Bioprinting EphrinB2-Modified Dental Pulp Stem Cells with Enhanced Osteogenic Capacity for Alveolar Bone Engineering.

Bioprinting, a technology that allows depositing living cells and biomaterials together into a complex tissue architecture with desired pattern, becomes a revolutionary technology for fabrication of engineered constructs. Previously, we have demonstrated that EphrinB2-modified dental pulp stem cells (DPSCs) are expected to be promising seed cells with enhanced osteogenic differentiation capability for alveolar bone regeneration. In this study, we aimed to bioprint EphrinB2-overexpressing DPSCs with low-concentrated Gelatin methacrylate (GelMA) hydrogels into three-dimensional (3D) constructs. The printability of GelMA (5% w/v) and the structural fidelity of bioprinted constructs were examined. Then, viability, proliferation, morphology, and osteogenic differentiation of DPSCs in bioprinted constructs were measured. Finally, the effect of EphrinB2 overexpression on osteogenic differentiation of DPSCs in bioprinted constructs was evaluated. Our results demonstrated that GelMA (5% w/v) in a physical gel form was successfully bioprinted into constructs with various shapes and patterns using optimized printing parameters. Embedded DPSCs showed round-like morphology, and had a high viability (91.93% ± 8.38%) and obvious proliferation (∼1.9-fold increase) 1 day after printing. They also showed excellent osteogenic potential in bioprinted constructs. In bioprinted 3D constructs, EphrinB2-overexpressing DPSCs expressed upregulated osteogenic markers, including ALP, BMP2, RUNX2, and SP7, and generated more mineralized nodules, as compared with Vector-DPSCs. Taken together, this study indicated that fabrication of bioprinted EphrinB2-DPSCs-laden constructs with enhanced osteogenic potential was possible, and 3D bioprinting strategy combined with EphrinB2 gene modification was a promising way to create bioengineered constructs for alveolar bone regeneration.

Efficacy of antibacterial agents combined with erbium laser and photodynamic therapy in reducing titanium biofilm vitality: an in vitro study.

BACKGROUND AND OBJECTIVE: The emergence of peri-implant diseases has prompted various methods for decontaminating the implant surface. This study compared the effectiveness of three different approaches, chlorhexidine digluconate (CHX) combined with erbium-doped yttrium-aluminum-garnet (Er:YAG) laser, photodynamic therapy (PDT), and CHX only, for reducing biofilm vitality from implant-like titanium surfaces. STUDY DESIGN/MATERIALS AND METHODS: The study involved eight volunteers, each receiving a custom mouth device containing eight titanium discs. The volunteers were requested to wear the device for 72 h for biofilm development. Fluorescence microscopy was used to evaluate the remaining biofilm with a two-component nucleic acid dye kit. The vital residual biofilm was quantified as a percentage of the surface area using image analysis software. Sixty-four titanium discs were assigned randomly to one of four treatment groups. RESULTS: The percentage of titanium disc area covered by vital residual biofilm was 43.9% (7.7%), 32.2% (7.0%), 56.6% (3.6%), and 73.2% (7.8%) in the PDT, Er:YAG, CHX, and control groups, respectively (mean (SD)). Compared to the control group, the treatment groups showed significant differences in the area covered by residual biofilm (P < 0.001). CHX combined with Er:YAG laser treatment was superior to CHX combined with PDT, and CHX only was better than the control. CONCLUSION: Within the current in vitro model's limitations, CHX combined with Er:YAG laser treatment is a valid method to reduce biofilm vitality on titanium discs.

Strontium-doping promotes bone bonding of titanium implants in osteoporotic microenvironment.

