Mesenchymal Stromal Cells Derived from Dental Tissues: Immunomodulatory Properties and Clinical Potential.

Mesenchymal stem/stromal cells (MSCs) are multipotent cells located in different areas of the human body. The oral cavity is considered a potential source of MSCs because they have been identified in several dental tissues (D-MSCs). Clinical trials in which cells from these sources were used have shown that they are effective and safe as treatments for tissue regeneration. Importantly, immunoregulatory capacity has been observed in all of these populations; however, this function may vary among the different types of MSCs. Since this property is of clinical interest for cell therapy protocols, it is relevant to analyze the differences in immunoregulatory capacity, as well as the mechanisms used by each type of MSC. Interestingly, D-MSCs are the most suitable source for regenerating mineralized tissues in the oral region. Furthermore, the clinical potential of D-MSCs is supported due to their adequate capacity for proliferation, migration, and differentiation. There is also evidence for their potential application in protocols against autoimmune diseases and other inflammatory conditions due to their immunosuppressive capacity. Therefore, in this review, the immunoregulatory mechanisms identified at the preclinical level in combination with the different types of MSCs found in dental tissues are described, in addition to a description of the clinical trials in which MSCs from these sources have been applied.

A diet rich in omega-3 fatty acid improves periodontitis and tissue destruction by MMP2- and MMP9-linked inflammation in a murine model.

Periodontitis is an oral-cavity inflammatory disease and is the principal cause associated with tooth loss. Matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) are important proteases involved in periodontal tissue destruction. The omega-3 polyunsaturated fatty acids (ω-3 PUFA) have been demonstrated to possess immunoregulatory properties in periodontitis. The aim of the study was to investigate the effects of ω-3 PUFA on inflammation and on the expression of MMP-2 and -9 in a murine periodontitis model. Twenty-four male C57BL/6 mice were divided into control mice (Control), control mice treated with ω-3 PUFA (O3), mice with periodontitis (P), and mice with periodontitis treated with ω-3 PUFA (P + O3). ω-3 PUFA were administered orally once a day for 70 days. Periodontitis in mice was induced by Porphyromonas gingivalis-infected ligature placement around the second maxillary molar. The mice were sacrificed, and blood and maxillary samples were collected. Flow cytometry was used to quantify tumor necrosis factor-alpha (TNFα), interleukin (IL)-2, IL-4, IL-5, and interferon-gamma. Histologic analysis and immunohistochemistry for MMP-2 and -9 were performed. The data were statistically evaluated using analysis of variance (ANOVA) and the Tukey post hoc test. Histological analysis showed that ω-3 PUFA supplementation prevented inflammation and tissue destruction and revealed that bone destruction was more extensive in the P group than in the P + O3 group (p < 0.05). Also, it decreased the serum expressions of TNFα and IL-2 and the tissue expression of MMP-2 and -9 in the periodontitis-induced model (p < 0.05). ω-3 PUFA supplementation prevented alveolar bone loss and periodontal destruction, probably by decreasing the expression of MMP-2 and MMP-9 and its immunoregulatory properties.

Oxide nanoparticles based in magnesium as a potential dental tool to inhibit bacterial activity and promote osteoblast viability.

Functional nano-fillers are commonly used to reduce bacterial colonization in dentistry. This study aimed to synthesize, characterize, and evaluate the biological effects of magnesium oxide (MgO) nanoparticles (NP) obtained by mechanosynthesis. XRD, TEM, FT-IR, and UV-Vis were used to characterize MgO-NP which were subsequently tested for their activity against Staphylococcus aureus, Enterococcus faecalis and Escherichia coli (E. coli). The effects of MgO-NP on osteoblast cells were also analyzed. Three variables were studied: microbial inhibition by optical density (OD; 570-nm), viability estimated by colony-forming-units, and cell proliferation. The characterization of NP is consistent with nanostructures, minimum inhibitory concentration between 1.5-5 mg/mL, and microbial inhibition at 9.75 ug/mL concentration for E. coli were determined. There were different concentration-dependent effects on cell proliferation. Results were observed with 0.156 mg/mL MgO-NP, which increased cell proliferation at 24 and 48 h. The results suggest the antibacterial suitability of MgO-NP, with tolerable viability of mammalian cells for dental applications.

In Vitro Bone Differentiation of 3D Microsphere from Dental Pulp-Mesenchymal Stem Cells.

