Heat stress defense in dental pulp stem cells

Abstract

Many dental treatment procedures can generate excessive heat within a short period of time. The heat on the tooth surface can be transduced to the dental pulp chamber and lead to alteration of dental pulp stem cells, vascular structures and sensory neurons within the chamber. It has been reported that elevation of temperature by 5.5°C in the pulp chamber caused 15% irreversible pulpal damage. However, the molecular changes of dental pulp cells post heat stress has not been characterized. In this study, we explored the changes in human dental pulp Stem Cells from the Exfoliated Deciduous teeth (SHED) after exposure to heat stress. Lysate of SHED cells were collected after exposure to heat stress at 42°C or normal culture temperature at 37°C. Western blots were used to examine the expression of Heat Shock Proteins (HSP). Human cytokine arrays (AAH‐CYT‐5, RayBiotech) were used to evaluate the changes in the expression of 80 human cytokines in SHED cells after heat stress. Short term exposure to heat stress induced phosphorylation of HSP27. Prolonged exposure further increased expression of other heat shock proteins, which have been reported to play an important role in cell protection under stress. In addition, transient exposure to heat stress caused differential expression of cytokines in SHED cells, suppressing expression of cytokines as IL‐1a and IL‐10, while increasing expression of glial cell derived neurotrophic factor (GDNF) and insulin‐like growth factor ‐1 (IGF‐1). The results showed HSPs and multiple cytokines play important role in detecting and responding to heat stress on the SHED cells. These factors could potentially protect SHED cells from thermal damage and promote stem cell regeneration post thermal damage. Support or Funding Information Faculty Scholarly/Artistic Activities Award DDNA12‐013 University of the Pacific.