The Function and Role of Intercellular Adhesion Molecule 2 in Dental Pulp Cells and Tissue

Direct pulp capping using mineral trioxide aggregate (MTA) is commonly used to preserve dental pulp tissue, but the molecular mechanisms underlying reparative dentin formation during this procedure and the restoration of dental pulp homeostasis remain unclear. To elucidate these mechanisms, we investigated the expression and function of intercellular adhesion molecule 2 (ICAM2) in dental pulp cells and tissue. ICAM2 expression in human dental pulp cells (HDPCs) was confirmed by the gene and protein expression analysis. ICAM2 expression during reparative dentin formation after direct pulp capping was investigated using a rat direct pulp capping model. The effect of ICAM2 on odontoblast-like differentiation of HDPCs was assessed using siRNA and magnetic cell sorting (MACS). The gene and protein expression analysis showed that ICAM2 is expressed in approximately 10% of HDPCs. Immunofluorescence staining of rat mandibular bone sections showed that ICAM2 is expressed in dental pulp tissue. During reparative dentin formation, ICAM2 expression significantly increased to nearly three-fold higher than pretreatment levels on the 3 days after direct pulp capping and then returned to normal levels. ICAM2 knockdown by siRNA enhanced odontoblast-like differentiation of HDPCs. In contrast, culture supernatant from ICAM2-positive HDPCs separated by MACS inhibited odontoblast-like differentiation of HDPCs. These findings suggest that ICAM2 may regulate reparative dentin formation in dental pulp tissue.