Oxidative stress impairs the calcification ability of human dental pulp cells

BACKGROUND: The relationship between internal root resorption and oxidative stress has not yet been reported. This study aimed to add molecular insight into internal root resorption. The present study was conducted to investigate the effect of hydrogen peroxide (H(2)O(2)) as an inducer of oxidative stress on the calcification ability of human dental pulp cells (hDPCs) and the involvement of inositol 1, 4, 5-trisphosphate (IP3). MATERIAL AND METHODS: hDPCs (Lonza, Basel, Switzerland) were exposed to H(2)O(2). Cell viability and reactive oxygen species (ROS) production were then evaluated. To investigate the effect of H(2)O(2) on the calcification ability of hDPCs, real-time PCR for alkaline phosphatase (ALP) mRNA expression, ALP staining, and Alizarin red staining were performed. Data were compared with those of hDPCs pretreated with 2-aminoethyldiphenylborate (2-APB), which is an IP3 receptor inhibitor. RESULTS: H(2)O(2) at concentrations above 250 µM significantly reduced cell viability (P < 0.01). More ROS production occurred in 100 µM H(2)O(2)-treated hDPCs than in control cells (P < 0.01). 2-APB significantly decreased the production (P < 0.05). H(2)O(2)-treated hDPCs showed significant reductions in ALP mRNA expression (P < 0.01), ALP activity (P < 0.01), and mineralized nodule deposition compared with negative control cells (P < 0.01). 2-APB significantly inhibited these reductions (P < 0.01, P < 0.05 and P < 0.01, respectively). Data are representative of three independent experiments with three replicates for each treatment and values are expressed as means ± SD. CONCLUSION: To the best of our knowledge, this is the first study documenting the involvement of IP(3) signaling in the calcification ability of human dental pulp cells impaired by H(2)O(2).