Bone defects lead to the structural loss of normal architecture, and those in the field of bone tissue engineering are searching for new alternatives to aid bone regeneration. Dental pulp-mesenchymal stem cells (DP-MSC) could provide a promising alternative to repair bone defects, principally due to their multipotency and capacity to fabricate three-dimensional (3D) spheroids. The present study aimed to characterize the 3D DP-MSC microsphere and the osteogenic differentiation capacity potential cultured by a magnetic levitation system. To achieve this, the 3D DP-MSC microsphere was grown for 7, 14, and 21 days in an osteoinductive medium and compared to 3D human fetal osteoblast (hFOB) microspheres by examining the morphology, proliferation, osteogenesis, and colonization onto PLA fiber spun membrane. Our results showed good cell viability for both 3D microspheres with an average diameter of 350 µm. The osteogenesis examination of the 3D DP-MSC microsphere revealed the lineage commitment, such as the hFOB microsphere, as evidenced by ALP activity, the calcium content, and the expression of osteoblastic markers. Finally, the evaluation of the surface colonization exhibited similar patterns of cell-spreading over the fibrillar membrane. Our study demonstrated the feasibility of forming a 3D DP-MSC microsphere structure and the cell-behavior response as a strategy for the applications of bone tissue guiding.

Advances in tissue engineering of cancer microenvironment-from three-dimensional culture to three-dimensional printing.

Cancer treatment development is a complex process, with tumor heterogeneity and inter-patient variations limiting the success of therapeutic intervention. Traditional two-dimensional cell culture has been used to study cancer metabolism, but it fails to capture physiologically relevant cell-cell and cell-environment interactions required to mimic tumor-specific architecture. Over the past three decades, research efforts in the field of 3D cancer model fabrication using tissue engineering have addressed this unmet need. The self-organized and scaffold-based model has shown potential to study the cancer microenvironment and eventually bridge the gap between 2D cell culture and animal models. Recently, three-dimensional (3D) bioprinting has emerged as an exciting and novel biofabrication strategy aimed at developing a 3D compartmentalized hierarchical organization with the precise positioning of biomolecules, including living cells. In this review, we discuss the advancements in 3D culture techniques for the fabrication of cancer models, as well as their benefits and limitations. We also highlight future directions associated with technological advances, detailed applicative research, patient compliance, and regulatory challenges to achieve a successful bed-to-bench transition.

Comparison of two obturation techniques on adhesion and proliferation of human periodontal ligament fibroblasts / Comparación de la adhesión y proliferación de fibroblastos periodontales humanos en dos técnicas de obturación endodóntica

The present study aimed to compare the adhesion and proliferation of human periodontal ligament fibroblasts (hPDL) in transverse sections of the teeth sealed with two different obturation techniques, BioRoot RCS/hydraulic obturation (HO) and AH-Plus/continuous-wave condensation (CWC). The techniques were tested using an in vitro model to simulate the interaction between periodontal tissues and the materials. The root canals were instrumented and sterilized. A total of 15 samples were obturated with BioRoot RCS/HO and 15 samples with AH-Plus/CWC. Then, roots were sectioned to obtain obturated teeth slices, and hPDL cells were seeded onto the root slices. The results were obtained at intervals of 4 and 24h for cell adhesion; and at 3,7,14, and 21 days for cell proliferation. Empty cell culture plates were use as controls. The cell adhesion was increased at 4 and 24h for both groups, with an increased response observed in the BioRoot RCS/HO group (p<0.05). The difference in cell proliferation was also found between experimental groups. After 14 days of culture, BioRoot RCS/HO group showed an increase response than control and AH-Plus/CWC groups (p<0.05), and after 21 days both groups behaved better than control group, with an increased response observed in the BioRoot RCS/HO group. This study demonstrated that both root canal sealers allow the attach and growth of periodontal ligament fibroblasts, with an increased biological response in the BioRoot RCS/HO group.

