Comparative analysis of the in vivo kinetic properties of various bone substitutes filled into a peri-implant canine defect model.

PURPOSE: Deproteinized bovine bone or synthetic hydroxyapatite are 2 prevalent bone grafting materials used in the clinical treatment of peri-implant bone defects. However, the differences in bone formation among these materials remain unclear. This study evaluated osteogenesis kinetics in peri-implant defects using 2 types of deproteinized bovine bone (Bio-Oss® and Bio-Oss/Collagen®) and 2 types of synthetic hydroxyapatite (Apaceram-AX® and Refit®). We considered factors including newly generated bone volume; bone, osteoid, and material occupancy; and bone-to-implant contact. METHODS: A beagle model with a mandibular defect was created by extracting the bilateral mandibular third and fourth premolars. Simultaneously, an implant was inserted into the defect, and the space between the implant and the surrounding bone walls was filled with Bio-Oss, Bio-Oss/Collagen, Apaceram-AX, Refit, or autologous bone. Micro-computed tomography and histological analyses were conducted at 3 and 6 months postoperatively (Refit and autologous bone were not included at the 6-month time point due to their rapid absorption). RESULTS: All materials demonstrated excellent biocompatibility and osteoconductivity. At 3 months, Bio-Oss and Apaceram-AX exhibited significantly greater volumes of formation than the other materials, with Bio-Oss having a marginally higher amount. However, this outcome was reversed at 6 months, with no significant difference between the 2 materials at either time point. Apaceram-AX displayed notably slower bioresorption and the largest quantity of residual material at both time points. In contrast, Refit had significantly greater bioresorption, with complete resorption and rapid maturation involving cortical bone formation at the crest at 3 months, Refit demonstrated the highest mineralized tissue and osteoid occupancy after 3 months, albeit without statistical significance. CONCLUSIONS: Overall, the materials demonstrated varying post-implantation behaviors in vivo. Thus, in a clinical setting, both the properties of these materials and the specific conditions of the defects needing reinforcement should be considered to identify the most suitable material.

Mitigating RANKL-induced cholesterol overload in macrophages with ß-cyclodextrin-threaded polyrotaxanes suppresses osteoclastogenesis.

Free cholesterol acts as an endogenous agonist for estrogen-related receptor α (ERRα), a nuclear receptor that regulates osteoclastogenesis. Because stimulation of macrophages with receptor activator of nuclear factor κB ligand (RANKL) induces an overload of free cholesterol and activates ERRα, we hypothesized that direct removal of cellular cholesterol would suppress osteoclastogenesis. In this study, the effect of 2-hydroxypropyl ß-cyclodextrin (HP-ß-CD), a highly water-soluble cyclic glucopyranose, and ß-CD-threaded polyrotaxanes (PRXs), supramolecular polymers designed to release threaded ß-CDs in acidic lysosomes, on RANKL-induced cholesterol overload and osteoclast differentiation of murine macrophage-like RAW264.7 cells were investigated. PRXs suppressed RANKL-induced cholesterol overload. Additionally, RANKL-induced osteoclast differentiation of RAW264.7 cells was inhibited by PRXs. In contrast, HP-ß-CD did not reduce cholesterol levels or inhibit osteoclast differentiation in RAW264.7 cells. Gene expression analysis of osteoclast markers suggested that PRXs suppress only the early stage of osteoclast differentiation, as PRXs cannot be internalized into multinucleated osteoclasts. However, modification of PRXs with cell-penetrating peptides facilitated their cellular uptake into multinucleated osteoclasts and inhibited osteoclast maturation. Thus, PRXs are promising candidates for inhibiting osteoclast differentiation by suppressing cholesterol overload and may be useful for treating osteoporosis or other bone defects caused by the overactivity of osteoclasts.

Chemical Diagnosis of Calcium Pyrophosphate Deposition Disease of the Temporomandibular Joint: A Case Report.

Calcium pyrophosphate dihydrate (CPPD) deposition disease is a benign disorder characterized by acute gouty arthritis-like attacks and first reported by McCarty. CPPD deposition disease rarely occurs in the temporomandibular joint (TMJ), and although confirmation of positive birefringence by polarized light microscopy is important for diagnosis, it is not reliable because other crystals also show birefringence. We reported a case of CPPD deposition disease of the TMJ that was diagnosed by chemical analysis. A 47-year-old man with a chief complaint of persistent pain in the right TMJ and trismus was referred to our department in 2020. Radiographic examination revealed destruction of the head of the mandibular condyle and cranial base with a neoplastic lesion involving calcification tissue. We suspected CPPD deposition disease and performed enucleation of the white, chalky masses. Histopathologically, we confirmed crystal deposition with weak birefringence. SEM/EDS revealed that the light emitting parts of Ca and P corresponded with the bright part of the SEM image. Through X-ray diffraction, almost all peaks were confirmed to be CPPD-derived. Inductively coupled plasma atomic emission spectroscopy revealed a Ca/P ratio of nearly 1. These chemical analyses further support the histological diagnosis of CPPD deposition disease.

