Distinctive cytokine profiles of stem cells from human exfoliated deciduous teeth and dental pulp stem cells

Advances in oral mesenchymal stem cell-derived extracellular vesicles in health and disease

Extracellular vesicles (EVs) are nano-size vesicles secreted naturally by all cells into the extracellular space and have been recognized as important cell-cell mediators in multicellular organisms. EVs contain nucleic acids, proteins, lipids, and other cellular components, regulating many basic biological processes and playing an important role in regenerative medicine and diseases. EVs can be traced to their cells of origin and exhibit a similar function. Moreover, EVs demonstrate low immunogenicity, good biocompatibility, and fewer side effects, compared to their parent cells. Mesenchymal stem cells (MSCs) are one of the most important resource cells for EVs, with a great capacity for self-renewal and multipotent differentiation, and play an essential role in stem cell therapy. The mechanism of MSC therapy was thought to be attributed to the differentiation of MSCs after targeted migration, as previously noted. However, emerging evidence shows the previously unknown role of MSC-derived paracrine factors in stem cell therapy. Especially EVs derived from oral tissue MSCs (OMSC-EVs), show more advantages than those of all other MSCs in tissue repair and regeneration, due to their lower invasiveness and easier accessibility for sample collection. Here, we systematically review the biogenesis and biological characteristics of OMSC-EVs, as well as the role of OMSC-EVs in intercellular communication. Furthermore, we discuss the potential therapeutic roles of OMSC-EVs in oral and systemic diseases. We highlight the current challenges and future directions of OMSC-EVs to focus more attention on clinical translation. We aim to provide valuable insights for the explorative clinical application of OMSC-EVs.

Secretome of stem cells from human exfoliated deciduous teeth (SHED) and its extracellular vesicles improves keratinocytes migration, viability, and attenuation of H2 O2 -induced cytotoxicity

Therapies for wound healing using the secretome and extracellular vesicles (EVs) of mesenchymal stem/stromal cells have been shown to be successful in preclinical studies. This study aimed to characterise the protein content of the secretome from stem cells from human exfoliated deciduous teeth (SHED) and analyse the in vitro effects of SHED-conditioned medium (SHED-CM) and SHED extracellular vesicles (SHED-EVs) on keratinocytes. EVs were isolated and characterised. The keratinocyte viability and migration of cells treated with SHED-EVs and conditioned medium (CM) were evaluated. An HaCaT apoptosis model induced by H2 O2 in vitro was performed with H2 O2 followed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and live/dead assays. Finally, the expression of vascular endothelial growth factor (VEGF) in keratinocytes treated with secretome and EVs was evaluated by immunofluorescence staining and confirmed with RT-qPCR. SHED-EVs revealed a cup-shaped morphology with expression of the classical markers for exosomes CD9 and CD63, and a diameter of 181 ± 87 nm. The internalisation of EVs by HaCaT cells was confirmed by fluorescence microscopy. Proteomic analysis identified that SHED-CM is enriched with proteins related to stress response and development, including cytokines (CXCL8, IL-6, CSF1, CCL2) and growth factors (IGF2, MYDGF, PDGF). The results also indicated that 50% CM and 0.4-0.6 μg/mL EVs were similarly efficient for improving keratinocyte viability, migration, and attenuation of H2 O2 -induced cytotoxicity. Additionally, expression of VEGF on keratinocytes increased when treated with SHED secretome and EVs. Furthermore, VEGF gene expression in keratinocytes increased significantly when treated with SHED secretome and EVs. Both SHED-CM and SHED-EVs may therefore be promising therapeutic tools for accelerating re-epithelialization in wound healing.

Evaluation of the Efficacy of Human Dental Pulp Stem Cell Transplantation in Sprague-Dawley Rats with Sensorial Neural Hearing Loss

OBJECTIVES

 The purpose of the present study was to evaluate the efficacy of spiral ganglion neuron (SGN) regeneration after dental pulp stem cell (DPSC) transplantation in a rat sensorineural hearing loss (HL) model.

MATERIALS AND METHODS

 Sham or experimental HL was induced in adult Sprague-Dawley rats by cochlear round window surgery. An HL rat model was established with a single 10 mM ouabain intratympanic injection. After 7 days, the rats received DPSCs, stem cells from human exfoliated deciduous teeth (SHED), or culture medium in the sutural area to establish four groups: sham, HL-DPSC, HL-SHED, and HL-medium. Histological analyses were performed at 4, 7, and 10 weeks after transplantation, and the number of SGNs, specific SGN protein expression, and the function of SGNs were evaluated.

