Seung-Yun Shin

Porphyromonas gingivalis oral infection exacerbates the development and severity of collagen-induced arthritis

IntroductionClinical studies suggest a direct influence of periodontal disease (PD) on serum inflammatory markers and disease assessment of patients with established rheumatoid arthritis (RA). However, the influence of PD on arthritis development remains unclear. This investigation was undertaken to determine the contribution of chronic PD to immune activation and development of joint inflammation using the collagen-induced arthritis (CIA) model.MethodsDBA1/J mice orally infected with Porphyromonas gingivalis were administered with collagen II (CII) emulsified in complete Freund’s adjuvant (CFA) or incomplete Freund’s adjuvant (IFA) to induce arthritis. Arthritis development was assessed by visual scoring of paw swelling, caliper measurement of the paws, mRNA expression, paw micro-computed tomography (micro-CT) analysis, histology, and tartrate resistant acid phosphatase for osteoclast detection (TRAP)-positive immunohistochemistry. Serum and reactivated splenocytes were evaluated for cytokine expression.ResultsMice induced for PD and/or arthritis developed periodontal disease, shown by decreased alveolar bone and alteration of mRNA expression in gingival tissues and submandibular lymph nodes compared to vehicle. P. gingivalis oral infection increased paw swelling and osteoclast numbers in mice immunized with CFA/CII. Arthritis incidence and severity were increased by P. gingivalis in mice that received IFA/CII immunizations. Increased synovitis, bone erosions, and osteoclast numbers in the paws were observed following IFA/CII immunizations in mice infected with P gingivalis. Furthermore, cytokine analysis showed a trend toward increased serum Th17/Th1 ratios when P. gingivalis infection was present in mice receiving either CFA/CII or IFA/CII immunizations. Significant cytokine increases induced by P. gingivalis oral infection were mostly associated to Th17-related cytokines of reactivated splenic cells, including IL-1β, IL-6, and IL-22 in the CFA/CII group and IL-1β, tumor necrosis factor-α, transforming growth factor-β, IL-6 and IL-23 in the IFA/CII group.ConclusionsChronic P. gingivalis oral infection prior to arthritis induction increases the immune system activation favoring Th17 cell responses, and ultimately accelerating arthritis development. These results suggest that chronic oral infection may influence RA development mainly through activation of Th17-related pathways.

Dual Delivery of rhPDGF-BB and Bone Marrow Mesenchymal Stromal Cells Expressing the BMP2 Gene Enhance Bone Formation in a Critical-Sized Defect Model

Bone tissue healing is a dynamic, orchestrated process that relies on multiple growth factors and cell types. Platelet-derived growth factor-BB (PDGF-BB) is released from platelets at wound sites and induces cellular migration and proliferation necessary for bone regeneration in the early healing process. Bone morphogenetic protein-2 (BMP-2), the most potent osteogenic differentiation inducer, directs new bone formation at the sites of bone defects. This study evaluated a combinatorial treatment protocol of PDGF-BB and BMP-2 on bone healing in a critical-sized defect model. To mimic the bone tissue healing process, a dual delivery approach was designed to deliver the rhPDGF-BB protein transiently during the early healing phase, whereas BMP-2 was supplied by rat bone marrow stromal cells (BMSCs) transfected with an adenoviral vector containing the BMP2 gene (AdBMP2) for prolonged release throughout the healing process. In in vitro experiments, the dual delivery of rhPDGF-BB and BMP2 significantly enhanced cell proliferation. However, the osteogenic differentiation of BMSCs was significantly suppressed even though the amount of BMP-2 secreted by the AdBMP2-transfected BMSCs was not significantly affected by the rhPDGF-BB treatment. In addition, dual delivery inhibited the mRNA expression of BMP receptor type II and Noggin in BMSCs. In in vivo experiments, critical-sized calvarial defects in rats showed enhanced bone regeneration by dual delivery of autologous AdBMP2-transfected BMSCs and rhPDGF-BB in both the amount of new bone formed and the bone mineral density. These enhancements in bone regeneration were greater than those observed in the group treated with AdBMP2-transfected BMSCs alone. In conclusion, the dual delivery of rhPDGF-BB and AdBMP2-transfected BMSCs improved the quality of the regenerated bone, possibly due to the modulation of PDGF-BB on BMP-2-induced osteogenesis.

