Adult Mesenchymal Stem Cells from Oral Cavity and Surrounding Areas: Types and Biomedical Applications

The role of mesenchymal stem cells-derived from oral and teeth in regenerative and reconstructive medicine

Defects and abnormalities of the skull, jaw, and face tissues due to various physiological problems such as speech, chewing, and swallowing disorders, cause illness and psychological effects with creation of significant public health challenges. Both autograft and allograft reconstruction methods, have different limitations, especially in the complete reconstruction of complex tissues such as sensory and periodontal tissues, which cannot be wholly relied on for treatment. Recently, mesenchymal stem cells (MSCs)-derived from oral and teeth have emerged as a promising alternative way in regenerative and reconstructive medicine. These types of stem cells with the high differentiation potential and self-renewal capabilities include dental pulp stem cells (DPSCs), stem cells from human exfoliated deciduous teeth (SHEDs), periodontal stem cells (PDLSCs) and gum-derived stem cells (GMSCs). These stem cells can be easily collected from accessible and numerous sources, such as extracted molars and milk teeth, with minimal invasiveness, playing pivotal roles in clinical application. This review explains the applications and therapeutic effects of the above-mentioned MSCs-derived from oral and dental tissues. Each of these stem cells, have unique characteristics and used for the treatment of specific abnormalities and defects. In this article, we aims to elucidate the indispensable and pivotal roles of MSCs-derived from the oral and teeth in addressing intractable and complex challenges in restorative and reconstructive medicine.

Subcutaneous implantation of tooth germ stem cells over the masseter muscle in mice: An in vivo pilot study

Objectives

This study aimed to explore the potential of tooth germ stem cells for regenerating tooth-like structures by subcutaneously implanting first molar tooth germ stem cells over the masseter muscle in mice.

Methods

Five pairs of house mice, Mus musculus, were selected for mating. At gestational day 14 (E14), the fetuses were extracted, and the first molar tooth germ at the cap stage was isolated. Tooth germ stem cells were prepared into a suspension and seeded onto scaffolds, which were then implanted subcutaneously over the masseter muscle in male mice. The control group (n = 5 male mice) received acellular scaffolds implanted at the same site. After 20 days, the regenerated tissues were resected and analyzed histologically using hematoxylin and eosin (H & E) staining, Masson's trichrome staining, and immunohistochemical (IHC) staining for cytokeratin (CK) and vimentin markers.

Results

H & E staining showed the formation of integrated oval structures at the implant site in all samples. Masson's trichrome staining identified dispersed accumulations of cellular mineralized matrix within the connective tissue. IHC staining was positive for vimentin, confirming the mesenchymal origin of the loose tissue at the center, indicating future dental pulp development. Positive CK staining indicated the ectodermal origin of dense peripheral tissues, suggesting the future formation of inner enamel epithelium. The combined immunohistochemical results for vimentin and CK confirmed the ecto-mesenchymal origin of the regenerated tissue, which resembled a late bell-stage tooth germ observed around gestational days 17.5-18 and showed early indications of dentin formation (D0).

Conclusion

The study indicates that tooth germ stem cells may have the potential to produce dense, tooth-like structures when implanted subcutaneously in mice. These findings provide preliminary insights into the possible applications of tooth germ stem cells in regenerative dental tissue engineering.

NIR Laser Irradiation Promotes Osteogenic Differentiation of PDLSCs Through the Activation of TRPV1 Channels and Subsequent Calcium Signaling