STATISTICAL ANALYSIS

 Data were statistically by MS Excel and SPSS v.15.0. Intergroup level of significance was determined via a one-way analysis of variance and Duncan's multiple range test with 95% confidence intervals.

RESULTS

 New SGN formation was observed in the HL-DPSC and HL-SHED rat groups. The number of SGNs was significantly higher in the HL-DPSC and HL-SHED groups than in the HL-medium group over 4 to 10-week survival period. HL-DPSC rats exhibited higher SGN density compared with that in HL-SHED group, which was statistically significant at week 10. The regenerated SGNs expressed cochlear wiring regulator GATA-binding-protein 3. Moreover, the SGNs from the HL-DPSC group also exhibited a higher expression of synaptic vesicle protein and regulated action potential-dependent neurotransmitter release compared with SGNs from the HL-SHED group.

CONCLUSIONS

 Our findings suggest that DPSCs and SHED repair and regenerate SGNs in rat HL model. Dental pulp stem cells represent a promising treatment strategy for restoring damage to the sensory circuits associated with deafness.

The Role of Box A of HMGB1 in Enhancing Stem Cell Properties of Human Mesenchymal Cells: A Novel Approach for the Pursuit of Anti-aging Therapy

BACKGROUND/AIM

Box A is a highly conserved DNA-binding domain of high-mobility group box 1 (HMGB1) and has been shown to reverse senescence and aging features in many cell models. We investigated whether the activation of box A can influence stem cell properties.

MATERIALS AND METHODS

Human dermal papilla (DP) cells and primary human white pre-adipocytes (HWPc) were employed as mesenchymal cell models. Box A-overexpressing plasmids were used to induce cellular box A expression. mRNA and protein levels of stemness markers POU class 5 homeobox 1 pseudogene 5 (OCT4, HGNC: 9221), Nanog homeobox (NANOG, HGNC: 20857), and SRY-box transcription factor 2 (SOX2, HGNC:11195) in DP cells and HWPc were measured by real-time polymerase chain reaction and immunofluorescence analysis, respectively.

RESULTS

Transfection efficiency of box A-overexpressing plasmid was 80% and 50% in DP cells and HWPc, respectively. The proliferative rate of both cell types significantly increased 72 h after transfection. Levels of OCT4, NANOG and SOX2 mRNA and protein expression were significantly increased in box A-transfected DP cells and HWPc compared to empty plasmid-transfected cells. Immunofluorescence analysis confirmed the induction of OCT4, NANOG and SOX2 protein expression in response to box A in DP cells and HWPc. OCT4 and SOX2 were expressed in both the nuclear and cytoplasmic compartments, while NANOG was intensely located in the nucleus of box A-transfected cells.

CONCLUSION

Our findings suggest that box A may potentially enhance stemness, which may have significant benefits in improving stem cell function due to aging processes and disease. This research may have implications for regenerative medicine applications.

Cigarette smoking exposure disrupts the regenerative potential of dental pulp stem cells

INTRODUCTION

Smoking is known to alter the regenerative and immunomodulatory properties of many types of mesenchymal stem cells (MSCs). This study investigates the impact of cigarette smoke exposure on the regenerative potential of dental pulp stem cells (DPSCs).

METHODS

DPSCs were treated with various doses of cigarette smoke condensate (CSC) or nicotine. Cell proliferation and survival were evaluated by a water-soluble tetrazolium salt (WST-1) and a survival assay. DPSC migration, cytokine expression, mutagenesis, and the signaling pathway were also measured during CSC and nicotine treatment.

RESULTS

Low concentrations of CSC and nicotine did not impair cell proliferation, but higher concentrations reduced cell proliferation. CSC and nicotine could impede DPSC survival and migration in a dose-dependent manner. In addition, the cytokine secretion expression profile was altered with CSC or nicotine treatments. In particular, secretion of IL-6, TNF-α, and IL-10 significantly increased, while TGF-β1 levels showed different patterns after exposure to CSC or nicotine, as shown by ELISA and quantitative PCR. Nicotine treatment increased AKT (also known as protein kinase B) and extracellular signal-regulated kinase (ERK) phosphorylation. Finally, CSC induced higher levels of mutagenicity than nicotine, as shown by the Ames test.

