Background Alcohol is known to be one ofthe leading risk factors for osteonecrosis of the femoral head. However, the underlying etiology and protective strategiesof alcohol-induced osteonecrosis of the femoral headhavenot been clarified.
Objectives The aim of this study was to explore the molecular mechanism of alcohol-induced osteonecrosis of the femoral head, and to investigate the protective effect of SC-79 on the disease.
Methods In vitro, we employed RT-PCR, alizarin red staining, alkaline phosphatase activity testing, western blot, immunofluorescence staining to investigate the effect of ethanol on hBMSCs. In vivo experiments, immunofluorescence staining, TRAP, TUNEL and micro-CT were performed to investigate the development of ONFH.
Results In vitro, we found that ethanol could significantly impair the expression of osteogenic genes of RUNX2 and OCN, downregulate osteogenic differentiation, impair IGF-1 induced membrane recruitment of the Akt, suppress the Akt-Ser473 phosphorylationand the subsequent activation of Akt/GSK3β/β-catenin signaling in bone mesenchymal stem cells. Functional studies further confirmed this signaling was the critical mediator during the ethanol-induced inhibitory effects on osteogenesis of BMSCs.Thus, the dephosphorylation of Akt-Ser473 in Akt/GSK3β/β-catenin signaling pathway might be a potential mechanism in the pathogenesis of alcohol-induced osteonecrosis of the femoral head.SC-79, a novel Akt activator was introduced in this study to block the dephosphorylation effect of ethanol on Akt-Ser473 both in vitro and in vivo. In the rat model of alcohol-induced osteonecrosis of the femoral head, micro-CT and histopathological analyses revealed obvious osteonecrosis changes in alcohol-administrated rats while significantly less developed in SC-79 injected rats. OPN, OCN and COL1 immunofluorescence staining revealed that osteogenic response of femoral heads was markedly reduced after alcohol administration, but significantly reversed by SC-79 treatment.
Conclusions Hence, we discovered alcohol-induced osteonecrosis of the femoral headwas associated with the suppression of the Akt-Ser473 in Akt/GSK3β/β-catenin pathway in BMSCs. The administration of SC-79, to elevate Akt activation, might be a clinical strategy to prevent the development of alcohol-inducedosteonecrosis of the femoral head.
Acknowledgements The current study was supported by National Natural Science Foundation of China (81272003, 81301572) and SMC-Chen Xing Plan for Splendid Young Investigators of Shanghai Jiao Tong University.
Disclosure of Interest None declared