Melatonin Promotes Osteogenic Differentiation in Lipopolysaccharide-Stimulated Human Periodontal Ligament Stem Cells Through Bone Morphogenic Proteins-2-Related Signaling

摘要

Periodontitis is one of the most widespread infectious diseases that troubled the majority of adults. Human periodontal ligament stem cells (hPDLSCs) have been reported as a promising therapy for the treatment of periodontitis. Melatonin, an indoleamine hormone from pineal gland, has various biological activities such as anti-inflammation, anti-cancer and so on. However, whether it is functional in periodontitis is still unclear. The aim of this study was to investigate the effect of melatonin in periodontitis and elucidate the molecular mechanism. Lipopolysaccharide (LPS) was used to stimulate hPDLSCs, and viability of hPDLSCs that was treated with melatonin (0, 1, 10, 50 and 100 mu mol/L) for 24 h or 48 h was determined by MTT assay. Flow cytometry analysis was carried out to detect the influence of melatonin on cell proliferation. Osteogenic differentiation ability of melatonin was determined by Alkaline phosphatase (ALP) assay kit and Alizarin Red Staining. Lastly, western blot was used for the determination of protein expressions related to proliferation, differentiation and ERK/Wnt signaling activity. The results showed that LPS significantly inhibited cell viability, which was reversed by melatonin, especially at 10 mu M for 48 h and at 50 mu M for 24 h. Melatonin (10 mu M, 48 h) and melatonin (50 mu M, 24 h) notably induced G0/G1 phase cell arrest, increased the expression of CDK2, cyclin E and decreased the expression of p27 in LPS-stimulated hPDLSCs. Besides, melatonin significantly promoted cell differentiation through increasing ALP activity, mineralization and protein expressions of Oct4, Sox-2, Runx2 and bone morphogenic protein-2 (BMP-2). Additionally, BMP-2 related ERK and Wnt signaling was activated with the treatment of melatonin in LPS-stimulated hPDLSCs. Collectively, melatonin could improve cell proliferation and osteogenic differentiation in LPS-stimulated hPDLSCs, partly through regulating BMP2-related ERK/Wnt pathway.