A novel self-assembled oligopeptide amphiphile for biomimetic mineralization of enamel.

BACKGROUND: Researchers are looking for biomimetic mineralization of ena/mel to manage dental erosion. This study evaluated biomimetic mineralization of demineralized enamel induced by a synthetic and self-assembled oligopeptide amphiphile (OPA). RESULTS: The results showed that the OPA self-assembled into nano-fibres in the presence of calcium ions and in neutral acidity. The OPA was alternately immersed in calcium chloride and sodium hypophosphate solutions to evaluate its property of mineralization. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed nucleation and growth of amorphous calcium phosphate along the self-assembled OPA nano-fibres when it was repetitively exposed to solutions with calcium and phosphate ions. Energy dispersive spectrometry (EDS) confirmed that these nano-particles contained calcium and phosphate. Furthermore, electron diffraction pattern suggested that the nano-particles precipitated on OPA nano-fibres were comparable to amorphous calcium phosphate. Acid-etched human enamel slices were incubated at 37°C in metastable calcium phosphate solution with the OPA for biomimetic mineralization. SEM and X-ray diffraction indicated that the OPA induced the formation of hydroxyapatite crystals in organized bundles on etched enamel. TEM micrographs revealed there were 20-30 nm nano-amorphous calcium phosphate precipitates in the biomimetic mineralizing solution. The particles were found separately bound to the oligopeptide fibres. Biomimetic mineralization with or without the oligopeptide increased demineralized enamel microhardness. CONCLUSIONS: A novel OPA was successfully fabricated, which fostered the biomimetic mineralization of demineralized enamel. It is one of the primary steps towards the design and construction of novel biomaterial for future clinical therapy of dental erosion.

A novel oligopeptide simulating dentine matrix protein 1 for biomimetic mineralization of dentine.

OBJECTIVE: The objectives were to design and fabricate an oligopeptide that simulates dentine matrix protein 1 (DMP1) to study its ability to bind to dentine collagen fibrils and induce biomimetic mineralization for the management of dentine hypersensitivity. MATERIALS AND METHODS: A novel oligopeptide was developed by connecting the collagen-binding domain of DMP1 to the hydrophilic C-terminal of amelogenin. Fluorescein isothiocyanate-coupled oligopeptide was applied to the completely demineralized dentine collagen and examined using fluorescent microscopy. The nucleation and growth of hydroxyapatite were initiated by immersing oligopeptide into calcium chloride and sodium hydrogen phosphate solutions. Scanning electron microscopy (SEM), transmission electron microscopy, and selected area electron diffraction (SAED) were used to examine the formation. Dentine slices were acid-etched, coated with oligopeptide, and immersed into a metastable calcium phosphate solution. Dentine mineralization was evaluated by SEM, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). RESULTS: Fluorescent dentine collagen was identified in the specimens. The nucleation and growth of crystals were detected after immersing the oligopeptide into calcium chloride and sodium hydrogen phosphate solutions. Under SEM, crystals were observed covering the oligopeptide-coated dentine surface, within the demineralized dentine collagen matrix and occluding dentinal tubules. SAED, XRD, and FTIR confirmed that the crystals were hydroxyapatite. CONCLUSION: A novel oligopeptide-simulating DMP1 was developed, that can bind to collagen fibrils, initiate mineralization, and induce biomimetic mineralization of dentine. CLINICAL RELEVANCE: Biomimetic mineralization of dentine facilitated by this oligopeptide is a potential therapeutic technique for the management of dentine hypersensitivity.

Membrane Type 1 Matrix Metalloproteinase induces an epithelial to mesenchymal transition and cancer stem cell-like properties in SCC9 cells.

