Ameloblastomas Exhibit Stem Cell Potential, Possess Neurotrophic Properties, and Establish Connections with Trigeminal Neurons

A Systematic Review on Organ-on-a-Chip in PDMS or Hydrogel in Dentistry: An Update of the Literature

Organs-on-a-chip (OoCs) are microfluidic devices constituted by PDMS or hydrogel in which different layers of cells are separated by a semipermeable membrane. This technology can set many parameters, like fluid shear stress, chemical concentration gradient, tissue-organ interface, and cell interaction. The use of these devices in medical research permits the investigation of cell patterning, tissue-material interface, and organ-organ interaction, mimicking the complex structures and microenvironment of human and animal bodies. This technology allows us to reconstitute in vitro complex conditions that recapitulate in vivo environments. One of the main advantages of these systems is that they represent a very realistic model that, in many cases, can replace animal experimentation, eliminating costs and related ethical issues. Organ-on-a-chip can also contain bacteria or cancer cells. This technology could be beneficial in dentistry for testing novel antibacterial substances and biomaterials, performing studies on inflammatory disease, or planning preclinical studies. A significant number of publications and reviews have been published on this topic. Still, to our knowledge, they mainly focus on the materials used for fabrication and the different patterns of the chip applied to the experimentations. This review presents the most recent applications of organ-on-a-chip models in dentistry, starting from the reconstituted dental tissues to their clinical applications and future perspectives.

An in silico study of protein-protein interactions and design of novel peptides for TrkA in ameloblastoma

Ameloblastoma is a benign odontogenic jawbone tumor. The binding of Nerve growth factor (NGF) to receptor tyrosine kinase A (TrkA) promotes cell survival, proliferation, and differentiation via PI3K/AKT and Ras/MAPK signaling. Although the exact cause of ameloblastoma remains unknown, elevated levels of NGF and TrkA expression in ameloblastoma are associated with aggressive tumor behavior and poor patient outcomes. It is previously demonstrated that His 4, Arg 9, and Glu 11 residues of NGF made crucial interactions with the TrkA subunit. The main aim of our present study to develop potential therapeutic strategies by identifying promising peptide candidates. The objectives include starting with a detailed in silico analysis to identify a crucial peptide sequence of NGF that is bound by TrkA, creating a library of novel peptides from the identified peptide sequence through a single-point mutation on interacting residues (His 4, Arg 9, and Glu 11), and selecting the top peptides based on docking score, interactions analysis, and desirable pose analysis. The study ultimately designed a hybrid peptide candidate through the simultaneous and continuous mutation of the top residues, resulting in a peptide that exhibited a more specific interaction with TrkA, blocking the binding site and preventing the interaction between NGF and TrkA.Communicated by Ramaswamy H. Sarma.

The Application of Organs-on-a-Chip in Dental, Oral, and Craniofacial Research

The current development of microfluidics-based microphysiological systems (MPSs) will rapidly lead to a paradigm shift from traditional static 2-dimensional cell cultivation towards organized tissue culture within a dynamic cellular milieu. Especially organs-on-a-chip (OoCs) can very precisely re-create the mechanical and unique anatomical structures of the oral environment. This review provides an introduction to such technology, from commonly used chip materials and fabrication methods to the application of OoC in in vitro culture. OoCs are advantageous because of their small-scaled culture environment, the highly controlled dynamic experimental conditions, and the likeness to the in vivo structure. We specifically focus on current chip designs in dental, oral, and craniofacial (DOC) research. Also, future perspectives are discussed, like model standardization and the development of integrated platforms with advanced read-out functionality. By doing so, it will be possible for OoCs to serve as an alternative for animal testing and to develop highly predictive human models for clinical experiments and even personalized medicine.

The Nervous System as a Regulator of Cancer Hallmarks: Insights into Therapeutic Implications

Simple Summary

The nervous system communicates with the whole organism, regulating several physiological pathways. The modification of nerve activity could deregulate the state of cellular and tissue homeostasis which could drive cancer development. This paper provides the current state of knowledge, in an evidence-oriented manner, that the nervous system is able to participate in the carcinogenesis process by inducing biochemical, physiological, and cellular modifications involved in the hallmarks of cancer.

