Osteogenic Response of Human Osteoblasts Derived from Mandible and Maxilla: A Preliminary Study

ABSTRACT

PURPOSE: Maxilla and mandible have different patterns of cortical and trabecular bone and different bone mineral densities, even though both are components of the jaw bone. However, cellular differences between maxilla- and mandible derived osteoblasts (OBs) have rarely been studied. We hypothesize that maxilla- and mandible-derived OBs show different responses to 17beta-estradiol (E2), which is one of the critical factors for bone formation. This study compares skeletal site-specific cell responses between maxilla- and mandible-derived human OBs to E2.METHODS: Maxilla- and mandible-derived OBs derived from an identical donor were separately isolated from a total of five normal healthy subjects aged 18~44 years old, cultured with a treatment of 100 nM estrogen. The responses between maxilla- and mandible-derived OBs to E2 were evaluated and compared using cell proliferation, alkaline phosphatase (ALP) activity and gene expression of osteoprotegerin (OPG), ALP, insulin-like growth factor-1 (IGF-1), and estrogen receptor alpha (ERalpha).RESULTS: E2 did not have any distinct effects on the proliferation of both types of OBs. Mandible-derived OBs exhibited higher ALP activity than maxilla-derived OBs in the non-treated condition, which was common in all tested individuals. ALP activities of both types of OBs showed a minor increasing tendency with the treatment of E2, even though there was no statistical significance in some specimens. The gene expression of OB by E2 was diverse, depending on the individuals. There was increased expression of OPG, IGF-1, or ERalpha gene in the part of subjects, which was more repeated in maxilla-derived OBs. In particular, OPG or ALP induction by E appeared less frequently in mandible-derived OBs.CONCLUSION: Current results revealed that E2 affects maxilla- and mandible-derived OBs into facilitating the osteogenic process despite individual differences. Mandible-derived OBs are less sensitive to bone-forming gene expression by E2.