Ca1.2 regulated odontogenic differentiation of NG2 pericytes during pulp injury.

NG2 pericytes, as the possible precursor cells of mesenchymal stem cells (MSCs), have drawn attention due to their ability to differentiate into odontoblasts. Ca1.2 is involved in the differentiation process of stem cells, but its role in the differentiation of NG2 pericytes is not clear. The aim of the present study was to examine the role of Ca1.2 in the differentiation of NG2 pericytes into odontoblasts. NG2 pericytes were obtained from human dental pulp cells by magnetic-activated cell sorting. During the odontogenic differentiation of NG2 pericytes, the effects of the Ca1.2 inhibitors, nimodipine and Ca1.2 knockdown shRNA, were analyzed by real-time polymerase chain reaction and alizarin red staining. NG2CreERT2/Rosa26-GFP lineage-tracing mice were established to further investigate the roles of NG2 pericytes and Ca1.2 in incisor self-repair after injury in vivo. At 10 min, 1 day, and 3 days after pulp injuries in transgenic mice, NG2-GFP and Ca1.2 immunofluorescence co-staining was performed on the incisors. Nimodipine treatment and Ca1.2 knockdown showed similar inhibition of calcium nodule formation and mRNA levels of osteogenic markers (DSPP, DMP1, and Runx2, p < 0.05). NG2 pericytes migrated from their inherent perivascular location to the odontoblast layers after pulp injury. Ca1.2 showed a similar response pattern as NG2 pericytes and gradually returned to normal levels. In addition, many co-stained areas of Ca1.2 and NG2 pericytes, both near the perivascular and odontoblast layers, were observed. These results indicate that Ca1.2 played a vital role in the odontogenic differentiation of NG2 pericytes, and that it might be closely linked to the NG2 pericytes-mediated repair of dental pulp injury in vivo.