Odontogenic Cells Research Articles

Regulatory role of N-myc downregulated genes in amelogenesis in rats.

Cytodifferentiation of odontogenic cells, a late stage event in odontogenesis is based on gene regulation. However, studies on the identification of the involved genes are scarce. The present study aimed to search for molecules for the cytodifferentiation of ameloblastic cells in rats. Differential display-PCR revealed a differentially expressed gene between cap/early bell stage and hard tissue formation stage in molars. This gene was identified as N-myc Downregulated Gene 1 (Ndrg1), which is the first report in tooth development. Real time PCR and western blotting confirmed that the mRNA level of Ndrg1 was higher during enamel formation than the cap stage. Ndrg1 expression was upregulated in the early bell, crown, and root stages in a time-dependent manner. These patterns of expression were similar in Ndrg2, but Ndrg3 and Ndrg4 levels did not change during the developmental stages. Immunofluorescence revealed that strong immunoreactivity against Ndrg1 were detected in differentiated ameloblasts only, not inner enamel epithelium, odontoblasts and ameloblastic cells in defected enamel regions. Alkaline phosphatase and alizarin red s stains along with real time PCR, revealed that Ndrg1 and Ndrg2 were involved in cytodifferentiation and enamel matrix mineralization by selectively regulating amelogenin and ameloblastin genes in SF2 ameloblastic cells. These results suggest that Ndrg may play a crucial functional role in the cytodifferentiation of ameloblasts for amelogenesis.

Atp6i deficient mouse model uncovers transforming growth factor-β1 /Smad2/3 as a key signaling pathway regulating odontoblast differentiation and tooth root formation

The biomolecular mechanisms that regulate tooth root development and odontoblast differentiation are poorly understood. We found that Atp6i deficient mice (Atp6i−/−) arrested tooth root formation, indicated by truncated Hertwig’s epithelial root sheath (HERS) progression. Furthermore, Atp6i deficiency significantly reduced the proliferation and differentiation of radicular odontogenic cells responsible for root formation. Atp6i−/− mice had largely decreased expression of odontoblast differentiation marker gene expression profiles (Col1a1, Nfic, Dspp, and Osx) in the alveolar bone. Atp6i−/− mice sample RNA-seq analysis results showed decreased expression levels of odontoblast markers. Additionally, there was a significant reduction in Smad2/3 activation, inhibiting transforming growth factor-β (TGF-β) signaling in Atp6i−/− odontoblasts. Through treating pulp precursor cells with Atp6i−/− or wild-type OC bone resorption-conditioned medium, we found the latter medium to promote odontoblast differentiation, as shown by increased odontoblast differentiation marker genes expression (Nfic, Dspp, Osx, and Runx2). This increased expression was significantly blocked by anti-TGF-β1 antibody neutralization, whereas odontoblast differentiation and Smad2/3 activation were significantly attenuated by Atp6i−/− OC conditioned medium. Importantly, ectopic TGF-β1 partially rescued root development and root dentin deposition of Atp6i−/− mice tooth germs were transplanted under mouse kidney capsules. Collectively, our novel data shows that the prevention of TGF-β1 release from the alveolar bone matrix due to OC dysfunction may lead to osteopetrosis-associated root formation via impaired radicular odontoblast differentiation. As such, this study uncovers TGF-β1 /Smad2/3 as a key signaling pathway regulating odontoblast differentiation and tooth root formation and may contribute to future therapeutic approaches to tooth root regeneration.

