Mesenchymal stem cells derived from human gingiva are capable of immunomodulatory functions and ameliorate inflammation-related tissue destruction in experimental colitis

Gold nanoparticles biosynthesized by Nocardiopsis dassonvillei NCIM 5124 enhance osteogenesis in gingival mesenchymal stem cells

Gold nanoparticles are widely used for biomedical applications owing to their biocompatibility, ease of functionalization and relatively non-toxic nature. In recent years, biogenic nanoparticles have gained attention as an eco-friendly alternative for a variety of applications. In this report, we have synthesized and characterized gold nanoparticles (AuNPs) from an Actinomycete, Nocardiopsis dassonvillei NCIM 5124. The conditions for biosynthesis were optimized (100 mg/ml of cell biomass, 2.5 mM tetrachloroauric acid (HAuCl₄) at 80 °C and incubation time of 25 min) and the nanoparticles were characterized by TEM, SAED, EDS and XRD analysis. The nanoparticles were spherical and ranged in size from 10 to 25 nm. Their interactions with human gingival tissue-derived mesenchymal stem cells (GMSCs) and their potential applications in regenerative medicine were evaluated further. The AuNPs did not display cytotoxicity towards GMSCs when assessed by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay, DNA fragmentation patterns and Annexin V/propidium iodide staining techniques. These AuNPs induced faster cell migration when monitored by the in vitro wound healing assay. The effect of these nanoparticles on osteogenesis of GMSCs was also studied. Based on the results obtained from alkaline phosphatase, Von Kossa staining and Alizarin Red S staining, the AuNPs were seen to positively affect differentiation of GMSCs and enhance mineralization of the synthesized matrix. We therefore conclude that the biogenic, non-toxic AuNPs are of potential relevance for tissue regeneration applications.

Oral Mesenchymal Stem/Progenitor Cells: The Immunomodulatory Masters

Oral mesenchymal stem/progenitor cells (MSCs) are renowned in the field of tissue engineering/regeneration for their multilineage differentiation potential and easy acquisition. These cells encompass the periodontal ligament stem/progenitor cells (PDLSCs), the dental pulp stem/progenitor cells (DPSCs), the stem/progenitor cells from human exfoliated deciduous teeth (SHED), the gingival mesenchymal stem/progenitor cells (GMSCs), the stem/progenitor cells from the apical papilla (SCAP), the dental follicle stem/progenitor cells (DFSCs), the bone marrow mesenchymal stem/progenitor cells (BM-MSCs) from the alveolar bone proper, and the human periapical cyst-mesenchymal stem cells (hPCy-MSCs). Apart from their remarkable regenerative potential, oral MSCs possess the capacity to interact with an inflammatory microenvironment. Although inflammation might affect the properties of oral MSCs, they could inversely exert a multitude of immunological actions to the local inflammatory microenvironment. The present review discusses the current understanding about the immunomodulatory role of oral MSCs both in periodontitis and systemic diseases, their "double-edged sword" uniqueness in inflammatory regulation, their affection of the immune system, and the underlying mechanisms, involving oral MSC-derived extracellular vesicles.

Effect of Inflammation on Gingival Mesenchymal Stem/Progenitor Cells' Proliferation and Migration through Microperforated Membranes: An In Vitro Study

Background

In the field of periodontal guided tissue regeneration, microperforated membranes have recently proved to be very promising periodontal regenerative tissue engineering tools. Regenerative periodontal approaches, employing gingival mesenchymal stem/progenitor cells in combination with these novel membranes, would occur mostly in inflamed microenvironmental conditions intraorally. This in turn entails the investigation into how inflammation would affect the proliferation as well as the migration dynamics of gingival mesenchymal stem/progenitor cells. Materials and Methods. Clones of human gingival mesenchymal stem/progenitor cells (GMSCs) from inflamed gingival tissues were characterized for stem/progenitor cells' characteristics and compared to clones of healthy human GMSCs (n = 3), to be subsequently seeded on perforated collagen-coated poly-tetra-floro-ethylene (PTFE) membranes with a pore size 0.4 and 3 microns and polycarbonic acid membranes of 8 microns pore size in Transwell systems. The population doubling time and the MTT test of both populations were determined. Fetal bovine serum (FBS) was used as a chemoattractant in the culturing systems, and both groups were compared to their negative controls without FBS. Following 24 hours of incubation period, migrating cells were determined on the undersurface of microperforated membranes and the membrane-seeded cells were examined by scanning electron microscopy.

Results

GMSCs demonstrated all predefined stem/progenitor cell characteristics. GMSCs from inflamed gingival tissues showed significantly shorter population doubling times. GMSCs of inflamed and healthy tissues did not show significant differences in their migration abilities towards the chemoattractant, with no cellular migration observed in the absence of FBS. GMSCs from healthy gingival tissue migrated significantly better through larger micropores (8 microns). Scanning electron microscopic images proved the migratory activity of the cells through the membrane pores.

Conclusions

Inflammation appears to boost the proliferative abilities of GMSCs. In terms of migration through membrane pores, GMSCs from healthy as well as inflamed gingival tissues do not demonstrate a difference in their migration abilities through smaller pore sizes, whereas GMSCs from healthy gingival tissues appear to migrate significantly better through larger micropores.

Conditioned medium derived from FGF-2-modified GMSCs enhances migration and angiogenesis of human umbilical vein endothelial cells

BACKGROUND

Angiogenesis plays an important role in tissue repair and regeneration, and conditioned medium (CM) derived from mesenchymal stem cells (MSC-CM) possesses pro-angiogenesis. Nevertheless, the profile and concentration of growth factors in MSC-CM remain to be optimized. Fibroblast growth factor-2 (FGF-2) has been proven to be an effective angiogenic factor. Thus, the aim of this study was to verify whether FGF-2 gene overexpression optimized CM from human gingival mesenchymal stem cells (hGMSCs) and whether such optimized CM possessed more favorable pro-angiogenesis effect.

METHODS

First, FGF-2 gene-modified hGMSCs were constructed using lentiviral transfection technology (LV-FGF-2+-hGMSCs) and the concentration of angiogenesis-related factors in LV-FGF-2+-hGMSC-CM was determined by ELISA. Then, human umbilical vein endothelial cells (HUVECs) were co-cultured for 3 days with LV-FGF-2+-hGMSC-CM, and the expression level of placenta growth factor (PLGF), stem cell factor (SCF), vascular endothelial growth factor receptor 2 (VEGFR2) in HUVECs were determined by qRT-PCR, western blot, and cellular immunofluorescence techniques. The migration assay using transwell and in vitro tube formation experiments on matrigel matrix was conducted to determine the chemotaxis and angiogenesis enhanced by LV-FGF-2+-hGMSC-CM. Finally, NOD-SCID mice were injected with matrigel mixed LV-FGF-2+-hGMSC-CM, and the plug sections were analyzed by immunohistochemistry staining with anti-human CD31 antibody.

RESULTS

LV-FGF-2+-hGMSC-CM contained significantly more FGF-2, vascular endothelial growth factor A (VEGF-A), and transforming growth factor β (TGF-β) than hGMSC-CM. HUVECs pretreated with LV-FGF-2+-hGMSC-CM expressed significantly more PLGF, SCF, and VEGFR2 at gene and protein level than hGMSC-CM pretreated HUVECs. Compared with hGMSC-CM, LV-FGF-2+-hGMSC-CM presented significantly stronger chemotaxis to HUVECs and significantly strengthened HUVECs mediated in vitro tube formation ability. In vivo, LV-FGF-2+-hGMSC-CM also possessed stronger promoting angiogenesis ability than hGMSC-CM.

CONCLUSIONS

Overexpression of FGF-2 gene promotes hGMSCs paracrine of angiogenesis-related growth factors, thereby obtaining an optimized conditioned medium for angiogenesis promotion.

Mesenchymal stromal cell derived CCL2 is required for accelerated wound healing

Mesenchymal stromal cells (MSC) have immunomodulatory effects impacting macrophages, promoting polarisation towards a reparative phenotype. CCL2 is a potent cytokine involved in the recruitment of macrophages. We hypothesised that MSC derived CCL2 may be involved in the MSC therapeutic effect by facilitating macrophage repolarisation. To further delineate this mechanism, MSC isolated from CCL2 deficient mice (MSC-KO) were applied to excisional wounds in wild-type (WT) mice. CCL2 deficiency in MSC completely abrogated the therapeutic response compared to MSC-WT. MSC-KO were unable to repolarise macrophages to the same extent as WT and this was accompanied by a reduced angiogenesis and re-epithelialisation of the wounds at day 10. This study demonstrates that MSC derived CCL2 is required for MSC induced accelerated wound healing. The role of CCL2 in the interaction between MSC and Macrophages has not been previously demonstrated in accelerated wound healing. CCL2 has a potent effect on the ability to reduce the inflammatory response through local recruitment of macrophages. This research highlights CCL2 as a possible target for augmentation of MSC therapy to enhance therapeutic potential.

