Odontogenic MSC Heterogeneity: Challenges and Opportunities for Regenerative Medicine

Impacts of Circular RNAs on the Osteogenic Differentiation of Dental Stem Cells

Dental stem cells are widely viewed as good options for bone regeneration because of their ease of acquisition, innate ability to renew themselves, and ability to differentiate into different types of cells. However, the process of osteogenic differentiation of dental stem cells is orchestrated by an intricate system of regulatory mechanisms. Recent studies have demonstrated the critical impacts of circular RNAs (circRNAs) on osteogenic differentiation of dental stem cells. Exploring the roles and regulatory pathways of circRNAs in dental stem cells could identify novel targets and approaches for utilizing dental stem cell therapy in clinical settings. This review provides a comprehensive overview of the functions and mechanisms of circRNAs, with a particular focus on their expression patterns and regulatory roles in osteogenic differentiation of various dental stem cell types. Furthermore, this review discusses current research challenges in this field and proposes future directions for advancing our understanding of circRNA-mediated regulation in dental stem cell biology.

Regulation and functional importance of human periodontal ligament mesenchymal stromal cells with various rates of CD146+ cells

Introduction

Mesenchymal stromal cells (MSCs) with high expression of CD146 have superior properties for tissue regeneration. However, high variability in the rate of CD146+ cells among donors is observed. In this study, the possible reasons behind this variability in human periodontal ligament MSCs (hPDL-MSCs) were explored.

Methods

hPDL-MSCs were isolated from 22 different donors, and rates of CD146+ cells were analyzed by flow cytometry. Furthermore, populations with various rates of CD146+ cells were isolated with magnetic separation. The dependency of cell proliferation, viability, cell cycle, and osteogenic differentiation on the rates of CD146+ cells was investigated. Besides, the effects of various factors, like cell density, confluence, and inflammatory environment on the CD146+ rate and expression were analyzed.

Results

The rate of CD146+ cells exhibited high variability between donors, with the percentage of CD146+ cells ranging from 3% to 67%. Higher percentage of CD146+ cells was associated with higher proliferation, presumably due to the higher percentage of cells in the S-phase, and higher osteogenic differentiation potential. Prolonged cell confluence and higher cell seeding density led to the decline in the rate of CD146+ cells. The surface rate of CD146 in hPDL-MSCs was stimulated by the treatment with interleukin-1β and tumor necrosis factor-α, and inhibited by the treatment with interferon-γ.

Conclusion

These results suggest that hPDL-MSCs with high rate of CD146+ cells are a promising subpopulation for enhancing the effectiveness of MSC-based regenerative therapies, however the rate of CD146 is affected by various factors, which must be considered for cell propagation and their potential application in vivo.

Adipose-Derived Mesenchymal Stem Cells from Arthritis Patients: Differential Modulation of CD4⁺ T Cell Activation and Cytokine Production

BACKGROUND Adipose-derived stem cells (ASCs) from intra-articular adipose tissue of osteoarthritis (OA) and rheumatoid arthritis (RA) patients similarly regulate the proliferation of activated CD4⁺ T lymphocytes and exhibit comparable differentiation potential. This study aimed to assess the impact of ASCs from RA patients on CD4⁺ T cell activation and differentiation into Th17 and T regulatory (Treg) cells. MATERIAL AND METHODS Intra-articular adipose tissue samples were obtained from patients with RA and OA, who underwent knee replacement surgery. ASCs were isolated and cultured either with isolated CD4⁺ cells or with peripheral blood mononuclear cells. After culture, CD4⁺ T cell phenotype was evaluated by flow cytometry, and cytokine concentrations in culture supernatants were analyzed via ELISA. Blocking experiments were conducted to identify the soluble agents responsible for the immunomodulatory effects of ASCs. RESULTS RA- and OA-derived ASCs effectively modulated CD25 and CD69 expression on CD4⁺ cells. RA-derived ASCs failed to induce Tregs, decreased HLA-DR expression, and increased IL-35 production. RA- and OA-derived ASCs reduced TNF and IFN-γ production but increased IL-17 production. The immunomodulatory activities of ASCs were linked to the kynurenine pathway and prostaglandin E2. CONCLUSIONS This study indicates that ASCs modulate the phenotype of CD4⁺ T cells and influence the production of both pro-inflammatory and anti-inflammatory cytokines. However, ASCs from RA patients appear to have impaired immunomodulatory abilities, raising concerns about their therapeutic potential. Further research is needed to enhance our understanding of ASCs biology and their therapeutic utility.

