Specific microRNAs regulate dental pulp stem cell behavior

How epigenetics and miRNA affect gene expression in dental pulp inflammation: A narrative review

BACKGROUND

Pulpitis, an inflammatory condition of the dental pulp, typically arises due to caries. It can remain asymptomatic for extended periods, complicating its diagnosis. The inflammatory response induced by bacterial invasion encompasses both cell-mediated and humoural immunity, accompanied by neural and vascular changes. The primary aim of inflammation is to eradicate invading pathogens from the pulp. However, failure to eliminate pathogens may result in necrosis of the pulp. Before direct bacterial contact with cells occurs, the pulp initiates protective responses like the formation of tertiary dentine. The interaction between bacterial surface proteins and specific receptors on pulp cells, primarily odontoblasts and dendritic cells, activates intracellular signalling pathways. These cascades, mediated by transcription factors, regulate gene expression and subsequent protein synthesis, thereby modulating the inflammatory response. In addition to proinflammatory and anti-inflammatory mediators, microRNAs and epigenetic modifications play a key role in gene expression in dental pulp. Epigenetic changes including DNA methylation and histone modifications can occur within the pulp.

OBJECTIVES

Dental pulp inflammation represents a highly intricate network of signalling pathways, messenger molecules and cellular interactions. The ongoing research continuously expands our understanding of these processes. The objective of this review is to investigate mechanisms of dental pulp inflammation, concentrating on the regulation of gene expression. This consists of transcription factors, microRNAs, epigenetic modifications and mitochondrial DNA, among others. This review aims to highlight recent findings about biomolecular and epigenetical mechanisms of pulpitis as well as their role in gene expression.

CONCLUSIONS

Pulp inflammation is a complex series of events happening on a molecular and cellular level. Even though the pulp tissue is hardly examined in vivo, laboratory studies offer great new insights and potential for our understanding of its inflammatory mechanisms. Recognition of bacterial components by pulp cells is the initiator of overlapping signalling pathways that will eventually lead to gene activation or repression. Specific genes might be activated, resulting in the production of messenger molecules like cytokines and chemokines. Trending topics of medicine like microRNA and epigenetics are also discussed in the context of dentistry. This knowledge could be used to develop new therapeutics in endodontics.

Assessing the Impact of Stem Cell-based Therapy on Periodontal Health: A Meta-analysis of Clinical Studies

OBJECTIVE

While clinical trials exploring stem cells for regenerating periodontal tissues have demonstrated positive results, there is a limited availability of systematic literature reviews on this subject. To gain a more comprehensive understanding of stem cell interventions in periodontal regeneration, this meta-analysis is undertaken to assess the beneficial effects of stem cells in human periodontal regeneration.

METHODS

"PubMed," "PubMed Central," "Web of Science," "Embase Scopus" "Wanfang," and "CNKI," were used to extract clinical studies related to the utilization of stem cells in repairing periodontal tissue defects. This search included studies published up until October 5, 2023. The inclusion criteria required the studies to compare the efficacy of stem cell-based therapy with stem cell-free therapy for regenerating periodontal tissues. Meta-analysis was conducted using Review Manager software (version 5.4).

RESULTS

This meta-analysis synthesized findings from 15 selected studies investigating the impact of stem cell interventions on periodontal tissue regeneration. The "stem cell" group displayed a substantial reduction in clinical attachment level (CAL) compared to the "control" group within 3 to 12 months post-surgery. However, no significant differences in CAL gain were found between groups. Probing pocket depth (PPD) significantly decreased in the "stem cell" group compared to the "control" group, particularly for follow-up periods exceeding 6 months, and dental stem cell treatment exhibited notable improvements. Conversely, no significant differences were observed in PPD reduction. Gingival recession (GR) significantly decreased in the "stem cell" group compared to the "control" group at 3 to 12 months post-surgery. No significant differences were observed in GR reduction between groups. No significant differences were identified in cementoenamel junction-bone distance reduction, infrabony defect reduction, or bone mineral density increase between the two groups. Furthermore, no significant changes were observed in the gingival index, plaque index, or width of keratinized gingiva.

CONCLUSION

In conclusion, while stem cell-based therapy offers promising prospects for periodontal defect treatment, there are notable limitations in the current body of research. Larger, multicenter, double-blind RCTs with robust methodologies are needed to provide more reliable evidence for stem cell-based intervention in periodontitis.

Notch signaling regulates mineralization via microRNA modulation in dental pulp stem cells

OBJECTIVES

This study investigated the miRNA expression profile in Notch-activated human dental stem pulp stem cells (DPSCs) and validated the functions of miRNAs in modulating the odonto/osteogenic properties of DPSCs.