Biocompatibility of Biodentine™ ® with Periodontal Ligament Stem Cells: In Vitro Study

Biodentine™ is a tricalcium silicate-based cement material that has a great impact on different biological processes of dental stem cells, compared to other biomaterials. Therefore, we aimed to investigate the optimum biocompatible concentration of Biodentine™ with stem cells derived from periodontal ligament (hPDLSCs) by determining cell proliferation, cytotoxicity, migration, adhesion and mineralization potential. hPDLSCs were treated with Biodentine™ extract at different concentrations; 20, 2, 0.2 and 0.02 mg/mL. Cells cultured without Biodentine™ were used as a blank control. The proliferation potential of hPDLSCs was evaluated by MTT viability analysis for 6 days. Cytotoxicity assay was performed after 3 days by using AnnexinV/7AAD. Migration potential was investigated by wound healing and transwell migration assays at both cellular and molecular levels. The expression levels of chemokines CXCR4, MCP-1 and adhesion molecules FGF-2, FN, VCAM and ICAM-1 were measured by qPCR. The communication potentials of these cells were determined by adhesion assay. In addition, mineralization potential was evaluated by measuring the expression levels of osteogenic markers; ALP, OCN, OPN and Collagen type1 by qPCR. Our results showed significant increase in the proliferation of hPDLSCs at low concentrations of Biodentine™ (2, 0.2 and 0.02 mg/mL) while higher concentration (20 mg/mL) exhibited cytotoxic effect on the cells. Moreover, 2 mg/mL Biodentine™ showed a significant increase in the migration, adhesion and mineralization potentials of the derived cells among all concentrations and when compared to the blank control. Our findings suggest that 2 mg/mL of Biodentine™ is the most biocompatible concentration with hPDLSCs, showing a high stimulatory effect on the biological processes.

Repair and regeneration of small intestine: A review of current engineering approaches

The small intestine (SI) is difficult to regenerate or reconstruct due to its complex structure and functions. Recent developments in stem cell research, advanced engineering technologies, and regenerative medicine strategies bring new hope of solving clinical problems of the SI. This review will first summarize the structure, function, development, cell types, and matrix components of the SI. Then, the major cell sources for SI regeneration are introduced, and state-of-the-art biofabrication technologies for generating engineered SI tissues or models are overviewed. Furthermore, in vitro models and in vivo transplantation, based on intestinal organoids and tissue engineering, are highlighted. Finally, current challenges and future perspectives are discussed to help direct future applications for SI repair and regeneration.

Time-Course Transcriptome Analysis of Gingiva-Derived Mesenchymal Stem Cells Reveals That Fusobacterium nucleatum Triggers Oncogene Expression in the Process of Cell Differentiation

Fusobacterium nucleatum has pathogenic effects on oral squamous cell carcinoma and colon cancer, while the effects of continuously altered gene expression in normal human cells, as induced by persistent exposure to F. nucleatum, remain unclear. In this study, a microarray Significant Profiles (maSigPro) analysis was used to obtain the transcriptome profile of gingiva-derived mesenchymal stem cells (GMSCs) stimulated by F. nucleatum for 3, 7, 14, and 21 day, and the results revealed 790 (nine clusters) differentially expressed genes (DEGs), which were significantly enriched in cell adherens junctions and cancer-related pathways. On the basis of a short time-series expression miner (STEM) analysis, all the expressed genes in the GMSCs were grouped into 50 clusters according to dynamic gene expression patterns, and the expression levels of three gene clusters in the F. nucleatum-treated GMSCs were significantly different than the predicted values. Among the 790 DEGs, 50 tumor-associated genes (TAGs; such as L3MBTL4, CD163, CCCND2, CADM1, BCL7A, and IGF1) and five core dynamic DEGs (PLCG2, CHI3L2, L3MBTL4, SH2D2A, and NLRP3) were identified during F. nucleatum stimulation. Results from a GeneMANIA database analysis showed that PLCG2, CHI3L2, SH2D2A, and NLRP3 and 20 other proteins formed a complex network of which 12 genes were enriched in cancer-related pathways. Based on the five core dynamic DEGs, the related microRNAs (miRNAs) and transcription factors (TFs) were obtained from public resources, and an integrated network composed of the related TFs, miRNAs, and mRNAs was constructed. The results indicated that these genes were regulated by several miRNAs, such as miR-372-3p, miR-603, and miR-495-3p, and several TFs, including CREB3, GATA2, and SOX4. Our study suggests that long-term stimulation by F. nucleatum may trigger the expression of cancer-related genes in normal gingiva-derived stem cells.

Gingival mesenchymal stem cells as an alternative source to bone marrow mesenchymal stem cells in regeneration of bone defects: In vivo study

Healing of critical sized bone defects represents a challenging issue in clinical and research fields. Current therapeutic techniques, such as bone grafts or bone grafts substitutes, still have limitations and drawbacks. Therefore, stem cell-based therapy provides a prospective approach to enhance bone regeneration. The present study aimed to assess the regenerative capacity of Gingival mesenchymal stem cells (GMSCs) as well as Bone marrow mesenchymal stem cells (BMSCs) loaded on NanoBone scaffold, in comparison to the unloaded one, in surgically created bone defects in rabbits' tibiae. To achieve this aim, critical sized bone defects, of 6-mm diameter each, were unilaterally created in tibiae of adult New Zeeland male white rabbits (n = 27). The rabbits were then divided randomly into three groups (9 each) and received the following: Group I: Unloaded NanoBone Scaffold, Group II: GMSCs Loaded on NanoBone Scaffold, and Group III: BMSCs Loaded on NanoBone Scaffold. Three rabbits from each group were then sacrificed at each time point (2, 4 and 6 weeks postoperatively), tibiae were dissected out to evaluate bone healing in the created bony defects; both histologically and histomorphometrically. The findings of this study indicate that both GMSCs and BMSCs exhibited fibroblast morphology and expressed phenotypic MSCs markers. Histologically, local application of GMSCs and BMSCs loaded on NanoBone scaffold showed enhanced the pattern of bone regeneration as compared to the unloaded scaffold. Histomorphometrically, there was astatistically insignificant difference in the new bone area % between the bony defects treated with GMSCs and BMSCs. Thus, GMSCs can be considered as a comparable alternative source to BMSCs in bone regeneration.

Oral Rehabilitation of Patients Sustaining Orofacial Injuries: The UPenn Initiative

Tissue injuries in the oral and maxillofacial structures secondary to trauma, warfare, ablative cancer, and benign tumor surgery result in significant losses of speech, masticatory and swallowing functions, aesthetic deformities, and overall psychological stressors and compromise. Optimal oral rehabilitation remains a formidable challenge and an unmet clinical need due to the influence of multiple factors related to the physiologic limitations of tissue repair, the lack of site and function-specific donor tissues and constructs, and an integrated team of multidisciplinary professionals. The advancements in stem cell biology, biomaterial science, and tissue engineering technologies, particularly the 3-dimensional bioprinting technology, together with digital imaging and computer-aided design and manufacturing technologies, have paved the path for personalized/precision regenerative medicine. At the University of Pennsylvania, we have launched the initiative to integrate multidisciplinary health professionals and translational/clinical scientists in medicine, dentistry, stem cell biology, tissue engineering, and regenerative medicine to develop a comprehensive, patient-centered approach for precision and personalized reconstruction, as well as oral rehabilitation of patients sustaining orofacial tissue injuries and defects, especially oral cancer patients.

Anti-Inflammatory Action of Heterogeneous Nuclear Ribonucleoprotein A2/B1 in Patients with Autoimmune Endocrine Disorders

Our previous studies documented that human fibroblast-limbal stem cells (f-LSCs) possess immunosuppressive capabilities, playing a role in regulating T-cell activity. This study highlights the molecular activities by which human f-LSCs can attenuate the inflammatory responses of self-reactive peripheral blood mononuclear cells (PBMCs) collected from patients with autoimmune endocrine diseases (AEDs). Anti-CD3 activated PBMCs from twenty healthy donors and fifty-two patients with AEDs were cocultured on f-LSC monolayer. 2D-DIGE proteomic experiments, mass spectrometry sequencing and functional in vitro assays were assessed in cocultured PBMCs. We identified the downmodulation of several human heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) isoforms in healthy and AED activated PBMCs upon f-LSC interaction. The reduction of hnRNPA2/B1 protein expression largely affected the cycling ki67⁺, CD25⁺, PD-1⁺ reactive cells and the double marked CD8⁺/hnRNPA2B1⁺ T cell subset. Anti-PD1 blocking experiments evoked hnRNPA2/B1 overexpression, attributing putative activation function to the protein. hnRNPA2/B2 transient silencing inverted immunopolarization of the self-reactive PBMCs from AEDs toward a M2/Th2-type background. Pharmacological inhibition and co-immunoprecipitation experiments demonstrated the involvement of NF-ĸB in hnRNPA2/B activity and turnover. Our data indicate cardinal involvement of hnRNP A2/B1 protein in peripheral mechanisms of tolerance restoration and attenuation of inflammation, identifying a novel immunoplayer potentially targetable in all AEDs.