Single cell RNA sequencing reveals mesenchymal heterogeneity and critical functions of Cd271 in tooth development

BACKGROUND

Accumulating evidence suggests that the maxillary process, to which cranial crest cells migrate, is essential to tooth development. Emerging studies indicate that Cd271 plays an essential role in odontogenesis. However, the underlying mechanisms have yet to be elucidated.

AIM

To establish the functionally heterogeneous population in the maxillary process, elucidate the effects of Cd271 deficiency on gene expression differences.

METHODS

p75NTR knockout (Cd271^-/-) mice (from American Jackson laboratory) were used to collect the maxillofacial process tissue of p75NTR knockout mice, and the wild-type maxillofacial process of the same pregnant mouse wild was used as control. After single cell suspension, the cDNA was prepared by loading the single cell suspension into the 10x Genomics Chromium system to be sequenced by NovaSeq6000 sequencing system. Finally, the sequencing data in Fastq format were obtained. The FastQC software is used to evaluate the quality of data and CellRanger analyzed the data. The gene expression matrix is read by R software, and Seurat is used to control and standardize the data, reduce the dimension and cluster. We search for marker genes for subgroup annotation by consulting literature and database; explore the effect of p75NTR knockout on mesenchymal stem cells (MSCs) gene expression and cell proportion by cell subgrouping, differential gene analysis, enrichment analysis and protein-protein interaction network analysis; understand the interaction between MSCs cells and the differentiation trajectory and gene change characteristics of p75NTR knockout MSCs by cell communication analysis and pseudo-time analysis. Last we verified the findings single cell sequencing in vitro.

RESULTS

We identified 21 cell clusters, and we re-clustered these into three subclusters. Importantly, we revealed the cell–cell communication networks between clusters. We clarified that Cd271 was significantly associated with the regulation of mineralization.

CONCLUSION

This study provides comprehensive mechanistic insights into the maxillary- process-derived MSCs and demonstrates that Cd271 is significantly associated with the odontogenesis in mesenchymal populations.

[To strengthen the basic and translational research of mesenchymal stem cell-based therapy for refractory wounds]

In recent years, the application of cell-based therapy in the field of refractory wound repair has shown broad prospects, among which the mesenchymal stem cell is the most concerned and widely studied cell type. Despite the rapid development of clinical translational research, the therapeutic effect of cell-based therapy is not consistent, and most clinical trials have not achieved the desired results. Further studies have found that heterogeneity is an important issue that restricts the further development of cell-based therapy and urgently needs to be studied. Based on the research progress of mesenchymal stem cells, in the review, we discuss the current status and challenges of cell-based therapy strategies for refractory wounds.

Biomaterials constructed for MSC-derived extracellular vesicle loading and delivery—a promising method for tissue regeneration

Mesenchymal stem cells (MSCs) have become the preferred seed cells for tissue regeneration. Nevertheless, due to their immunogenicity and tumorigenicity, MSC transplantation remains questionable. Extracellular vesicles (EVs) derived from MSCs are becoming a promising substitute for MSCs. As a route of the MSC paracrine, EVs have a nano-sized and bilayer lipid-enclosed structure, which can guarantee the integrity of their cargoes, but EVs cannot obtain full function in vivo because of the rapid biodegradation and clearance by phagocytosis. To improve the efficacy and targeting of EVs, methods have been proposed and put into practice, especially engineered vesicles and EV-controlled release systems. In particular, EVs can be cell or tissue targeting because they have cell-specific ligands on their surfaces, but their targeting ability may be eliminated by the biodegradation of the phagocytic system during circulation. Novel application strategies have been proposed beyond direct injecting. EV carriers such as biodegradable hydrogels and other loading systems have been applied in tissue regeneration, and EV engineering is also a brand-new method for higher efficacy. In this review, we distinctively summarize EV engineering and loading system construction methods, emphasizing targeting modification methods and controlled release systems for EVs, which few literature reviews have involved.