CONCLUSIONS

These findings suggest that cigarette smoke exposure alters the regenerative abilities of DPSCs in various ways. Future studies are warranted to further characterize the underlying molecular mechanisms of smoking-mediated damage to DPSCs, which will guide the personalized stem cell treatment plan for smoking patients.

From Teeth to Therapy: A Review of Therapeutic Potential within the Secretome of Stem Cells from Human Exfoliated Deciduous Teeth

Stem cells derived from human exfoliated deciduous teeth (SHED) have emerged as an alternative stem cell source for cell therapy and regenerative medicine because they are readily available, pose fewer ethical concerns, and have low immunogenicity and tumourigenicity. SHED offer a number of advantages over other dental stem cells, including a high proliferation rate with the potential to differentiate into multiple developmental lineages. The therapeutic effects of SHED are mediated by multiple mechanisms, including immunomodulation, angiogenesis, neurogenesis, osteogenesis, and adipogenesis. In recent years, there is ample evidence that the mechanism of action of SHED is mainly due to its paracrine action, releasing a wide range of soluble factors such as cytokines, chemokines, and trophic factors (also known as 'secretome') into the local tissue microenvironment to promote tissue survival and recovery. This review provides an overview of the secretome derived from SHED and highlights the bioactive molecules involved in tissue regeneration and their potential applications in regenerative medicine.

Immunomodulatory effect of IL-1RA in LPS-activated macrophage/dental pulp stem cells co-culture

AIMS

Lipopolysaccharides (LPS)-activated human dental pulp stem cells (hDPSCs) and macrophage co-cultures showed downregulated TNF-α secretion that is modulated by hDPSCs through IDO axis, whereas the secretory levels of IL-1β remained unchanged. Therefore, sustained production of IL-1β could contribute to progressive dental pulp inflammation. However, the role of interleukin-1 receptor antagonist (IL-1RA) in downregulating the secretion of IL-1β and TNF-α in LPS-activated M0/M1/M2 macrophage and hDPSCs co-culture has not been studied yet. Therefore, the aim of the present study was to determine the immunomodulatory role of blocking IL-1 receptors in DPSCs macrophage co-culture activated with LPS.

METHODOLOGY

Human monocytic cell line THP-1 was polarized to M0, M1 and M2 macrophages and co-cultured with hDPSCs. The viability of the co-cultured cells was assessed by apoptosis assay. Co-cultures were activated with LPS followed by the assessment of gene expression and protein levels of IL-1β and TNF-α with and without IL-1RA blocking via qRT-PCR and cytokine flex assay by flow cytometry. Data from three separate experiments were analysed using one-way anova followed by Tukey's post hoc test and a p-value of <.05 was considered statistically significant.

RESULTS

THP-1-derived M0, M1 and M2 macrophages co-cultured with hDPSCs showed spindle and round-shaped cells, with >90% viability when assessed by apoptosis assay. Inflammatory TNF-α and IL-1β profiles in stimulated co-cultures showed upregulated IL-1β, whereas TNF-α was downregulated (p < .05). Anti-inflammatory gene expression levels of IL-10 and TGF-β were downregulated (p < .05). Blocking with IL-1RA resulted in a remarkable decrease in IL-1β at the gene expression and protein production levels whilst TNF-α levels remained low (p < .05). Levels of anti-inflammatory cytokine IL-10 showed no significant difference.

CONCLUSION

Blocking the IL-1 receptor in hDPSCs and macrophage (M0, M1, M2) co-cultures activated with LPS resulted in downregulation of inflammatory cytokines IL-1β and TNF-α. These findings highlight the immunomodulatory effect of IL-1RA in inflammatory conditions of dental pulp infections.

Biological characteristics and pulp regeneration potential of stem cells from canine deciduous teeth compared with those of permanent teeth

BACKGROUND

Clinical studies have demonstrated that dental pulp stem cells isolated from permanent teeth (PT-DPSCs) are safe and efficacious for complete pulp regeneration in mature pulpectomized permanent teeth with complete apical closure. Moreover, dental pulp stem cells from deciduous teeth (DT-DPSCs) have also been shown to be useful for pulp regenerative cell therapy of injured immature permanent teeth. However, direct comparisons of the pulp regenerative potential of DT-DPSCs and PT-DPSCs from the same individual have not been performed. This study aimed to compare the differences in stem cell properties and pulp regenerative potential of DT-DPSCs and PT-DPSCs of identical origin.