El presente estudio se enfocó en comparar la adhesión y proliferación de fibroblastos de ligamento periodontal humano (hPDL) en secciones transversales de raíces previamente obturadas con dos técnicas de obturación diferentes: obturación hidráulica empleando cono único de gutapercha y BioRoot RCS como sellador (HO), y obturación de condensación de onda continua y AH-Plus como sellador (CWC). Los selladores se usaron en un modelo in vitro que simula la interacción entre los tejidos periodontales y los materiales de obturación. Los conductos radiculares fueron instrumentados, esterilizados y obturados. La muestra se compuso de un total de 15 raíces con la técnica BioRoot RCS/HO y 15 raíces con la técnica AH-Plus/CWC. Las células de hPDL fueron sembradas en condiciones estándar de cultivo sobre las raíces seccionadas. Los resultados fueron obtenidos a intervalos de 4 y 24h para adhesión celular, y a los 3,5,7,14 y 21 días de cultivo para proliferación celular. La adhesión celular a las 4 y 24 horas mostró ser diferente para ambas técnicas en comparación con el grupo control, siendo más importante en el grupo BioRoot RCS/HO. La diferencia en la proliferación entre grupos se observó a los 14 días de cultivo, únicamente para el grupo BioRoot RCS/HO; Sin embargo para el día 21 ambas técnicas mostraron mayor proliferación celular que el grupo control, con mejor respuesta para el grupo BioRoot RCS/HO. Este estudio ha demostrado que ambos selladores de conductos permiten la adhesión y crecimiento de fibroblastos de ligamento periodontal, siendo el grupo BioRoot RCS/HO el que mostró mayor biocompatibilidad.

Docosahexaenoic acid improves altered mineralization proteins, the decreased quality of hydroxyapatite crystals and suppresses oxidative stress induced by high glucose.

Patients with type 2 diabetes mellitus (DM2) experience an increased risk of fractures and a variety of bone pathologies, such as osteoporosis. The suggested mechanisms of increased fracture risk in DM2 include chronic hyperglycaemia, which provokes oxidative stress, alters bone matrix, and decreases the quality of hydroxyapatite crystals. Docosahexaenoic acid (DHA), an omega-3 fatty acid, can increase bone formation, reduce bone loss, and it possesses antioxidant/anti-inflammatory properties. The present study aimed to determine the effect of DHA on altered osteoblast mineralisation and increased reactive oxygen species (ROS) induced by high glucose concentrations. A human osteoblast cell line was treated with 5.5 mM glucose (NG) or 24 mM glucose (HG), alone or in combination with 10 or 20 µM DHA. The collagen type 1 (Col1) scaffold, the expression of osteocalcin (OCN) and bone sialoprotein type-II (BSP-II), the alkaline phosphatase (ALP) specific activity, the mineral quality, the production of ROS and the mRNA expression of nuclear factor erythroid 2-related factor-2 (NRF2) were analysed. Osteoblasts cultured in HG and treated with either DHA concentration displayed an improved distribution of the Col1 scaffold, increased OCN and BSP-II expression, increased NRF2 mRNA, decreased ALP activity, carbonate substitution and reduced ROS production compared with osteoblasts cultured in HG alone. DHA counteracts the adverse effects of HG on bone mineral matrix quality and reduces oxidative stress, possibly by increasing the expression of NRF2.

Case Report: Formation of 3D Osteoblast Spheroid Under Magnetic Levitation for Bone Tissue Engineering.

Skeletal reconstruction is necessary in cases of bone defects created by tumors, trauma, and abnormalities. Regeneration of bone defects remains a critical problem, and current approaches are based on biocompatible scaffolds. Spheroids represent a simple 3D system since no supporting material is required for cell growth. Different techniques are used to generate spheroids, such as hanging drop, low-attachment plates, and magnetic nanoparticles. The idea of using magnetic nanoparticles is to cross-link through cell membrane overnight to create complex 3D cellular spheroid by using magnets to guide the cellular response. Herein, the current study aimed to achieve 3D human fetal osteoblast (hFOB) spheroid under magnetic levitation. Formation of 3D spheroid culture under magnetic levitation was evaluated by cell viability at 3, 7, and 14 days. Morphology of the 3D hFOB spheroid was analyzed by SEM and fluorescence microscopy and the differentiation towards mineralized lineage by ALP assay, qPCR, and alizarin red staining. The cell viability indicated that the 3D hFOB spheroid still viable after 14 days of culture. ALP assay, qPCR analysis expression of Col1, ALP, and Itg-ß1 molecules, and calcium deposition with alizarin red showed a high level of bioactivity of the 3D hFOB spheroid. SEM images allowed the morphological analysis of the 3D microtissue-like spheroid with the presence of matrix deposition. These results indicate that magnetic levitation culture enables 3D stable osteoblast spheroids and could be a promising strategy for engineering application in the 3D construct in surgery regeneration of mineralized tissue.