Bone Formation on the Apatite-coated Zirconia Porous Scaffolds within a Rabbit Calvarial Defect:

Previously, a strong and bioactive ceramic scaffold consisting of a porous zirconia body coated with apatite double layers (fluorapatite (FA) as an inner layer and hydroxyapatite (HA) as an outer layer) was successfully fabricated. In this contribution, the authors investigate the in vivo performance of the engineered bioceramic scaffolds using a rabbit calvarial defect model. In particular, the porosity and pore size of the scaffolds are varied in order to observe the geometrical effects of the scaffolds on their bone formation behaviors. The scaffolds supported on a zirconia framework can be produced with an extremely high porosity (~84—87%), while retaining excellent compressive strength (~7—8 MPa), which has been unachievable in the case of pure apatite scaffolds (~74% porosity with ~2MPa strength). The experimental groups used in this study include three types of zirconia scaffolds coated with apatite; high porosity (~87%) with large pore size (~500— 700 μm): AZ-HL, high porosity (~84%) with small pore size (~150—200 μm): AZ-HS, and low porosity (~75%) with large pore size (~500—700 μm): AZ-LL, as well as one type of HA porous scaffold: low porosity (~74%) with a large pore size (~500—700 μm) for the purpose of comparison. The scaffolds prepared with dimensions of ~ 10 mm (diameter) × 1.2 mm (thickness) are grafted in rabbit calvaria defects. The histological sections are made at 4 and 12 weeks after surgery and immunohistochemical analyses are performed on the samples. All of the specimens show a good healing response without adverse tissue reactions. Good healing is shown at 4 weeks post-surgery with the ingrowth of new bone into the macropore-channels of the scaffolds. The newly formed bone amounts to ~19.9—24.2% of the initial defect area, depending on the scaffold type, but there is no statistical significance between the scaffold groups. However, the defects without the scaffolds (control group) show a significantly lower bone formation ratio (~4.3%). At twelve weeks after surgery, the extent of new bone formation is more pronounced in all of the scaffold groups. All of the scaffold groups show significantly higher bone formation ratios (26.7—46.9%) with respect to the control without the graft. In the comparison between the scaffold groups, those with high porosities (AZ-HL and AZ-HS) exhibit significantly higher bone formation as compared to the scaffold with low porosity (AZ-LL). Based on the present in vivo test performed within a rabbit calvaria defect model, it is concluded that the apatite-coated zirconia scaffolds show good bone forming ability and are considered to be a promising scaffolding material for bone regeneration since they possess a high level of both mechanical and biological properties.

Ex vivo bone morphogenetic protein 2 gene delivery using periodontal ligament stem cells for enhanced re-osseointegration in the regenerative treatment of peri-implantitis

Peri-implantitis is a chronic inflammatory process with advanced bone loss and impaired healing potential. For peri-implantitis treatment, tissue engineering can be applied to enhance bone regeneration of peri-implant defects. This study aimed to evaluate ex vivo bone morphogenetic protein 2 (BMP2) gene delivery using canine periodontal ligament stem cells (PDLSCs) for regeneration of peri-implantitis defects. Canine PDLSCs were transduced with adenoviral vectors containing BMP2 (BMP2/PDLSCs). After peri-implantitis was induced by ligature placement in six beagle dogs, regenerative procedures were performed; hydroxyapatite (HA) particles and collagen gel with autologous canine PDLSCs (PDLSC group) or BMP2/PDLSCs (BMP/PDLSC group) or without cells (control group) were grafted into the defects and covered by an absorbable membrane. Three months later, the animals were sacrificed. In vitro, BMP2/PDLSCs showed similar levels of stem cell properties to PDLSCs, such as colony-forming efficiency and expression of MSC markers STRO-1 and CD 146. BMP2/PDLSCs produced BMP-2 until day 21 at a concentration of 4-8 ng/mL. In vivo, the BMP2/PDLSC group showed significantly more new bone formation and re-osseointegration in peri-implantitis defects compared to the other groups. In conclusion, ex vivo BMP2 gene delivery using PDLSCs enhanced new bone formation and re-osseointegration in peri-implantitis defects.

The role of PIN1 on odontogenic and adipogenic differentiation in human dental pulp stem cells.

