Insulin-like Growth Factor-¢ò Affects Periodontal Ligament Cells Expressing Osteoprotegerin

Objective: This study was carried out to investigate the effects of insulin-like growth factor-¢ò(IGF-¢ò) on osteoprotegerin(OPG) secretion of periodontal ligament cells (PDLCs) Methods: Healthy human premolars extracted for orthodontic reasons from 12°«14 years old donators were obtained, and periodontal tissues were collected and cultured to obtain PDL cells. Primary or first passage PDLCs were cloned by means of limited dilutions. PDLCs with osteoblastic phenotypes were characterized as follows: Alkaline phosphatase activity, collagen ¢ó production and bone-like nodules formation. IGF-¢òwere added into culture media and their effects on PDLCs proliferation and OPG secretion were observed. The OPG concentrations in cell culture supernatants were detected by sandwich ELISA. Living cell numbers were demonstrated by MTT test. The average levels of OPG secretion by a single cell were calculated by dividing OPG concentration with MTT-test result. Results: IGF-¢òupregulated the mtt values (P£¼0.05,ANOVA ), but downregulated the opg/mtt values (P£¼0.05,ANOVA). Conclusion: IGF-¢òenhances the proliferation of PDL cells but prohibits OPG secretion. This study suggests that before cytokines were used to enhance periodontal regeneration, their effects on local bone balance should also be studied.