The present study aimed to investigate the effects of vascular endothelial growth factor (VeGF) and insulin-like growth factor-1 (iGF-1) on the proliferation, migration and differentiation of human carious dental pulp stem cells (hcdPScs), and to elucidate the underlying mechanism(s). cell counting kit-8 assay was used to detect the effect of different concentrations of iGF-1 and VeGF on the proliferation of hcdPScs. Transwell assay was used to detect the migratory ability of the hcdPScs. alizarin red and alkaline phosphatase (alP) staining were used to detect the osteogenic ability of hcdPScs, whereas the angiogenic ability of the hcdPScs was tested by tube formation assay. reverse transcription-quantitative polymerase chain reaction (rT-qPcr) and western blotting were used to detect the expression levels of associated genes and proteins. iGF-1 (100 ng/ml) or VeGF (25 ng/ml) alone were revealed to be able to promote proliferation and migration of hcdPScs; however, the combined use of iGF-1 and VeGF enhanced this effect when compared with the use of either agent in isolation. alizarin red and alP staining revealed that the use of either VeGF or iGF-1 alone did not result in any significant effects, whereas their use in combination promoted the osteogenic differentiation of hcdPScs. in addition, the rT-qPcr and western blotting analyses revealed that the expression levels of runt-related transcription factor 2 (runX2), bone sialoprotein (BSP) and alP were increased upon combined treatment of the cells with VeGF and iGF-1. The expression levels of VeGF and plateletderived growth factor (PdGF) in hcdPScs were enhanced upon treatment with either VeGF or iGF-1 in isolation, with greater effects observed when VeGF and iGF-1 were added in combination, indicating that VeGF and iGF-1 may exert a synergistic role in these events. Further experiments revealed that the combination of VeGF and iGF-1 led to an activation of the aKT signaling pathway. The proliferation and angiogenesis of hcdPScs were also shown to be more effective compared with treatment with either VeGF or iGF-1 in isolation. Taken together, the present study has demonstrated that the combined use of VeGF and iGF-1 leads to an increase in the proliferation, migration, osteogenesis and angiogenesis of hcdPScs and, furthermore, these signaling molecules may mediate their effects via activation of the aKT signaling pathway.

Background/purpose Dental pulp stem cells can be isolated from human teeth with deep caries (cDPSCs), but their biological characteristics are still unclear. The aim of this study was to investigate the angiogenic potential of cDPSCs and compare them to dental pulp stem cells from human normal teeth (nDPSCs). Materials and methods Cells were isolated from human pulp tissue of normal and infected teeth with deep caries. Basic mesenchymal stem cell (MSC) characterization was conducted. Colony forming units and proliferation ability were evaluated in nDPSCs and cDPSCs. Expression of VEGF in both tissues and cells was examined by immunohistochemical staining. After stimulating nDPSCs and cDPSCs with an angiogenic medium, angiogenic markers were evaluated by qRT-PCR and western blotting. Finally, tube formation assays were used to evaluate the in vitro angiogenesis potential of both cell populations. Results Both nDPSCs and cDPSCs possessed typical MSC characteristics. cDPSCs had enhanced colony formation and proliferation capacities than nDPSCs did. The expression of VEGF was higher in pulp tissue from teeth with deep caries and cDPSCs than in normal tissue and nDPSCs. When both cell types were grown in vitro under angiogenic conditions, cDPSCs expressed a higher level of angiogenic markers and showed a stronger angiogenesis potential than nDPSCs did. Conclusion cDPSCs maintained MSC traits and presented a higher angiogenesis potential than nDPSCs.

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Elevated glycolytic activity and redox imbalance induced by tissue hypoxia are common phenomena of chronic inflammation, including inflammatory bone diseases such as arthritis. However, relation between glycolysis and redox signaling in the inflammatory milieu is unclear. The histone deacetylase sirtuin 6 (SIRT6) is a crucial modulator of inflammation and glucose metabolism, and it is also involved in cellular protection against oxidative injury. The aims of the study were to examine the connection between glycolysis and reactive oxygen species (ROS) production in human osteoblastic cells (HOB) and whether SIRT6 modulates inflammatory response via regulation of glycolytic activity and ROS generation. In HOB cultured under hypoxia, expression of lactate dehydrogenase A (LDHA), lactate production and ROS generation were examined. The reciprocal effects between lactate and ROS production and their impact on inflammatory cytokine induction were assessed. The action of SIRT6 on the above reactions was determined. In a rat model of collagen-induced arthritis (CIA), the relation between inflammatory activity and osteoblastic expression of LDHA, level of oxidative lesions, Cyr61 synthesis and macrophage recruitment were examined in joints with or without lentiviral-SIRT6 gene therapy. Results showed that hypoxia stress enhanced lactate and LDHA production in HOB. ROS generation was also increased, and there was a positive feedback between glycolysis and ROS formation. Overexpression of SIRT6 attenuated hypoxia-enhanced glycolysis and ROS generation. Hypoxia-induced expressions of Cyr61, TNF-α, IL-1β, and IL-6 were suppressed by SIRT6 and the inhibitory effects overlapped with antiglycolytic and antioxidation mechanisms. In the model of CIA, forced expression of SIRT6 ameliorated disease progression, osteoblastic synthesis of Cyr61, and macrophage recruitment. More importantly, expression of LDHA and oxidative lesions were decreased in osteoblasts of SIRT6-treated joints. Our findings suggest that SIRT6 suppresses inflammatory response in osteoblasts via modulation of glucose metabolism and redox homeostasis. SIRT6-based strategy may possess therapeutic potential for inflammatory bone resorption. © 2016 BioFactors, 43(2):170-180, 2017.