Near-infrared (NIR) irradiation has shown potential to stimulate osteogenic differentiation, but the mechanisms are not fully understood. The study is to investigate the effects of NIR laser irradiation on osteoblastic differentiation. Human periodontal ligament stem cells (hPDLSCs) were cultured in osteogenic medium and exposed to 810 nm NIR laser at 0.5 J/cm2 every 48 h. The transient receptor potential vanilloid (TRPV1) channel inhibitor capsazepine (CPZ) was used to evaluate the role of calcium influx. Osteogenic differentiation was assessed by proliferation (CCK-8), alkaline phosphatase (ALP) activity, mineralization (Alizarin Red), and expression of bone markers by PCR and Western blot over 2 weeks. Intracellular calcium was measured by Fluo-4M dye and flow cytometry. Results showed that NIR irradiation enhanced hPDLSC proliferation, ALP activity, mineralization, and bone marker expression, indicating increased osteogenic differentiation. These effects were inhibited by CPZ. NIR induced a transient rise in intracellular calcium peaking at 3 min, which was blocked by CPZ. In conclusion, this study demonstrates that NIR laser irradiation promotes osteogenic differentiation of PDLSCs through the activation of TRPV1 channels and subsequent calcium signaling. Further research is warranted to optimize the treatment parameters and elucidate the detailed signaling pathways involved, paving the way for the clinical application of NIR therapy in the treatment of bone disorders and periodontal disease.

Low level laser therapy and rheumatoid arthritis: a systematic review and meta-analysis study

This systematic review and meta-analysis aimed to evaluate the efficacy of Low-Level Laser Therapy (LLLT) in the treatment of Rheumatoid Arthritis (RA), focusing on its effects on pain relief, grip strength, and morning stiffness. A comprehensive search was conducted across PubMed, Scopus, and Web of Science, yielding 3,111 articles. After eliminating duplicates and screening titles and abstracts, 94 full-text articles were assessed, and 23 studies met the eligibility criteria for inclusion in the systematic review. Of these, 22 studies were included in the meta-analysis. Data were extracted and analyzed using a random-effects model, with pooled Mean Differences (MD) calculated for the primary outcomes. The meta-analysis revealed that LLLT did not significantly reduce pain compared to placebo (MD = 0.00, 95% CI [-0.09, 0.09], p = 0.97). However, LLLT significantly improved grip strength (MD = -12.38, 95% CI [-17.42, -7.34], p < 0.01) and reduced morning stiffness (MD = -0.84, 95% CI [-1.33, -0.36], p < 0.01), despite substantial heterogeneity in these outcomes. LLLT shows promise in improving grip strength and reducing morning stiffness in RA patients, though it does not significantly impact pain relief. These findings highlight the potential role of LLLT as an adjunctive treatment for RA, with further research needed to optimize treatment protocols and clarify underlying mechanisms.

Impact of compression forces on different mesenchymal stem cell types regarding orthodontic indication

The potential of stem cells, for example upper periodontal ligament stem cells from the maxilla (u-PDLSC) and from the mandible (l-PDLSC), adipose-derived mesenchymal stem cells (AD-MSC), and bone marrow-derived mesenchymal stem cells (BM-MSC), with respect to periodontal remodeling and orthodontic treatment is of great importance. In this work, we focus on the comprehensive adaptability of different stem cell types to mechanical forces with the aim to better understanding cell behavior and to refine a new mechanistic approach to investigate periodontal remodeling. We comprehensively analyze stem cells and observe distinct morphological and proliferation changes under compression in dependence on stem cell type. The cell signaling of extracellular signal-regulated kinase (ERK) and protein kinase B, also called AKT, and their respective phosphorylation shows diverse responses to compression. Additionally, vascular endothelial growth factor and hepatocyte growth factor secretion were reduced under mechanical stress in all cell types, with cell-specific variations. Osteoprotegerin secretion was reduced under compression, particularly in u-PDLSC. At least, diverse soluble receptors of NF-kB-ligand secretion patterns among cell types under pressure were observed, providing crucial insights into bone metabolism. These findings offer a deeper understanding of the behavior of mesenchymal stem cells under mechanical stimuli, highlighting their roles in bone remodeling, wound healing, and tissue regeneration in orthodontic and regenerative medicine contexts. Our results underscore the potential of u-PDLSC, l-PDLSC, and AD-MSC in periodontal regeneration, with AD-MSC showing notable resilience under compression, indicating its promising role for further investigation for orthodontic research. While these findings are encouraging, further research is essential to fully comprehend the mechanism of stem cell-based periodontal therapies.