Mesenchymal stem cells and biologic factors leading to bone formation

BACKGROUND

Physiological bone formation and bone regeneration occurring during bone repair can be considered distinct but similar processes. Mesenchymal stem cells (MSC) and associated biologic factors are crucial to both bone formation and bone regeneration.

AIM

To perform a narrative review of the current literature regarding the role of MSC and biologic factors in bone formation with the aim of discussing the clinical relevance of in vitro and in vivo animal studies.

METHODS

The literature was searched for studies on MSC and biologic factors associated with the formation of bone in the mandible and maxilla. The search specifically targeted studies on key aspects of how stem cells and biologic factors are important in bone formation and how this might be relevant to bone regeneration. The results are summarized in a narrative review format.

RESULTS

Different types of MSC and many biologic factors are associated with bone formation in the maxilla and mandible.

CONCLUSION

Bone formation and regeneration involve very complex and highly regulated cellular and molecular processes. By studying these processes, new clinical opportunities will arise for therapeutic bone regenerative treatments.

Human gingiva tissue-derived MSC ameliorates immune-mediated bone marrow failure of aplastic anemia via suppression of Th1 and Th17 cells and enhancement of CD4+Foxp3+ regulatory T cells differentiation

Accumulating evidence has revealed that human gingiva-derived mesenchymal stem cells (GMSCs) are emerging as a new line of mesenchymal stem cells and may have the potential to control or even treat autoimmune diseases through maintaining the balance between Th and Treg cells. Given that GMSCs have a robust immune regulatory function and regenerative ability, we investigated the effect of GMSCs on preventing T cell-mediated bone marrow failure (BMF) in a mouse model. We observed that GMSCs markedly improved mice survival and attenuated histological bone marrow (BM) damage. Moreover, we found GMSCs significantly reduced cell infiltration of CD8+ cells, Th1 and Th17 cells, whereas increased CD4+Foxp3+ regulatory T cells (Tregs) differentiation in lymph nodes. GMSCs also suppressed the levels of TNF-α, IFN-γ, IL-17A and IL-6, but IL-10 was increased in serum. The live in vivo imaging identified that GMSCs can home into inflammatory location on BM. Our results demonstrate that GMSCs attenuate T cell-mediated BMF through regulating the balance of Th1, Th17 and Tregs, implicating that application of GMSCs may provide a promising approach in prevention and treatment of patients with aplastic anemia.

Acetylsalicylic acid rescues the immunomodulation of inflamed gingiva-derived mesenchymal stem cells via upregulating FasL in mice

Background

Gingiva-derived mesenchymal stem cells (GMSCs) obtained multipotent differentiation and immunomodulatory properties. However, collecting healthy gingival tissues may be challenging in the clinical situation. Thus, in our present study, we aim to evaluate whether the immunomodulatory capacity of gingiva-derived mesenchymal stem cells from inflamed gingival tissues (iGMSCs) is impaired and find a way to rescue their deficient properties.

Methods

We compared the immunomodulation capacity of GMSCs and iGMSCs using an in vitro co-culture system and a mouse colitis model. T cell apoptosis, T helper 17 (Th17), and regulatory T (Treg) cell differentiation were detected by flow cytometry analysis.

Results

We demonstrated that iGMSCs obtained a decreased immunomodulatory capacity compared with GMSCs. Acetylsalicylic acid (ASA) pretreatment was able to rescue iGMSCs’ impaired immunomodulatory properties. Mechanistically, ASA was capable of upregulating the expression of Fas ligand (FasL) in iGMSCs, leading to an improvement in iGMSC-mediated T cell apoptosis and therapeutic efficacy in the treatment in colitis mice.

Conclusions

This study indicates that the deficient immunomodulatory function of iGMSCs could be rescued by ASA pretreatment via upregulating of FasL in mice. This strategy might serve as a practical approach to rescue deficient MSC function for further therapeutic application.

Systematically transplanted human gingiva-derived mesenchymal stem cells regulate lipid metabolism and inflammation in hyperlipidemic mice with periodontitis

Gingiva-derived mesenchymal stem cells (GMSCs) have been the focus of extensive research due to their numerous distinct properties, including their homing to injury sites and their contribution to tissue regeneration. However, the role of transplanted GMSCs in the regulation of lipid metabolism and inflammation in hyperlipidemic mice with periodontitis has not been demonstrated. In the present study, apolipoprotein E-deficient (ApoE^−/−) mice were used to establish a hyperlipidemia model with periodontitis and divided into two groups: Group B and Group C (n=20 per group), and wild-type C57BL/6J mice without any treatment were assigned to Group A (n=20). Animals in Group C were then injected with human GMSCs through the tail vein and animals in Group B were injected with α-MEM as control. Animals were sacrificed at indicated time points. Serum was collected to determine the lipids and inflammatory cytokines. Liver samples were collected to estimate lipid-associated gene expression. Morphometric and histological analyses were performed to maxillaries. The results demonstrated that the delivery of GMSCs led to a significant decrease in triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL), interleukin (IL)-6, tumor necrosis factor (TNF)-α, alveolar bone loss (ABL), and sterol regulatory element binding protein-1c (SREBP-1c) mRNA, and a significant increase in high density lipoprotein cholesterol (HDL), IL-10 and peroxisome proliferator-activated receptor α (PPARα) mRNA in Group C compared to Group B. Histological examination showed increased formation of new bone and higher alveolar bone height in Group C. Systematically transplanted GFP-positive cells were detected through both fluorescence microscope observation and immunohistochemical staining in the periodontal tissues. Overall, systematically transplanted GMSCs attenuated the hyperlipidemia and inflammatory responses in hyperlipidemic mice with periodontitis, and improved periodontal tissue regeneration.

Mesenchymal Stem/Stromal Cells Derived from Dental Tissues: A Comparative In Vitro Evaluation of Their Immunoregulatory Properties Against T cells

Bone marrow mesenchymal stem/stromal cells (BM-MSCs) have immunoregulatory properties and have been used as immune regulators for the treatment of graft-versus-host disease (GVHD). Human dental tissue mesenchymal stem cells (DT-MSCs) constitute an attractive alternative to BM-MSCs for potential clinical applications because of their accessibility and easy preparation. The aim of this in vitro study was to compare MSCs from dental pulp (DP-MSCs), gingival tissue (G-MSCs), and periodontal ligament (PDL-MSCs) in terms of their immunosuppressive properties against lymphoid cell populations enriched for CD3⁺ T cells to determine which MSCs would be the most appropriate for in vivo immunoregulatory applications. BM-MSCs were included as the gold standard. Our results demonstrated, in vitro, that MSCs from DP, G, and PDL showed immunoregulatory properties similar to those from BM, in terms of the cellular proliferation inhibition of both CD4⁺- and CD8⁺-activated T-cells. This reduced proliferation in cell co-cultures correlated with the production of interferon-γ and tumor necrosis factor alpha (TNF-α) and the upregulation of programmed death ligand 1 (PD-L1) in MSCs and cytotoxic T-cell-associated Ag-4 (CTLA-4) in T-cells and increased interleukin-10 and prostaglandin E₂ production. Interestingly, we observed differences in the production of cytokines and surface and secreted molecules that may participate in T-cell immunosuppression in co-cultures in the presence of DT-MSCs compared with BM-MSCs. Importantly, MSCs from four sources favored the generation of T-cell subsets displaying the regulatory phenotypes CD4⁺CD25⁺Foxp3⁺ and CD4⁺CD25⁺CTLA-4⁺. Our results in vitro indicate that, in addition to BM-MSCs, MSCs from all of the dental sources analyzed in this study might be candidates for future therapeutic applications.

Therapeutic Application of Mesenchymal Stem Cells Derived Extracellular Vesicles for Immunomodulation

The immunosuppressive potential of mesenchymal stem cells has been extensively investigated in many studies in vivo and in vitro. In recent years, a variety preclinical and clinical studies have demonstrated that mesenchymal stem cells ameliorate immune-mediated disorders, including autoimmune diseases. However, to date mesenchymal stem cells have not become a widely used therapeutic agent due to safety challenges, high cost and difficulties in providing long term production. A key mechanism underpinning the immunomodulatory effect of MSCs is the production of paracrine factors including growth factors, cytokines, chemokines, and extracellular vesicles (EVs). MSCs derived EVs have become an attractive therapeutic agent for immunomodulation and treatment of immune-mediated disorders. In addition to many preclinical studies of MSCs derived EVs, their beneficial effects have been observed in patients with both acute graft-vs.-host disease and chronic kidney disease. In this review, we discuss the current findings in the field of MSCs derived EVs-based therapies in immune-mediated disorders and approaches to scale EV production for clinical use.

