The Regulatory Role of Vitamin D on Dental Pulp Stem Cells in Inflammatory Conditions: An In Vitro Study.

INTRODUCTION

This study evaluated the effects of vitamin D on the immune response and regenerative properties of dental pulp stem cells (DPSCs) under lipopolysaccharide (LPS)-induced inflammatory conditions.

METHODS

DPSCs were exposed to predetermined concentrations of vitamin D and LPS, administered individually, concomitantly, or sequentially. DPSCs cultured in the growth medium without further treatment were used as the control group. Cell proliferation and migration assays were performed, and inflammatory mediator expression was assessed to determine the immunomodulatory impact of vitamin D. Odontogenic/osteogenic differentiation was assessed using Alizarin Red staining, alkaline phosphatase (ALP) assay and immunocytochemical analysis of dentin matrix protein 1, dentin sialophosphoprotein and nestin expression. Data were analyzed statistically.

RESULTS

LPS stimulation significantly reduced cell proliferation, migration, ALP activity, and mineral deposition while increasing inflammatory mediator expression (P < .05). In contrast, vitamin D treatment attenuated mediator levels and preserved cellular functional capacity (P < .05). Concomitant exposure to vitamin D and LPS resulted in improved proliferation and migration compared with LPS exposure alone (P < .05). Both concomitant exposure and the sequential protocol in which vitamin D was administered after LPS exposure demonstrated significantly higher ALP activity, enhanced mineralization, increased dentin matrix protein 1 and dentin sialophosphoprotein expression and decreased nestin expression compared with LPS exposure alone (P < .05). However, the sequential protocol in which LPS was administered after vitamin D exposure showed no significant differences compared with LPS exposure alone (P > .05).

CONCLUSIONS

Continuous vitamin D exposure was associated with attenuation of the inflammatory response and better preservation of the regenerative capacity of DPSCs compared with prior vitamin D exposure alone.