BACKGROUND:Studies have shown that dental pulp cells can differentiate into odontoblastic like cells under certain stimulations, which is regulated by several signal pathways network. OBJECTIVE:To summarize the research progress of stimulating molecules and underlying molecular mechanisms of dental pulp cells’ odontoblastic differentiation. METHODS:A computer-based online search of CNKI and Wanfang databases was undertaken for the related Chinese articles dated from January 1998 to July 2014 with the keywords of“dental pulp cells”and“odontoblastic differentiation”in Chinese. Meanwhile, PubMed database was searched for the related English articles dated from January 1998 to July 2014 with the same keywords in English. Those with unrelated research subjects, or repetitive studies were excluded. Final y, 63 articles were reviewed. RESULTS AND CONCLUSION:Various stimuli, including bone morphogenetic protein,β-glycerophosphate and ascorbic acid, can stimulate dental pulp cells differentiation into odontoblastic like cells under certain conditions regulated by several signal pathways network. But odontoblastic differentiation is a complex process, and further research into stimulating molecules and underlying molecular mechanisms of dental pulp cells’ odontoblastic differentiation is significantly important for clinical applications of dental regenerative therapy.

Objective To investigate the effects of enamel matrix proteins (EMP) on odontogenic differentiation of human dental pulp cells (HDPC) in vitro.Methods HDPC were isolated by explant culture methods and expanded to passage 4 for experiments.The cells were seeded into 6-well plates (2 × 105 cells/well) and divided into 5 groups,treated with 1,10 or 100 mg/L EMP,10-8 mol/L dexamethasone and 100 mg/L ascorbic acid (Dex-AA) or basal media respectively.Alkaline phosphatase (ALP) activity was measureded after up to 10 days in culture.The mRNA expression of dentin matrix protein-1 (DMP-1)and dentin sialophosphoprotein (DSPP) were determined by quantitative real-time reverse transcriptase polymerase chain reaction.Calcified nodule formation was evaluated by alizarin red staining and spectroscopic method.Results The ALP activity levels of all 5 groups were increased in a time-dependent manner.There was no significant difference among each group after 1 day.After 5 days,the ALP activity was increased significantly especially for the 10 mg/L EMP,100 mg/L EMP and Dex-AA groups,values were 7.573 ± 0.267,6.119 ± 0.502 and 5.846 ± 0.096,respectively (P ＜ 0.05).After 10 days,the increase of ALP activity in the 10 mg/L EMP(21.035 ± 0.149) and Dex-AA groups(13.223 ± 0.797) was remarkable,compared with the negative control group (5.825 ± 0.404) (P ＜ 0.01).Statistical differences were detected for DMP-1 and DSPP mRNA expressions in 10mg/L EMP group(14.791 ± 0.164,12.238 ± 0.421),compared with negative control group (4.959 ± 0.184,2.645 ± 0.570) (P ＜ 0.01).Phase contrast microscopy revealed orange-red stained nodules in 1 mg/L and 10 mg/L EMP groups.Such staining was not that much obvoius in the negative control group.After quantifying the staining,it can be clearly seen that 10 mg/L EMP enhanced calcium deposition [(191.8 ± 2.0) μmol/L] significantly,compared to the negative control[(81.1 ± 8.1) μmol/L] (P ＜ 0.01).Conclusions This study showed that optimized concentration of EMP can stimulate odontoblastic differentiation of HDPC,which suggests that EMP may be useful for directing HDPC down the odontoblastic lineage in dentine tissue engineering.