Abstract

The involvement of the nervous system in the development of cancer is controversial. Several authors have shown opinions and conflicting evidence that support the early effect of the nervous system on the carcinogenic process. For about a century, research has not been enough, questions remain open, ideas are not discarded, and although more research is still needed to answer all the questions, there is now enough evidence to support the theories and give hope of finding one more possible form of treatment. It is clear that malignant neoplasms have endogenous characteristics that allow them to establish and progress. Some of these characteristics known as hallmarks of cancer, are damage mechanisms in the pathology but necessary during other physiological processes which show some nerve dependence. The nervous system communicates with the whole organism, regulating physiological processes necessary to respond to external stimuli and for the maintenance of homeostasis. The modification of nerve activity could generate an overload and deregulate the state of cellular and tissue homeostasis; this could drive cancer development. In this review, we will address the issue in an evidence-oriented manner that supports that the nervous system is able to participate in the initial and progressive process of carcinogenesis by inducing biochemical, physiological, and cellular modifications involved in the hallmarks of cancer.

The Regulation of miR-206 on BDNF: A Motor Function Restoration Mechanism Research on Cerebral Ischemia Rats by Meridian Massage

As a frequent disease affecting the nervous system, cerebral infarction has emerged as a major cause of disability and elicits disorders in motor, sensation, and cognition as sequelae. No clear mechanism has been known in meridian massage despite it having been proved to be an effective therapeutic option. The study was carried out to explore the treatment of meridian massage on cerebral ischemia in rats and its effects on motor function restoration and nerve cell’s ultrastructure in the ischemic territory. The alleviated nerve damages and recovered injured brain tissues were found in the cerebral infarction model of SD rats after meridian massage. Expressions of miR-206 and the brain-derived neurotrophic factor (BDNF) in the gastrocnemius muscle were all well observed. The effects of miR-206 on BDNF were testified by overexpressed and interfered miR-206 in the C2C12 myoblast. Moreover, at the molecular level, meridian massage downregulated miR-206 expression at an elevated level of BDNF. Consequently, meridian massage exerts a vital role in promoting cerebral ischemia restoration, which is expected to provide an addition to the application of traditional Chinese medicine (TCM) in the reconstruction and treatment of cerebral ischemia.

Inhibition of L-type voltage-gated calcium channel-mediated Ca2+ influx suppresses the collective migration and invasion of ameloblastoma

Objectives

Ameloblastoma (AM) has been known as a benign but locally invasive tumour with high recurrence rates. Invasive behaviour of the AM results in destruction of the adjacent jawbone and the non‐detectable remnants during surgery, interrupting the complete elimination of cancer cells.

Methods

To explore novel targets for the tumour cell invasion, a transcriptomic analysis between AM and odontogenic keratocyst were performed through next‐generation sequencing in detail.

Results

Enrichment of CACNA1C gene (encoding Cav1.2) in AM, a subunit of the L‐type voltage‐gated calcium channel (VGCC) was observed for the first time. The expression and channel activity of Cav1.2 was confirmed by immunostaining and calcium imaging in the patient samples or primary cells. Verapamil, L‐type VGCC blocker revealed suppression of the Ca²⁺‐induced cell aggregation and collective invasion of AM cells in vitro. Furthermore, the effect of verapamil in suppressing AM invasion into the adjacent bone was confirmed through orthotopic xenograft model specifically.

Conclusion

Taken together, Cav1.2 maybe considered to be a therapeutic candidate to decrease the collective migration and invasion of AM.

The Versatile Roles of Nerve Growth Factor in Neuronal Attraction, Odontoblast Differentiation, and Mineral Deposition in Human Teeth

Nerve growth factor (NGF) is an important molecule for the development and differentiation of neuronal and non-neuronal cells. Here we analyze by immunohistochemistry the distribution of NGF in the dental pulp mesenchyme of embryonic and functional human teeth. In the dental pulp of both embryonic and healthy functional teeth, NGF is mainly expressed in the odontoblasts that are responsible for dentine formation, while in functional teeth NGF is also expressed in nerve fibers innervating the dental pulp. In injured teeth, NGF is expressed in the newly formed odontoblastic-like cells, which replace the dying odontoblasts. In these teeth, NGF expression is also upregulated in the intact odontoblasts, suggesting a role for this molecule in dental tissue repair. Similarly, in cultures of human dental pulp cells, NGF expression is strongly upregulated during their differentiation into odontoblasts as well as during the mineralization process. In microfluidic devices, release of NGF from cultured human dental pulp cells induced neuronal growth from trigeminal ganglia toward the NGF secreting cells. These results show that NGF is closely linked to the various functions of odontoblasts, including secretory and neuronal attraction processes.

