Induction of Rhesus Keratinocytes into Functional Ameloblasts by Mouse Embryonic Dental Mesenchyme

Animal models and related techniques for dentin study

The intricate and protracted process of dentin formation has been extensively explored, thanks to the significant advancements facilitated by the use of animal models and related techniques. Despite variations in their effectiveness, taking into account factors such as sensitivity, visibility, and reliability, these models or techniques are indispensable tools for investigating the complexities of dentin formation. This article focuses on the latest advances in animal models and related technologies, shedding light on the key molecular mechanisms that are essential in dentin formation. A deeper understanding of this phenomenon enables the careful selection of appropriate animal models, considering their suitability in unraveling the underlying molecular intricacies. These insights are crucial for the advancement of clinical drugs targeting dentin-related ailments and the development of comprehensive treatment strategies throughout the duration of the disease.

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.

Identification of novel candidate genes implicated in odontogenic potential in the developing mouse tooth germ using transcriptome analysis

BACKGROUND

In tooth bioengineering for replacement therapy of missing teeth, the utilized cells must possess an inductive signal-forming ability to initiate odontogenesis. This ability is called odontogenic potential. In mice, the odontogenic potential signal is known to be translocated from the epithelium to the mesenchyme at the early bud stage in the developing molar tooth germ. However, the identity of the molecular constituents of this process remains unclear.

OBJECTIVE

The purpose of this study is to determine the molecular identity of odontogenic potential and to provide a new perspective in the field of tooth development research.

METHODS

In this study, whole transcriptome profiles of the mouse molar tooth germ epithelium and mesenchyme were investigated using the RNA sequencing (RNA-seq) technique. The analyzed transcriptomes corresponded to two developmental stages, embryonic day 11.5 (E11.5) and 14.5 (E14.5), which represent the odontogenic potential shifts.

RESULTS

We identified differentially expressed genes (DEGs), which were specifically overexpressed in both the E11.5 epithelium and E14.5 mesenchyme, but not expressed in their respective counterparts. Of the 55 DEGs identified, the top three most expressed transcription factor genes (transcription factor AP-2 beta isoform 3 [TFAP2B], developing brain homeobox protein 2 [DBX2], and insulin gene enhancer protein ISL-1 [ISL1]) and three tooth development-related genes (transcription factor HES-5 [HES5], platelet-derived growth factor D precursor [PDGFD], semaphrin-3 A precursor [SEMA3A]) were selected and validated by quantitative RT-PCR. Using immunofluorescence staining, the TFAP2B protein expression was found to be localized only at the E11.5 epithelium and E14.5 mesenchyme.

CONCLUSIONS

Thus, our empirical findings in the present study may provide a new perspective into the characterization of the molecules responsible for the odontogenic potential and may have an implication in the cell-based whole tooth regeneration strategy.