Expressions of MMPs in dental pulp cells from deciduous teeth

Objectives: Human dental pulp cells from deciduous teeth (HDPCs) were useful for the reproduction and tissue engineering because of its higher proliferation rate. When gram-negative bacteria proliferate in the carious cavity, LPS induced pulp inflammation and some kinds of proteases were produced in dental pulp. MMPs have been focused on because of its various capacities, and elevated levels of some MMPs have been reported in inflamed pulp and periapical lesions. In this study, we examined the MMPs gene expressions after LPS stimulation to clarify the restoration and the reproduction mechanism of dental pulp tissue. 

Methods: Deciduous noncarious tooth extracted for orthodontic reasons or prolonged retention of deciduous tooth were collected. HDPCs cultures were established from cells growing out of the dental pulp tissue. HDPCs at passage 3 to 7 were utilized in experiments. The experiments were approved by the Ethical Committee of Osaka Dental University (No.110713) and informed consent was obtained.Proliferation was evaluated using the CellTiter 96®AQueouds One Solution Cell Proliferation Assay. Real-time PCR was performed in a Step One Plus. MMP1, MMP3 and GAPDH genes were used. ELISA was assayed according to the way of Quantikine® Human Total MMP-1 and MMP -3.

 Results: HDPCs proliferated in a time-dependent manner, and LPS had no effects on the proliferation of HDPCs at any of the concentrations examined. LPS at 0.1, 1, 5 µg/mL significantly increased MMP-3 gene expressions. Moreover, LPS at 1, 5 µg/mL elevated the protein expressions of MMP-3 in HDPCs.

Conclusions: These results suggest that LPS affected productions of MMPs in HDPCs. The mechanisms by which LPS induces MMPs expression may be an important link in the pathogenesis of inflammatory diseases. Therefore, understanding the mechanisms underlying LPS-induced MMPs expression is important for developing new therapeutic strategies.