CONSERVATIVE TREATMENT OF ADENOID AMELOBLASTOMA: A CASE REPORT

A 27-year-old female presented painful swelling in the face, on the right mandibular side, 4 months prior to her appointment. Intraoral examination made it possible to observe swelling in the lower mandibular molar vestibule on the right side. Panoramic radiography disclosed a well corticated unilocular radiolucent lesion involving lower mandibular molars on the right side, with root resorption of teeth #46 and #47. Needle aspiration was performed, and a negative result was observed. The total enucleation of the lesion was then performed. The pathological examination revealed a benign odontogenic neoplasm characterized by the presence of infiltrating odontogenic cells arranged in whorls, duct-like structures in a cribriform arrangement, with peripheral palisading ameloblast-like cells, surrounded by a fibrous vascular stroma, with the presence of a moderate inflammatory infiltrate. The histopathological diagnosis was adenoid ameloblastoma. After 8 months, clinical and radiographic follow-up was performed, and a complete bone formation was observed. A 27-year-old female presented painful swelling in the face, on the right mandibular side, 4 months prior to her appointment. Intraoral examination made it possible to observe swelling in the lower mandibular molar vestibule on the right side. Panoramic radiography disclosed a well corticated unilocular radiolucent lesion involving lower mandibular molars on the right side, with root resorption of teeth #46 and #47. Needle aspiration was performed, and a negative result was observed. The total enucleation of the lesion was then performed. The pathological examination revealed a benign odontogenic neoplasm characterized by the presence of infiltrating odontogenic cells arranged in whorls, duct-like structures in a cribriform arrangement, with peripheral palisading ameloblast-like cells, surrounded by a fibrous vascular stroma, with the presence of a moderate inflammatory infiltrate. The histopathological diagnosis was adenoid ameloblastoma. After 8 months, clinical and radiographic follow-up was performed, and a complete bone formation was observed.

AMELOBLASTOMA IN A 2-YEAR-OLD BOY: A CASE REPORT

A 2-year-old boy presented a normochromic swelling on the left cheek for an unknown period. Panoramic radiography revealed a well-circumscribed, unilocular, radiolucent area extending from body to angle and ramus of mandible, measuring around 4 cm. The exploratory puncture was negative, and an incisional biopsy was performed. In the histopathology, the sections revealed neoplastic proliferation of sheets and strings of odontogenic cells, in a solid arrangement. Epithelial cells had a hyperstained nucleus with a basaloid pattern. Peripheral cells occasionally showed reverse polarization and nuclei arranged in a palisade, and central cells were loosely arranged like the stellate reticulum of the enamel organ. The neoplasm is externally lined by a thin fibrous connective tissue capsule, and the presence of tumor cell nests was observed within the capsule. There were significant hypercellularity and multiple mitotic figures throughout the lesion. The patient was sent to treatment. A 2-year-old boy presented a normochromic swelling on the left cheek for an unknown period. Panoramic radiography revealed a well-circumscribed, unilocular, radiolucent area extending from body to angle and ramus of mandible, measuring around 4 cm. The exploratory puncture was negative, and an incisional biopsy was performed. In the histopathology, the sections revealed neoplastic proliferation of sheets and strings of odontogenic cells, in a solid arrangement. Epithelial cells had a hyperstained nucleus with a basaloid pattern. Peripheral cells occasionally showed reverse polarization and nuclei arranged in a palisade, and central cells were loosely arranged like the stellate reticulum of the enamel organ. The neoplasm is externally lined by a thin fibrous connective tissue capsule, and the presence of tumor cell nests was observed within the capsule. There were significant hypercellularity and multiple mitotic figures throughout the lesion. The patient was sent to treatment.

Axin2-CreERT2 mediated knockout of bone morphogenetic protein receptor type 1A caused abnormal secondary dentine and altered cell fate of Axin2-expressing odontogenic cells.

Inducing odontogenic differentiation and tubular dentine formation is extremely important in dentine repair and tooth regeneration. Bone morphogenic proteins (BMPs) signalling plays a critical role in dentine development and tertiary dentine formation, whilst how BMPR1A-mediated signalling affects odontoblastic differentiation of Axin2-expressing (Axin2+ ) odontogenic cells and tubular dentine formation remains largely unknown. This study aims to reveal the cellular and molecular mechanisms involved in the formation of secondary dentine. Axin2lacZ/+ mice harvested at post-natal 21 (P21) were used to map Axin2+ mesenchymal cells. Axin2CreERT2/+ ; R26RtdTomato/+ mice and Axin2CreERT2/+ ; R26RDTA/+ ; R26RtdTomato/+ mice were generated to observe the tempo-spatial distribution pattern of Axin2-lineage cells and the effect of ablation of Axin2+ cells on dentinogenesis, respectively. A loss-of-function model was established with Axin2CreERT2/+ ; Bmpr1afl/fl ; R26RtdTomato/+ (cKO) mice to study the role of BMP signalling in regulating Axin2+ cells. Micro-computed tomography, histologic and immunostainings, and other approaches were used to examine biological functions, including dentine formation, mineralization and cell differentiation in cKO mice. The results showed rich expression of Axin2 in odontoblasts at P21. Lineage tracing assay confirmed the wide distribution of Axin2 lineage cells in odontoblast layer and dental pulp during secondary dentine formation (P23 to P56), suggesting that Axin2+ cells are important cell source of primary odontoblasts. Ablation of Axin2+ cells (DTA mice) significantly impaired secondary dentine formation characterized with notably reduced dentine thickness (Mean of control: 54.11 μm, Mean of DTA: 27.79 μm, p = .0101). Furthermore, malformed osteo-dentine replaced the tubular secondary dentine in the absence of Bmpr1a with irregular cell morphology, abnormal cellular process formation and lack of cell-cell tight conjunction. Remarkably increased expression of osteogenic markers like Runx2 and DMP1 was detected, whilst DSP expression was observed in a dispersed manner, indicating an impaired odontogenic cell fate and failure in producing tubular dentine in cKO mice. Axin2+ cells are a critical population of primary odontoblasts which contribute to tubular secondary dentine formation, and BMP signalling pathway plays a vital role in maintaining the odontogenic fate of Axin2+ cells.

