Effects of epicatechin, a crosslinking agent, on human dental pulp cells cultured in collagen scaffolds

ABSTRACT Objective The purpose of this study was to investigate the biological effects of epicatechin (ECN), a crosslinking agent, on human dental pulp cells (hDPCs) cultured in collagen scaffolds. Material and Method To evaluate the effects of ECN on the proliferation of hDPCs, cell counting was performed using optical and fluorescent microscopy. Measurements of alkaline phosphatase (ALP) activity, alizarin red staining, and real-time polymerase chain reactions were performed to assess odontogenic differentiation. The compressive strength and setting time of collagen scaffolds containing ECN were measured. Differential scanning calorimetry was performed to analyze the thermal behavior of collagen in the presence of ECN. Results Epicatechin increased ALP activity, mineralized nodule formation, and the mRNA expression of dentin sialophosphoprotein (DSPP), a specific odontogenic-related marker. Furthermore, ECN upregulated the expression of DSPP in hDPCs cultured in collagen scaffolds. Epicatechin activated the extracellular signal-regulated kinase (ERK) and the treatment with an ERK inhibitor (U0126) blocked the expression of DSPP. The compressive strength was increased and the setting time was shortened in a dose-dependent manner. The number of cells cultured in the ECN-treated collagen scaffolds was significantly increased compared to the cells in the untreated control group. Conclusions Our results revealed that ECN promoted the proliferation and differentiation of hDPCs. Furthermore, the differentiation was regulated by the ERK signaling pathway. Changes in mechanical properties are related to cell fate, including proliferation and differentiation. Therefore, our study suggests the ECN treatment might be desirable for dentin-pulp complex regeneration.

Involvement of mitogen-activated protein kinases and nuclear factor-kappa B activation in nitric oxide-induced interleukin-8 expression in human pulp cells.

OBJECTIVE: This study examined the effect of nitric oxide (NO) on interleukin-8 (IL-8) production and the involvement of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-kappaB) signaling pathways in primary cultured human pulp cells. STUDY DESIGN: IL-8 production was measured using enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. MAPK activation and IkappaB degradation and phosphorylation were determined by western blotting. RESULTS: Sodium nitroprusside (SNP), an NO donor, has increased IL-8 secretion and mRNA expression in a dose- and time-dependent manner. SNP induced the phosphorylation of p38 MAPK and extracellular-regulated kinase (ERK), degradation and phosphorylation of IkappaB, and activation of NF-kappaB. Furthermore, inhibition of the ERK, p38, and NF-kappaB pathways blocked SNP-induced IL-8 secretion. CONCLUSION: Human pulp cells showed NO-induced IL-8 expression via the MAPK and NF-kappaB pathways, which may play an important role in the inflammatory responses of pulp and periapical lesions.

Evaluation of the radiopacity and cytotoxicity of Portland cements containing bismuth oxide.

OBJECTIVE: This study aimed at evaluating the radiopacity and cytotoxicity of Portland cements containing bismuth oxide (PcBo) in varying ratios. STUDY DESIGN: Specimens measuring 10 mm in diameter and 1 mm in thickness were radiographed with an aluminum step wedge using an occlusal film. The radiographs were digitized, and the radiopacity of each material was compared to the different thicknesses of the aluminum step wedge. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the cytotoxicity of each material was determined in immortalized human periodontal ligament (IPDL) cells. RESULTS: The results demonstrated that Portland cement with 20% bismuth oxide presented greater radiopacity (P < .05) compared to the mixtures with less bismuth oxide. The cell viabilities of all PcBo groups were statistically similar (P > .05) throughout the experimental period. CONCLUSION: These results indicate that Portland cement with 20% bismuth oxide has a greater potential for being used as a root-end filling material compared to Portland cement with less bismuth oxide.

Human pulp cells response to Portland cement in vitro.

The aim of this study was to investigate the cellular effects of Portland cement on cultured human pulp cells. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, no cytotoxicity was observed in the Portland cement group in comparison with the negative control group, whereas the glass ionomer cement, intermediate restorative material, and Dycal groups showed a survival rate of less than 40% at 12 hours. Scanning electron microscopy revealed that human pulp cells attached to the Portland cement were flat and had numerous cytoplasmic extensions. In the groups in which other materials were used, a few rounded cells were observed on the material but no living cells were observed. The expression of both osteonectin and dentin sialophosphoprotein mRNAs was induced in the Portland cement-treated group. These results suggest that Portland cement is biocompatible, allows the expression of mineralization-related genes on cultured human pulp cells, and has the potential to be used as a proper pulp-capping material.