Cyclodextrin-Based Supramolecular Complexes of Osteoinductive Agents for Dental Tissue Regeneration.

Oral tissue regeneration has received growing attention for improving the quality of life of patients. Regeneration of oral tissues such as alveolar bone and widely defected bone has been extensively investigated, including regenerative treatment of oral tissues using therapeutic cells and growth factors. Additionally, small-molecule drugs that promote bone formation have been identified and tested as new regenerative treatment. However, treatments need to progress to realize successful regeneration of oral functions. In this review, we describe recent progress in development of regenerative treatment of oral tissues. In particular, we focus on cyclodextrin (CD)-based pharmaceutics and polyelectrolyte complexation of growth factors to enhance their solubility, stability, and bioactivity. CDs can encapsulate hydrophobic small-molecule drugs into their cavities, resulting in inclusion complexes. The inclusion complexation of osteoinductive small-molecule drugs improves solubility of the drugs in aqueous solutions and increases in vitro osteogenic differentiation efficiency. Additionally, various anionic polymers such as heparin and its mimetic polymers have been developed to improve stability and bioactivity of growth factors. These polymers protect growth factors from deactivation and degradation by complex formation through electrostatic interaction, leading to potentiation of bone formation ability. These approaches using an inclusion complex and polyelectrolyte complexes have great potential in the regeneration of oral tissues.

Prognostic factors in mucoepidermoid carcinoma of the minor salivary glands: A single-center retrospective study.

OBJECTIVE: The objective of this study was to investigate the prognostic effects of clinical and histologic findings in patients with mucoepidermoid carcinoma (MEC) of minor salivary glands. STUDY DESIGN: This retrospective clinical review included 63 patients (30 males, mean age 52.8 years) with minor salivary gland MEC treated at our hospital from 1994 to 2019. Overall survival (OS) or disease-free survival was determined using the Kaplan-Meier limit method. Correlations between different factors and survival rates were assessed using chi-square tests. RESULTS: The 10-year OS rate was 91.2%. Low- or intermediate-grade MEC had a good prognosis regardless of the surgical margin, whereas high-grade MEC had a poor 10-year OS rate (64.2%). Ten patients developed recurrence or metastasis after primary surgical resection, of whom 6 were diagnosed with a high-grade tumor. The most frequently affected site was the palate, whereas the mandibular gingiva was the most commonly affected site during recurrence. Of 4 patients who received chemotherapy and/or radiotherapy postsurgery, 2 had local recurrence and/or neck lymph node metastasis and 1 died from MEC. CONCLUSION: Patients with low- or intermediate-grade MEC exhibited satisfactory survival after surgery. In patients with high-grade tumors, it has been suggested that survival rates are poor and do not improve following adjuvant therapy.

Polyelectrolyte Complexes between Polycarboxylates and BMP-2 for Enhancing Osteogenic Differentiation: Effect of Chemical Structure of Polycarboxylates.

Bone morphogenetic protein 2 (BMP-2) has received considerable attention because of its osteoinductivity, but its use is limited owing to its instability and adverse effects. To reduce the dose of BMP-2, complexation with heparin is a promising approach, because heparin enhances the osteoinductivity of BMP-2. However, the clinical use of heparin is restricted because of its anticoagulant activity. Herein, to explore alternative polymers that show heparin-like activity, four polycarboxylates, poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), poly(aspartic acid) (PAsp), and poly(glutamic acid) (PGlu), were selected and their capability to modulate the osteoinductivity of BMP-2 was evaluated. Dynamic light scattering indicated that these polycarboxylates formed polyelectrolyte complexes with BMP-2. The osteogenic differentiation efficiency of MC3T3-E1 cells treated with the polycarboxylate/BMP-2 complexes was investigated in comparison to that of the heparin/BMP-2 complex. As a result, PGlu/BMP-2 complex showed the highest activity of alkaline phosphatase, which is an early-stage marker of osteogenic differentiation, and rapid mineralization. Based on these observations, PGlu could serve as an alternative to heparin in the regenerative therapy of bone using BMP-2.

An Analysis of Dentigerous Cysts Developed around a Mandibular Third Molar by Panoramic Radiographs.