In vivo Regeneration of Mineralized Bone Tissue in Anisotropic Biomimetic Sponges.

In the last two decades, alginate scaffolds have been variously studied as extracellular matrix analogs for tissue engineering. However, relevant evidence is still lacking concerning their ability to mimic the microenvironment of hierarchical tissues such as bone. Hence, an increasing amount of attention has recently been devoted to the fabrication of macro/microporous sponges with pore anisotropy able to more accurately replicate the cell niche structure as a trigger for bioactive functionalities. This paper presents an in vivo study of alginate sponges with anisotropic microporous domains (MAS) formed by ionic crosslinking in the presence of different fractions (30 or 50% v) of hydroxyapatite (HA). In comparison with unloaded sponges (MAS0), we demonstrated that HA confers peculiar physical and biological properties to the sponge, depending upon the inorganic fraction used, enabling the sponge to bio-mimetically support the regeneration of newly formed bone. Scanning electron microscopy analysis showed a preferential orientation of pores, ascribable to the physical constraints exerted by HA particles during the pore network formation. Energy dispersive spectroscopy (EDS) and X-Ray diffraction (XRD) confirmed a chemical affinity of HA with the native mineral phase of the bone. In vitro studies via WST-1 assay showed good adhesion and proliferation of human Dental Pulp-Mesenchymal Stem Cells (hDP-MSC) that increased in the presence of the bioactive HA signals. Moreover, in vivo studies via micro-CT and histological analyses of a bone model (e.g., a rat calvaria defect) confirmed that the maximum osteogenic response after 90 days was achieved with MAS30, which supported good regeneration of the calvaria defect without any evidence of inflammatory reaction. Hence, all of the results suggested that MAS is a promising scaffold for supporting the regeneration of hard tissues in different body compartments.

Physicochemical and Tissue Response of PLA Nanofiber Scaffolds Sterilized by Different Techniques / Evaluación fisicoquímica y respuesta tisular de andamios nanofibrilares de PLA esterilizados por diferentes técnicas

ABSTRACT In recent years, tissue engineering has evolved considerably, due to the problems in the biomedical area concerning tissue regeneration therapies. Currently, work has been focused on the synthesis and physicochemical characterization of poly lactic acid scaffolds, a synthetic polyester that has been extensively study for its excellent biocompatibility and biodegradability. Moreover, sterilization strategies of scaffold are a crucial step for its application in tissue regeneration, however, the sterilization process have to maintain the structural and biochemical properties of the scaffold. Therefore, it is very important to carry out studies on the sterilization methods of the sample's material, since translational medicine is intended for in vivo applications. The aim of the present study was designed to analyze the effects of different sterilization techniques, i.e. ethylene oxide (ETO), gamma radiation (GR) and hydrogen peroxide- based plasma (H2O2) in biodegradable PLA scaffolds, and to determine the best sterilization technique to render a sterile product with minimal degradation and deformation, and good tissue response. Analysis of surface morphology showed that ETO and GR modified the PLA scaffolds without any change in its chemical composition. Moreover, the histological response showed that the scaffolds are biocompatible and those sterilized by GR showed a more severe inflammatory response, accompanied with the presence of giant foreign body cells. In conclusion, the results show that among sterilization techniques used in the preset study, the best results were observed with H2O2 sterilization, since it did not significantly modify the surface structure of the PLA fibers and their in vivo response did not cause an unfavorable tissue reaction.