Odontogenic MSC Heterogeneity: Challenges and Opportunities for Regenerative Medicine.

Cellular heterogeneity refers to the genetic and phenotypic differences among cells, which reflect their various fate choices, including viability, proliferation, self-renewal probability, and differentiation into different lineages. In recent years, research on the heterogeneity of mesenchymal stem cells has made some progress. Odontogenic mesenchymal stem cells share the characteristics of mesenchymal stem cells, namely, good accessibility, low immunogenicity and high stemness. In addition, they also exhibit the characteristics of vasculogenesis and neurogenesis, making them attractive for tissue engineering and regenerative medicine. However, the usage of mesenchymal stem cell subgroups differs in different diseases. Furthermore, because of the heterogeneity of odontogenic mesenchymal stem cells, their application in tissue regeneration and disease management is restricted. Findings related to the heterogeneity of odontogenic mesenchymal stem cells urgently need to be summarized, thus, we reviewed studies on odontogenic mesenchymal stem cells and their specific subpopulations, in order to provide indications for further research on the stem cell regenerative therapy.

Single cell atlas of developing mouse dental germs reveals populations of CD24+ and Plac8+ odontogenic cells

The spatiotemporal relationships in high-resolution during odontogenesis remain poorly understood. We report a cell lineage and atlas of developing mouse teeth. We performed a large-scale (92,688 cells) single cell RNA sequencing, tracing the cell trajectories during odontogenesis from embryonic days 10.5 to 16.5. Combined with an assay for transposase-accessible chromatin with high-throughput sequencing, our results suggest that mesenchymal cells show the specific transcriptome profiles to distinguish the tooth types. Subsequently, we identified key gene regulatory networks in teeth and bone formation and uncovered spatiotemporal patterns of odontogenic mesenchymal cells. CD24+ and Plac8+ cells from the mesenchyme at the bell stage were distributed in the upper half and preodontoblast layer of the dental papilla, respectively, which could individually induce nonodontogenic epithelia to form tooth-like structures. Specifically, the Plac8+ tissue we discovered is the smallest piece with the most homogenous cells that could induce tooth regeneration to date. Our work reveals previously unknown heterogeneity and spatiotemporal patterns of tooth germs that may lead to tooth regeneration for regenerative dentistry.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: The Novel Therapeutic Option for Regenerative Dentistry.

Dental mesenchymal stem cells (MSCs) are characterized by unlimited self-renewal ability and high multidirectional differentiation potential. Since dental MSCs can be easily isolated and exhibit a high capability to differentiate into odontogenic cells, they are considered as attractive therapeutic agents in regenerative dentistry. Recently, MSC-derived extracellular vesicles (MSC-EVs) have attracted widespread attention as carriers for cell-free therapy due to their potential functions. Many studies have shown that MSC-EVs can mediate microenvironment at tissue damage site, and coordinate the regeneration process. Additionally, MSC-EVs can mediate intercellular communication, thus affecting the phenotypes and functions of recipient cells. In this review, we mainly summarized the types of MSCs that could be potentially applied in regenerative dentistry, the possible molecular cargos of MSC-EVs, and the major effects of MSC-EVs on the therapeutic induction of osteogenic differentiation.