Ameloblastoma: clinical presentation, multidisciplinary management and outcome

We studied 21 patients who underwent radical ameloblastoma excision followed by immediate reconstruction. Comorbidities, consumption of alcohol and/or tobacco and BMI status did not contribute to an unfavorable outcome. Giant ameloblastoma (≥5 cm) and/or tumor involving bony curvatures increased surgical complexity, the incidence of complications and hospital stay.

Conceptual changes in ameloblastoma: Suggested re-classification of a "veteran" tumor

OBJECTIVES

The merging of ameloblastoma (AM) with mural unicystic ameloblastoma (UAM-M) was suggested by the 2017 WHO based on similar treatment needs. In an international multicenter study, we investigated the characteristics of their merged product (merged-AM) and raised the possibility of unifying AM and UAM (total-AM).

MATERIALS AND METHODS

AM and UAM (luminal/intraluminal/mural), separate and combined, were analyzed for demographic/clinical/radiological features. ANOVA and chi-square tests were followed by univariate and multivariate analyses, and significance was set at p < .05.

RESULTS

The patients' mean age was 39.6 ± 20.3 years in merged-AM (147 AM, 76 UAM-M), 45.1 ± 19.4 years in AM (p = .009). Merged-AM comprised 51.3% multilocular/48.7% unilocular tumors, AM comprised 72.5%/27.5%, respectively (p < .001). Merged-AM was associated with impacted teeth in 30.8%, AM in 18% (p = .023). The probability of merged-AM for multilocularity increased by 2.4% per year of age (95%CI 0.6-4.2, p = .009). Association with impacted teeth decreased by 7.9% per year of age (95%CI 1.9-14.39, p = .009). Merged-AM did not differ from total-AM (p > .05).

CONCLUSIONS

Merged-AM partially differed from AM, but differences appeared to diminish in an age/time-wise manner. Merged-AM and total-AM were nearly indistinguishable. Therefore, AM and UAM may be considered a continuous spectrum of one type of tumor, further necessitating revision of the treatment approaches.

Exploiting teeth as a model to study basic features of signaling pathways

Teeth constitute a classical model for the study of signaling pathways and their roles in mediating interactions between cells and tissues in organ development, homeostasis and regeneration. Rodent teeth are mostly used as experimental models. Rodent molars have proved fundamental in the study of epithelial–mesenchymal interactions and embryonic organ morphogenesis, as well as to faithfully model human diseases affecting dental tissues. The continuously growing rodent incisor is an excellent tool for the investigation of the mechanisms regulating stem cells dynamics in homeostasis and regeneration. In this review, we discuss the use of teeth as a model to investigate signaling pathways, providing an overview of the many unique experimental approaches offered by this organ. We discuss how complex networks of signaling pathways modulate the various aspects of tooth biology, and the models used to obtain this knowledge. Finally, we introduce new experimental approaches that allow the study of more complex interactions, such as the crosstalk between dental tissues, innervation and vascularization.

Expression of stem cell markers in stroma of odontogenic cysts and tumors

BACKGROUND

The stroma of odontogenic cysts/tumors may confer them differential biological behavior. We aimed to investigate the immunoexpression of stem cell markers (Nanog, SOX2, Oct4, and CD34) in the stroma of odontogenic cysts and tumors. CD34 was investigated exclusively as a marker for stromal fibroblast/fibrocyte cells (CD34 + SFCs). CD34 + SFCs were also investigated ultrastructurally.

METHODS

Ten cases each of primary odontogenic keratocyst (OKC), recurrent OKC, dentigerous cyst, ameloblastoma, unicystic ameloblastoma, odontogenic myxoma, and 7 syndromic OKC were included. Results were represented as the mean score (%) of positive cells/field for each marker for each study group. For CD34 + SFCs, results are presented as the mean number of cells/field for each type of lesion. Kruskal-Wallis and Spearman's correlation statistical tests were used; significance was set at P < .05.

RESULTS

All markers except Oct4 were expressed by stromal cells in all lesions. Expression of SOX2 was significantly higher in tumors than in cysts (P < .05). CD34 + SFCs were more frequent in cysts than in tumors. Ultrastructurally, CD34 + SFCs were identified for the first time in odontogenic lesions and showed characteristic bipolar/dendritic morphology.

CONCLUSION

Among examined stromal stem cell markers, only SOX2 distinguished tumors from cysts. CD34 + SFCs may also contribute to the biological behavior of odontogenic lesions.