METHODS

DT-DPSCs and PT-DPSCs were isolated from the same individual dogs at 4 months and 9 months of age, respectively. The expression of cell surface antigen markers, proliferation and migration activities, and gene expression of stem cell markers, angiogenic/neurotrophic factors and senescence markers were compared. The effects of conditioned medium (CM) derived from these cells on cellular proliferation, migration, angiogenesis, neurite outgrowth and immunosuppression were also compared. Autologous transplantation of DT-DPSCs or PT-DPSCs together with G-CSF was performed to treat pulpectomized teeth in individual dogs. The vascularization and reinnervation of the regenerated pulp tissues were qualitatively and quantitatively compared between groups by histomorphometric analyses.

RESULTS

The rates of positive CXCR4 and G-CSFR expression in DT-DPSCs were significantly higher than those in PT-DPSCs. DT-DPSCs migrated at a higher rate with/without G-CSF and exhibited increased expression of the stem cell markers Oct3/4 and CXCR4 and the angiogenic factor VEGF and decreased expression of the senescence marker p16 than PT-DPSCs. DT-DPSC-derived CM promoted increased cell proliferation, migration with G-CSF, and angiogenesis compared with PT-DPSC-derived CM; however, no difference was observed in neurite outgrowth or immunosuppression. The regenerated pulp tissues in the pulpectomized teeth were quantitatively and qualitatively similar between the DT-DPSCs and PT-DPSCs transplant groups.

CONCLUSIONS

These results demonstrated that DT-DPSCs could be a potential clinical alternative to PT-DPSCs for pulp regenerative therapy. DT-DPSCs can be preserved in an individual cell bank and used for potential future pulp regenerative therapy before the supply of an individual's own sound discarded teeth has been exhausted.

Global scientific trends on the immunomodulation of mesenchymal stem cells in the 21st century: A bibliometric and visualized analysis

Background

Since the discovery of the immunomodulatory functions of mesenchymal stem cells (MSCs), their application in immunomodulation has attracted considerable attention, and an increasing number of studies have been conducted worldwide. Our research aimed to investigate the global status and trends in this field.

Methods

Publications on the immunomodulatory functions of MSCs from 1 January 2000 to 7 March 2022 were retrieved from the Web of Science Core Collection. The data were studied and indexed using the bibliometric methodology. Visualization analysis, co-authorship, co-occurrence analysis, and publication trends in MSC immunomodulation were conducted using the VOSviewer software.

Results

In total, 4,227 papers were included in the study. The number of publications and research interests has significantly increased globally. China published the highest number of related articles, while the US published articles with the highest number of citations. Stem Cell Research & Therapy had the highest number of publications. Sun Yat-sen University, Shanghai Jiao Tong University, Harvard University, and Seoul National University were the most contributive institutions. Furthermore, the studies were divided into four research hotspots for MSC immunomodulation: MSC immunomodulation in regenerative medicine, the effects and mechanisms of MSC immunomodulation, MSC therapy for immune diseases, and the cell source of MSCs.

Conclusion

This study indicates that the number of publications on MSC immunomodulation will increase in the future, and MSC immunomodulation mechanisms and clinical applications of MSC immunotherapy should be the next hotspots in this research field.

Investigating the Effects of Conditioned Media from Stem Cells of Human Exfoliated Deciduous Teeth on Dental Pulp Stem Cells

Pulp regeneration has recently attracted interest in modern dentistry. However, the success ratio of pulp regeneration is low due to the compromising potential of stem cells, such as their survival, migration, and odontoblastic differentiation. Stem cells from human exfoliated deciduous teeth (SHED) have been considered a promising tool for regenerative therapy due to their ability to secrete multiple factors that are essential for tissue regeneration, which is achieved by minimally invasive procedures with fewer ethical or legal concerns than those of other procedures. The aim of this study is to investigate the potency of SHED-derived conditioned media (SHED CM) on dental pulp stem cells (DPSCs), a major type of mesenchymal stem cells for dental pulp regeneration. Our results show the promotive efficiency of SHED CM on the proliferation, survival rate, and migration of DPSCs in a dose-dependent manner. Upregulation of odontoblast/osteogenic-related marker genes, such as ALP, DSPP, DMP1, OCN, and RUNX2, and enhanced mineral deposition of impaired DPSCs are also observed in the presence of SHED CM. The analysis of SHED CM found that a variety of cytokines and growth factors have positive effects on cell proliferation, migration, anti-apoptosis, and odontoblast/osteogenic differentiation. These findings suggest that SHED CM could provide some benefits to DPSCs in pulp regeneration.