Odontogenic stem cells and their prospects in practical use (literature review)

Objective. To analyze the latest literature data on the possibilities of using stem cells of odontogenic origin in the practice of regenerative medicine.Material and methods. The bibliosemantic method was applied, and the structural-logical analysis of the received data was carried out. Electronic databases such as PubMed, MEDLINE, Scopus, Web of Science and EMBASE were used for modern scientific literature searching by keywords «regenerative medicine», «regenerative dentistry», «dental mesenchymal stem cells», «stem cell therapy», «dental pulp stem cells».Results. Stem cells derived from the maxillofacial area differ in origin, differential activity and obtaining source. These cell populations have significant potential for cell line differentiation. It is possible to establish their origin by identifying the expression of stem cell markers during the process of receiving a new pure culture. Scientific research in the field of regenerative medicine has shown that the use of stem cells for therapeutic purposes has a positive therapeutic effect on the illnesses of the gastrointestinal tract, musculoskeletal system, and dental diseases of various etiologies. However, further studies of the possibilities to use these cells during the stages of clinical trials remain relevant.Conclusions. To sum up, based on the literature’s analysis, there is a significant interest in scientific and practical medicine for stem cells of odontogenic origin because there are perspectives for their use both in dentistry and in other branches of medicine.

Conditioned medium derived from 3D tooth germs: A novel cocktail for stem cell priming and early in vivo pulp regeneration.

ObjectivesConditioned medium (CM) from 2D cell culture can mitigate the weakened regenerative capacity of the implanted stem cells. However, the capacity of 3D CM to prime dental pulp stem cells (DPSCs) for pulp regeneration and its protein profile are still elusive. We aim to investigate the protein profile of CM derived from 3D tooth germs, and to unveil its potential for DPSCs‐based pulp regeneration.Materials and MethodsWe prepared CM of 3D ex vivo cultured tooth germ organs (3D TGO‐CM) and CM of 2D cultured tooth germ cells (2D TGC‐CM) and applied them to prime DPSCs. Influences on cell behaviours and protein profiles of CMs were compared. In vivo pulp regeneration of CMs‐primed DPSCs was explored using a tooth root fragment model on nude mice.ResultsTGO‐CM enhanced DPSCs proliferation, migration, in vitro mineralization, odontogenic differentiation, and angiogenesis performances. The TGO‐CM group generated superior pulp structures, more odontogenic cells attachment, and enhanced vasculature at 4 weeks post‐surgery, compared with the TGC‐CM group. Secretome analysis revealed that TGO‐CM contained more odontogenic and angiogenic growth factors and fewer pro‐inflammatory cytokines. Mechanisms leading to the differential CM profiles may be attributed to the cytokine–cytokine receptor interaction and PI3K‐Akt signalling pathway.ConclusionsThe unique secretome profile of 3D TGO‐CM made it a successful priming cocktail to enhance DPSCs‐based early pulp regeneration.

The interplay of hypoxia and autophagy in epithelium-derived ameloblastoma cell survival: a pilot study

