Abstract: PURPOSE: To study the changes of expression of dentin sialophosphoprotein (DSPP), bone sialoprotein (BSP) and alkaline phosphatase (ALP) in rat dental pulp cells, which were treated with lipopolysaccharide (LPS). METHODS: Rat dental pulp cells were cultured by the method of tissue block in vitro and identified. The cells were treated with Porphyromonas gingivalis (P.g) LPS at concentrations of 0.1, 1, 10, 100 and 10000 ng/mL. The effects of treatment were respectively examined by the expression of DSPP, BSP and ALP in rat dental pulp cells with real time PCR (RT-PCR) after 1, 3, 5 days of culture. The data was statistically analyzed with SPSS17.0 software package. RESULTS: Under phase contrast microscopy, the adherent cells were found to be primarily typical fibroblasts, and part of the polygonal cells with protuberant cytoplasm. RT-PCR showed that rat dental pulp cells expressed higher mRNA of BSP, DSPP and ALP at concentrations of 1 ng/mL and 10 ng/mL, whereas the expression of BSP, DSPP and ALP mRNA were lower at concentrations of 100 ng/mL and 10000 ng/mL. After 1, 3, 5 days treatment, the expression of BSP, DSPP and ALP gradually reduced in the cells treated with 1, 10, 100 and 10000 ng/mL LPS; while they had no significant change at the concentration of 0.1 ng/mL LPS. CONCLUSIONS: Lower concentration of P.g LPS promotes the expression of ALP, BSP and DSPP in rat dental pulp cells, but larger concentration has inhibitory effect. With the increase of incubation time, the promoting effect decreases gradually, while the inhibition effect increases gradually.

Key words: Dental pulp cells, Lipopolysaccharide, Mineralization factor