RESUMO
OBJECTIVE: Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a common clinical complication in patients receiving bisphosphonate therapy. Furthermore, melatonin has been proposed as a therapeutic drug for the oral cavity due to its antioxidant properties. This study aimed to evaluate the cytoprotective effects of melatonin on zoledronic acid (ZA)-treated human mesenchymal stem cells from periodontal ligament (PDLSCs) and bone marrow (BMMSCs). METHODS: PDLSCs and BMMSCs were exposed to ZA, melatonin or ZA + melatonin for 72 h. Cell proliferation was measured by a colorimetric assay, whereas their mesenchymal phenotype was analyzed by flow cytometry. RESULTS: Proliferation assays showed that BMMSCs presented higher ZA resistance than PDLSCs, as well as a difference in response to the simultaneous treatment of ZA + melatonin. Using PDLSCs, high doses of melatonin significantly increased their proliferation, whereas lower concentrations were enough to enhance ZA-treated BMMSC proliferation. Moreover, PDLSCs displayed a CD90/CD105 downregulation and CD73 upregulation in response to ZA, which was more pronounced in response to melatonin. Furthermore, ZA or ZA + low doses of melatonin induced a decrease of expression of CD90/CD105/CD73 on BMMSCs, while a higher concentration recovered CD73 levels. CONCLUSION: These results suggest that melatonin has a cytoprotective effect on ZA-treated PDLSCs and BMMSCs. Thus, it could be used for BRONJ prevention.