Objectives Ameloblastoma is the most clinically significant benign odontogenic tumor of the jaws. Ameloblastomas have a locally aggressive growth pattern and a high rate of malignant transformation. The etiopathogenesis of ameloblastoma is still unknown, and there is still a paucity of information on the factors regulating the locally aggressive growth characteristics of ameloblastoma. Hypoxia and autophagy are 2 mechanistic processes associated with tumor behavior as several tumor cells induce a hypoxic microenvironment to survive. Epithelium-derived ameloblastoma cells (EPAMCs) demonstrate enhanced basal autophagy, but the roles of hypoxia and autophagy in EPAMC survival and ameloblastoma recurrence are still unknown. To understand ameloblastoma pathogenicity and behavior, the goals of this study were to assess differential expression of ameloblastoma-specific and autophagy markers in primary and recurrent ameloblastoma and to assess the roles of hypoxia and autophagy in EPAMC survival. Our hypotheses were that ameloblastoma expresses markers similar to odontogenic epithelial tissue and hypoxia induces oxidative stress and activates autophagy in EPAMCs, favoring their survival and recurrence. Methods Primary and recurrent ameloblastoma tissues from 2 patients were immunostained with pan-cytokeratin, vimentin, and SQSTM1/p62 to assess the expression levels of ameloblastoma and autophagic markers. Additionally, EPAMCs were subjected to severe hypoxia (0.1% O2) and then allowed to recover for 24 hours in order to define responsiveness to hypoxia based on expression levels of hypoxic (hypoxia-inducible factor [HIF]-1α), survival (phosphorylated extracellular signal-regulated kinase 1/2), and autophagic (Beclin1, phosphorylated 40S ribosomal protein S6 [pS6], SQSTM1/p62, LC3A/B) markers as detected by Western blotting. Previously characterized human odontoma-derived cells (HODCs) served as control odontogenic cells. All experiments were performed in at least triplicates. Data were analyzed as fold change relative to normoxia and expressed as mean ± standard deviation. A paired t test comparison of means was done to compare the expression of autophagy proteins when cells were under normoxia to protein expression under hypoxia and recovery conditions. The Welch 2-sample t test was used to compare fold changes from normoxia in EPAMCs and HODCs with each other. P values were adjusted for multiple comparisons using the Benjamini-Hochberg procedure. Results Both primary and recurrent tissue samples stained positive for pan-cytokeratin in the cytoplasm of the ameloblastoma islands. Vimentin and SQSTM1/p62 were undetectable in all samples, but the connective tissue stained positive for vimentin. Relative to normoxia, HIF-1α and SQSTM1/p62 expression was increased when the EPAMCs were reoxygenated (P = .056). pS6 levels were decreased in EPAMCs in both hypoxia (P = .005) and recovery (P = .005) compared with basal levels. Hypoxia, however, did not induce any significant changes among the remainder of the hypoxic, survival, and autophagic markers; no statistically significant difference was observed between the EPAMCs and HODCs. Conclusions The results of this pilot study provide insight into the pathogenicity of ameloblastoma and the possible behavior of EPAMCs when subjected to hypoxia. Our observation of vimentin expression alongside the pan-cytokeratin pattern is consistent with an epithelial origin of both primary and recurrent ameloblastoma. In EPAMCs, canonical autophagy tended to increase with hypoxia and did not recover when cells were reoxygenated, as evident by the increased HIF-1α and SQSTM1/p62 and the reduced levels of pS6 24 hours following hypoxia. This supports EPAMCs re-establishing basal autophagy after severe hypoxia and that recurrence of ameloblastoma may be related to autophagy.

PFK activation is essential for the odontogenic differentiation of human dental pulp stem cells

Dental pulp stem cells (DPSCs) can differentiate into diverse cell lineages, including odontogenic cells that are responsible for dentin formation, which is important in pulp repair and tooth regeneration. While glycolysis plays a central role in various cellular activities in both physiological and pathological conditions, its role and regulation in odontogenic differentiation are unknown. Here, we show that aerobic glycolysis is induced during odontoblastic differentiation from human DPSCs. Importantly, we demonstrate that during odontoblastic differentiation, protein expression levels of phosphofructokinase 1 muscle isoform (PFKM) and PFK2, but not other glycolytic enzymes, are mainly upregulated by AKT activation, resulting in increased total PFK enzyme activity. Increased PFK activity is essential to enhance aerobic glycolysis, which plays an important role in the odontoblastic differentiation of human DPSCs. These findings underscore that PFK activation-induced aerobic glycolysis accompanies, and participates in, human DPSCs differentiation into odontogenic lineage, and could play a role in the regulation of dental pulp repair.

Complex Odontoma: An Overview

The dental tissues comprising of dentin, enamel,sometimes pulp, and cementum are the hamartomas whichare known as odontoma. These have behavior not so aggressive. The common type of tumor of odontogenicorigin about (35-76)% is the odontoma. It is a tumor of benign type arising from epithelial and mesenchymaldifferentiated alteration, odontogenic cells. These odontomas are of two types–complex and compound,the both are differentiated from each other by the organization of the tissue of dental origin in a ratio of1:2. Although the etiology is not known till now but may be related to anomalies of hereditary origin,infection,also by trauma and by hyperactivity of odontoblast process. By the means of radiological viewthese odontomas can be recognized and these in very few case causes expansion of the cortical bone. Theseodontomas occur in the second decade in number and usually takes place in the mandibular second or thirdmolar tooth. This particular article summarizes the complex composite odontoma.

