Department of Oral Physiology, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, South Korea.
J Endod. 2013 Jun;39(6):801-5. doi: 10.1016/j.joen.2012.12.037. Epub 2013 Feb 14.
Mineral trioxide aggregate (MTA) can induce differentiation of the dental pulp cells into odontoblast-like cells and generate a dentin-like mineral structure. The mechanisms underlying MTA-induced odontoblastic differentiation in human dental pulp cells (HDPCs) are not completely understood. The purpose of this study was to evaluate the effect of nifedipine as calcium channel blocker on MTA-induced odontoblastic differentiation in HDPCs.
HDPCs extracted from maxillary supernumerary incisors and third molars were directly cultured on MTA with or without nifedipine in the culture medium. Cell growth and expression of odontoblastic differentiation markers were determined by using methyl-thiazol-diphenyl-tetrazolium assay and reverse transcription-polymerase chain reaction analysis, respectively. Phosphorylation of mitogen-activated protein kinase was measured by Western blotting, and calcium deposition was assessed by using alizarin red S staining.
MTA at a concentration of 1 mg/mL significantly up-regulated the expression of dentin sialophosphoprotein and dentin matrix protein-1 and enhanced mineralized nodule formation. However, nifedipine attenuated the MTA-induced odontoblastic differentiation in HDPCs. In addition, MTA-induced mineralization was blocked by inhibition of extracellular signal-regulated kinase (ERK), p38, and Jun N-terminal kinase (JNK) by using U0126, SB203580, and SP600125, respectively. Furthermore, phosphorylation of ERK and JNK in response to MTA was inhibited when the medium was supplemented with nifedipine.
This study showed that calcium ions released from MTA play an important role in odontoblastic differentiation of HDPCs via modulation of ERK and JNK activation.
矿化三氧化物凝聚体（MTA）可以诱导牙髓细胞向成牙本质细胞样细胞分化，并生成类似牙本质的矿化结构。然而，MTA 诱导人牙髓细胞（HDPC）成牙本质分化的机制尚不完全清楚。本研究旨在评估钙通道阻滞剂硝苯地平对 MTA 诱导 HDPC 成牙本质分化的影响。
从上颌多生牙和第三磨牙中提取 HDPC，并直接在含有或不含有硝苯地平的培养基中在 MTA 上培养。通过甲基噻唑二苯基四唑测定法和逆转录聚合酶链反应分析分别测定细胞生长和牙本质分化标志物的表达。通过 Western blot 测定丝裂原活化蛋白激酶的磷酸化，并用茜素红 S 染色评估钙沉积。
浓度为 1 mg/mL 的 MTA 显著上调牙本质涎磷蛋白和牙本质基质蛋白-1 的表达，并增强矿化结节形成。然而，硝苯地平减弱了 MTA 诱导的 HDPC 成牙本质分化。此外，通过使用 U0126、SB203580 和 SP600125 分别抑制细胞外信号调节激酶（ERK）、p38 和 Jun N-末端激酶（JNK），MTA 诱导的矿化被阻断。此外，当培养基中补充硝苯地平时，MTA 对 ERK 和 JNK 的磷酸化作用受到抑制。
本研究表明，MTA 释放的钙离子通过调节 ERK 和 JNK 的激活在 HDPC 的成牙本质分化中发挥重要作用。
