Role of CTGF/CCN2 in reparative dentinogenesis in human dental pulp

Connective tissue growth factor/CCN family 2 (CTGF/CCN2) has been considered to participate in tooth development. To date, the expression and role of CTGF/CCN2 in reparative dentinogenesis have been unclear. Our previous study revealed that matrix metalloproteinase-3 (MMP-3) stimulates cell migration via CTGF/CCN2 expression and secretion in human dental pulp cells, and that this is dependent on dynamin-related endocytosis and independent of protease activity. The objective of the present study was to determine the expression of CTGF/CCN2 in reparative dentin in human carious teeth and to examine the effect of CTGF/CCN2 on mineralization in cultured human dental pulp cells. Minimal expression of CTGF/CCN2 was evident in odontoblasts subjacent to the dentin-pulp junction in healthy teeth, whereas strong expression was detected in odontoblast-like cells lining the reparative dentin subjacent to dental caries. In human dental pulp cells, CTGF/CCN2 promoted mineralization but failed to induce proliferation, suggesting that this molecule has the ability to induce the differentiation of human dental pulp cells. Taken together, the data suggest that CTGF/CCN2 is likely involved in reparative dentinogenesis through formation of hard tissue in human carious teeth.