METHODS

DPSCs were treated with indirect immobilized Jagged1. The miRNA expression profile was examined using NanoString analysis. Bioinformatic analysis was performed, and miRNA expression was validated. Odonto/osteogenic differentiation was examined using alkaline phosphatase staining, Alizarin Red S staining, as well as odonto/osteogenic-related gene and protein expression.

RESULTS

Fourteen miRNAs were differentially expressed in Jagged1-treated DPSCs. Pathway analysis revealed that altered miRNAs were associated with TGF-β, Hippo, ErbB signalling pathways, FoxO and Ras signalling. Target prediction analysis demonstrated that 7604 genes were predicted to be targets for these altered miRNAs. Enrichment analysis revealed relationships to various DNA bindings. Among differentially expressed miRNA, miR-296-3p and miR-450b-5p were upregulated under Jagged1-treated conditions. Overexpression of miR-296-3p and miR-450b-5p enhanced mineralization and upregulation of odonto/osteogenic-related genes, whereas inhibition of these miRNAs revealed opposing results. The miR-296-3p and miR-450b-5p inhibitors attenuated the effects of Jagged1-induced mineralization in DPSCs.

CONCLUSIONS

Jagged-1 promotes mineralization in DPSCs that are partially regulated by miRNA. The novel understanding of these miRNAs could lead to innovative controlled mechanisms that can be applied to modulate biology-targeted dental materials.

Dental pulp stem cells - A basic research and future application in regenerative medicine

Dental pulp is a valuable and accessible source of stem cells (DPSCs) with characteristics similar to mesenchymal stem cells. DPSCs can regenerate a range of tissues and their potential for clinical application in regenerative medicine is promising. DPSCs have been found to express low levels of Class II HLA-DR (MHC) molecules, making them potential candidates for allogeneic transplantation without matching the donor's tissue. Research on the correlation between non-coding RNAs (ncRNAs) and human dental pulp stem cells (DPSCs) provides promising insights into the use of these cells in clinical settings for a wide range of medical conditions. It is possible to use a number of ncRNAs in order to restore the functional role of downregulated ncRNAs that are correlated with osteoblastogenesis, or to suppress the functional role of overexpressed ncRNAs associated with osteoclast differentiation in some cases.

Chemically modified microRNA delivery via DNA tetrahedral frameworks for dental pulp regeneration

Dental pulp regeneration is a promising strategy for addressing tooth disorders. Incorporating this strategy involves the fundamental challenge of establishing functional vascular networks using dental pulp stem cells (DPSCs) to support tissue regeneration. Current therapeutic approaches lack efficient and stable methods for activating DPSCs. In the study, we used a chemically modified microRNA (miRNA)-loaded tetrahedral-framework nucleic acid nanostructure to promote DPSC-mediated angiogenesis and dental pulp regeneration. Incorporating chemically modified miR-126-3p into tetrahedral DNA nanostructures (miR@TDNs) represents a notable advancement in the stability and efficacy of miRNA delivery into DPSCs. These nanostructures enhanced DPSC proliferation, migration, and upregulated angiogenesis-related genes, enhancing their paracrine signaling effects on endothelial cells. This enhanced effect was substantiated by improvements in endothelial cell tube formation, migration, and gene expression. Moreover, in vivo investigations employing matrigel plug assays and ectopic dental pulp transplantation confirmed the potential of miR@TDNs in promoting angiogenesis and facilitating dental pulp regeneration. Our findings demonstrated the potential of chemically modified miRNA-loaded nucleic acid nanostructures in enhancing DPSC-mediated angiogenesis and supporting dental pulp regeneration. These results highlighted the promising role of chemically modified nucleic acid-based delivery systems as therapeutic agents in regenerative dentistry and tissue engineering.

MicroRNAs Function in Dental Stem Cells as a Promising Biomarker and Therapeutic Target for Dental Diseases

Undifferentiated, highly proliferative, clonogenic, and self-renewing dental stem cells have paved the way for novel approaches to mending cleft palates, rebuilding lost jawbone and periodontal tissue, and, most significantly, recreating lost teeth. New treatment techniques may be guided by a better understanding of these cells and their potential in terms of the specificity of the regenerative response. MicroRNAs have been recognized as an essential component in stem cell biology due to their role as epigenetic regulators of the processes that determine stem cell destiny. MicroRNAs have been proven to be crucial in a wide variety of molecular and biological processes, including apoptosis, cell proliferation, migration, and necrocytosis. MicroRNAs have been recognized to control protein translation, messenger RNA stability, and transcription and have been reported to play essential roles in dental stem cell biology, including the differentiation of dental stem cells, the immunological response, apoptosis, and the inflammation of the dental pulp. Because microRNAs increase dental stem cell differentiation, they may be used in regenerative medicine to either preserve the stem cell phenotype or to aid in the development of tooth tissue. The development of novel biomarkers and therapies for dental illnesses relies heavily on progress made in our knowledge of the roles played by microRNAs in regulating dental stem cells. In this article, we discuss how dental stem cells and their associated microRNAs may be used to cure dental illness.

