Does elevated osteopontin level play an important role in the development of scoliosis in bipedal mice?

Background Context: Previous studies implied indirectly that an elevated osteopontin (OPN) level might play a key role in the pathomechanism of adolescent idiopathic scoliosis. Nonetheless, up to now, no direct evidence was proposed to determine this issue.

Purpose: The aim was to determine the role of OPN in the pathomechanism of scoliosis.

Study Design: This was an experimental study to investigate the role of OPN in a bipedal mouse scoliosis model.

Methods: All procedures were performed under the approval and supervision of the Institutional Animal Care and Use Committee of our university. A new bipedal mouse model with elevated OPN level was established in this study. Amputation of forelimbs and tail was performed on 80 male C3H/HeJ mice at the age of 3 weeks. Then, these mice were randomly divided into two groups: Group A consisted of 40 mice treated with OPN 40 mg/kg daily and Group B consisted of the remaining 40 mice treated with saline. Then, 40 quadruped mice with saline were included in Group C. Body length, X-rays, and computed tomographic scans were obtained at the twentieth week. Then, scoliosis incidence, curve magnitude, and circulating OPN level were compared among groups.

Results: Osteopontin level was significantly higher in Group A compared with that in Groups B and C. Spine deformity was identified in 37 mice in Group A, 21 mice in Group B, and 5 mice in Group C. The average Cobb angle was 29.8° in Group A, 20.9° in Group B, and 17.5° in Group C. Although no significant difference of body length was found, significant statistical difference was noted in terms of scoliosis incidence and curve magnitude, among the three groups.

Conclusions: The results of the present study indicated that the elevated OPN level might play an important role in the etiopathogenesis of scoliosis, that is, it not only raises the risk for scoliosis in bipedal mice but also contributes to curve progression.