Recently, the involvement of PIN1, a peptidyl-prolyl cis/trans isomerase, has been reported in age-related bone homeostasis and adipogenesis. However, the role of PIN1 during odontogenic and adipogenic differentiation remains to be fully understood, particularly regarding human dental pulp stem cells (HDPSCs). Thus, in the present study, we have investigated the role of PIN1 in odontogenic and adipogenic differentiation of HDPSCs and signaling pathways possibly involved. PIN1 mRNA and protein level were upregulated in a time-dependent manner during adipogenic differentiation, increasing until 1 day of odontogenic induction and then steadily declined during odontogenic differentiation. Treatment of a known PIN1 inhibitor, juglone, significantly increased odontogenic differentiation as confirmed by alkaline phosphatase (ALP) activity, calcium deposition, and mRNAs induction of odontogenic markers [ALP, osteopontin (OPN), osteocalcin (OCN), dentin sialophosphoprotein (DSPP), and dentin matrix protein 1 (DMP-1)]. On the contrary, adipogenic differentiation was dramatically reduced upon juglone treatment, with concomitant downregulation of lipid droplet accumulation and adipogenic marker genes [peroxisome proliferation-activated receptor gamma (PPARγ), lipoprotein lipase (LPL), and adipocyte fatty acid-binding protein (AP2)]. In contrast to PIN1 inhibition, the overexpression of PIN1 via adenoviral infection (Ad-PIN1) in HDPSCs inhibited odontogenic differentiation but increased adipogenic differentiation, in which stem cell property markers such as stage-specific embryonic antigen-4 (SSEA-4) and STRO-1 were upregulated during odontogenic differentiation but downregulated in adiopogenic differentiation. Consistently, juglone-mediated inhibition of PIN1 augmented the osteogenic medium (OM)-induced activation of bone morphogenetic protein (BMP), Wnt/β-catenin, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and nuclear factor-kappa B (NF-κB) pathway, which response was reversed by Ad-PIN1. Moreover, juglone blocked the adipogenic induction medium-induced activation of PPARγ, C/EBPα, C/EBPβ, ERK, and NF-κB pathways, which was rescued by Ad-PIN1 infection. In summary, the present study shows for the first time that PIN1 acts as an important modulator of odontogenic and adipogenic differentiation of HDPSCs and may have clinical implications for regenerative dentistry.

Immediate implant placement into infected and noninfected extraction sockets: a pilot study

OBJECTIVE This study compared the osseointegration of immediate implants in dogs in infection-free sites and in sites with periradicular lesions which were removed by simulated periradicular surgery. STUDY DESIGN Periradicular surgeries were performed to remove intentionally induced periradicular lesions, followed by teeth extraction and immediate implant placement with (experimental group 1) or without (experimental group 2) membranes. In the control group, implants were placed at healthy extraction sockets. After 12 weeks, the animals were killed and the results of histomorphometric study were analyzed by Kruskal-Wallis test. RESULTS Both the control and the experimental implants were clinically acceptable. The control group showed significantly higher bone-implant contact (BIC; 76.03 +/- 7.98%) than the experimental groups 1 (59.55 +/- 14.21%) and 2 (48.62 +/- 20.22%) (P < .05). CONCLUSIONS Despite the lower BIC of the experimental groups, this pilot study showed the possibility that immediate implant placement might be successful in extraction sockets with periradicular lesions. Further studies with larger sample sizes are required.

Correlation study between distal caries in the mandibular second molar and the eruption status of the mandibular third molar in the Korean population

OBJECTIVES The purpose of this study was to analyze the correlation parameters between the distal caries of the mandibular second molars (M2Ms) and the eruption status of the mandibular third molars (M3Ms). STUDY DESIGN The records of 786 patients who had their M3Ms extracted from 2002 to 2007 at Samsung Medical Center were reviewed. The distal caries of M2Ms, age, gender, angulations, impaction degree, and distance between M2M and M3M were assessed. RESULTS Among 883 M2Ms, 152 had distal caries (17.2%, caries group). In the caries group, 79.6% of M3Ms exhibited mesial angulation between 40 degrees and 80 degrees and 82.2% of M3Ms exhibited an impaction level in which the most coronal aspect of the M3M was located superior to the occlusal surface of the M2M. The distance between M2M and M3M (between cemontoenamel junctions) was 7-9 mm for 57.2% of the caries group. CONCLUSIONS The M3Ms under eruption status as described here could be considered for preventive extraction.