A Tetra-PEG Hydrogel Based Aspirin Sustained Release System Exerts Beneficial Effects on Periodontal Ligament Stem Cells Mediated Bone Regeneration

Bone defects, massive bone defects in particular, is still an issue clinically. Acetylsalicylic acid (ASA), also known as aspirin, has been proven to be conducive for mesenchymal stem cells osteogenic differentiation, which may be benefited for bone regeneration. In order to achieve a more appealing prognosis of bone defect, here we develop a well-defined tetra-PEG hydrogel sealant with rapid gelation speed, strong tissue adhesion, and high mechanical strength. After in-situ encapsulation of aspirin, this drug-loaded tetra-PEG hydrogel possessed a sustained release, anti-inflammation, and osteoinductive properties. In vitro experiments showed that the cell proliferation was slightly facilitated, and the osteogenic differentiation was notably augmented when periodontal ligament stem cells (PDLSCs) were co-incubating with the hydrogel materials. Moreover, in vivo study manifested that the aspirin sustained release system significantly facilitated the PDLSCs mediated bone defect regeneration. Overall, tetra-PEG hydrogel-based aspirin sustained release system is applicable not only for enhancing the osteogenesis capacity of PDLSC but also providing a new thought of bone regenerative therapy.

Inhibition of Tet1- and Tet2-mediated DNA demethylation promotes immunomodulation of periodontal ligament stem cells

Periodontal ligament stem cells (PDLSCs) possess great potential for clinical treatment of immune diseases due to their extensive immunomodulatory properties. However, the underlying mechanisms that govern the immunomodulatory properties of mesenchymal stem cells (MSCs) are still not fully elucidated. Here, we show that member of the Ten-eleven translocation (Tet) family, a group of DNA demethylases, are capable of regulating PDLSC immunomodulatory functions. Tet1 and Tet2 deficiency enhance PDLSC-induced T cell apoptosis and ameliorate the disease phenotype in colitis mice. Mechanistically, we found that downregulation of Tet1 and Tet2 leads to hypermethylation of DKK-1 promoter, leading to the activation of WNT signaling pathway and therefore promoting Fas ligand (FasL) expression, which results in elevated immunomodulatory capacity of PDLSCs. These results reveal a previously unrecognized role of Tet1 and Tet2 in regulating immunomodulation of PDLSCs. This Tet/DKK-1/FasL cascade may serve as a promising target for enhancing PDLSC-based immune therapy.

The effects of Sema3A overexpression on the proliferation and differentiation of rat gingival mesenchymal stem cells in the LPS-induced inflammatory environment

Semaphorin3A has been identified as a potent osteoprotective factor that simultaneously inhibits bone resorption and promotes bone formation. The present study demonstrates the effect of the overexpression of Sema3A on the proliferation and differentiation of rat gingival mesenchymal stem cells (GMSCs) in the lipopolysaccharide (LPS)-induced inflammatory environment. rGMSCs were transfected with viral stocks of pLenO-GTP-Sema3A (Lv-Sema3A group) or pLenO-GTP (Lv-NC group), with rGMSCs as a control. The transfection efficiency was determined by flow cytometry. Cell proliferation was assessed using a Cell Counting Kit-8 assay. The expressions of alkaline phosphatase (ALP), osteocalcin (OCN), and runt-related transcription factor 2 (Runx2) were determined at 3, 7 and 14 days after the osteogenic induction culture with or without LPS using real-time PCR and Western blot. Alizarin Red staining was performed at 28 days. A pLenO-GTP-Sema3A-mediated transfection of rGMSC stably overexpressing Sema3A was built up. The overexpression of Sema3A promoted cell proliferation in the LPS-induced inflammatory environment. In addition, osteogenesis-related genes were upregulated in the Lv-Sema3A group compared with the control group. Also, after LPS administration, the overexpression of Sema3A enhanced the expression of the osteogenic genes in the LPS-induced inflammatory environment. Hence, Sema3A gene-modified rGMSCs show better osteogenic differentiation and proliferation capacities compared with rGMSCs in the LPS-induced inflammatory environment.

Immunomodulatory properties of dental tissue-derived mesenchymal stem cells: Implication in disease and tissue regeneration

Mesenchymal stem cells (MSCs) are considered as an attractive tool for tissue regeneration and possess a strong immunomodulatory ability. Dental tissue-derived MSCs can be isolated from different sources, such as the dental pulp, periodontal ligament, deciduous teeth, apical papilla, dental follicles and gingiva. According to numerous in vitro studies, the effect of dental MSCs on immune cells might depend on several factors, such as the experimental setting, MSC tissue source and type of immune cell preparation. Most studies have shown that the immunomodulatory activity of dental MSCs is strongly upregulated by activated immune cells. MSCs exert mostly immunosuppressive effects, leading to the dampening of immune cell activation. Thus, the reciprocal interaction between dental MSCs and immune cells represents an elegant mechanism that potentially contributes to tissue homeostasis and inflammatory disease progression. Although the immunomodulatory potential of dental MSCs has been extensively investigated in vitro, its role in vivo remains obscure. A few studies have reported that the MSCs isolated from inflamed dental tissues have a compromised immunomodulatory ability. Moreover, the expression of some immunomodulatory proteins is enhanced in periodontal disease and even shows some correlation with disease severity. MSC-based immunomodulation may play an essential role in the regeneration of different dental tissues. Therefore, immunomodulation-based strategies may be a very promising tool in regenerative dentistry.

Noncoding RNAs: new insights into the odontogenic differentiation of dental tissue-derived mesenchymal stem cells

Odontoblasts are cells that contribute to the formation of the dental pulp complex. The differentiation of dental tissue-derived mesenchymal stem cells into odontoblasts comprises many factors and signaling pathways. Noncoding RNAs (ncRNAs), comprising a substantial part of poly-A tail mature RNAs, are considered “transcriptional noise.” Emerging evidence has shown that ncRNAs have key functions in the differentiation of mesenchymal stem cells. In this review, we discussed two major types of ncRNAs, including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), in terms of their role in the odontogenic differentiation of dental tissue-derived stem cells. Recent findings have demonstrated important functions for miRNAs and lncRNAs in odontogenic differentiation. It is expected that ncRNAs will become promising therapeutic targets for dentin regeneration based on stem cells.

Reduced enamel epithelium-derived cell niche in the junctional epithelium is maintained for a long time in mice

BACKGROUND

Although numerous reports have demonstrated that the junctional epithelium (JE) is derived from the reduced enamel epithelium (REE), the fate of the REE-derived JE remains controversial. The present study elucidated the fate of the REE-derived JE and the cell dynamics of stem/progenitor cells in the JE following tooth eruption.

METHODS

Mandibular first molar germs (embryonic days 15 to postnatal 1-day-old) were transplanted into the socket of 2-week-old mice after extraction of the upper first molars of B6 wild-type (WT) and green fluorescent protein (GFP) transgenic mice. After analysis by µ-CT, paraffin sections were processed for immunohistochemistry for Nestin, Ki67 and GFP. We also performed chasing analysis using BrdU-administered TetOP-H2B-GFP mice.

RESULTS

Amelogenesis progressed normally in the cervical areas, and the structure of the JE was like that in normal tooth development. The JE was GFP-negative in transplantations using GFP transgenic mice as the host, and the oral epithelium (OE) showed a positive reaction. By contrast, the JE remained GFP-positive throughout the experimental period in transplantations using GFP transgenic mice as the donor. Chasing analysis revealed that H2B-GFP- and 5-Bromo-2'-deoxyuridine (BrdU)-labeled cells in the basal side of the JE translocated to oral side of the JE as the chasing time increased. Some label-retaining cells remained at the supra-basal cell layer in the JE.

CONCLUSION

These results suggest that REE-derived cell niche in the JE is maintained for a long time following tooth eruption. Therefore, the JE may be available as the source of the odontogenic epithelium.

Muscone Promotes The Adipogenic Differentiation Of Human Gingival Mesenchymal Stem Cells By Inhibiting The Wnt/β-Catenin Signaling Pathway

Objectives

This study was performed to evaluate the effects of muscone on the proliferation, migration and differentiation of human gingival mesenchymal stem cells (GMSCs) and to explore the relevant mechanisms.

Materials and methods

We performed studies to determine the effects and mechanisms of muscone on GMSC proliferation, migration and differentiation. We conducted CCK-8, colony formation, transwell chamber, scratch wound, alkaline phosphatase (ALP) staining and activity, and alizarin red and oil red O staining assays, as well as real-time quantitative polymerase chain reaction (qRT-PCR), to ascertain the effects of muscone on GMSC proliferation, migration and differentiation in vitro. The mechanism by which muscone influences the osteogenic and adipogenic differentiation of GMSCs was elucidated by qRT-PCR and Western blotting.

