Osteoprotegerin Gene Therapy Preventing Bone Loss Induced by Periodontitis

Objectives: The objective of this study was to investigate the effects of osteoprotegerin (OPG) gene therapy on alveolar bone resorption caused by experimental periodontitis in rats thus forming a foundation for potential clinical applications of OPG gene therapy in the treatment of periodontitis and peri-implantitis. Methods: To study the effects of OPG on alveolar bone protection, an experimental periodontitis model was used by placing a bacterial plaque retentive silk ligature in the gingival sulcus around the maxillary second molar tooth, injection of Porphyromonas gingivalis and high-carbohydrate diet. A total of 30 Sprague-Dawley (SD) rats were randomly divided into three groups, each with 10. Group I (control) was treated with 100μg normal saline injection, Group II was treated with 100μg mock vector and Group III with 100μg local OPG gene transfer by transfection with in-vitro constructed pcDNA3.1-hOPG. Four weeks later, all the animals were sacrificed and radiographic, histological and immunohistochemical examinations were performed. Statistical analysis included ANOVA and LSD-Bonferroni test. Results: Group III (OPG gene therapy) had significantly enhanced (P < 0.05) integrated optical density (IOD) of OPG, had significantly decreased alveolar bone resorption volume and active osteoclasts number (P < 0.05) through descriptive histological examination when compared with the other two groups at weeks 4. Conclusions: Local recombinant OPG plasmid-mediated gene therapy suppresses osteoclastogenesis in vivo and inhibits alveolar bone height reduction caused by experimental periodontitis in rats. OPG gene therapy may be beneficial in preventing progressive periodontal bone loss.