Osteoporosis is a major challenge to oral implants, and this study focused on improving the osseointegration ability of titanium (Ti) implants in osteoporosis environment via surface modification, including doping of strontium ion and preparation of nanoscale surface feature. Our previous studies have shown that strontium (Sr) ions can enhance osteogenic activity. Therefore, we aimed to comprehensively evaluate the effect of hydrothermal treatment of Sr-doped titanium implant coating on bone-binding properties in the microenvironment of osteoporosis in this study. We fabricated Sr-doped nanocoating (AHT-Sr) onto the surface of titanium implants via hydrothermal reaction. The rough Sr-doping had good biological functions and could apparently promote osteogenic differentiation of osteoporotic bone marrow mesenchymal stem cells (OVX-BMSCs). Most importantly, AHT-Sr significantly promoted bone integration in the osteoporosis environment. This study provides an effective approach to implant surface modification for better osseointegration in an osteoporotic environment.

Dental Implants Loaded With Bioactive Agents Promote Osseointegration in Osteoporosis: A Review.

Implant-supported dentures are widely used in patients with defect or loss of dentition because these have higher chewing efficiency and do not damage the adjacent teeth compared with fixed or removable denture. An implant-supported denture carries the risk of failure in some systemic diseases, including osteoporosis, because of a non-ideal local microenvironment. Clinically common physical and chemical modifications are used to change the roughness of the implant surface to promote osseointegration, but they have limitations in promoting osteoinduction and inhibiting bone resorption. Recently, many researchers have focused on the study of bioactive modification of implants and have achieved promising results. Herein we have summarized the progress in bioactive modification strategy to promote osseointegration by regulating the local osteoporotic microenvironment.

Characteristic comparison between canine and human dental mesenchymal stem cells for periodontal regeneration research in preclinical animal studies.

The effectiveness of stem cell-based periodontal tissue engineering need to be assessed by preclinical animal studies. Dog models are widely used animal models; however, there are not sufficient data on characterization of canine dental mesenchymal stem cells. Therefore, we aimed to compare the characteristics among canine and human periodontal ligament stem cells and canine and human dental pulp stem cells. Canine periodontal ligament stem cells and dental pulp stem cells showed significantly weaker clonogenic capability, and proliferation and migration capacity, and they displayed lower positive rates for CD90, CD73, CD105, and STRO-1. All of these canine and human cells showed multilineage differentiation potential. After osteogenic induction, the expression of alkaline phosphatase was obviously upregulated in human dental mesenchymal stem cells, but it was not upregulated in canine dental pulp stem cells. Other osteogenic genes, such as runt-related transcription factor 2 and bone morphogenetic protein 2, were upregulated in all induced canine and human cells, but their upregulation occurred later in canine cells. These results confirmed the stem cell properties of canine mesenchymal stem cells, but also suggested that more attention should be paid to the choice of appropriate research approaches, osteogenic gene markers, and time points for the utilization of canine dental mesenchymal stem cells due to their distinct characteristics.

Lipopolysaccharide inhibits osteogenic differentiation of periodontal ligament stem cells partially through toll-like receptor 4-mediated ephrinB2 downregulation.

OBJECTIVES: This study aimed to investigate the possible crosstalk between LPS/toll-like receptor 4 (TLR4) and ephrinB2 signaling in mediating osteogenic differentiation of PDLSCs. MATERIALS AND METHODS: Human periodontal ligament stem cells (hPDLSCs) were harvested and treated with different concentrations of LPS under osteogenic induction. qPCR, alkaline phosphatase (ALP) staining, and Alizarin Red S staining were performed to assess osteogenic gene expression, ALP activity, and mineralized nodule formation. EphrinB2 mRNA and protein expressions after LPS treatment were also determined. To explore the role of ephrinB2 in LPS-impaired osteogenic differentiation of hPDLSCs, hPDLSCs were stimulated with ephrinB2-Fc or transfected with ephrinB2 lentivirus, and then, the osteogenic differentiation capacity was evaluated. RESULTS: LPS inhibited osteogenic differentiation of hPDLSCs and downregulated ephrinB2 expression in hPDLSCs during osteogenic differentiation. Blockage of TLR4 partially reversed LPS-induced decrease in ephrinB2 expression. EphrinB2-Fc promoted mineralized nodule formation and increased the expression of ALP, osteocalcin (OCN), and bone morphogenetic protein 2 (BMP2) in hPDLSCs. EphrinB2-overexpressing hPDLSCs treated with LPS expressed higher ALP and BMP2 mRNA and higher ALP activity and showed more mineralized nodule formation, when compared with wide-type hPDLSCs treated with LPS. CONCLUSIONS: Our data suggested that LPS decreased the osteogenic differentiation capacity of hPDLSCs partially through downregulation of ephrinB2 expression via LPS/TLR4 signaling. Upregulation of ephrinB2 partially reversed the impaired osteogenic potential of hPDLSCs induced by LPS. CLINICAL RELEVANCE: Our results provided a new insight of mechanism underling LPS-mediated osteogenic differentiation inhibition of PDLSCs and clarified a potential target for the management of periodontitis.

