Expression and influence of BMP-4 in human dental pulp cells cultured in vitro

Effects of bone morphogenetic protein (BMP)-4 on proliferation and differentiation capacities of dental pulp cells through BMP-4 acting on human dental pulp cells cultured in vitro were investigated. Dental pulp tissues of lesion-free teeth extracted from patients due to orthodontics were taken, and human dental pulp cells were cultured in vitro using the tissue explant method. Immunocytochemical staining was used for the identification of vimentin and keratin. The dental pulp cells were divided into groups A and B. A total of 100 ng/ml BMP-4 was added into group A, while no inducer was added into group B as the control group. The cell growth curves at day 1, 2, 3, 5 and 7 after culture were drawn. At day 7, the cell count, alkaline phosphatase (ALP) activity, number of calcified nodules, and expression levels of dentin sialophosphoprotein (DSPP), dentin matrix protein-1 (DMP-1) and each gene related to dentinogenesis in each group were detected, respectively. Human dental pulp cells were conformed to the biological characteristics of dental pulp cells according to the identification of vimentin and keratin via immunocytochemical staining. With the prolongation of culture time, the number of cells in both groups was gradually increased, reaching the peak at day 5 and began to decline at day 7. The number of cells in group A was significantly greater than that in group B (p<0.05). According to the results of reverse transcription-quantitative polymerase chain reaction (RT-qPCR), the relative messenger ribonucleic acid (mRNA) expression levels of ALP, DSPP and DMP-1 in group A were significantly higher than those in group B (p<0.05). BMP-4 can promote the growth of dental pulp cells and remarkably enhance the differentiation of dental pulp cells into odontoblasts.