The Effect Of Cadherin-11 On The Migration,Adhesion And Differentiation Of Rat Dental Pulp Cells

ObjectivePulp cells also called precursor cells, locating in adult dental pulp tissue, as a class of undifferentiated cells, whose biological characteristics were similar with adult stem cells in other organizations that they were multi-differentiated and self-renewaled. Once the pulpodentinal complex was damaged, these pulp cells migrated and adhered to the site of injury, differentiated into odontoblasts, then repaired the injury. As known, the cell adhesion molecules contained the immunoglobulin superfamily, the integrin family, the selectin family and the cadherin family. Cadherin family was one class of single-chain transmembrane glycoprotein, whose molecular weight was 120～140ku, mediated calcium-dependent cell-cell adhesion by homophilic manner. Cadherins can divide into type Ⅰ and type Ⅱ based on the differences in structure, cadherin-11 belongs to the latter. Via mediating cells adhesion that it could regulate the morphogenesis and physiological processes in tissues and organs, such as cell recognition, migration, proliferation, differentiation and programmed cell death. Previous studies indicated that cadherin-11 was abundant in bone tissue, a high expression in the early differentiation of bone tissue. Recent studies showed that cadherin-11 regulated the absorption process of the radices dentis. A high expression of cadherin-11 mRNA in rat pulp tissue was discovered in Wu’s microarray studies, suggesting that cadherin-11 might play an vital role in the growth and development of rat dental pulp tissue. We suspected that cadherin-11 may have similar function in two cells, osteoblasts and odontoblasts, because of both two cells could release mineralized moleculars. But the effects of cadherin-11 on the migration, adhesion, and a tooth/osteogenic differentiation in pulp cells was unkown. Therefore, it is significance to illustrate a novel mechanisms that cadherin-11 mediate migration, adhesion and odontoblastic differentiation in rat dental pulp cells. Our study is to investigate the effects of high expression cadherin-11 on the migration, adhesion and odontoblastic differentiation in cells, and to prefer a new methodology guidance for repairing and regenerating pulp tissues.Methods1. Rat pulp cells were isolated and cultured by tissue block enzymatic digestion method. The 3-5 generations pulp cells were collected for vimentin, cytokeratin immunohi-stochemistry to identify cell sources.2. Cadherin-11 mRNA expression of rat incisor dental pulp tissue was detected by RT-PCR, and immunohistochemistry was used to detect its distribution in the pulp tissue.3. Adenovirus infection:the 3-5 generations pulp cell was transfected by pDC316-mCMV-EGFP-Cadherinll recombinant adenoviral. Cadherin-11 mRNA expression was detected by RT-PCR,and immunohistochemistry was used to detect its protein expression. The rat pulp cells were divided into three groups, including the experimental group with pDC316-mCMV-EGFP-Cadherin11 recombinant adenovirus infection, the negative control group with the empty vector adenovirus infection and the normal cells as a blank control group.4. Detection of cell migration, adhesion and different-iation:Alizarin red staining and cetylpyridinium chloride assay were performed to investigate the odontogenic ability of rat dental pulp cells. Then the adhesion and migration of rat dental pulp cells were tested. Semi-quantitative PCR was used to detect the expression of differentiation associated gene DMP1, DSPP and ALP in dental pulp cells.Results1. In vitro, rat dental pulp cells were successfully isolated and cultured, and the model of rat dental pulp cells were established. Immunohistochemical staining showed that vimentin was positive, but cytokeratin negative, suggesting that pulp cells come from the mesoderm.2. RT-PCR results demonstrated cadherin-11 existed in rat incisor pulp tissue. In the immunohistochemical staining of rat dental pulp tissue, cadherin-11 widely expressed in cytoplasm and membrane of pulp cells and odontoblast cells. Cadherin-11 was weakly positive in the apical pulp cell, but the stain enhanced in crown, and it was strongly positive in the pulp of crown. The expression of cadherin-11 in odontoblasts was higher than that in the dental pulp cell.3. A high mRNA and protein expression of cadherin-11 indicated rat dental pulp cells were successfully transfected by pDC316-mCMV-EGFP-Cadherin11.4. Compared with the negative control group and blank control group, ALP activity in experimental group was significantly increased, and the formed calcified nodules was also significantly increased (P<0.05). It was found that Cadherin-11 coulld influence the adhesion and migration in rat dental pulp cells(P<0.05).Conclusion1. Isolated and cultured from rat pulp tissue, rat dental pulp cells maintain a stable growth capacity when they are passaged, which will lay a foundation for the next cadherin-11 transfecting experiments.2. A selective expression of cadherin-11 in rat dental pulp suggests that cadherin-11 may play an important role in odontogenesis. This is the basis to further research cadherin-11 in occurrence and development of dental tissue.3. Cadherin-11 could promote the migration, adhesion and odontoblastic differentiation in rat dental pulp cells.