EphrinB2 overexpression enhances osteogenic differentiation of dental pulp stem cells partially through ephrinB2-mediated reverse signaling.

BACKGROUND: Alveolar bone loss is a frequent occurrence. Dental pulp stem cells (DPSCs) which have invasive accessibility and high osteogenic potential is a promising source for cell-based bone regeneration. EphrinB2 is involved in bone homeostasis and osteogenesis. The aim of this study was to investigate the effect and mechanism of ephrinB2 overexpression on osteogenic differentiation of DPSCs and bone defect repair. METHODS: EphrinB2 expression was analyzed during osteogenic induction of human DPSCs (hDPSCs). Endogenous ephrinB2 expression in hDPSCs was then upregulated using EfnB2 lentiviral vectors. The effect of ephrinB2 overexpression on osteogenic differentiation capacity of hDPSCs was investigated in vitro, and activation of ephrinB2-EphB4 bidirectional signaling in ephrinB2-overexpressing hDPSCs was detected. In vivo, a canine alveolar bone defect model was established and canine DPSCs (cDPSCs) were cultured, characterized, EfnB2-tranfected, and combined with a PuraMatrix scaffold. Micro-CT analysis was performed to evaluate the therapeutic effect of ephrinB2-overexpressing cDPSCs on bone defect repair. RESULTS: EphrinB2 was upregulated after osteogenic induction of hDPSCs. EphrinB2 overexpression enhanced osteogenic differentiation capacity of hDPSCs in vitro. Moreover, p-ephrinB2 instead of p-EphB4 was upregulated by ephrinB2 overexpression, and activation of ephrinB2-mediated reverse signaling promoted osteogenic differentiation of hDPSCs. In a canine bone defect model, ephrinB2 overexpression in cDPSCs significantly improved trabecular bone volume per tissue volume (BV/TV) and trabecular thickness, as demonstrated by radiographic analysis. CONCLUSIONS: EphrinB2 overexpression enhanced osteogenic potential of DPSCs partially via upregulation of ephrinB2-mediated reverse signaling and effectively promoted alveolar bone defect repair.

Overexpression of ephrinB2 in stem cells from apical papilla accelerates angiogenesis.

OBJECTIVES: We aimed to accelerate angiogenesis in pulp regeneration by modulating ephrinB2 expression in stem cells from apical papilla (SCAPs). MATERIALS AND METHODS: Stem cells from apical papilla were transducted with ephrinB2-lentiviral expression vector (ephrinB2-SCAPs) in experimental group and green fluorescent protein (GFP-SCAPs) in control group. The transduction efficiency was confirmed by real-time PCR and Western blot assays. MTT assay was performed to detect the proliferative capacity of SCAPs after transduction. In vitro Matrigel assay and in vivo Matrigel plug assay were carried out to evaluate the angiogenic capacity. RESULTS: Results showed that ephrinB2-SCAPs had significantly higher ephrinB2 expression than GFP-SCAPs. EphrinB2-SCAPs upregulated vascular endothelial growth factor (VEGF) secretion under hypoxia. In vitro Matrigel assay demonstrated that human umbilical vein endothelial cells (HUVECs) cocultured with ephrinB2-SCAPs under hypoxia formed vascular-like structures earlier than GFP-SCAPs. Animal experiments confirmed that SCAPs co-transplanted with HUVECs enabled to generate greater amount of blood vessels than SCAPs alone. EphrinB2-SCAPs produced increased number of blood vessels with references to GFP-SCAPs, and those co-transplanted with HUVECs generated vessels with larger and functional tubule volumes. CONCLUSIONS: Regulating ephrinB2 expression in SCAPs may act as a new avenue for enhancing angiogenesis in dental pulp regeneration.

