Electrical Stimulations Generated by P(VDF-TrFE) Films Enhance Adhesion Forces and Odontogenic Differentiation of Dental Pulp Stem Cells (DPSCs).

Biophysical and biochemical cues of biomaterials can regulate cell behaviors. Dental pulp stem cells (DPSCs) in pulp tissues can differentiate to odontoblast-like cells and secrete reparative dentin to form a barrier to protect the underlying pulp tissues and enable complete pulp healing. Promotion of the odontogenic differentiation of DPSCs is essential for dentin regeneration. The effects of the surface potentials of biomaterials on the adhesion and odontogenic differentiation of DPSCs remain unclear. Here, poly(vinylidene fluoride-trifluoro ethylene) (P(VDF-TrFE)) films with different surface potentials were prepared by the spin-coating technique and the contact poling method. The cytoskeletal organization of DPSCs grown on P(VDF-TrFE) films was studied by immunofluorescence staining. Using atomic force microscopy (AFM), the lateral detachment forces of DPSCs from P(VDF-TrFE) films were quantified. The effects of electrical stimulation generated from P(VDF-TrFE) films on odontogenic differentiation of DPSCs were evaluated in vitro and in vivo. The unpolarized, positively polarized, and negatively polarized films had surface potentials of -52.9, +902.4, and -502.2 mV, respectively. DPSCs on both negatively and positively polarized P(VDF-TrFE) films had larger cell areas and length-to-width ratios than those on the unpolarized films (P < 0.05). During the detachment of DPSCs from P(VDF-TrFE) films, the average magnitudes of the maximum detachment forces were 29.4, 72.1, and 53.9 nN for unpolarized, positively polarized, and negatively polarized groups, respectively (P < 0.05). The polarized films enhanced the mineralization activities and increased the expression levels of the odontogenic-related proteins of DPSCs compared to the unpolarized films (P < 0.05). The extracellular signal-regulated kinase (ERK) signaling pathway was involved in the odontogenic differentiation of DPSCs as induced by surface charge. In vivo, the polarized P(VDF-TrFE) films enhanced adhesion of DPSCs and promoted the odontogenic differentiation of DPSCs by electrical stimulation, demonstrating a potential application of electroactive biomaterials for reparative dentin formation in direct pulp capping.

Enhancing Effects of Immobilized Chondroitin Sulfate on Odontogenic Differentiation of Dental Pulp Stem Cells and Reparative Dentin Formation.

INTRODUCTION: Chondroitin sulfate (CS) is a major proteoglycan involved in the mineralization of the organic matrix of dentin. In this study, the roles of CS immobilized in cross-linked collagen I (Col I) hydrogels on odontogenic differentiation of dental pulp stem cells (DPSCs) and reparative dentin formation were investigated. METHODS: Different concentrations of CS were incorporated into the genipin-cross-linked Col I hydrogels (CS-0.05, CS-0.1, and CS-0.2, respectively). The influences of CS on the proliferation and odontogenic differentiation of DPSCs were investigated. Finally, the effect of the functionalized hydrogel on the formation of reparative dentin was analyzed in a rat pulp capping model in vivo. RESULTS: CS improved the proliferation of DPSCs seeded on the hydrogels (P < .05). CS also enhanced the mineralization activities and increased the expression levels of the odontogenic-related proteins of DPSCs on days 7 and 14 (P < .05). In vivo, CS-0.1 hydrogel induced reparative dentin formation with higher quality compared with mineral trioxide aggregate. CONCLUSIONS: CS immobilized in Col I hydrogels could induce odontogenic differentiation of DPSCs in vitro and promote homogeneous mineralized barrier formation in vivo. CS-Col I hydrogel has the potential for reparative dentin formation of high quality in direct pulp capping.

Exosomes derived from dental pulp stem cells accelerate cutaneous wound healing by enhancing angiogenesis via the Cdc42/p38 MAPK pathway.

Skin wound healing is a common challenging clinical issue which requires advanced treatment strategies. The present study investigated the therapeutic effects of exosomes derived from dental pulp stem cells (DPSC­Exos) on cutaneous wound healing and the underlying mechanisms. The effects of DPSC­Exos on cutaneous wound healing in mice were examined by measuring wound closure rates, and using histological and immunohistochemical analysis. A series of functional assays were performed to evaluate the effects of DPSC­Exos on the angiogenic activities of human umbilical vein endothelial cells (HUVECs) in vitro. Tandem mass tag­based quantitative proteomics analysis of DPSCs and DPSC­Exos was performed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were used to evaluate the biological functions and pathways for the differentially expressed proteins in DPSC­Exos. Western blot analysis was used to assess the protein levels of cell division control protein 42 (Cdc42) and p38 in DPSC­Exos and in HUVECs subjected to DPSC­Exos­induced angiogenesis. SB203580, a p38 mitogen­activated protein kinase (MAPK) signaling pathway inhibitor, was employed to verify the role of the p38 MAPK pathway in vitro and in vivo. Histological and immunohistochemical staining revealed that the DPSC­Exos accelerated wound healing by promoting neovascularization. The DPSC­Exos promoted the migration, proliferation and capillary formation capacity of HUVECs. Proteomics data demonstrated that proteins contained in DPSC­Exos regulated vasculature development and angiogenesis. Pathway analysis revealed that proteins expressed in DPSC­Exos were involved in several pathways, including MAPK pathway. Western blot analysis demonstrated that the DPSC­Exos increased the protein levels of Cdc42 and phosphorylation of p38 in HUVECs. SB203580 suppressed the angiogenesis induced by DPSC­Exos. On the whole, the present study demonstrates that DPSC­Exos accelerate cutaneous wound healing by enhancing the angiogenic properties of HUVECs via the Cdc42/p38 MAPK signaling pathway.