BACKGROUND:Steroid-induced osteonecrosis of the femoral head (SONFH) is a common bone disease characterized as high morbidity and poor prognosis,but the pathogenesis is unclear.Oxidative stress treatment is closely related to the occurrence and development of SONFH,and has tremendous potential in the treatment of SONFH,which can be realized by Nano-Se.OBJECTIVE:To observe the protective effect of porous Se@SiO2 nanocomposite on chondrocytes by antioxidant stress,and to further explore its mechanism of protection and treatment of SONFH.METHODS:(1) In vitro experiment:The rat chondrocytes were isolated,cultured and identified.Then,the chondrocytes were cultured with porous Se@SiO2 nanocomposite to suppress the production of reactive oxygen species (ROS).(2) In vivo experiment:A total of 36 rats were randomly divided into three groups.Steroid-induced group and experimental group were treated with intraperitoneal injection of lipopolysaccharide and intramuscular injection of methylprednisolone to induce SON FH models.Seven days after modeling,the experimental group was intraperitoneally injected with porous Se@SiO2 nanocomposite.No intervention was done in control group (blank control).At 8 weeks after modeling,rat bilateral femoral heads were taken for hematoxylin-eosin staining and Micro-CT scanning.RESULTS AND CONCLUSION:Results from the ROS detection and TUNEL apoptosis tests showed that the level of ROS in the chondrocytes was significantly reduced after intervention with Se@SiO2 (P ＜ 0.05).Micro-CT scanning findings showed that the bone mineral density,bone volume,bone area/bone volume,trabecular number,trabecular thickness,and trabecular separation in the steroid-induced and experimental groups were significantly different from those in the control group (P ＜ 0.05).Hematoxylin-eosin staining results showed smooth femoral head,normal bone cells,chondrocytes and trabecular bone,as well as few empty bone lacunae and fat cells in the control group,while in the steroid-induced group,there was bone trabecular fracture,fat cell hypertrophy fusion,a large number of empty bone lacunae and obvious osteonecrosis.These manifestations were significantly improved in the experimental group.To conclude,the porous Se@SiO2 nanocomposite has good antioxidative stress ability,suppresses the ROS production and exerts therapeutic effects on SONFH.