Results

We found that muscone significantly promoted GMSC proliferation, chemotaxis, wound healing and fat droplet formation and inhibited ALP activity and mineral deposition. Notably, we observed that the Wnt/β-catenin pathway was closely related to the ability of muscone to inhibit the osteogenic differentiation and promote the adipogenic differentiation of GMSCs. The effect of muscone on the multidirectional differentiation capacity of GMSCs was significantly reversed by the agonist lithium chloride through the Wnt/β-catenin signaling pathway.

Conclusion

Muscone effectively increased the proliferation and migration, promoted the adipogenic differentiation and inhibited the osteogenic differentiation of GMSCs by inhibiting the Wnt/β-catenin signaling pathway. These results may provide a theoretical basis for the application of GMSCs and muscone in tissue engineering and regenerative medicine.

Dental Follicle Cells: Roles in Development and Beyond

Dental follicle cells (DFCs) are a group of mesenchymal progenitor cells surrounding the tooth germ, responsible for cementum, periodontal ligament, and alveolar bone formation in tooth development. Cascades of signaling pathways and transcriptional factors in DFCs are involved in directing tooth eruption and tooth root morphogenesis. Substantial researches have been made to decipher multiple aspects of DFCs, including multilineage differentiation, senescence, and immunomodulatory ability. DFCs were proved to be multipotent progenitors with decent amplification, immunosuppressed and acquisition ability. They are able to differentiate into osteoblasts/cementoblasts, adipocytes, neuron-like cells, and so forth. The excellent properties of DFCs facilitated clinical application, as exemplified by bone tissue engineering, tooth root regeneration, and periodontium regeneration. Except for the oral and maxillofacial regeneration, DFCs were also expected to be applied in other tissues such as spinal cord defects (SCD), cardiomyocyte destruction. This article reviewed roles of DFCs in tooth development, their properties, and clinical application potentials, thus providing a novel guidance for tissue engineering.

Comparison of gingiva-derived and bone marrow mesenchymal stem cells for osteogenesis

Presently, bone marrow is considered as a prime source of mesenchymal stem cells; however, there are some drawbacks and limitations. Compared with other mesenchymal stem cell (MSC) sources, gingiva‐derived mesenchymal stem cells (GMSCs) are abundant and easy to obtain through minimally invasive cell isolation techniques. In this study, MSCs derived from gingiva and bone marrow were isolated and cultured from mice. GMSCs were characterized by osteogenic, adipogenic and chondrogenic differentiation, and flow cytometry. Compared with bone marrow MSCs (BMSCs), the proliferation capacity was judged by CCK‐8 proliferation assay. Osteogenic differentiation was assessed by ALP staining, ALP assay and Alizarin red staining. RT‐qPCR was performed for ALP, OCN, OSX and Runx2. The results indicated that GMSCs showed higher proliferative capacity than BMSCs. GMSCs turned more positive for ALP and formed a more number of mineralized nodules than BMSCs after osteogenic induction. RT‐qPCR revealed that the expression of ALP, OCN, OSX and Runx2 was significantly increased in the GMSCs compared with that in BMSCs. Moreover, it was found that the number of CD90‐positive cells in GMSCs elevated more than that of BMSCs during osteogenic induction. Taking these results together, it was indicated that GMSCs might be a promising source in the future bone tissue engineering.

Guided tissue regeneration of intrabony defects with perforated barrier membranes, simvastatin, and EDTA root surface modification: A clinical and biochemical study

BACKGROUND

Perforated barrier membranes (PBM) were suggested to enhance periodontal regeneration by allowing positive charity of wanted elements from the gingival tissue side. The present study was designed to evaluate clinically and biochemically the use of PBM combined with simvastatin (SMV) gel with and without an associated EDTA gel root surface etching as a suggested option that could improve SMV availability and clinical outcomes of PBM.

METHODS

Forty patients having moderate-to-severe chronic periodontitis with 40 intrabony defects were randomly divided into four treatment groups (10 sites each). Patients in group 1 received 1.2% SMV gel and covering the defect with occlusive membrane (OM). Patients in group 2 received 1.2% SMV gel and covering the defect with PBM. Group 3 received 24% EDTA root surface etching, 1.2% SMV gel, and defect coverage with OM (eOM). Patients in group 4 were treated as in group 3 but the defect was covered with PBM (ePBM). Clinical parameters were recorded at baseline before surgical procedures and were reassessed at 6 and 9 months after therapy. The mean concentration of SMV in gingival crevicular fluid (GCF) was estimated by reverse-phase high-performance liquid chromatography at days 1, 7, 14, 21, and 30.

RESULTS

At 6- and 9-month observation periods, groups 3 and 4 showed a statistically significant improvement in PD reduction and CAL gain compared with groups 1 and 2. Group 4 showed a statistically significant more defect fill compared with groups 1, 2, and 3 (P ≤ .05). Group 2 showed statistically significant higher defect fill compared with group 1 and group 3 (P < .05). Bone density was significantly increased with no significant difference between the four groups at 6- and 9-month observation periods. SMV-GCF concentration in group 4 showed the highest mean concentration with no significant difference than that of group 3.

CONCLUSION

The use of perforated barrier membranes in association with SMV enhances the clinical hard tissue parameters compared with occlusive ones in treating intrabony periodontal defects. Moreover, EDTA root surface treatment could enhance SMV availability in the defect area.

A protocol for isolation and culture of mesenchymal stem cells from human gingival tissue

Human gingiva-derived mesenchymal stem cells (GMSCs) have been considered to be a better source of MSCs for cell therapy in some immunological diseases. We describe a protocol for isolation and culture of mesenchymal stem cells (MSCs) from human gingival tissue in detail, which provides a methodology to help clinical researches and clinical trial. GMSCs are generally isolated from a remnant or discarded tissue following a routine dental procedure, then cultured in complete culture medium at 37°C in a humidified tissue culture incubator with 5% CO₂ and 95% O₂. Non-adherent cells are removed after 48~72 h and the fresh medium is replaced. When primary cultures become 80%~90% confluent, the plastic-adherent cells are treated with 0.25% trypsin-EDTA and subcultured. A purified population of GMSCs can be obtained 2-3 weeks after the initiation of culture.

IFN-γ-tethered hydrogels enhance mesenchymal stem cell-based immunomodulation and promote tissue repair

Because of their immunomodulatory activities, human mesenchymal stem cells (hMSCs) are being explored to treat a variety of chronic conditions such as inflammatory bowel disorders and graft-vs-host disease. Treating hMSCs with IFN-γ prior to administration augments these immunomodulatory properties; however, this ex vivo treatment limits the broad applicability of this therapy due to technical and regulatory issues. In this study, we engineered an injectable synthetic hydrogel with tethered recombinant IFN-γ that activates encapsulated hMSCs to increase their immunomodulatory functions and avoids the need for ex vivo manipulation. Tethering IFN-γ to the hydrogel increases retention of IFN-γ within the biomaterial while preserving its biological activity. hMSCs encapsulated within hydrogels with tethered IFN-γ exhibited significant differences in cytokine secretion and showed a potent ability to halt activated T-cell proliferation and monocyte-derived dendritic cell differentiation compared to hMSCs that were pre-treated with IFN-γ and untreated hMSCs. Importantly, hMSCs encapsulated within hydrogels with tethered IFN-γ accelerated healing of colonic mucosal wounds in both immunocompromised and immunocompetent mice. This novel approach for licensing hMSCs with IFN-γ may enhance the clinical translation and efficacy of hMSC-based therapies.

Mesenchymal stem cells: Cell therapy and regeneration potential

Rapid advances in the isolation of multipotent progenitor cells, routinely called mesenchymal stromal/stem cells (MSCs), from various human tissues and organs have provided impetus to the field of cell therapy and regenerative medicine. The most widely studied sources of MSCs include bone marrow, adipose, muscle, peripheral blood, umbilical cord, placenta, fetal tissue, and amniotic fluid. According to the standard definition of MSCs, these clonal cells adhere to plastic, express cluster of differentiation (CD) markers such as CD73, CD90, and CD105 markers, and can differentiate into adipogenic, chondrogenic, and osteogenic lineages in vitro. However, isolated MSCs have been reported to vary in their potency and self-renewal potential. As a result, the MSCs used for clinical applications often lead to variable or even conflicting results. The lack of uniform characterization methods both in vitro and in vivo also contributes to this confusion. Therefore, the name "MSCs" itself has been increasingly questioned lately. As the use of MSCs is expanding rapidly, there is an increasing need to understand the potential sources and specific potencies of MSCs. This review discusses and compares the characteristics of MSCs and suggests that the variations in their distinctive features are dependent on the source and method of isolation as well as epigenetic changes during maintenance and growth. We also discuss the potential opportunities and challenges of MSC research with the hope to stimulate their use for therapeutic and regenerative medicine.