Dentigerous cysts are one of the most prevalent types of odontogenic cysts and are associated with the crown of an unerupted tooth, especially of the mandibular third molar. In this study, the characteristics of a dentigerous cyst developed around a mandibular third molar on panoramic radiographs were investigated. The panoramic images of 257 consecutive dentigerous cyst cases associated with a mandibular third molar were analyzed. The mean age of the patients was 45.9 ± 13.3 years. The size of the cyst did not significantly correlate to the age of the patient. The unilocular type (89.1%) and the crown side type (68.5%) were significant. The associated mandibular third molars had a high frequency of class III (64.6%) and position B (48.3%) in Pell and Gregory classification and of horizontal position (36.3%) in angulation. Dentigerous cysts were thought to originate and grow commonly around deeply impacted third molars. The associated third molar with dentigerous cyst tends to have a mesial inclination. Dentigerous cysts do not appear to develop gradually after the crown formation has finished, but arise at various periods randomly.

Mannosylated Polyrotaxanes for Increasing Cellular Uptake Efficiency in Macrophages through Receptor-Mediated Endocytosis.

Macrophages play an important role in the regulation of inflammation and immune response as well as the pathogenesis of chronic inflammatory diseases and cancer. Therefore, targeted delivery of therapeutic reagents to macrophages is an effective method for treatment and diagnosis. We previously examined the therapeutic applications of polyrotaxanes (PRXs) comprised of multiple cyclodextrins (CDs) threaded on a polymer chain and capped with bulky stopper molecules. In the present study, we designed an α-d-mannose-modified α-CD/poly(ethylene glycol)-based PRX (Man-PRX). The intracellular uptake of Man-PRX through the interaction with macrophage mannose receptor (MMR) in macrophage-like RAW264.7 cells was examined. Intracellular Man-PRX uptake was observed in MMR-positive RAW264.7 cells but was negligible in MMR-negative NIH/3T3 cells. In addition, the intracellular Man-PRX uptake in RAW264.7 cells was significantly inhibited in the presence of free α-d-mannose and an anti-MMR antibody, which suggests that MMR is involved in the intracellular uptake of Man-PRX. Moreover, the polarization of RAW264.7 cells affected the Man-PRX internalization efficiency. These results indicate that Man-PRX is an effective candidate for selective targeting of macrophages through a specific interaction with the MMR.

Enhanced cellular uptake and osteogenic differentiation efficiency of melatonin by inclusion complexation with 2-hydroxypropyl ß-cyclodextrin.

Melatonin (MLT), a hormone secreted from the pineal gland, is recognized as a potential candidate for stimulation of bone regeneration. However, because of its hydrophobicity, the administration of MLT to stimulate bone regeneration is difficult. In this study, an inclusion complex of MLT with 2-hydroxypropyl ß-cyclodextrin (HP-ß-CD) was prepared to improve the water solubility, and the osteogenic differentiation ability of the inclusion complex was investigated in MC3T3-E1 cells. The formation of HP-ß-CD/MLT inclusion complex was confirmed by 1H and 13C nuclear magnetic resonance spectroscopy and wide-angle X-ray diffraction. The water solubility of MLT increased linearly upon addition of HP-ß-CD because of the formation of the inclusion complex. Additionally, treatment of the cells with HP-ß-CD/MLT inclusion complex showed higher uptake amount of MLT than that treated with free MLT. In addition, treatment of MC3T3-E1 cells with HP-ß-CD/MLT inclusion complex increased alkaline phosphatase activity and mineralized matrix deposition, compared to that in free MLT-treated and untreated cells. Furthermore, cells treated with HP-ß-CD/MLT inclusion complex exhibited higher expression levels of osteogenic differentiation genes than those in the untreated and free MLT-treated cells. Accordingly, these results suggested that inclusion complexation of MLT with HP-ß-CD would be a potential formulation for bone regeneration because of its improved solubility and enhanced osteogenic differentiation efficiency.

A silencing-mediated enhancement of osteogenic differentiation by supramolecular ternary siRNA polyplexes comprising biocleavable cationic polyrotaxanes and anionic fusogenic peptides.

Gene silencing of noggin by small interfering RNA (siRNA) is a promising approach for the treatment of bone defects, because noggin deactivates bone morphogenetic protein-2 (BMP-2) and suppresses osteogenic differentiation. Here, we demonstrated the silencing of the noggin gene by siRNA polyplexes composed of noggin-targeted siRNA and biocleavable cationic polyrotaxanes (DMAE-SS-PRX). To improve the endosomal escape efficiencies of the DMAE-SS-PRX/siRNA polyplexes, anionic and fusogenic GALA peptides were integrated onto the DMAE-SS-PRX/siRNA polyplexes via simple electrostatic interactions. The formation of ternary complexes was confirmed by gel electrophoresis, dynamic light scattering, and zeta-potential measurements. Although the association of GALA peptides with the DMAE-SS-PRX/siRNA polyplexes did not remarkably affect the cellular uptake efficiency of siRNA, the endosomal escape efficiency was remarkably increased for GALA/DMAE-SS-PRX/siRNA ternary polyplexes because of the endosomal and lysosomal membrane destabilization by GALA peptides. Consequently, GALA/DMAE-SS-PRX/siRNA ternary polyplexes showed significantly higher gene silencing efficiency against noggin and enhanced the BMP-2-mediated osteogenic differentiation efficiency. Therefore, we concluded that GALA/DMAE-SS-PRX/siRNA ternary polyplexes can be effective siRNA carriers for suppressing the expression of specific endogenous genes. Consequently, we believe that a more practical approach in vivo will be the combined use of BMP-2 and GALA/DMAE-SS-PRX/siRNA ternary polyplexes, because it will improve the efficacy of bone regeneration therapy.