FoxO1-Overexpressed Small Extracellular Vesicles Derived from hPDLSCs Promote Periodontal Tissue Regeneration by Reducing Mitochondrial Dysfunction to Regulate Osteogenesis and Inflammation

Purpose

Periodontitis is a chronic infectious disease characterized by progressive inflammation and alveolar bone loss. Forkhead box O1 (FoxO1), an important regulator, plays a crucial role in maintaining bone homeostasis and regulating macrophage energy metabolism and osteogenic differentiation of mesenchymal stem cells (MSCs). In this study, FoxO1 was overexpressed into small extracellular vesicles (sEV) using engineering technology, and effects of FoxO1-overexpressed sEV on periodontal tissue regeneration as well as the underlying mechanisms were investigated.

Methods

Human periodontal ligament stem cell (hPDLSCs)-derived sEV (hPDLSCs-sEV) were isolated using ultracentrifugation. They were then characterized using transmission electron microscopy, Nanosight, and Western blotting analyses. hPDLSCs were treated with hPDLSCs-sEV in vitro after stimulation with lipopolysaccharide, and osteogenesis was evaluated. The effect of hPDLSCs-sEV on the polarization phenotype of THP-1 macrophages was also evaluated. In addition, we measured the reactive oxygen species (ROS) levels, adenosine triphosphate (ATP) production, mitochondrial characteristics, and metabolism of hPDLSCs and THP-1 cells. Experimental periodontitis was established in vivo in mice. HPDLSCs-sEV or phosphate-buffered saline (PBS) were injected into periodontal tissues for four weeks, and the maxillae were collected and assessed by micro-computed tomography, histological staining, and small animal in vivo imaging.

Results

In vitro, FoxO1-overexpressed sEV promoted osteogenic differentiation of hPDLSCs in the inflammatory environment and polarized THP-1 cells from the M1 phenotype to the M2 phenotype. Furthermore, FoxO1-overexpressed sEV regulated the ROS level, ATP production, mitochondrial characteristics, and metabolism of hPDLSCs and THP-1 cells in the inflammatory environment. In the in vivo analyses, FoxO1-overexpressed sEV effectively promoted bone formation and inhibited inflammation.

Conclusion

FoxO1-overexpressed sEV can regulate osteogenesis and immunomodulation. The ability of FoxO1-overexpressed sEV to regulate inflammation and osteogenesis can pave the way for the establishment of a therapeutic approach for periodontitis.

Regenerative application of oral and maxillofacial 3D organoids based on dental pulp stem cell

Dental pulp stem cells (DPSCs) originate from the neural crest and the present mesenchymal phenotype showed self-renewal capabilities and can differentiate into at least three lineages. DPSCs are easily isolated with minimal harm, no notable ethical constraints, and without general anesthesia to the donor individuals. Furthermore, cryopreservation of DPSCs provides this opportunity for autologous transplantation in future studies without fundamental changes in stemness, viability, proliferation, and differentiating features. Current approaches for pulp tissue regeneration include pulp revascularization, cell-homing-based regenerative endodontic treatment (RET), cell-transplantation-based regenerative endodontic treatment, and allogeneic transplantation. In recent years, a novel technology, organoid, provides a mimic physiological condition and tissue construct that can be applied for tissue engineering, genetic manipulation, disease modeling, single-cell high throughput analysis, living biobank, cryopreserving and maintaining cells, and therapeutic approaches based on personalized medicine. The organoids can be a reliable preclinical prediction model for evaluating cell behavior, monitoring drug response or resistance, and comparing healthy and pathological conditions for therapeutic and prognostic approaches. In the current review, we focused on the promising application of 3D organoid technology based on DPSCs in oral and maxillofacial tissue regeneration. We discussed encountering challenges and limitations, and found promising solutions to overcome obstacles.

Conservative Management of Odontogenic Myxoma - A Case Report

Rationale

This is a 14-year-old girl with odontogenic myxoma of the right posterior mandibular region, which was managed conservatively by intraoral marginal mandibulectomy rather than segmental mandibulectomy.

