Effect of Preheating on Thermotolerance In Human Dental Pulp Cells

Objectives: While heat stress induced by dental procedure can damage to the human dental pulp cells (hDPCs), preheating with mild heat may be beneficial to cell survival. This study investigated the effect of the mild heat stress on thermotolerance in hDPCs. We also examined the expression of thermotolerance-related proteins.
Methods: The hDPCs were cultured at 41°C for 0, 1, 3, and 6 h, and then the lethal heat stress (49°C) was applied for 5 min. Then, the cell viability was measured by MTT assay. For evaluating the cell apotosis induced by the heat stress, AnnexinV-FITC/PI staining was performed, followed by FACS analysis. The expression of the thermotolerance-related proteins including HSP-27, HSP-70, HSP-90, and HSF-1 was evaluated by western blotting. The data were analyzed by one-way ANOVA followed by Tukey’s test (p<0.05).
Results: The hDPCs pre-heated for 6 h showed higher viability than the cells pre-heated for 0, 1 or 3 h (p<0.05). The results of AnnexinV-FITC/PI staining indicated that the cell apoptosis rate was lower in the 6-h pre-heated group compared to other groups (p<0.05). The expression of HSP-27, HSP-70, HSP-90 and HSF-1 in hDPCs preheated for 6 h was higher compared to the cells preheated for 0, 1 or 3 h (p<0.05).
Conclusions: The pretreatment with mild heat stress for 6 h can provide protection against lethal heat shock in hDPCs.