Induction of Cardiomyogenesis in Stem Cells Isolated from Human Exfoliated Deciduous Teeth

Background: The natural transition from neonatal deciduous teeth to adult permanent teeth is a physiological phenomenon. Miura et al. reported the isolation and characterization of stem cells from the pulp of human exfoliated deciduous teeth (SHED). The great majority of current stem cell therapies use human adult stem cells. Since adult stem cells are multi-potent. SHED have demonstrated to have the capability to differentiate into osteogenic and odontogenic cells, adipocytes, and neural cells. When transplanted in immunocompromised mice, SHED were able to form bone. In addition, SHED have been able to differentiate into functional odontoblast and angiogenic endothelial cells. Aims and Objective: There are two objectives in our study; First, we want to confirm that SHED cells differentiate into osteogenic and neurotic cells. Second, we shall also examine whether SHED stem cells can also differentiate into cardiomyocytes. Material and Method: SHED stem cells are subjected to cardiomyogenic, neurogenic, and osteogenic induction treatment. The treated cells are the subjected to real time PCR and mmuno-histochemical analysis. The presence of calcium deposits with Alizarin Red S staining for SHED cells treated with osteogenic media was used to confirm osteogenic differentiation. Results: Our study confirmed that SHED cells differentiate into osteogenic and neurotic cells. For the first time we showed that SHED cells can also differentiate into cardiomyocytes. Conclusion: Due to their potentials and its neural crest origin, SHED are an ideal stem cell source for tissue regeneration.

Desmoplastic ameloblastoma of the mandible: A rare case report

Desmoplastic ameloblastoma (DA) is a rare variant of ameloblastoma that shows unique features, behavior, and presentation. This article reports a rare case of desmoplastic ameloblastoma in a 67-year-old male patient, who presented with a slow-growing, asymptomatic lesion in the anterior mandible which was observed over a period of 4 years. Radiographic findings revealed an ill-defined mixed radiolucent and radiopaque lesion with displacement of adjacent teeth. Histopathological examination showed proliferation of odontogenic cells in the form of islands separated by dense, fibrous connective tissue stroma compressing the islands. Although the incidence of this variant is very low, a differential diagnosis of the same must be taken into consideration when locally aggressive, chronic swellings of jaw are encountered in routine practice to aid in early diagnosis and in initiating a prompt management.

Human Freeze-dried Dentin Matrix as a Biologically Active Scaffold for Tooth Tissue Engineering

IntroductionDentin is a suitable scaffold for tooth tissue engineering and can provide the appropriate combinations and concentrations of bioactive proteins to accommodate odontogenic cells. Freeze drying is a possible strategy to treat dentin because it ensures long-term stability of biopharmaceutical products and can increase the stability of dentin for improved distribution and storage. We hypothesized that freeze-dried dentin matrix (FDDM) constitutes a novel bioinstructive scaffold for tooth tissue engineering. MethodsThis study used a modified technique to prepare an FDDM that preserved the mechanical and biological properties of dentin. The compression resistance and microhardness of FDDM were determined. Similarly, various biological characteristics, including cell morphology, cell proliferation, collagen secretion, alkaline phosphatase activity, and gene and protein expression, were investigated. To assess the inductive capacity of FDDM in vivo, FDDM and human dental pulp stem cell (DPSC) sheets were subcutaneously implanted in the dorsal pockets of nude mice. At 8 weeks postimplantation, the transplants were removed and histologically studied. ResultsThe results show that FDDM has mechanical and biological characteristics similar to those of dentin (P > .05). DPSCs cultured on FDDM and dentin showed superior attachment, growth, viability, and collagen secretion capacity but decreased mineral capability compared with DPSCs cultured with alpha minimum essential medium or hydroxyapatite (P < .05). The histologic results show that FDDM, which is similar to dentin, supported dentin/pulplike tissue regeneration in vivo as shown by the related expression levels of dentin markers, such as dentin sialoprotein and alkaline phosphatase. ConclusionsThese results suggest that FDDM constitutes a novel superior scaffold for tooth tissue engineering.

