Physiological concentrations of denosumab enhance osteogenic differentiation in human mesenchymal stem cells of the jaw bone

Objective: The aim of this study was to evaluate the possible influence of denosumab and zoledronate on pro-liferation and osteogenic differentiation of alveolar bone stem cells. Design: Mesenchymal stem cells (MSCs) and dental follicle cells (DFCs) were grown under osteogenic differentiation with concentrations from 0.25 mu M to 10 mu M (zoledronate) and to 20 mu M (denosumab). Vitality was assessed after 7 days by CCK-8 Kit. Osteogenic differentiation was measured by alkaline phosphatase (ALP) assay and additionally by RT-qPCR of key enzymes COL1, RUNX2 and ALP. Results: MSCs expressed receptor activator of NF-kappa B (RANK), as requirement to interact with denosumab. DFCs did not express RANK. Denosumab significantly reduced proliferation and ALP activity of MSCs in high concentrations (10 mu M and 20 mu M). Growth of DFCs was not influenced at all by denosumab. Zoledronate reduced proliferation of DFCs in higher concentrations (5 mu M and 10 mu M) (p > 0.05). Physiological and medium concentrations of denosumab (0.25 mu M, 1 mu M 5 mu M) significantly enhanced ALP activity in MSCs and COL1, RUNX2 and ALP were upregulated. Zoledronate had no effect on ALP activity in DFCs. Conclusion: Our evaluations suggest receptor and dose depending effects of denosumab in MSCs. High concentrations mediate toxic effects, whereas physiological and medium concentrations enhance osteogenic differentiation.