Osteoprotegerin and Receptor Activator of Nuclear Factor-Kappa B Ligand Modulation by Enamel Matrix Derivative in Human Alveolar Osteoblasts.

Background: Bone regeneration techniques increasingly rely on the use of exogenous molecules able to enhance tissue formation in pathologic and traumatic defects. An enamel matrix derivative (EMD) has been largely used to promote tooth ligament regeneration within periodontal pockets. Recent evidence suggests that EMD may contribute to inducing osteoblast growth and differentiation. We investigated the effects of EMD on growth and osteogenic marker modulation in human mandibular osteoblasts. Methods: We focused our attention on cell growth by 3-(4,5-dimethyl[thiazol-2-yl]-3,5-diphery)tetradium bromide (MTT) assay, cell differentiation, mineralized nodule formation, and, in particular, the expression of receptor activator of nuclear factor-kappa B ligand (RANKL), the main osteoclast differentiation factor, and its decoy receptor, osteoprotegerin (OPG), by enzyme-linked immunosorbent assay. Results: Cell growth was significantly increased by EMD. Similarly, a significantly higher quantity of OPG and a lower amount of RANKL were detectable in groups treated with 50 and 100 μg/ml at weeks 1, 2, and 3, and alkaline phosphatase activity and osteocalcin production were enhanced in cultures treated with 50 and 100 μg/ml at weeks 2 and 3. Mineralized nodules appeared bigger and more numerous in cultures treated with 50 and 100 μg/ml EMD. Conclusions: EMD was able to enhance osteoblast cell growth and the expression of markers of osteoblastic phenotype and differentiation. EMD also seemed able to create a favorable osteogenic microenvironment by reducing RANKL release and enhancing osteoblastic OPG production.