Effects of pH on mineralization ability of human dental pulp cells

The purpose of this study was to investigate the effect of alkaline pH on calcification in human dental pulp (HDP) cells. HDP cells were cultured in pH 7.8 conditioned medium, and alkaline phosphatase (ALP) activity was measured. The ALP activity was higher in the pH 7.8 conditioned medium group than in the pH 7.2 conditioned medium group. Expression of mRNAs for bone morphogenetic protein (BMP)-2 was measured by the RT-PCR technique. The expression of BMP-2 in the pH 7.8 groups was greater than that in the pH 7.2 group. Furthermore, we determined Calcified nodule formation by von Kossa staining. The number of calcified nodules was increased in the pH 7.8 conditioned medium. These results suggest that HDP cell mineralization was enhanced in alkaline pH (pH 7.8) conditioned medium.