RESUMEN En los últimos años, la ingeniería de tejidos ha evolucionado considerablemente, debido a las incógnitas en las terapias de regeneración en el área biomédica. Actualmente, se ha trabajado en la síntesis y caracterización fisicoquímica de andamios de poliácido láctico, el cual es un polímero sintético que se ha estudiado para aplicaciones en ingeniería de tejidos, debido a su biocompatibilidad y biodegradabilidad. El proceso de esterilización es un paso crucial en la aplicación de andamios en terapias de regeneración, sin embargo, la técnica de esterilización debe mantener las propiedades estructurales y bioquímicas del andamio. Por lo tanto, es muy importante realizar estudios sobre los métodos de esterilización de dichos andamios, ya que la medicina traslacional está diseñada para aplicaciones in vivo. El objetivo del presente estudio fue analizar los efectos de diferentes técnicas de esterilización como óxido de etileno (ETO), radiación gamma (GR) y plasma a base de peróxido de hidrógeno (H2O2) en andamios biodegradables de PLA, y determinar la mejor técnica de esterilización con mínima degradación y deformación, así como una respuesta tisular favorable. La estructura de la superficie de los andamios de PLA se modificó principalmente con las técnicas de óxido de etileno y radiación gamma, sin embargo, ninguna técnica modificó su composición química. Con la respuesta histológica se demostró que los andamios de PLA son biocompatibles y que los esterilizados por radiación gamma desencadenan una mayor respuesta inflamatoria y la formación de células gigantes de cuerpo extraño. En conclusión, los resultados muestran que las técnicas de esterilización utilizadas pueden modificar la morfología del andamio, sin embargo; los mejores resultados se observaron con la esterilización por plasma a base de peróxido de hidrógeno, ya que no modificó significativamente la estructura de la superficie de las fibras de PLA y su respuesta in vivo no provocó una reacción desfavorable en el tejido.

Upregulation of proteins of the NLRP3 inflammasome in patients with periodontitis and uncontrolled type 2 diabetes.

OBJECTIVES: To evaluate the expression of proteins related to activation of the NLRP3 inflammasome in patients with chronic periodontitis (CP) and type 2 diabetes mellitus (T2D), and to determine whether the exacerbated periodontal pathological process observed in diabetic patients is related to its upregulation. MATERIALS AND METHODS: We performed an observational, analytical, cross-sectional study in three study groups: individuals systemically and orally healthy, and patients with CP with and without T2D. Gingival biopsies were taken from the three study groups. The expression of mRNAs for CASP1, NLRP3 and ASC was detected using real-time PCR, and the expression of NLRP3 and ASC proteins was determined by immunohistochemistry. The quantification of IL-18 and IL-1ß was determined in the gingival crevicular fluid using ELISA. The results were analysed by ANOVA followed by Tukey's test to compare differences between individual groups. RESULTS: Patients with CP and uncontrolled T2D presented severe periodontal disease and inflammation (PPD, p = 0.0072; CAL, p = 0.0480; bone loss, p = 0.0088), higher levels of CASP1 mRNA expression (p = 0.0026), a stronger pattern of staining for NLRP3 and ASC proteins in the epithelium and connective tissues, and significantly higher production of IL-18 (p = 0.0063) and IL-1ß (p = 0.0018) in comparison with healthy or CP subjects. CONCLUSION: The upregulation of genes and proteins involved in the activation of the NLRP3 inflammasome components in patients with periodontitis and uncontrolled T2D suggests a possible role in the more severe pathological processes leading to destruction of periodontal tissues observed in these patients.

Antibacterial Activity of Homeopathic Medications Lycopodium clavatum and Arsenicum album Against Periodontal Bacteria / Evaluación antibacteriana de los medicamentos homeopáticos sobre bacterias periodontales

Abstract There are several controversies regarding the efficacy of homeopathic substances; however, these remedies are used in many countries for the treatment of various pathological conditions. The purpose of this study was to evaluate the in vitro antibacterial activity of two homeopathic tinctures Arsenicum album (mineral extract) and Lycopodium clavatum (plant extract) on the periodontal bacteria Actinomyces israelii, Streptococcus sanguinis, Prevotella intermedia, Aggregatibacter actinomycetemcomitans and Phorphyromonas gingivalis (P. gingivalis). Materials and methods: Equal numbers of bacteria were seeded on agar plates containing enriched media with the homeopathic solutions at 1dH and 1cH dilutions. After 7 days of incubation under anaerobic conditions, colony forming units (CFUs) were counted. The antibacterial effect was calculated based on the total number of CFUs observed on non-tincture containing agar, and on the tincture containing plates. Results: No visible growth of any of the strains was observed on the plates containing Arsenicum album at any of the dilutions tested. In contrast, when Lycopodium clavatum at 1cH dilution was tested, only P. gingivalis was susceptible to this compound. Conclusions: The results suggest that the mineral extract tincture had a greater antibacterial activity than the plant extract tincture, also Lycopodium clavatum preparation could be an effective inhibitor of periodontal pathogens bacteria such as P. gingivalis.

Resumen Se necesita un mayor número de estudios in vitro e in vivo para validar estos resultados.