BACKGROUND: Tissue invasion and metastasis are acquired abilities of cancer and related to the death in oral squamous cell carcinoma (OSCC). Emerging observations indicate that the epithelial-to-mesenchymal transition (EMT) is associated with tumor progression and the generation of cells with cancer stem cells (CSCs) properties. Membrane Type 1 Matrix Metalloproteinase (MT1-MMP) is a cell surface proteinase, which is involved in degrading extracellular matrix components that can promote tumor invasion and cell migration. METHODS: In the current study, we utilized SCC9 cells stably transfected with an empty vector (SCC9-N) or a vector encoding human MT1-MMP (SCC9-M) to study the role of MT1-MMP in EMT development. RESULTS: Upon up-regulation of MT1-MMP, SCC9-M cells underwent EMT, in which they presented a fibroblast-like phenotype and had a decreased expression of epithelial markers (E-cadherin, cytokeratin18 and ß-catenin) and an increased expression of mesenchymal markers (vimentin and fibronectin). We further demonstrated that MT1-MMP-induced morphologic changes increased the level of Twist and ZEB, and were dependent on repressing the transcription of E-cadherin. These activities resulted in low adhesive, high invasive abilities of the SCC9-M cells. Furthermore, MT1-MMP-induced transformed cells exhibited cancer stem cell (CSC)-like characteristics, such as low proliferation, self-renewal ability, resistance to chemotherapeutic drugs and apoptosis, and expression of CSCs surface markers. CONCLUSIONS: In conclusion, our study indicates that overexpression of MT1-MMP induces EMT and results in the acquisition of CSC-like properties in SCC9 cells. Our growing understanding of the mechanism regulating EMT may provide new targets against invasion and metastasis in OSCC.

Snail overexpression induces an epithelial to mesenchymal transition and cancer stem cell-like properties in SCC9 cells.

Local invasiveness and distant metastasis are critical factors that contribute to oral squamous cell carcinoma-related deaths. Increasing evidence has shown that the epithelial to mesenchymal transition (EMT) is involved in cancer progression and is associated with the 'stemness' of cancer cells. Snail is a transcriptional factor that can induce EMT and preserve stem-cell function, which may induce resistance to radio- and chemotherapies in the cells. In the present study, SCC9 cells were transfected with an empty vector or a vector encoding human Snail (SCC9-S). Overexpression of Snail induced SCC9 cells to undergo EMT, in which the cells presented a fibroblast-like appearance, downregulated the epithelial markers E-cadherin and ß-catenin, upregulated the mesenchymal marker vimentin, and associated with highly invasive and metastatic properties. Furthermore, the induction of EMT promoted cancer stem cell (CSC)-like characteristics in the SCC9-S cells, such as low proliferation, self-renewal, and CSC-like markers expression. These results indicate that overexpression of Snail induces EMT and promotes CSC-like traits in the SCC9 cells. Further understanding the role of Snail in cancer progression may reveal new targets for the prevention or therapy of oral cancers.

[Synthesis and evaluation of a novel injectable and water-swelling gingival displacement materials].

OBJECTIVE: To synthesize and evaluate a novel injectable and water-swelling gingival displacement materials. METHODS: A kind of water-swelling polymer, kaolin and aluminum chloride were mechanically mixed at certain ratio in water solution, resulting to a novel paste materials for gingival displacement. Then, its stability in aqueous solution and water swelling properties were evaluated in vitro. The effect on gingival displacement was evaluated by animal experiments in dogs. A commercial gingival displacement materials paste of Expasyl was used as control. RESULTS: While contacting with water, the novel gingival displacement paste did not collapse, maintained its integrity structure, and could expand for adsorbing water. Animal experiments in dogs showed that the materials could lead to displace the gingival margins from the dental root surfaces. CONCLUSION: The novel injectable and expanded gingival displacement material is efficient to retract free gingival margin with potential clinical application.

Biomimetic mineralization of dentin induced by agarose gel loaded with calcium phosphate.

A novel biomimetic mineralization system was designed to induce a layer of hydroxyapatite on a demineralized dentin surface. This system was constructed as follows. A layer of 0.5% agarose gel containing 0.26M Na(2) HPO(4) was used to cover acid-etched dentin slices, followed by a layer of agarose gel without phosphate ions. Then a neutral 0.13M CaCl(2) solution was added onto the ion-free gel surface. The mineralization system (dentin-agarose gel containing phosphate ions-CaCl(2) solution) was kept in a water bath at 37°C, and the gel and CaCl(2) solution were replaced at various intervals. The results showed that the deposited hydroxyapatite crystals densely packed to each other, completely covered the dentin surface, and occluded the dentinal tubules after 10 days of biomimetic mineralization in vitro. Therefore, this method may provide the experimental basis for dentin remineralization and for a new method to treat dentin hypersensitivity and dental caries.