Determinants of Dental Pulp Stem Cell Heterogeneity

Aspirin promotes odontogenic differentiation via a mechanism involving FOXC1, RUNX2, and MCAM expression

OBJECTIVES

This study aimed to investigate the effects of aspirin on the early stages of odontogenic differentiation. The roles of FOXC1, RUNX2, and MCAM gene expression in the mechanism of odontogenic differentiation were evaluated by examining the effects of downregulated FOXC1 or RUNX2 expression using small interfering RNAs (siRNAs).

METHODS

Dental pulp cells were treated with aspirin (0, 2.5, 50, 100 μg/ml) to assess its impact on mineralization. The gene expression levels of FOXC1, RUNX2, and MCAM were measured using digital polymerase chain reaction, and the effects of siRNA-mediated knockdown of FOXC1 and RUNX2 were analyzed. The mineralization potential was quantitatively assessed using Alizarin Red S staining and a calcium assay.

RESULTS

Analysis of cell growth curves and doubling times indicated that aspirin did not affect cell proliferation at 2.5 μg/ml and 50 μg/ml; however, 50 μg/ml aspirin promoted mineralization. In the FOXC1 and RUNX2 knockdown experiments, fluctuations in FOXC1, RUNX2, and MCAM gene expression were observed in the aspirin-treated group, suggesting the involvement of these genes in mineralization. Alizarin red S staining and calcium assays further demonstrated that aspirin enhanced mineralization.

CONCLUSIONS

These findings indicate that aspirin promotes odontogenic differentiation and regulates the expression of FOXC1, RUNX2, and MCAM. This suggests that aspirin may serve as a promising new therapeutic agent in dental pulp regenerative medicine.

Decoding SFRP2 progenitors in sustaining tooth growth at single-cell resolution

BACKGROUND

Single-cell transcriptomics has revolutionized tooth biology by uncovering previously unexplored areas. The mouse is a widely used model for studying human tissues and diseases, including dental pulp tissues. While human and mouse molars share many similarities, mouse incisors differ significantly from human teeth due to their continuous growth throughout their lifespan. The application of findings from mouse teeth to human disease remains insufficiently explored.

METHODS

Leveraging multiple single-cell datasets, we constructed a comprehensive dental pulp cell landscape to delineate tissue similarities and species-specific differences between humans and mice.

RESULTS

We identified a distinct cell population, Sfrp2hi fibroblast progenitors, found exclusively in mouse incisors and the developing tooth root of human molars. These cells play a crucial role in sustaining continuous tissue growth. Mechanistically, we found that the transcription factor Twist1, regulated via MAPK phosphorylation, binds to the Sfrp2 promoter and modulates Wnt signaling activation to maintain stem cell identity.

CONCLUSIONS

Our study reveals a previously unrecognized subset of dental mesenchymal stem cells critical for tooth growth. This distinct subset, evolutionarily conserved between humans and mice, provides valuable insights into translational approaches for dental tissue regeneration and repair.

Insulin-like growth factor binding protein 7 identified in aged dental pulp by single-cell RNA sequencing

INTRODUCTION

Aging influences the regenerative and reparative functions of dental pulp, and an in-depth and complete understanding of aged dental pulp is highly important.

OBJECTIVE

This study aimed to explore the heterogeneity of young and aged dental pulp tissue via single-cell RNA sequencing (scRNA-seq), search novel markers of aged dental pulp, and further explore their mechanism.

METHODS

ScRNA-seq was employed to analyze the heterogeneity of young and aged dental pulp tissue, and immunohistochemical staining was used to detect new marker Insulin-like Growth Factor Binding Protein 7 (IGFBP7) in aged dental pulp. Differentially expressed genes (DEGs) between young and aged dental pulp tissue related with senescence-associated secretory phenotype (SASP) were validated in aging model of H2O2-induced dental pulp fibroblast (DPF). The effect of IGFBP7 on cellular senescence were validated by SA-β-Gal, γ-H2AX, and F-actin cytoskeletal staining. RNA-seq was used to analyze the mechanism of IGFBP7 alleviating senescence of H2O2-induced DPFs.

RESULTS

A total of 32,012 cells were sequenced from 8 dental pulp samples and categorized into 8 main clusters, including fibroblasts (FB), endothelial cells, monocytes, T cells, B cells, mesenchymal stem cells, Schwann cells, and nonmyelinating ScCs. The ratio of fibroblasts was the highest, and FB1 was the largest subcluster of fibroblasts in the young group. In aged dental pulp, the ratio of fibroblasts was relatively low, and fibroblasts had more cellular communication with other cell types in fibroblast growth factor (FGF) and insulin-like growth factor (IGF) signal pathways. IGFBP7 was significantly upregulated in the aged group. Recombinant IGFBP7 reduced the senescence of H2O2-induced DPFs.