Wnt/\u03b2-catenin signaling, which is activated in odontomas, reduces Sema3A expression to regulate odontogenic epithelial cell proliferation and tooth germ development

Odontomas, developmental anomalies of tooth germ, frequently occur in familial adenomatous polyposis patients with activated Wnt/β-catenin signaling. However, roles of Wnt/β-catenin signaling in odontomas or odontogenic cells are unclear. Herein, we investigated β-catenin expression in odontomas and functions of Wnt/β-catenin signaling in tooth germ development. β-catenin frequently accumulated in nucleus and/or cellular cytoplasm of odontogenic epithelial cells in human odontoma specimens, immunohistochemically. Wnt/β-catenin signaling inhibited odontogenic epithelial cell proliferation in both cell line and tooth germ development, while inducing immature epithelial bud formation. We identified Semaphorin 3A (Sema3A) as a downstream molecule of Wnt/β-catenin signaling and showed that Wnt/β-catenin signaling-dependent reduction of Sema3A expression resulted in suppressed odontogenic epithelial cell proliferation. Sema3A expression is required in appropriate epithelial budding morphogenesis. These results suggest that Wnt/β-catenin signaling negatively regulates odontogenic epithelial cell proliferation and tooth germ development through decreased-Sema3A expression, and aberrant activation of Wnt/β-catenin signaling may associate with odontoma formation.

Effect of Calcium-enriched Mixture (CEM) cement on increasing mineralization in stem cells from the dental pulps of human exfoliated deciduous teeth

Background.Stem cells isolated from human exfoliated deciduous teeth (SHED) are highly capable of proliferation and differentiation into odontogenic, osteogenic, adipose tissue and neural cells. The aim of this study was to investigate the effect of CEM cement on increasing mineralization in stem cells of exfoliated deciduous teeth. Methods.Dental pulps were isolated from extracted exfoliating primary teeth and immersed in a digestive solution. The dental pulp cells were immersed in α-MEM (modified culture medium) and 10% fetal bovine serum (FBS) was added. The culture cells were used for mineral deposit formation after the third passage. The cells were cultured in osteogenic cell culture medium in the control group and in osteogenic culture medium supplemented with CEM cement in the case group. Alizarin red staining was used to evaluate the mineral deposit formation on day 21. Statistical significance was determined with t-test. Results.Quantification of alizarin red staining showed that cells exposed to CEM cement induced more mineralized nodules (P=0.03). Conclusion.Mineral deposit formation in SHEDs was stimulated by CEM cement. Based on these data it might be suggested that CEM could improve osteoblastic differentiation.

Case Report of Follicular Ameloblastoma-Extra(node)inary Presentation?

Odontogenic tumours comprise of those neoplasms that arise from odontogenic cells and are restricted to the jaws which clinically manifest as swellings intraorally. Ameloblastoma is one of the odontogenic tumours which can be frequently seen affecting the mandibular third molar regions with an age range of 33 to 44 years. Here we present a case of Ameloblastoma which presented with its “textbook” intraoral presentation and radiographic features along with the unusual finding of single lymph node involvement which can elaborate the differential diagnosis to other tumours including malignant or aggressive transformation of a de novo tumor.

Porcine Dental Epithelial Cells Differentiated in a Cell Sheet Constructed by Magnetic Nanotechnology.

Magnetic nanoparticles (MNPs) are widely used in medical examinations, treatments, and basic research, including magnetic resonance imaging, drug delivery systems, and tissue engineering. In this study, MNPs with magnetic force were applied to tissue engineering for dental enamel regeneration. The internalization of MNPs into the odontogenic cells was observed by transmission electron microscopy. A combined cell sheet consisting of dental epithelial cells (DECs) and dental mesenchymal cells (DMCs) (CC sheet) was constructed using magnetic force-based tissue engineering technology. The result of the iron staining indicated that MNPs were distributed ubiquitously over the CC sheet. mRNA expression of enamel differentiation and basement membrane markers was examined in the CC sheet. Immunostaining showed Collagen IV expression at the border region between DEC and DMC layers in the CC sheet. These results revealed that epithelial–mesenchymal interactions between DEC and DMC layers were caused by bringing DECs close to DMCs mechanically by magnetic force. Our study suggests that the microenvironment in the CC sheet might be similar to that during the developmental stage of a tooth bud. In conclusion, a CC sheet employing MNPs could be developed as a novel and unique graft for artificially regenerating dental enamel.