Effects of Thai propolis mixed in mineral trioxide aggregate on matrix metalloproteinase-2 expression and activity in inflamed human dental pulp cells

Objectives: This study sought to determine effects of Thai propolis extract mixed in mineral trioxide aggregate (MTA) on matrix metalloproteinase-2 (MMP-2) expression and its activity in inflamed human dental pulp cells (HDPCs). Materials and Methods: Interleukin-1 beta-primed HDPCs were treated with either the eluate of MTA mixed with distilled water, of MTA mixed with 0.75 mg/ml of the propolis extract, or of Dycal (R), 0.75 mg/ml of the propolis extract, or 0.2% (v/v) of chlorhexidine for 24 or 72 h. The viability of HDPCs was determined by the PrestoBlue (R) cytotoxic assay. HDPCs' lysates were analyzed for MMP-2 mRNA expression by RT-qPCR, while their supernatants were measured for MMP-2 activity by gelatin zymography. Results: At 24 and 72 h, a non-toxic dose of the propolis extract at 0.75 mg/ml by itself or mixed in MTA tended to reduce MMP-2 expression upregulated by MTA, while it further decreased the MMP-2 activity as compared to that of MTA mixed with distilled water. The MMP-2 activity of interleukin-1 beta-primed HDPCs treated with the eluate of the propolis extract mixed in MTA was significantly lower than that of interleukin-1 beta-primed HDPCs at 24 h (p=0.012). As a control, treatment with chlorhexidine significantly inhibited MMP-2 expression induced by MTA and MMP-2 activity enhanced by interleukin-1 beta (p<0.05). Treatment with Dycal (R) caused a significant increase in HDPC's death, resulting in a significant decrease in MMP-2 expression and activity (p<0.05). Conclusions: MTA mixed with Thai propolis extract can reduce MMP-2 mRNA expression and activity when compared to MTA mixed with distilled water in inflamed HDPCs.