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Previous studies have assumed that amelogenin is responsible for the therapeutic effect of the enamel matrix derivative (EMD) in periodontal tissue healing and regeneration. However, it is difficult to confirm this hypothesis because both the EMD and the amelogenins are complex mixtures of multiple proteins. Further adding to the difficulties is the fact that periodontal tissue regeneration involves various types of cells and a sequence of associated cellular events including the attachment, migration and proliferation of various cells. In this study, we investigated the potential effect of a 25-kDa recombinant porcine amelogenin (rPAm) on primarily cultured periodontal ligament fibroblasts (PDLF), gingival fibroblasts (GF) and gingival epithelial cells (GEC). The cells were treated with 25-kDa recombinant porcine amelogenin at a concentration of 10 microg/mL. We found that rPAm significantly promoted the proliferation and migration of PDLF, but not their adhesion. Similarly, the proliferation and adhesion of GF were significantly enhanced by treatment with rPAm, while migration was greatly inhibited. Interestingly, this recombinant protein inhibited the growth rate, cell adhesion and migration of GEC. These data suggest that rPAm may play an essential role in periodontal regeneration through the activation of periodontal fibroblasts and inhibition of the cellular behaviors of gingival epithelial cells.

The Porphyromonas gingivalis bacterium is one of the most influential pathogens in oral infections. In the current study, the antimicrobial activity of α-amylase and pentamidine against Porphyromonas gingivalis was evaluated. Their in vitro inhibitory activity was investigated with the agar overlay technique, and the minimal inhibitory and bactericidal concentrations were determined. Using the bactericidal concentration, the antimicrobial actions of the inhibitors were investigated. In the present study, multiple techniques were utilized, including scanning electron microscopy (SEM), general structural analysis and differential gene expression analysis. The results obtained from SEM and bactericidal analysis indicated a notable observation; the pentamidine and α-amylase treatment destroyed the structure of the bacterial cell membranes, which led to cell death. These results were used to further explore these inhibitors and the mechanisms by which they act. Downregulated expression levels were observed for a number of genes coding for hemagglutinins and gingipains, and various genes involved in hemin uptake, chromosome replication and energy production. However, the expression levels of genes associated with iron storage and oxidative stress were upregulated by α-amylase and pentamidine. A greater effect was noted in response to pentamidine treatment. The results of the present study demonstrate promising therapeutic potential for α-amylases and pentamidine. These molecules have the potential to be used to develop novel drugs and broaden the availability of pharmacological tools for the attenuation of oral infections caused by Porphyromonas gingivalis.

To investigate the potential effect of recombinant 25kDa porcine amelogenin (rPAm) on attachment, proliferation and migration of primarily cultured human gingival epithelial cells (HGEC).The second passage of HGECs were exposed to different concentrations of rPAm (0, 5, 10, 20μg/mL, respectively). Proliferation and attachment activities was measured by using cell counting method. Cellular migration was assayed by using an in vitro wound healing model. The data was quantified by the analysis of GraphPad Prism software.rPAm inhibited HGEC attachment in the adhesion assay, the effect was depended on time and rPAm dose. rPAm suppressed the growth rate of HGEC, that was also dose and time dependent. rPAm inhibited the migration ability of HGEC, the concentration of 20μg/mL group had the most significant effect.rPAm significantly inhibit the growth rate, cell adhesion and migration of HGEC, and the effect was dose- and time- dependent.

To investigate gene expression of amelogenin (Am) in human gingival epithelial cells(HGEC) and also other oral ectomesenchyme cells (human gingival fibroblasts, human periodontal ligament fibroblasts and human pulp cells).The amelogenin mRNA expression patterns were determined by the reverse transcription polymerase chain reaction (RT-PCR),and the protein expression was studied with Western blotting.There was no amelogenin expression detected in any of the cells.These findings suggest that amelogenin expression could not be detected in cultured human periodontium-related cells. Supported by National Natural Science Foundation of China (Grant No.30672315) and Research Fund of Science and Technology Commission of Shanghai Municipality(Grant No.08DZ2271100).

To investigate the effect of hypoxia on proliferation and expression of HIF-1alpha and Caspase-3 in human periodontal ligament cells (PDLCs).Human PDLCs were exposed to cobalt chloride in order to mimic hypoxia. Cell viability of PDLCs was determined by MTT methods. Expression of HIF-1alpha and Caspase-3 was measured by real time PCR and Western blot. The data was statistically analyzed with SAS6.12 software package for one-way ANOVA.Cell viability of PDLCs significantly decreased when exposed to hypoxia in a time- and dose-dependent manner. Hypoxia induced the expression of HIF-1alpha,up-regulated the expression of Caspase-3.Hypoxia inhibits cell proliferation, which involves the expression of HIF-1alpha and Caspase-3, resulting in the production of the apoptosis. The results suggest that hypoxia may play a role in the induction and progression of chronic periodontitis. Supported by National Natural Science Foundation of China(Grant No.30801292), Shanghai Leading Academic Discipline (Grant No.S30206) and Research Fund for Excellent Young Teachers of Shanghai Municipal College and University (Grant No.JDY07059).