Effects of Low-Dose Dexamethasone on Metabolic Readouts and Lineage-associated Gene Expression in Human Dental Pulp
Simony H H Kataoka1, Huey-Jiun Lin2, Galib Ovik2
1Department of Periodontics and Endodontics, School of Dental, Medicine, University at Buffalo, Buffalo, New York.
Introduction:
Injury to the dental pulp activates reparative responses involving dental pulp cells (DPCs). While dexamethasone (Dex) is widely used in differentiation protocols, its isolated effects on metabolic activity and lineage-associated gene expression in DPCs remain incompletely characterized, particularly when evaluated independently of conventional odontogenic supplements. The aim of this study was to explore Dex effects on human DPCs. We hypothesized that low-dose Dex would yield changes in metabolic profiles and modulate lineage-associated gene expression in vitro.
Methods:
Primary human DPCs derived from 6 healthy human third molars (n = 3 donors) were treated with increasing concentrations of Dex. Cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Metabolic readouts were evaluated by measuring glucose, lactate, β-hydroxybutyrate, glutamate, and ammonium levels in conditioned medium. Gene expression was analyzed by quantitative real-time polymerase chain reaction and protein levels by Western blotting. Mineralization was assessed by Alizarin Red staining.
Results:
Dex exhibited a dose-dependent effect on DPC proliferation, with 10 nM associated with increased cell growth, while higher concentrations showed a nonsignificant trend toward reduced proliferation. At 10 nM, Dex was associated with increased total RNA and protein levels, an effect attenuated by rapamycin. Dex treatment was also associated with changes in metabolic readouts, including reduced glucose levels and increased lactate levels in conditioned medium. Increased expression of odontogenic-associated markers such as Osterix (2.5-fold) and DMP-1 (1.5-fold) and mineralization were observed. Additionally, Dex was associated with altered expression of genes previously associated with neurogenic-related and angiogenic-related processes.
Conclusions:
Within the limitations of this in vitro study, low-dose Dex is associated with changes in metabolic profiles and lineage-associated gene expression in human DPCs. These findings provide exploratory insight into the cellular responses of DPCs to Dex.