Localización de las proteínas específicas del cemento radicular CEMP1 y CAP en células neoplásicas / Immunolocalization of cementum specific proteins CEMP1 and CAP in tumor cells

Introducción: Las proteínas CEMP1 y CAP presentes en los cementoblastos y sus progenitores contribuyen a los procesos de mineralización en tejidos del ligamento periodontal, incluyendo la migración y la proliferación de fibroblastos gingivales; sin embargo su papel y relación con procesos neoplásicos no se han estudiado a profundidad. Para lograr un mejor entendimiento de la posible contribución de estas proteínas en los procesos tumorales, particularmente en las metástasis óseas, se investigó su expresión y localización en tejidos y líneas celulares de cáncer humano. Materiales y métodos: Trece casos de cáncer de próstata y mama que desarrollaron enfermedad metastásica ósea fueron analizados por medio de inmunohistoquímica; mientras que la expresión de las proteínas en dos líneas celulares de carcinoma de próstata (PC-3) y mama (MCF-7) se estudió por medio de ensayos de Western Blot. Resultados: Los tejidos de cáncer revelaron expresión citoplasmática y ocasionalmente nuclear de CAP en células tumorales y estructuras glandulares pequeñas, así como en el citoplasma de los fibroblastos estromales adyacentes al frente de invasión tumoral. En lo correspondiente a CEMP1, su expresión se localizó en el citoplasma de las células tumorales de 5 casos, pero no en el estroma. Ensayos de Wester Blot mostraron expresión de CEMP1 en las células PC-3 y MCF-7; y de CAP en las MCF-7. Conclusiones: Los resultados muestran que las proteínas de cemento radicular CEMP1 y CAP se expresan en tejidos neoplásicos y células neoplásicas, y que posiblemente contribuyen en ciertas condiciones patológicas como el cáncer metastásico en humanos.

Introduction: CEMP1 and CAP are recognized as cementum proteins, they appear to be limited to cementoblasts and their progenitors, and participate in the mineralization process of periodontal ligament tissues, including the proliferation and migration of periodontal ligament fibroblasts. However, their contribution in neoplastic processes had not been explored. In the present study, we investigated their protein expression and localization in cancer tissues and cells. Materials and Methods: CEMP1 and CAP expressions were analyzed immunohistochemically in 13 cancer cases with bone metastasis. In addition, Wester Blot essays were use to detect expression of the proteins in the prostate (PC-3) and mama (MCF-7) cancer cell lines. Results: CAP expression was detected in all tissues examined. Strong cytoplasmatic and rarely nuclear staining was found in small tumor nests, glandular structures and, in the stromal fibroblasts at the immediate vicinity of the tumor nests. CEMP1 was found in the cytoplasm of tumor cells in 5 cases, but its expression was negative in the stromal tissues. Also, cancer lines PC-3 and MCF-7 showed CEMP1 expression; however, CAP expression was observed only in MCF-7 cells. Conclusions: The results suggest that CEMP1 and CAP are present in tissues other that cementum and possibly contribute to pathological conditions such as metastatic cancer.

Immunohistochemical expression of podoplanin in so-called hard α-keratin-expressing tumors, including calcifying cystic odontogenic tumor, craniopharyngioma, and pilomatrixoma.

Podoplanin, a transmembrane sialomucin-like glycoprotein, is a specific marker of lymphatic vessels, and its expression is also considered to be associated with tumor invasion and tooth development. In this study, we examined the expression of podoplanin in calcifying cystic odontogenic tumor (CCOT) in comparison with that in other so-called hard α-keratin-expressing tumors such as craniopharyngioma (CP) and pilomatrixoma (PM). Immunohistochemical staining for podoplanin was carried out using surgical specimens of 15 CCOTs of the jaw, 19 CPs of the pituitary gland, and 15 PMs of the skin. Positivity for hard α-keratin was evident in ghost, shadow and transitional cells in all of these tumors (100%). The podoplanin expression in CCOTs was evident in the periphery of ameloblastoma-like epithelium (86.6%) and the epithelial cells adjacent to ghost cells (60%). On the other hand, in adamantinomatous-type CPs, podoplanin expression was observed in epithelial components corresponding to the stratum intermedium (100%), but not in the periphery of ameloblastoma-like epithelium (0%). In squamous-type CPs podoplanin was expressed in basal cells (100%), but all of the PMs were podoplanin-negative (0%). In the periphery of the ameloblastoma-like epithelium or basophilic cell layer, podoplanin was expressed more strongly in CCOTs than in CPs or PMs. These findings suggest that the expression of podoplanin in CCOTs may reflect rapid turnover of cytoskeletal filaments and local invasiveness.