Relationship between implant stability measured by resonance frequency analysis (RFA) and bone loss during early healing period

OBJECTIVE The aim of this study was to monitor the changes in the stability-related bone loss during the early healing period. STUDY DESIGN A total of 43 implants were installed in 19 patients, and their stability was measured by resonance frequency analysis (RFA) at the time of surgery and once per week for 12 weeks. A total of 32 implants had radiographs taken at the placement of implant and 4, 8, and 12 weeks postoperatively. The data for gender, bone density, different surgery protocols, and bone loss around implant were analyzed. RESULTS The mean implant stability quotient values were not changed during the healing period. The marginal bone losses at 12 weeks were 1.28 +/- 0.51 mm and 1.32 +/- 0.57 mm on the mesial and distal sides, respectively. CONCLUSIONS The implant stability in normal and hard bone density did not change with time, and there was no correlation between the marginal bone loss and the change of implant stability.

Efficacy of rhBMP-2/Hydroxyapatite on Sinus Floor Augmentation A Multicenter, Randomized Controlled Clinical Trial

The aim of this randomized single-blinded active-controlled clinical study was to evaluate the early efficacy of low-dose Escherichia coli–derived recombinant human bone morphogenetic protein 2 (rhBMP-2) soaked with hydroxyapatite granules (BMP-2/H) as compared with an inorganic bovine bone xenograft (ABX) in maxillary sinus floor augmentation. In a total of 127 subjects who were enrolled at 6 centers, maxillary sinus floors were augmented with 1 mg/mL of rhBMP-2 (0.5 to 2.0 mg per sinus) and BMP-2/H (0.5 to 2.0 g; n = 65) or with ABX alone (0.5 to 2.0 g; n = 62). Core biopsies were obtained 3 mo after the augmentation surgery and were analyzed histomorphometrically. The mean new bone formation with BMP-2/H and ABX augmentation was 16.10% ± 10.52% and 8.25% ± 9.47%, respectively. The BMP-2/H group was noninferior to the ABX group; the lower limit of the 1-sided 97.5% confidence interval for the difference between the 2 groups was calculated as 4.33%, which was greater than the prespecified noninferiority margin of −3.75%. An additional test with the Wilcoxon rank-sum test with a 2-sided 5% significance level showed that bone formation between the 2 groups was significantly different (P < 0.0001). The soft tissue and residual graft areas showed no significant differences between the groups. With regard to safety, no significant difference between the 2 groups was observed; there was no significant increase in the amount of rhBMP-2 antibody in the serum after BMP-2/H grafting. Our study suggested that low-dose Escherichia coli–derived rhBMP-2 with hydroxyapatite was effective in early stages for enhanced bone formation after maxillary sinus floor augmentation without harmful adverse events (Clinicaltrials.gov NCT01634308).

Surface properties correlated with the human gingival fibroblasts attachment on various materials for implant abutments: A multiple regression analysis

Abstract Objectives. To reveal the suitable surface condition of an implant abutment for fibroblast attachment, the correlation between the surface characteristics of various materials and the human gingival fibroblast (HGF-1) attachment to the surfaces were analyzed. Methods. Six kinds of surfaces comprised of machined titanium alloy (SM), machined Co-Cr-Mo alloy (CCM), titanium nitride coated titanium alloy (TiN), anodized titanium alloy (AO), composite resin coating on titanium alloy (R) and zirconia (Zr) were used. The measured surface parameters were Sa, Sq, Sz, Sdr, Sdq, Sal, Str and water contact angle (WCA). The HGF-1 cell attachment was investigated and the correlations were analyzed using a multiple regression analysis. Results. The HGF-1 cell attachment was greater in the SM, TiN and Zr groups than the other groups and smallest in the CCM group (p = 0.0096). From the multiple regression analysis, the HGF-1 cell attachment was significantly correlated with Sdr, Sdq and WCA. When the R group was excluded, only WCA showed significant correlation with the fibroblast attachment. Conclusions. Within the limitations of this study, the cell attachment of human gingival fibroblasts was correlated with WCA, developed interfacial area ratio and surface slope. When the surfaces with Sa values of ∼ 0.2 μm or less were concerned, only WCA showed a correlation in a third order manner.