Odontoblasts and/or dental pulp cells are responsible for tooth repair as well as dentin formation. Adhesion and migration are critical processes for tissue regeneration. This study was performed to clarify whether Pam3 modulates adhesion and migration of a murine odontoblast-like cell line, MDPC-23 cell and TLR2 signaling is engaged in this process. TLR2 expression in MDPC-23 cells was examined by RT-PCR. Adhesion assay was performed using type Ⅰ collagen-coated plates. Migration ability was determined by a commercial assay kit. Phosphorylation of IκB-α, JNK, p38, and ERK was examined by Western blot analysis. TLR2 was functionally expressed in MDPC-23 cells. Pam3CSK treatment enhanced adhesion and migration of MDPC-23 cells in a dose-dependent manner. Blockade of TLR2 using its antibody restored Pam3CSK-induced adhesion and migration of MDPC-23 cells. These findings indicate that Pam3CSK, an immune activator from gram negative bacteria, can promote adhesion and migration ability of MDPC-23 cells via TLR2.

The effects of chitosan upon the experimentally induced differentiation of MDPC-23 cells, derived from mouse dental papilla cells, were investigated by RT-PCR, observations of cell morphology and Alizaline red-S staining. Chitosan was found to significantly increase and accelerate the expression of ALP mRNA but decrease the ColI transcript levels, as compared with the control, in a time-dependent manner during the differentiation of MDPC-23 cells. Chitosan also significantly downregulated ON mRNA expression and accelerated mineralization in differentiating MDPC-23 cells. These results suggest that chitosan facilitates odontoblast differentiation and mineralization and may have potential clinical applications as a dentin regeneration material.

Temperature signaling can be initiated by members of transient receptor potential (thermo-TRP) channels. Hot and cold substances applied to teeth usually elicit pain sensation. Since odontoblasts constitute a well-defined layer between the pulp and the mineralized dentin, being first to encounter thermal stimulation from oral cavity, they may be involved in sensory transduction process, in addition to their primary function as formation of dentin. We investigated whether thermo-TRP channels are expressed in a odontoblast cell line, MDPC-23. The expressions of thermo-TRP channels were examined using reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry, fluorometric calcium imaging. Analysis of RT-PCR revealed mRNA expression of TRPV1, TRPV2, TRPV4 and TRPM8, but no TRPV3, TRPA1. Immunohistochemical approach failed to detect TRPV1 expression. Whereas the application of 4-phorbol-12,13-didecanoate(10 μM, a TRPV4 agonist), menthol(1 mM, a TRPM8 agonist) and icilin(10 μM, a TRPM8 agonist) produced the enhancement of intracellular calcium concentration, capsaicin(1 μM, a TRPV1 agonist) did not. Our results suggest that subfamily of thermo-TRP channels expressed in odontoblasts may serve as thermal or mechanical transducer in teeth.