Podoplanin expression in odontomas: clinicopathological study and immunohistochemical analysis of 86 cases.

Podoplanin, a sialomucin-like transmembrane glycoprotein, is currently used as a specific marker for lymphatic vessels. However, podoplanin expression has also been linked to tooth development. To investigate the expression of podoplanin in odontomas, 86 tissue samples were classified and then analyzed using immunohistochemical methods. Formalin-fixed, paraffin-embedded specimens were collected and classified, followed by immunohistochemical examination. The majority of the odontomas (66.3%) were the compound type, and the remainder (33.7%) were the complex type. The patients ranged in age from 2 to 89 years (mean, 23.9 years), and 45 (52.3%) of them were male and 41 (47.7%) were female. The most common location for complex odontomas was the molar region of the mandibular bone, and that for compound odontomas was the maxillary incisor region. Immunohistochemistry revealed that developing and mature odontoblasts, Tomes' fibers, and pulp cells near podoplanin-positive odontoblasts were positive for podoplanin. In addition, podoplanin positivity was evident in secretory ameloblasts, but not in mature ameloblasts. The pattern of podoplanin expression in odontomas corresponds to development of the tooth germ, and appears to be influenced by the stage of differentiation of the lesion, suggesting that the protein may participate in the process of differentiation.

Expression of heparanase: a possible role in invasiveness and aggressive clinical behavior of ameloblastomas.

Heparanase is an endoglycosidase that cleaves heparan sulfate (HS), thus participating in degradation and remodeling of the extracellular matrix (ECM). Heparanase up-regulation is correlated with lymph node and distant metastasis, microvessel density and reduced postoperative survival of cancer patients. In the present study, we carried out an immunohistochemical investigation of heparanase to extend and confirm present knowledge regarding its expression in ameloblastomas (AMs), which are characterized by locally aggressive behavior. Paraffin-embedded tissue specimens of 53 AMs were stained using an antibody against heparanase. Immunohistochemical reactivity for heparanase was detected in 94.3% of the AMs examined. Heparanase was expressed strongly in peripheral columnar cells and slightly in central stellate reticulum-like cells. Small tumor nests and budding epithelial branches showed a stronger staining pattern. Stromal cells were negative for heparanase, or showed diffuse expression. However, an enhanced positive immunoreaction was present specifically near osseous tissue and adjacent to the invasive front of tumor nests. Areas of cystic degeneration showed intense heparanase immunoreactivity. The enzyme may facilitate the function of HS-binding growth factors that elicit an angiogenic response and favor osteoclastogenesis in AM.

Significance of podoplanin expression in keratocystic odontogenic tumor.

BACKGROUND: The most important clinical features of the keratocystic odontogenic tumor (KCOT) are its potential for locally destructive behavior, a tendency to recur, and its origin in the odontogenic epithelium. The clinical features of KCOT are similar to those of ameloblastoma (AM). Histologically, KCOT is distinguished from jaw cyst with keratinization (orthokeratinized odontogenic cyst; OOC). However, current scientifically based clinical parameters cannot predict any potential for neoplastic behavior, or aggressive and localized invasiveness, in patients with KCOT. We have shown that podoplanin, a lymphatic endothelial marker, is highly expressed in AM. The purpose of this study was to determine the usefulness of podoplanin for reclassification of the odontogenic keratocyst (OKC) from cyst to tumor status. METHODS: Paraffin-embedded tissue specimens of 57 OKCs (46 KCOTs and 11 OOCs) and 15 dentigerous cysts (DCs) were immunohistochemically examined using antibody against podoplanin. RESULTS: Immunohistochemical reactivity for podoplanin was detected in the cell membrane and cytoplasm of most of the basal and suprabasal layer, areas of budding basal cell proliferation, epithelial nests and peripheral cells of daughter cysts in the stromal connective tissue in KCOTs. In the case of OOC and DC, only cases associated with inflammation were positive for podoplanin. CONCLUSION: Podoplanin is strongly expressed in KCOTs in comparison with OOCs. The pattern of staining for podoplanin in KCOT could be related to its neoplastic nature, and suggests a role of the protein in tumor invasiveness.