Potentiating bioactivity of BMP-2 by polyelectrolyte complexation with sulfonated polyrotaxanes to induce rapid bone regeneration in a mouse calvarial defect.

Bone reconstruction is a challenging issue in the regeneration of surgically removed bone and disease-related bone defects. Although bone morphogenetic protein-2 (BMP-2) has received considerable attention as a bone regeneration inducer, a high dose of BMP-2 is typically required due to its short life-time under in vivo conditions. We have proposed a method to enhance the osteogenetic differentiation ability of BMP-2 in vitro that is based on supramolecular polyelectrolyte complexation with sulfonated polyrotaxanes (PRXs) consisting of sulfopropyl ether (SPE)-modified α-cyclodextrins threaded along a poly(ethylene glycol) chain capped with terminal bulky stopper molecules. In this study, we evaluated the in vivo bone regeneration ability of the SPE-PRX/BMP-2 complexes in a mouse calvarial defect model in comparison to free BMP-2 and heparin/BMP-2 complexes. The regenerated bone area was determined by X-ray computed microtomography, and the mice implanted with sulfonated PRX/BMP-2 complexes exhibited rapid and significant bone regeneration compared to those implanted with free BMP-2 and heparin/BMP-2 complexes. We concluded that the sulfonated PRX/BMP-2 complexes are a promising candidate for clinical bone regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1355-1363, 2017.

Supramolecular inclusion complexation of simvastatin with methylated ß-cyclodextrins for promoting osteogenic differentiation.

Statins are recognized as a potential candidate to induce the regeneration of bone. However, statins are a strongly hydrophobic drug and it is difficult to administer at the local sites. In this study, the inclusion complexes of simvastatin (SV) with hydroxypropyl-ß-cyclodextrin (HP-ß-CD) and randomly methylated ß-cyclodextrin (RM-ß-CD) were prepared to improve the water-solubility and the osteogenic differentiation ability of the inclusion complexes in MC3T3-E1 cells was investigated. The water-solubility of SV increased linearly upon the addition of both HP-ß-CD and RM-ß-CD, due to the formation of inclusion complexes. The osteogenic differentiation ability of the inclusion complexes were evaluated by the production of alkaline phosphatase (ALP) and late stage osteogenetic gene expression in MC3T3-E1 cells after 14 days of culture. As a result, the RM-ß-CD/SV inclusion complexes showed significantly higher ALP production and the expression of bone sialoprotein (BSP) and osteocalcin (OCN) than the untreated and free SV-treated cells. Additionally, the production of bone morphogenetic protein-2 (BMP-2) from MC3T3-E1 cells after the treatment with RM-ß-CD/SV inclusion complexes was significantly higher than the untreated and free SV-treated cells. Accordingly, it is concluded that the inclusion complexation of SV with RM-ß-CD is a potential formulation for bone regenerative therapy to improve water-solubility and osteodifferentiation efficiency.

Supramolecular Polyelectrolyte Complexes of Bone Morphogenetic Protein-2 with Sulfonated Polyrotaxanes to Induce Enhanced Osteogenic Differentiation.

Although bone morphogenetic protein-2 (BMP-2) has received considerable attention because of its strong osteoinductivity, the clinical application of BMP-2 is limited due to its degradation and deactivation under physiological conditions. Negatively charged heparin is known to form polyelectrolyte complexes with BMP-2 to prevent deactivation and enhance the osteoinduction capability of BMP-2. Herein, we report the sulfonated polyrotaxanes (S-PRX) composed of α-cyclodextrin threaded onto a linear polymer for the protection of BMP-2 through the polyelectrolyte complex formation. When MC3T3-E1 osteoprogenitor cells were treated with the S-PRX/BMP-2 complexes, significantly high alkaline phosphatase production and mineralized matrix deposition were observed compared with that of free BMP-2 and heparin/BMP-2 complexes. Note that the S-PRXs showed negligible anticoagulant activity and cytotoxicity, whereas heparin showed strong anticoagulant activity. Accordingly, the S-PRXs are promising candidates for enhanced osteoinduction ability of BMP-2 without toxicity and anticoagulant activity and could contribute to clinical bone regeneration.