting in an increase in intracellular reactive oxygen species(ROS)levels.Consequently,BMSCs activate a series of antioxidant systems via FOXO transcription factors to prevent cytotoxic damage due to increased ROS levels.We hypothesized that FOXO transcription factor were also involved in GCs-induced impaired osteogenic differentiation of BMSCs.In the present study,we explored the role of FOXO transcription factors in GCs-induced impaired osteogenic differentiation of BMSCs.Methods:After the patient's informed consent and the approval of the ethics committee of Huazhong University of Science and Technology Union Hospital,We collected bone marrow from patients with femoral neck fractures or osteoarthritis without a history of GCs,and isolated and cultured BMSCs.The third-generation cells,characterized by well shape and strong proliferation ability,were collected for subsequent experiments.The cells were treated with 10^-6M dexamethasone for 48 hours.QPCR,Brd U staining,Cell Counting Kit-8,and alizarin red staining were employed to detect the expression of FOXO as well as the changes of cell proliferation and osteogenic differentiation.The changes of cell proliferation and osteogenic differentiation were detected again after knocking down the FOXO1 and FOXO3a by RNA interference technique.Results:1)Dexamethasone up-regulates expression of FOXO1 and FOXO3a in BMSCs;2)Dexamethasone inhibits cell proliferation and osteogenic differentiation;3)Knockdown of FOXO1 and FOXO3a rescued the impairment of BMSCs proliferation and osteogenic differentiation by dexamethasone;Conclusion:Glucocorticoids inhibit the proliferation and osteogenic differentiation of BMSCs via up-regulating FOXO1 and FOXO3a.The present study provides a new therapeutic target for hormonal femoral head necrosis...