CONCLUSIONS

These findings offer insights into the mechanisms of dental pulp aging and enhance our understanding of dental pulp at the single-cell level. Further comprehensive studies are required to clarify the exact mechanisms through which IGFBP7 influences dental pulp aging.

scSemiProfiler: Advancing large-scale single-cell studies through semi-profiling with deep generative models and active learning

Single-cell sequencing is a crucial tool for dissecting the cellular intricacies of complex diseases. Its prohibitive cost, however, hampers its application in expansive biomedical studies. Traditional cellular deconvolution approaches can infer cell type proportions from more affordable bulk sequencing data, yet they fall short in providing the detailed resolution required for single-cell-level analyses. To overcome this challenge, we introduce "scSemiProfiler", an innovative computational framework that marries deep generative models with active learning strategies. This method adeptly infers single-cell profiles across large cohorts by fusing bulk sequencing data with targeted single-cell sequencing from a few rigorously chosen representatives. Extensive validation across heterogeneous datasets verifies the precision of our semi-profiling approach, aligning closely with true single-cell profiling data and empowering refined cellular analyses. Originally developed for extensive disease cohorts, "scSemiProfiler" is adaptable for broad applications. It provides a scalable, cost-effective solution for single-cell profiling, facilitating in-depth cellular investigation in various biological domains.

Current status of superoxide dismutase 2 on oral disease progression by supervision of ROS

The recent Global Burden of Disease results have demonstrated that oral diseases are some of the most significant public health challenges facing the world. Owing to its specific localization advantage, superoxide dismutase 2 (SOD2 or MnSOD) has the ability to process the reactive oxygen species (ROS) produced by mitochondrial respiration before anything else, thereby impacting the occurrence and development of diseases. In this review, we summarize the processes of common oral diseases in which SOD2 is involved. SOD2 is upregulated in periodontitis to protect the tissue from the distant damage caused by excessive ROS and further reduce inflammatory progression. SOD2 also participates in the specific pathogenesis of oral cancers and dental diseases. The clinical application prospects of SOD2 in oral diseases will be discussed further, referencing the differences and relationship between oral diseases and other clinical systemic diseases.

The Role of Sensory Nerves in Dental Pulp Homeostasis: Histological Changes and Cellular Consequences after Sensory Denervation

Homeostatic maintenance is essential for pulp function. Disrupting pulp homeostasis may lead to pulp degeneration, such as fibrosis and calcifications. Sensory nerves constitute a crucial component of the dental pulp. However, the precise involvement of sensory nerves in pulp homeostasis remains uncertain. In this study, we observed the short-term and long-term histological changes in the dental pulp after inferior alveolar nerve transection. Additionally, we cultured primary dental pulp cells (DPCs) from the innervated and denervated groups and compared indicators of cellular senescence and cellular function. The results revealed that pulp fibrosis occurred at 2 w after the operation. Furthermore, the pulp area, as well as the height and width of the pulp cavity, showed accelerated reductions after sensory denervation. Notably, the pulp area at 16 w after the operation was comparable to that of 56 w old rats. Sensory denervation induced excessive extracellular matrix (ECM) deposition and increased predisposition to mineralization. Furthermore, sensory denervation promoted the senescence of DPCs. Denervated DPCs exhibited decelerated cell proliferation, arrest in the G2/M phase of the cell cycle, imbalance in the synthesis and degradation of ECM, and enhanced mineralization. These findings indicate that sensory nerves play an essential role in pulp homeostasis maintenance and dental pulp cell fate decisions, which may provide novel insights into the prevention of pulp degeneration.

Biological properties of Ceraputty as a retrograde filling material: an in vitro study on hPDLSCs

OBJECTIVES

To assess the cytocompatibility and bioactive potential of the new calcium silicate-based cement Ceraputty on human periodontal ligament stem cells (hPDLSCs) compared to Biodentine and Endosequence BC root repair material (ERRM).

MATERIALS AND METHODS

hPDLSCs were isolated from extracted third molars from healthy donors. Standardized sample discs and 1:1, 1:2, and 1:4 eluates of the tested materials were prepared. The following assays were performed: surface element distribution via SEM-EDX, cell attachment and morphology via SEM, cell viability via a MTT assay, osteo/cemento/odontogenic marker expression via RT-qPCR, and cell calcified nodule formation via Alizarin Red S staining. hPDLSCs cultured in unconditioned or osteogenic media were used as negative and positive control groups, respectively. Statistical analysis was performed using one-way ANOVA or two-way ANOVA and Tukey's post hoc test. Statistical significance was established at p < 0.05.

RESULTS

The highest Ca2+ peak was detected from Biodentine samples, followed by ERRM and Ceraputty. hPDLSC viability was significantly reduced in Ceraputty samples (p < 0.001), while 1:2 and 1:4 Biodentine and ERRM samples similar results to that of the negative control (p > 0.05). Biodentine and ERRM exhibited an upregulation of at least one cemento/odonto/osteogenic marker compared to the negative and positive control groups. Cells cultured with Biodentine produced a significantly higher calcified nodule formation than ERRM and Ceraputty (p < 0.001), which were also higher than the control groups (p < 0.001).

CONCLUSION

Ceraputty evidenced a reduced cytocompatibility towards hPDLSCs on its lowest dilutions compared to the other tested cements and the control group. Biodentine and ERRM promoted a significantly higher mineralization and osteo/cementogenic marker expression on hPDLSCs compared with Ceraputty. Further studies are necessary to verify the biological properties of this new material and its adequacy as a retrograde filling material.

CLINICAL RELEVANCE

This is the first study to elucidate the adequate biological properties of Ceraputty for its use as a retrograde filling material.