Human gingiva-derived mesenchymal stem cells alleviate inflammatory bowel disease via IL-10 signalling-dependent modulation of immune cells

Current evidence indicates that inflammatory bowel disease (IBD) is caused primarily by impaired mucosal immunity, resulting in an imbalance between epithelial barrier function and tissue inflammation. Human gingiva-derived mesenchymal stem cells (GMSCs) exhibit immunomodulatory and anti-inflammatory effects in a variety of immunity- and inflammation-associated diseases. However, the role of GMSCs in treating IBD has not been elucidated. Our study, therefore, examined the therapeutic effect and mechanism of GMSCs in a murine colitis model of IBD. Our results indicate that the infusion of GMSCs significantly prolonged survival and relieved symptoms. Phenotype analyses showed that the frequencies of NK1.1⁺ and CD11b⁺ cells, as well as CD4 T cells in the spleen, were suppressed in GMSC-treated mice compared with the PBS- or fibroblast-treated control groups. Additionally, GMSC treatment markedly increased the numbers of interleukin (IL)-10⁺ regulatory T cells, reduced the secretion of pro-inflammatory cytokines, and increased production of anti-inflammatory cytokines. A mechanistic study revealed that anti-IL-10R antibody abolished the protective effect of GMSCs compared with mice treated with anti-IgG antibody. Thus, our results indicate that GMSCs play a critical role in alleviating colitis by modulating inflammatory immune cells via IL-10 signalling.

Role of hydrogen sulfide in the musculoskeletal system

Hydrogen sulfide (H₂S) has been known as a gasotransmitter, and it contributes to various physiological and pathological processes. Multiple enzymes such as cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-Mercaptopyruvate sulfurtransferase (MST) produce endogenous H₂S, and these are differentially expressed in the various tissue systems including the skeletal system. However, abnormal H₂S production is associated with deregulation of the signaling cascade and imbalanced tissue homeostasis. Several studies have previously provided evidence showing the essential regulatory action of H₂S in skeletal homeostasis. In this review, we have emphasized the novel function of H₂S in both bone and skeletal muscle anabolism, in particular. Additionally, we also reviewed the molecular and epigenetic basis of H₂S signaling in bone development and skeletal muscle function.

Human Mesenchymal Stem Cell-Treated Regulatory CD23+CD43+ B Cells Alleviate Intestinal Inflammation

Rationale: Mesenchymal stem cells (MSCs) have been demonstrated to ameliorate inflammatory bowel disease by their actions on multiple immune cells, especially on regulatory B cells (Breg cells). However, the phenotypes and functions of human MSCs (hMSCs)-treated Breg cell subsets are not yet clear.

Methods: Purified B cells were cocultured with MSCs and the phenotypes and immunomodulatory functions of the B cells were analyzed by FACS and proliferation assays in vitro. Also, a trinitrobenzenesulfonic acid-induced mouse colitis model was employed to detect the function of MSC-treated Breg cells in vivo.

Results: We demonstrated that coculturing with hMSCs significantly enhanced the immunomodulatory activity of B cells by up-regulating IL-10 expression. We then identified that a novel regulatory B cell population characterized by CD23 and CD43 phenotypic markers could be induced by hMSCs. The CD23⁺CD43⁺ Breg cells substantially inhibited the inflammatory cytokine secretion and proliferation of T cells through an IL-10-dependent pathway. More significantly, intraperitoneal injection of hMSCs ameliorated the clinical and histopathological severity in the mouse experimental colitis model, accompanied by an increase in the number of CD23⁺CD43⁺ Breg cells. The adoptive transfer of CD23⁺CD43⁺ B cells effectively alleviated murine colitis, as compared with the CD23^-CD43^- B cells. Treatment with CD23⁺CD43⁺ B cells, and not hMSCs, substantially improved the symptoms of colitis in B cell-depleted mice.

Conclusion: the novel CD23⁺CD43⁺ Breg cell subset appears to be involved in the immunomodulatory function of hMSCs and sheds new light on elucidating the therapeutic mechanism of hMSCs for the treatment of inflammation-related diseases.

MSC: immunoregulatory effects, roles on neutrophils and evolving clinical potentials

Mesenchymal stem cells (MSCs) are multipotent, non-hematopoietic stem cells capable of differentiating into varieties of mature cell types such as osteoblasts, chondrocytes, adipocytes, and myoblasts. MSCs can be isolated from different kinds of tissues and cultivated in vitro for amplification and passage easily. These cells have drawn researcher's attention lately due to their ability of tissue repair, properties of hematopoiesis support and function of immunoregulation through the secretion of a variety of cytokines and growth factors that have both paracrine and autocrine activities. MSCs can regulate the proliferation of T cells, the antibodies secretion of B cells, maturation of DC, polarization of macrophages and also have many effects on neutrophils such as the suppression of NO secretion, inhibition of apoptosis, reduction of their infiltration, decreasing of N-Formy l-L-Methionine-L-leucy l-L-phenylalanine, induction of respiratory bursts and promotion of survivals. In some conditions, MSCs exert their function of treatment through immunoregulation. We reviewed the multifaceted roles of MSCs in communicating with immune cells mainly neutrophils in both in vivo and in vitro experiments. MSCs may provide promising trends for cell therapy in future.

A preclinical study-systemic evaluation of safety on mesenchymal stem cells derived from human gingiva tissue

BACKGROUND

Mounting evidence has shown that a novel subset of mesenchymal stem cells (MSCs) derived from human gingiva referred to as gingival mesenchymal stem cells (GMSCs) displays a greater immunotherapeutic potential and regenerative repair expression than MSCs obtained from other tissues. However, the safety of the use of transplanted GMSCs in humans remains unclear.

METHODS

In this study, we evaluated the safety of GMSCs transplanted into mouse, rat, rabbit, beagle dog, and monkey as well as two animal models of autoimmune diseases.

RESULTS

In short- and long-term toxicity tests, infused GMSCs had no remarkable adverse effects on hematologic and biochemical indexes, particularly on the major organs such as heart, liver, spleen, and kidney in recipient animals. It was also shown that GMSCs were well tolerated in other assays including hemolysis, vascular, and muscular stimulation, as well as systemic anaphylaxis and passive skin Arthus reaction in animal models. GSMC infusion did not cause any notable side effects on animal models of either autoimmune arthritis or lupus. Significantly, GMSCs most likely play no role in genotoxicity and tumorigenesis. The biological features remained stable for an extended period after cell transfer.

CONCLUSIONS

GMSCs are safe in various animal models of autoimmunity, even during active disease episodes, especially in monkeys. This study paves a solid road for future clinical trials of GMSCs in patients with autoimmune and inflammatory diseases.

Small molecule inhibitor of TGF-β signaling enables robust osteogenesis of autologous GMSCs to successfully repair minipig severe maxillofacial bone defects

BACKGROUND

Clinically, for stem cell-based therapy (SCBT), autologous stem cells are considered better than allogenic stem cells because of little immune rejection and no risk of communicable disease infection. However, severe maxillofacial bone defects restoration needs sufficient autologous stem cells, and this remains a challenge worldwide. Human gingival mesenchymal stem cells (hGMSCs) derived from clinically discarded, easily obtainable, and self-healing autologous gingival tissues, have higher proliferation rate compared with autologous bone marrow mesenchymal stem cells (hBMSCs). But for clinical bone regeneration purpose, GMSCs have inferior osteogenic differentiation capability. In this study, a TGF-β signaling inhibitor SB431542 was used to enhance GMSCs osteogenesis in vitro and to repair minipig severe maxillofacial bone defects.

METHODS

hGMSCs were isolated and cultured from clinically discarded gingival tissues. The effects of SB431542 on proliferation, apoptosis, and osteogenic differentiation of hGMSCs were analyzed in vitro, and then, SB431542-treated hGMSCs composited with Bio-Oss® were transplanted into immunocompromised mice subcutaneously to explore osteogenic differentiation in vivo. After that, SB431542-treated autologous pig GMSCs (pGMSCs) composited with Bio-Oss® were transplanted into circular confined defects (5 mm × 12 mm) in minipigs maxillary to investigate severe bone defect regeneration. Minipigs were sacrificed at 2 months and nude mice at 8 weeks to retrieve specimens for histological or micro-CT or CBCT analysis. Effects of SB431542 on TGF-β and BMP signaling in hGMSCs were investigated by Western Blot or qRT-PCR.

RESULTS

One micromolar of SB431542 treatment induced a robust osteogenesis of hGMSCs in vitro, without adverse effect on apoptosis and growth. In vivo, 1 μM SB431542 treatment also enabled striking osteogenesis of hGMSCs subcutaneously in nude mice and advanced new bone formation of pGMSCs in minipig maxillary bone defect model. In addition, SB431542-treated hGMSCs markedly increased bone-related proteins expression, and BMP2 and BMP4 gene expression. Conversely, SMAD3 protein-dependent TGF-β signal pathway phosphorylation was decreased.

