Icariin Protects against Glucocorticoid-Induced Osteonecrosis of the Femoral Head in Rats

Abstract

Background/Aims: Glucocorticoid (GC)-related osteonecrosis of the femoral head (ONFH) is a common complication following administration of steroids to treat many diseases. Our previous study demonstrated that icariin (ICA) might have a beneficial effect on the bone marrow mesenchymal stem cells (BMSCs) of patients with steroid-associated osteonecrosis. In this study, we investigated the underlying mechanisms of ICA associated with the potential enhancement of osteogenesis and anti-adipogenesis in GC-related ONFH. Methods: In vitro cell proliferation was evaluated by CCK-8 assay. Alizarin red S and alkaline phosphatase (ALP) activity were used to measure osteogenic differentiation, while adipogenic differentiation was revealed by oil red O staining and TG content assay. The expression level of osteogenesis-associated genes and PPARγ was evaluated by RT-qPCR, western blotting and immunofluorescence. A total of 30 female SD rats were randomly separated into three groups: a control group, a methylprednisolone (MPS) group and a MPS + ICA group. Serum ALP and TG (triglyceride), micro-CT scanning, histological and immunohistochemical analyses were performed in the animal model. Results: In the in vitro study, ICA promoted proliferation, improved osteogenic differentiation and suppressed adipogenic differentiation of BMSCs treated with MPS. The group treated with MPS and 10^-6 M ICA expressed higher levels of Runx2, ALP, bone morphogenetic protein (BMP) 2, and OC and lower expression of PPARγ than the MPS group. In the in vivo study, ICA prevented bone loss in a rat model of GC-related ONFH as shown by micro-CT scanning, histological and immunohistochemical analyses. Conclusions: ICA is an effective compound for promoting bone repair and preventing or delaying the progression of GC-associated ONFH in rats. This effect can be explained by its ability to improve the balance between adipogenesis and osteogenesis, indicating that ICA is an effective candidate for management of GC-associated ONFH.