Differential Effects of Extracellular Matrix Glycoproteins Fibronectin and Laminin-5 on Dental Pulp Stem Cell Phenotypes and Responsiveness

Dental pulp stem cells (DPSCs) are mesenchymal stem cells (MSCs) with the potential to differentiate in a limited number of other tissue types. Some evidence has suggested the modulation of DPSC growth may be mediated, in part, by exogenous extracellular matrix (ECM) glycoproteins, including fibronectin (FN) and laminin-5 (LN5). Although preliminary research suggests that some ECM glycoproteins may work as functional biomaterials to modulate DPSC growth responses, the primary goal of this project is to determine the specific effects of FN and LN5 on DPSC growth and viability. Using an existing DPSC repository, n = 16 DPSC isolates were cultured and 96-well growth assays were performed, which revealed FN, LN5 and the combination of these were sufficient to induce statistically significant changes in growth among five (n = 5) DPSC isolates. In addition, the administration of FN (either alone or in combination) was sufficient to induce the expression of alkaline phosphatase (ALP) and dentin sialophosphoprotein (DSPP), while LN5 induced the expression of ALP only, suggesting differential responsiveness among DPSCs. Moreover, these responses appeared to correlate with the expression of MSC biomarkers NANOG, Oct4 and Sox2. These results add to the growing body of evidence suggesting that functional biomaterials, such as ECM glycoproteins FN and LN5, are sufficient to induce phenotypic and differentiation-specific effects in a specific subset of DPSC isolates. More research will be needed to determine which biomarkers or additional factors are necessary and sufficient to induce the differentiation and development of DPSCs ex vivo and in vitro for biomedical applications.

Creating a Microenvironment to Give Wings to Dental Pulp Regeneration-Bioactive Scaffolds

Dental pulp and periapical diseases make patients suffer from acute pain and economic loss. Although root canal therapies, as demonstrated through evidence-based medicine, can relieve symptoms and are commonly employed by dentists, it is still difficult to fully restore a dental pulp's nutrition, sensory, and immune-regulation functions. In recent years, researchers have made significant progress in tissue engineering to regenerate dental pulp in a desired microenvironment. With breakthroughs in regenerative medicine and material science, bioactive scaffolds play a pivotal role in creating a suitable microenvironment for cell survival, proliferation, and differentiation, following dental restoration and regeneration. This article focuses on current challenges and novel perspectives about bioactive scaffolds in creating a microenvironment to promote dental pulp regeneration. We hope our readers will gain a deeper understanding and new inspiration of dental pulp regeneration through our summary.

Rosmarinic and chlorogenic acid, isolated from ferns, suppress stem cell damage induced by hydrogen peroxide

OBJECTIVES

Evaluating the effects of rosmarinic (RA) and cryptochlorogenic (CGA) acids isolated from Blechnum binervatum extract on stem cell viability, toxicity and the protective effect on oxidative cell damage.

METHODS

MTT and LDH methods were employed, using stem cells from teeth. RA and CGA were evaluated at 100, 250 and 500 µM. The negative effect of hydrogen peroxide (H2O2) (200-2200 µM) and the capacity of RA and CGA (10-100 µM) as protective agents were also evaluated. DAPI followed by fluorescent microscopy was employed to photograph the treated and untreated cells.

KEY FINDINGS

At all tested concentrations, RA and CGA demonstrated the ability to maintain cell viability, and with no cytotoxic effects on the treated stem cells. RA also induced an increase of the cell viability and a reduction in cytotoxicity. H2O2 (1400 µM) induced >50% of cytotoxicity, and both compounds were capable of suppressing H2O2 damage, even at the lowest concentration. At 100 µM, in H2O2 presence, total cell viability was observed through microscope imaging.

CONCLUSIONS

These findings contribute to the continued research into natural substances with the potential for protecting cells against oxidative injury, with the consideration that RA and CGA are useful in the regeneration of damaged stem cells.