Enamel matrix derivative does not affect osteoclast formation or bone resorption in cultures of mouse bone marrow macrophages or human monocytes

Objective Enamel matrix derivative (EMD) is widely used under the brand name Emdogain(R) to promote periodontal regeneration in surgical treatment of periodontitis and peri-implantitis. The molecular mechanisms are unclear, but it has been proposed that EMD has stimulatory effects on the root cementum and periodontal ligament cells. Since dental implants lack these structures, we hypothesized that EMD-induced bone gain involve interactions with osteoclast precursor cells, with consequent inhibitory effect on osteoclast formation and/or activity. The aim was to evaluate this hypothesis. Material and methods Primary mouse bone marrow macrophages (BMMs) and human peripheral blood monocytes were cultured in the presence of receptor activator nuclear factor-kappa B ligand (RANKL) to stimulate osteoclast formation. A purified Emdogain(R) fraction was added to the cell cultures and the effect on number and size of newly formed osteoclasts were evaluated. In cultures on natural bone slices, bioanalytical methods were used to assay osteoclast number and bone resorption. Results EMD had a negative effect on osteoclastogenesis in mouse cultures on plastic surface, whereas addition of EMD to osteoclast precursor cells on bone substrate did not affect osteoclast formation or bone resorption. Conclusions The results on natural bone matrix contradict a direct effect of EMD on osteoclast precursor cells.