Patient Concerns

The patient and her parents were concerned about her aesthetics.

Diagnosis

The patient came with the complaint of swelling on the right lower back tooth region of the jaw, which was not associated with pain. On palpation, the swelling was bony hard and there was buccolingual expansion. On radiographic examination, there was a sunray appearance. Histopathological examination confirmed it to be an odontogenic myxoma.

Treatment

Marginal mandibulectomy was done for the patient. The whole procedure was done intraorally and closed using primary closure.

Outcomes

Postoperatively, the patient was asymptomatic and is on follow-up.

Take-away Lessons

We can say that odontogenic myxoma can be managed conservatively.

Mesenchymal Stromal Cells Derived from Dental Tissues: Immunomodulatory Properties and Clinical Potential

Mesenchymal stem/stromal cells (MSCs) are multipotent cells located in different areas of the human body. The oral cavity is considered a potential source of MSCs because they have been identified in several dental tissues (D-MSCs). Clinical trials in which cells from these sources were used have shown that they are effective and safe as treatments for tissue regeneration. Importantly, immunoregulatory capacity has been observed in all of these populations; however, this function may vary among the different types of MSCs. Since this property is of clinical interest for cell therapy protocols, it is relevant to analyze the differences in immunoregulatory capacity, as well as the mechanisms used by each type of MSC. Interestingly, D-MSCs are the most suitable source for regenerating mineralized tissues in the oral region. Furthermore, the clinical potential of D-MSCs is supported due to their adequate capacity for proliferation, migration, and differentiation. There is also evidence for their potential application in protocols against autoimmune diseases and other inflammatory conditions due to their immunosuppressive capacity. Therefore, in this review, the immunoregulatory mechanisms identified at the preclinical level in combination with the different types of MSCs found in dental tissues are described, in addition to a description of the clinical trials in which MSCs from these sources have been applied.

Application progress of single-cell sequencing technology in mesenchymal stem cells research

Single-Cell Sequencing (SCS) technology plays an important role in the field of Mesenchymal Stem Cells (MSCs) research. This paper comprehensively describes the application of SCS technology in the field of MSCs research, including (1) SCS enables more precise MSCs characterization and biomarker definition. (2) SCS reveals the prevalent gene expression heterogeneity among different subclusters within MSCs, which contributes to a more comprehensive understanding of MSCs function and diversity in developmental, regenerative, and pathological contexts. (3) SCS provides insights into the dynamic transcriptional changes experienced by MSCs during differentiation and the complex web of important signaling pathways and regulatory factors controlling key processes within MSCs, including proliferation, differentiation and regulation, and interactions mechanisms. (4) The analytical methods underpinning SCS data are rapidly evolving and converging with the field of histological research to systematically deconstruct the functions and mechanisms of MSCs. This review provides new perspectives for unraveling the biological properties, heterogeneity, differentiation potential, biological functions, and clinical potential of MSCs at the single-cell level.

Differential Expression of MicroRNA (MiR-27, MiR-145) among Dental Pulp Stem Cells (DPSCs) Following Neurogenic Differentiation Stimuli

This study sought to evaluate the expression of previously identified microRNAs known to regulate neuronal differentiation in mesenchymal stem cells (MSCs), including miR-27, miR-125, miR-128, miR-135, miR-140, miR-145, miR-218 and miR-410, among dental pulp stem cells (DPSCs) under conditions demonstrated to induce neuronal differentiation. Using an approved protocol, n = 12 DPSCs were identified from an existing biorepository and treated with basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF), which were previously demonstrated to induce neural differentiation markers including Sox1, Pax6 and NFM among these DPSCs. This study revealed that some microRNAs involved in the neuronal differentiation of MSCs were also differentially expressed among the DPSCs, including miR-27 and miR-145. In addition, this study also revealed that administration of bFGF and EGF was sufficient to modulate miR-27 and miR-145 expression in all of the stimulus-responsive DPSCs but not among all of the non-responsive DPSCs-suggesting that further investigation of the downstream targets of these microRNAs may be needed to fully evaluate and understand these observations.