CONCLUSIONS

Our study show that osteogenic differentiation of GMSCs treated with TGF-β signaling inhibitor SB431542 was increased, and SB431542-treated autologous pig GMSCs could successfully repair minipig severe maxillofacial bone defects. This preclinical study brings about a promising large bone regeneration therapeutic potential of autologous GMSCs induced by SB431542 in clinic settings.

Human gingival tissue-derived MSC suppress osteoclastogenesis and bone erosion via CD39-adenosine signal pathway in autoimmune arthritis

BACKGROUND

Bone destruction is one of many severe complications that occurs in patients with rheumatoid arthritis (RA) and current therapies are unable to cure this manifestation. This study here aims to determine whether GMSC can directly inhibit osteoclast formation and eventually attenuate osteoclastogenesis and bone erosion in an inflammatory milieu.

METHOD

GMSC were co-cultured with osteoclast precursors with or without CD39 inhibitor, CD73 inhibitor or adenosine receptors inhibitors pretreatment and osteoclast formation were evaluated in vitro. 2×10^6 GMSC per mouse were transferred to CIA mice and pathology scores, the frequency of osteoclasts, bone erosion in joints were assessed in vivo.

FINDING

GMSC but not control cells, markedly suppressed human or mice osteoclastogenesis in vitro. GMSC treatment also resulted in a dramatically decreased level of NF-κB p65/p50 in osteoclasts in vitro. Infusion of GMSC to CIA significantly attenuated the severity of arthritis, pathology scores, frequency of osteoclasts, particularly bone erosion, as well as a decreased expression of RANKL in synovial tissues in vivo. Blockade of CD39/CD73 or adenosine receptors has significantly abrogated the suppressive ability of GMSC in vitro and therapeutic effect of GMSC on bone erosion during CIA in vivo.

INTERPRETATION

GMSC inhibit osteoclast formation in vitro and in vivo partially via CD39-CD73-adenosine signals. Manipulation of GMSC may have a therapeutic implication on rheumatoid arthritis and other bone erosion related diseases. FUND: This study was supported by grants from the National Key R&D Program of China (2017YFA0105801 to F.H); the Zhujiang Innovative and Entrepreneurial Talent Team Award of Guangdong Province (2016 ZT 06S 252 to F·H) and National Institutes of Health (R01 AR059103, R61 AR073409 and NIH Star Award to S.G.Z).

Exosomes from Human Gingiva-Derived Mesenchymal Stem Cells Combined with Biodegradable Chitin Conduits Promote Rat Sciatic Nerve Regeneration

At present, repair methods for peripheral nerve injury often fail to get satisfactory result. Although various strategies have been adopted to investigate the microenvironment after peripheral nerve injury, the underlying molecular mechanisms of neurite outgrowth remain unclear. In this study, we evaluate the effects of exosomes from gingival mesenchymal stem cells (GMSCs) combined with biodegradable chitin conduits on peripheral nerve regeneration. GMSCs were isolated from human gingival tissue and characterized by surface antigen analysis and in vitro multipotent differentiation. The cell supernatant was collected to isolate the exosomes. The exosomes were characterized by transmission electron microscopy, Western blot, and size distribution analysis. The effects of exosomes on peripheral nerve regeneration in vitro were evaluated by coculture with Schwann cells and DRGs. The chitin conduit was prepared and combined with the exosomes to repair rat sciatic nerve defect. Histology, electrophysiology, and gait analysis were used to test the effects of exosomes on sciatic nerve function recovery in vivo. We have successfully cultured GMSCs and isolated exosomes. The exosomes from GMSCs could significantly promote Schwann cell proliferation and DRG axon growth. The in vivo studies showed that chitin conduit combined with exosomes from GMSCs could significantly increase the number and diameter of nerve fibers and promote myelin formation. In addition, muscle function, nerve conduction function, and motor function were also obviously recovered. In summary, this study suggests that GMSC-derived exosomes combined with biodegradable chitin conduits are a useful and novel therapeutic intervention in peripheral nerve repair.

Effect of tetrahedral DNA nanostructures on proliferation and osteogenic differentiation of human periodontal ligament stem cells

OBJECTIVE

To explore the effects and underlying biological mechanisms of tetrahedral DNA nanostructures (TDNs) on the proliferation and osteogenic differentiation of periodontal ligament stem cells (PDLSCs).

MATERIALS AND METHODS

Real-time cell analysis (RTCA) and CCK8 were used to screen the best concentration of TDN for PDLSCs. Cell proliferation and osteogenic differentiation were assessed after PDLSCs were treated with TDN. Data were analysed using one-way ANOVA.

RESULTS

Tetrahedral DNA nanostructures could play a crucial role in accelerating the proliferation of PDLSCs and had the strongest promotive effect on PDLSCs at a concentration of 250 nmol/L. Simultaneously, the osteogenic differentiation of PDLSCs could be promoted significantly by TDNs and the finding displayed that the Wnt/β-catenin signalling pathway might be the underlying biological mechanisms of TDNs on promoting the osteogenic differentiation of PDLSCs.

CONCLUSION

Tetrahedral DNA nanostructure treatment facilitated the proliferation of PDLSCs, significantly promoted osteogenic differentiation by regulating the Wnt/β-catenin signalling pathway. Therefore, TDNs could be a novel nanomaterial with great potential for application to PDLSC-based bone tissue engineering.

Non-woven bilayered biodegradable chitosan-gelatin-polylactide scaffold for bioengineering of tracheal epithelium

OBJECTIVES

The conversion of tissue engineering into a routine clinical tool cannot be achieved without a deep understanding of the interaction between cells and scaffolds during the process of tissue formation in an artificial environment. Here, we have investigated the cultivation conditions and structural features of the biodegradable non-woven material in order to obtain a well-differentiated human airway epithelium.

MATERIALS AND METHODS

The bilayered scaffold was fabricated by electrospinning technology. The efficiency of the scaffold has been evaluated using MTT cell proliferation assay, histology, immunofluorescence and electron microscopy.

RESULTS

With the use of a copolymer of chitosan-gelatin-poly-l-lactide, a bilayered non-woven scaffold was generated and characterized. The optimal structural parameters of both layers for cell proliferation and differentiation were determined. The basal airway epithelial cells differentiated into ciliary and goblet cells and formed pseudostratified epithelial layer on the surface of the scaffold. In addition, keratinocytes formed a skin equivalent when seeded on the same scaffold. A comparative analysis of growth and differentiation for both types of epithelium was performed.

CONCLUSIONS

The structural parameters of nanofibres should be selected experimentally depending on polymer composition. The major challenges on the way to obtain the well-differentiated equivalent of respiratory epithelium on non-woven scaffold include the following: the balance between scaffold permeability and thickness, proper combination of synthetic and natural components, and culture conditions sufficient for co-culturing of airway epithelial cells and fibroblasts. For generation of skin equivalent, the lack of diffusion is not so critical as for pseudostratified airway epithelium.

Angiogenic properties of dental pulp stem cells conditioned medium on endothelial cells in vitro and in rodent orthotopic dental pulp regeneration

Objectives

To evaluate the effect of SHED-CM on the proliferation, differentiation, migration ability, cell death, gene expression and production of VEGF of HUVEC in vitro and in a rodent orthotopic dental pulp regeneration.

Methods

Three culture media [M199, DMEM/Ham's F12 and DMEM/Ham's F12 conditioned by SHEDs] were used as experimental groups. SHED-CM was prepared maintaining confluent cells in culture without serum for 3 days. The proliferation and cell death marker of HUVECs were assessed using flow cytometry. The capacity of formation of vascular-like structures was analyzed in cells grown over Matrigel^® in hypoxic condition. HUVECs migration was followed using the scratch test. VEGF-A expression in HUVECs was assessed using real time RT-qPCR; and VEGF synthesis with ELISA test. SHED-CM was also applied in rodent ortotopic model of dental pulp regeneration in rats. The formed tissue was submitted to histological and immunohistochemical analyses.

Results

SHED-CM promoted significantly lower expression of 7AAD in HUVECs; whereas the expression of the Ki67 was similar in all groups. The vascular-like structures were observed in all groups. Migration of SHED-CM group was faster than DMEM/Ham's F12. SHED-CM induced similar expression of VEGF-A than M199, and higher than DMEM/Ham's F12. SHED-CM induced significantly higher VEGF synthesis than other media. SHED-CM induced formation of a vascularized connective tissue inside the root canal.

Conclusion

The study showed that SHEDs release angiogenic and cytoprotective factors, which are of great importance for tissue engineering.

Clinical significance

SHED-CM could be an option to the use of stem cells in tissue engineering.

