RESUMO
PURPOSE: Pamidronate disodium-associated bone necrosis is poorly understood at the cellular and molecular levels. This study proposes a pathway leading to the pamidronate disodium-mediated inhibition of osteogenic differentiation of human bone marrow mesenchymal stem cells (BMMSCs) derived from the mandible in vitro. MATERIALS AND METHODS: Primary human BMMSCs were isolated from the mandible and marrow tissue. A proliferation assay was performed to determine the experimental concentration of pamidronate disodium. Alkaline phosphatase (ALP) activity, ALP staining, and Alizarin red S (ARS) staining were assessed after treatment with pamidronate disodium (0, 0.1, 0.5, 1, 5, 10 µg/mL). Quantitative real-time polymerase chain reaction and western blotting specific for Wnt and ß-catenin signaling genes or proteins were performed after treatment with pamidronate disodium 0.5 µg/mL. Wnt3a was used to observe the osteogenic differentiation of BMMSCs during treatment with pamidronate disodium 0.5 µg/mL. RESULTS: As expected, pamidronate disodium 1, 5, and 10 µg/ml were unfavorable for BMMSC growth (P < .05), whereas 0.1 and 0.5 µg/mL did not affect BMMSC growth (P ≥ .05). BMMSCs treated with pamidronate disodium 0.5 µg/mL had lower ALP activity, ALP staining, and ARS staining (P < .05), and BMMSCs treated with low concentrations (<0.5 µg/mL) of pamidronate disodium had the same levels of ALP activity, ALP staining, and ARS staining as the control (0 µg/mL). Pamidronate disodium 0.5 µg/mL decreased the expression of genes and proteins involved in Wnt and ß-catenin signaling. BMMSCs with Wnt3a and pamidronate disodium 0.5 µg/mL had higher ALP activity, ALP staining, and ARS staining (P < .05). CONCLUSIONS: Pamidronate disodium inhibited Wnt and ß-catenin signaling, which controls osteogenic differentiation in BMMSCs. Wnt3a, a Wnt and ß-catenin signaling activator, reversed the negative effects caused by pamidronate disodium to salvage the osteogenic defect in BMMSCs.