EphrinB2 regulates osteogenic differentiation of periodontal ligament stem cells and alveolar bone defect regeneration in beagles.

EphrinB2, a membrane protein regulating bone homeostasis, has been demonstrated to induce osteogenic gene expression in periodontal ligament fibroblasts. The aim of this study was to explore the effects of ephrinB2 on osteogenic differentiation of periodontal ligament stem cells and on alveolar bone regeneration in vivo. We assessed the osteogenic gene expression and osteogenic differentiation potential of ephrinB2-modified human and canine periodontal ligament stem cells, in which ephrinB2 expression was upregulated via lentiviral vector transduction. EphrinB2-modified canine periodontal ligament stem cells combined with PuraMatrix were delivered to critical-sized alveolar bone defects in beagles to evaluate bone regeneration. Results showed that ephrinB2 overexpression enhanced osteogenic gene transcription and mineral deposition in both human and canine periodontal ligament stem cells. Animal experiments confirmed that ephrinB2-modified canine periodontal ligament stem cells + PuraMatrix resulted in greater trabecular bone volume per tissue volume and trabecular thickness compared with other groups. Our study demonstrated that ephrinB2 promoted osteogenic differentiation of periodontal ligament stem cells and alveolar bone repair in beagles, highlighting its therapeutic potential for the treatment of alveolar bone damage.

[Polymerization of flowable composite core materials irradiated by super-high intensity light with short time].

PURPOSE: To evaluate the polymerization of dual-cured flowable composite core irradiated by super-high intensity light with short time. METHODS: The light-proof silicon rubber cuboid mold with one end open was syringed and filled by dual-cured flowable resin composite core, then the open end of mold was irradiated directly by a light unit at 1000 mW/cm(2) ×10, ×20 s; or at 3200 mW/cm(2) × 3, ×6 s. The specimens were stored in the light-proof box. After irradiation for 1 h and 24 h, Knoop microhardness was measured along the vertical surfaces of specimens from 1mm to 10 mm depth at 1 mm interval. The data was analyzed by one-way ANOVA with SPSS 16.0 software package. RESULTS: 3200 mW/cm(2) ×3 s light irradiation did not initiate light curing of the specimens. The other three light irradiations could make specimens obtaining higher microhardness than that by pure chemical cure; however, the depth of specimens affected by light irradiation was limited. Within the area affected by light, the microhardness of specimens could be improved by increasing the light irradiation time; after irradiation for 24 h, the microhardness of specimens had no difference between 3200 mW/cm(2) ×6 s and 1000 mW/cm(2) ×20 s light irradiation. CONCLUSIONS: 3200 mW/cm(2) light intensity should be used for irradiation at least for 6 s, which could initiate light curing of flowable composite core to sufficient polymerization.

Intraoral management of iatrogenically displaced lower third molar roots in the sublingual space: a report of 2 cases.

Surgical removal of the mandibular third molars is one of the most common procedures performed by dentists, as well as by oral and maxillofacial surgeons. Accidental displacement of teeth or roots into the fascial spaces, during surgical removal of the mandibular third molars, is a rare, but serious complication. Herein, we present 2 cases of iatrogenically displaced mandibular third molar roots into the sublingual space, which were successfully removed under local anesthesia intraorally. In addition to methods to minimize the risk of accidental tooth or root displacement, the importance of recognizing this complication and the methods of retrieval are also discussed.