Bone augmentation in an osteoporosis rat model via a single local injection of simvastatin

Abstract

Objective To explore the bone anabolic effects after a single local injection of simvastatin into femoral cavities of osteoporotic rats.Methods Thirty-six female SD rats (3 months old,body weight 250-300 g) were ovariectomized (OVX) and low-calcium-diet fed for 3 months,OVX rats were randomized into 3 groups (n=12).Left femurs of group A,B and C were injected with 0,5 and 10 mg simvastatin,respectively.Half of the rats in each group were randomly euthanized separately 1 and 5 months after simvastatin injection.Left femurs were taken out for bone mineral density (BMD) assessment with dual energy X-ray absorptiometry,bone histomorphometic changes were analysized by Micro-CT,and two kinds of biomechanical tests were used to evaluate the osteogenic effects.Results One and five months after injection,BMD in mid-diaphysis significantly increased in simvastatin-injected groups compared to the control group.For Micro-CT analysis,significant increase in total bone volume/total tissue volume,cortical wall thickness,trabecular thickness,trabecular number,and a significant decrease in trabecular spacing were observed in simvastatin-injected groups compared to the control group.For both biomechanics (the three-pointbreaking test of condyles and axial compressive testing of proximal femur),the values were significantly higher in simvastatin-injected groups than the control group.Conclusion Local simvastatin treatment showed a positive effect on improving mechanical strength,structure of osteopenic femurs and BMD.Our findings may provide a new strategy for the prevention and treatment of osteoporosis,especially for osteoporotic fractures. Key words: Osteoporosis; Administration, topical; Osteogenesis