Modulation of proliferation and differentiation of gingiva‑derived mesenchymal stem cells by concentrated growth factors: Potential implications in tissue engineering for dental regeneration and repair

The aim of the present study was to evaluate the proliferation and osteogenic differentiation ability of gingiva-derived mesenchymal stem cells (GMSCs) cultured with different concentrations of concentrated growth factors (CGF). GMSCs were isolated from gingival connective tissues and characterized by flow cytometry, immunofluorescence staining and immunohistochemical staining. Cell proliferation activity was determined by the MTT assay, and the effect of CGF on MCSCs was detected with the Cell Counting Kit (CCK)-8 assay. Mineralization induction was evaluated by alkaline phosphatase (ALP)-positive cell staining and mineralized nodule formation assay. Dentin matrix acidic phosphoprotein (DMP)1, dentin sialophosphoprotein (DSPP), bone morphogenetic protein (BMP)2 and runt-related transcription factor (RUNX)2 mRNA and protein expression were evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis and western blotting. The flow cytometry, immunofluorescence staining and immunohistochemical staining results indicated that the cultured cells were GMSCs. The MTT assay results revealed that the third-generation gingival stem cells exhibited the highest proliferative capacity, and the CCK-8 results indicated that 10% CGF achieved the most prominent promotion of GMSC proliferation. ALP activity analysis and mineralized nodule assay demonstrated that CGF may successfully induce osteogenic differentiation of GMSCs, whereas RT-qPCR and western blot analyses demonstrated that CGF is involved in the differentiation of GMSCs by regulating the expression of DMP1, DSPP, BMP2 and RUNX2 (P<0.05). In conclusion, CGF were demonstrated to promote the proliferation and osteogenic differentiation of GMSCs. Therefore, CGF may be applied in tissue engineering for tooth regeneration and repair.

Stem cells from human exfoliated deciduous teeth as an alternative cell source in bio-root regeneration

A stem cell-mediated bioengineered tooth root (bio-root) has proven to be a prospective tool for the treatment of tooth loss. As shown in our previous studies, dental follicle cells (DFCs) are suitable seeding cells for the construction of bio-roots. However, the DFCs which can only be obtained from unerupted tooth germ are restricted. Stem cells from human exfoliated deciduous teeth (SHEDs), which are harvested much more easily through a minimally invasive procedure, may be used as an alternative seeding cell. In this case, we compared the odontogenic characteristics of DFCs and SHEDs in bio-root regeneration. Methods: The biological characteristics of SHEDs and DFCs were determined in vitro. The cells were then induced to secrete abundant extracellular matrix (ECM) and form macroscopic cell sheets. We combined the cell sheets with treated dentin matrix (TDM) for subcutaneous transplantation into nude mice and orthotopic jaw bone implantation in Sprague-Dawley rats to further verify their regenerative potential. Results: DFCs exhibited a higher proliferation rate and stronger osteogenesis and adipogenesis capacities, while SHEDs displayed increased migration ability and excellent neurogenic potential. Both dental follicle cell sheets (DFCSs) and sheets of stem cells from human exfoliated deciduous teeth (SHEDSs) expressed not only ECM proteins but also osteogenic and odontogenic proteins. Importantly, similar to DFCSs/TDM, SHEDSs/TDM also successfully achieved the in vivo regeneration of the periodontal tissues, which consist of periodontal ligament fibers, blood vessels and new born alveolar bone. Conclusions: Both SHEDs and DFCs possessed a similar odontogenic differentiation capacity in vivo, and SHEDs were regarded as a prospective seeding cell for use in bio-root regeneration in the future.

The periodontal stem/progenitor cell inflammatory-regenerative cross talk: A new perspective

Adult multipotent stem/progenitor cells, with remarkable regenerative potential, have been isolated from various components of the human periodontium. These multipotent stem/progenitor cells include the periodontal ligament stem/progenitor cells (PDLSCs), stem cells from the apical papilla (SCAP), the gingival mesenchymal stem/progenitor cells (G-MSCs), and the alveolar bone proper stem/progenitor cells (AB-MSCs). Whereas inflammation is regarded as the reason for tissue damage, it also remains a fundamental step of any early healing process. In performing their periodontal tissue regenerative/reparative activity, periodontal stem/progenitor cells interact with their surrounding inflammatory micro-environmental, through their expressed receptors, which could influence their fate and the outcome of any periodontal stem/progenitor cell-mediated reparative/regenerative activity. The present review discusses the current understanding about the interaction of periodontal stem/progenitor cells with their surrounding inflammatory micro-environment, elaborates on the inflammatory factors influencing their stemness, proliferation, migration/homing, differentiation, and immunomodulatory attributes, the possible underlying intracellular mechanisms, as well as their proposed relationship to the canonical and noncanonical Wnt pathways.

Small molecules enhance neurogenic differentiation of dental-derived adult stem cells

OBJECTIVE

Dental-derived stem cells originate from the embryonic neural crest, and exhibit high neurogenic potential. This study aimed to investigate whether a cocktail of eight small molecules (Valproic acid, CHIR99021, Repsox, Forskolin, SP600125, GO6983, Y-27632 and Dorsomorphin) can enhance the in vitro neurogenic differentiation of dental pulp stem cells (DPSCs), stem cells from apical papilla (SCAPs) and gingival mesenchymal stem cells (GMSCs), as a preliminary step towards clinical applications.

MATERIALS AND METHODS

Neural induction was carried out with a small molecule cocktail based two-step culture protocol, over a total duration of 14 days. At the 8 and 14 day timepoints, the cells were analyzed for expression of neural markers with immunocytochemistry, qRT-PCR and Western Blot. The Fluo 4-AM calcium flux assay was also performed after a further 14 days of neural maturation.

RESULTS

More pronounced morphological changes characteristic of the neural lineage (i.e. neuritogenesis) were observed in all three cell types treated with small molecules, as compared to the untreated controls. This was corroborated by the immunocytochemistry, qRT-PCR and western blot data, which showed upregulated expression of several early and mature neural markers in all three cell types treated with small molecules, versus the corresponding untreated controls. Finally, the Fluo-4 AM calcium flux assay showed consistently higher calcium transient (F/F_o) peaks for the small molecule-treated versus untreated control groups.

CONCLUSIONS

Small molecules can enhance the neurogenic differentiation of DPSCs, SCAPs and GMSCs, which offer much potential for therapeutic applications.

Comparative analysis of lncRNA and mRNA expression profiles between periodontal ligament stem cells and gingival mesenchymal stem cells

Oral tissue-derived mesenchymal stem cells, such as periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs), possess different biological characteristics, but the molecular mechanism remains unclear, which restricts their application in tissue engineering. Long noncoding RNAs (lncRNAs) are known to be significant regulators of gene expression, but our knowledge about their roles in the regulation of stem cell biological properties is still limited. This study compared the lncRNA and mRNA expression profiles between PDLSCs and GMSCs through microarray analysis, and applied bioinformatics methods to analyze and predict the function and connection of differentially expressed genes, aiming to screen potential key regulators of diverse biological characteristics in PDLSCs and GMSCs. Microarray analysis showed that 2162 lncRNAs and 1347 mRNAs were significantly differentially expressed between PDLSCs and GMSCs. Gene ontology (GO) analysis and pathway analysis indicated that these differentially expressed genes were involved in diverse biological processes and signaling pathways. The gene signal network and pathway relation network predicted some potentially important regulators. The coding-noncoding gene coexpression network (CNC network) revealed many potential lncRNA-mRNA connection pairs that participated in the regulation of biological behaviors. These results stressed the roles of lncRNAs in controlling stem cell biological behaviors and provided guides for molecular mechanistic study of different biological characteristics in PDLSCs and GMSCs.

Human pluripotent stem cell-derived mesenchymal stem cells prevent chronic allergic airway inflammation via TGF-β1-Smad2/Smad3 signaling pathway in mice

BACKGROUND

Asthma is a chronic disease involving inflamed airways, which were previously demonstrated, can be modulated by the mesenchymal stem cells derived from induced pluripotent stem cells (iPSC-MSCs). However, the long-term effects of iPSC-MSCs in inflamed airways are still unidentified. This study investigated the long-term effects and potential mechanisms involved in the immunomodulatory effects of iPSC-MSCs in the chronic mouse asthma model.

METHODS

Both human iPSC-MSCs and bone marrow (BM)-MSCs were transplanted into the long-term ovalbumin-induced mice before sensitization phase or during the challenge phase. Airway hyper-respnsiveness measurement, immunohistochemistry and ELISA were employed to assess the effects of MSCs. In addition, Smad2/3 levels were assessed by western blot analysis to investigate the possible mechanism involved.

RESULTS

The systemic administration of human iPSC-MSCs before the challenge protected the mice from the characters of the chronic allergic airway inflammation, in particular improving the airway remodeling and preventing fibrosis. In addition, the TGF-β1/Smad pathway was identified involved in the immunomodulatory effects of iPSC-MSCs on chronic allergic airway inflammation.

CONCLUSIONS

The study demonstrated that iPSC-MSCs are capable of preventing chronic allergic airway inflammation over a prolonged period, which further proved the iPSC-MSC therapeutic potential for allergic airway inflammation in a clinical scenario.