Indole-3-Acetic Acid Prevents Hydrogen Peroxide-Induced Toxicity in Human Dental Pulp Stem Cells

Objectives: Indole-3-acetic acid (IAA) is the most common plant hormone of the auxin class and known to have many effects including cell proliferation enhancement and antioxidant property. However no study has revealed its defensive effects against reactive oxygen species (ROS) in human dental pulp stem cells (hDPSCs). This study was performed to find out the effects of IAA on hydrogen peroxide (H₂O₂)-induced oxidative toxicity in hDPSCs.
Methods: First, the effects of H₂O₂ and IAA on cell viability at various concentration were assessed. Second, the viability and cell cycle assessed after the treatment of 180μM H₂O₂ and 150μM IAA. Then apoptosis-related gene expression and ROS levels were analyzed to investigate how IAA is reducing the apoptosis of H₂O₂-damaged hDPSCs.
Results: The viability of hDPSCs was significantly decreased after the treatment of H₂O₂ at 180μM and above. On the other hand, the viability of hDPSCs was not affected by IAA treatment. However cell viability assessed after the sequential treatment of 180μM H₂O₂ and 150μM IAA demonstrated that H₂O₂-induced cytotoxicity was remarkably attenuated by IAA. Damaged cell cycle and apoptosis induction by H₂O₂ treatment were recovered after the treatment of IAA. The expression of apoptosis-associated genes, BAX and P53, was increased by H₂O₂ treatment while anti-apoptosis gene, BCL-2 and AFS was decreased when compared with control. The level of ROS was co-related with BAX and P53 expression.
Conclusions: In conclusion, the IAA prevents H₂O₂-induced cytotoxic damage of hDPSCs by cell cycle restoration and reduction of apoptosis and ROS.