Enhanced expression of podoplanin in ameloblastomas.

OBJECTIVE: Podoplanin, a mucin-type transmembrane glycoprotein, is specifically expressed by lymphatic but not blood vascular endothelial cells, and is also widely expressed in various specialized cell types throughout the body. Recent studies have demonstrated that it mediates a pathway leading to collective cell migration and invasion in vivo and in vitro. In the present study, we carried out an immunohistochemical investigation of podoplanin to clarify whether it is expressed in human ameloblastomas (AMs), which are characterized by locally aggressive behavior with a high rate of recurrence. In addition, we examined the localization of the epithelial marker E-cadherin and the mesenchymal marker vimentin to clarify whether AMs show epithelial-mesenchymal transition (EMT). METHODS: Paraffin-embedded tissue specimens of 38 AMs were examined immunohistochemically using antibodies against podoplanin, E-cadherin, and vimentin. RESULTS: Immunohistochemical reactivity for podoplanin was detected in the cell membrane and cytoplasm of most odontogenic tumor epithelial cells in AMs. Podoplanin was expressed strongly in peripheral columnar cells and slightly in central stellate reticulum-like cells. E-cadherin was expressed in central stellate reticulum-like cells and showed decreased expression in peripheral columnar cells. Immunoreactivity for E-cadherin was weak or negative in keratinizing cells of acanthomatous AMs, suggesting terminal differentiation of the tumor cells. Immunohistochemical reactivity for vimentin was found in stromal cells, but partial or no reaction was observed in neoplastic cells. CONCLUSION: Expression of podoplanin in AMs is considered to be associated with neoplastic odontogenic tissues; this molecule might play a role in the collective cell migration of tumor nests in AMs. The pattern of expression of E-cadherin and vimentin suggests that invasion in AMs occurs in the absence of EMT. The migration and invasion mediated by podoplanin in AMs could be related to cytoskeletal reorganization.

The significance of podoplanin expression in human inflamed gingiva.

Podoplanin, a transmembrane glycoprotein, has been considered to be expressed specifically by lymphatic endothelial cells. However, recent studies have shown that the protein is expressed in a variety of normal as well as neoplastic tissues, and that its expression might be related to cell migration and invasion. In this study, we examined podoplanin expression in inflamed gingival tissues using an immunohistochemical method. Positive immunoreactivity for podoplanin was found in the cell membrane and cytoplasm of basal cells of oral gingival epithelium when severe inflammatory cell infiltration was present in the connective tissue just under the epithelium. When inflammatory changes were weak or absent, little or no reactivity for podoplanin in the basal cells was observed. Positive reactivity for podoplanin was also detected in basal cell extensions. Surprisingly, strong immunoreactivity for podoplanin was observed in all layers of oral sulcular and junctional epithelia associated with severe inflammatory reaction in the connective tissue. These findings suggest that increased expression of podoplanin in gingival epithelium is related to the progression of chronic periodontitis.

Keratocystic odontogenic tumor: a retrospective study of 183 cases.

In 2005, the WHO Working Group considered odontogenic keratocyst (OKC) to be a tumor and recommended the term keratocystic odontogenic tumor (KCOT), separating the lesion from the orthokeratinizing variant, which is now considered an odontogenic cyst. We analyzed the clinicopathological features of KCOTs encountered over a period of 28 years at Meikai University Hospital. The diagnosis was confirmed by reevaluation of hematoxylin and eosin-stained slides on the basis of the 2005 WHO Classification. Clinical history was also taken into consideration. A total of 183 KCOTs were found, and the two genders were affected almost evenly (51.3% male; 48.7% female; male to female ratio 1.05 to 1). Patient age at the time of diagnosis ranged from 6 to 78 years, with a peak in the third decade of life (mean age: 32.8 years). The mandible was the site of occurrence of 70.5% of tumors; 16.4% occurred in the maxilla and 13.1% in both. Association with the nevoid basal cell carcinoma syndrome (NBCCS) was found in 6.0% of all tumors, and recurrence was found in 13.1% of patients. We found that tumors that initially appeared in the maxilla alone had a higher recurrence rate than those that first appeared in the mandible alone. Pathological examination of KCOT is important to avoid misdiagnosis and provide appropriate treatment and follow-up.