RESUMO
Background/purpose: Sphingosine-1-phosphate (S1P) exhibits receptor-mediated physiological effects by facilitating the differentiation of mesenchymal stem cells toward the osteoblast lineage. This study aimed to determine the effect of S1P on odontogenic differentiation of mouse immortalized stem cells of dental apical papilla (iSCAP) and assess the distribution of the S1P receptor 1 (S1PR1) in the apical papilla and the root canal wall of immature rat molars. Materials and methods: Immunostaining for S1PR1 was conducted at the apex of the rat mandibular first molar and within the root canal wall. The iSCAP was treated with S1P and bone morphogenetic protein (BMP)-9 (for comparison), and the expression levels of the odontogenic differentiation marker were evaluated via real-time reverse-transcriptase quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. Mineralization and lipid droplet formation were evaluated via Alizarin red and Oil red O staining. Results: S1PR1-positive cells were expressed in areas of both apical papilla and dentin-pulp interface of root canal wall. During the odontogenic differentiation of iSCAP, S1P and BMP-9 increased the expression of the differentiation marker mRNA and secreted proteins including dentin sialophosphoprotein, dentin matrix phosphoprotein 1, and matrix extracellular phosphoglycoprotein. The S1PR1 signaling pathway is involved in the action of S1P, but not that of BMP-9. S1PR1 signaling also facilitated mineralization in iSCAP and suppressed the differentiation of these cells into adipocytes. Conclusion: S1P induced odontogenic differentiation of iSCAP through S1PR1. Furthermore, S1PR1-positive cells were expressed in the apical papilla of immature rat molars and in the dentin-pulp interface where odontoblast-like cells exist.
RESUMO
Background/purpose: Regarding root-end filling materials in apical surgery, sealing ability and biocompatibility are useful for treatment. Angiogenesis, which occurs in the process of periapical wound healing, is closely related to bone formation. In this study, we investigated the effects of root-end filling materials on vascular endothelial cell proliferation and angiogenesis. Materials and methods: Mineral trioxide aggregate (MTA), 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin, Super EBA, and CS-BG-multi, bioactive glass-related materials, were used. After curing, each material was soaked in a medium for 1 or 7 days, and then cultured for 1-7 days to investigate the effects on human umbilical vein endothelial cell (HUVEC) proliferation, angiogenesis, and vascular endothelial growth factor receptors (VEGFRs) mRNA expression. Results: In the 1-day soaked sample, there was significantly less proliferation in MTA and Super EBA on day 7 of culture. In the 7-day soaked sample, there was significantly less proliferation in Super EBA and CS-BG-multi on day 7 of culture. Tube formation was significantly high in MTA in both the 1-day and 7-day soaked samples, significantly high in SB in the 1-day soaked sample, and significantly low in Super EBA in both the 1-day and 7-day soaked samples. CS-BG-multi was comparable to the control. VEGFR-1 and VEGFR-2 mRNA expressions showed an upward trend in MTA, and a trend similar to the control in SB. Conclusion: MTA and 4-META/MMA-TBB resin had a higher pro-angiogenic effect while Super EBA had a less pro-angiogenic effect. CS-BG-multi had low toxicity on tube formation of HUVEC.
RESUMO
Background/purpose: Sphingosine-1-phosphate (S1P) is a lipid mediator that exerts its physiological functions in vivo through receptors. In the bone, S1P induces osteoblast differentiation. Here, we investigated the effects of S1P receptor agonists on the expression of osteoblast differentiation markers locally in the bone. Then, a rat apicoectomy and alveolar bone defect model was established to extend S1P applications to endodontics, and the effect of local administration of S1P receptor agonist on postoperative bone formation was examined. Materials and methods: Sphingosine-1-phosphate receptor (S1PR) 1/S1PR3 agonists, S1PR2 agonists, and their signal-related agents were intraperitoneally administered to mice. Using the mRNA collected from the tibial bone, the expression of osteoblast differentiation markers was evaluated by real-time reverse-transcriptase quantitative polymerase chain reaction. An apicoectomy and alveolar bone defect model was established on the mesial root of the rat mandibular first molar. Bone formation parameters were measured by micro-computed tomography analysis 3 weeks after the procedure. Results: Intraperitoneal administration of S1PR2 agonist significantly increased the mRNA expression of osteoblast differentiation markers, including alkaline phosphatase (ALP), osteopontin (OPN), bone sialoprotein (BSP), and osteocalcin, in the local tibial bone of mice. The S1PR2/Rho-associated coiled-coil forming kinase (ROCK) signaling was thought to be involved in the upregulated mRNA expression of ALP, OPN, and BSP. In the rat apical defects, bone formation parameters significantly increased following local administration of S1PR2 agonist. Conclusion: In the rat apicoectomy and alveolar bone defect model, therapeutic agents targeting S1PR2 agonist are effective against osteogenesis.