Vitamin C stimulates human gingival stem cell proliferation and expression of pluripotent markers

Autologous hGMSC-Derived iPS: A New Proposal for Tissue Regeneration

The high mortality in the global population due to chronic diseases highlights the urgency to identify effective alternative therapies. Regenerative medicine provides promising new approaches for this purpose, particularly in the use of induced pluripotent stem cells (iPSCs). The aim of the work is to establish a new pluripotency cell line obtained for the first time by reprogramming human gingival mesenchymal stem cells (hGMSCs) by a non-integrating method. The hGMSC-derived iPS line characterization is performed through morphological analysis with optical and electron scanning microscopy and through the pluripotency markers expression evaluation in cytofluorimetry, immunofluorescence, and RT-PCR. To confirm the pluripotency of new hGMSC-derived iPS, the formation of embryoid bodies (EBs), as an alternative to the teratoma formation test, is studied in morphological analysis and through three germ layers' markers' expression in immunofluorescence and RT-PCR. At the end, a comparative study between parental hGMSCs and derived iPS cells is performed also for the extracellular vesicles (EVs) and their miRNA content. The new hGMSC-derived iPS line demonstrated to be pluripotent in all aspects, thus representing an innovative dynamic platform for personalized tissue regeneration.

Can vitamins improve periodontal wound healing/regeneration?

Periodontitis is a complex inflammatory disorder of the tooth supporting structures, associated with microbial dysbiosis, and linked to a number if systemic conditions. Untreated it can result in an irreversible damage to the periodontal structures and eventually teeth loss. Regeneration of the lost periodontium requires an orchestration of a number of biological events on cellular and molecular level. In this context, a set of vitamins have been advocated, relying their beneficial physiological effects, to endorse the biological regenerative events of the periodontium on cellular and molecular levels. The aim of the present article is to elaborate on the question whether or not vitamins improve wound healing/regeneration, summarizing the current evidence from in vitro, animal and clinical studies, thereby shedding light on the knowledge gap in this field and highlighting future research needs. Although the present review demonstrates the current heterogeneity in the available evidence and knowledge gaps, findings suggest that vitamins, especially A, B, E, and CoQ10, as well as vitamin combinations, could exert positive attributes on the periodontal outcomes in adjunct to surgical or nonsurgical periodontal therapy.

The potential use of ascorbic acid to recover the cellular senescence of lipopolysaccharide-induced human apical papilla cells: an in vitro study

OBJECTIVES

To examine the effect of lipopolysaccharide (LPS) on cellular senescence induction of human apical papilla cells (hAPCs) and evaluate the potential use of 50 μg/ml ascorbic acid to recover cellular senescence and regenerative functions.

MATERIALS AND METHODS

hAPCs were treated with LPS at 1 and 10 μg/ml either with or without 50 μg/ml ascorbic acid for 48 h. The cellular senescence biomarkers were analyzed by senescence-associated β-galactosidase (SA-β-gal) staining and senescence-related gene expression, p16 and p21. Cell migration, at 12 h and 24 h, was evaluated using a scratch wound assay. Mineralization potential was assessed at 21 days using Alizarin red S staining and dentine sialophosphoprotein (DSPP) and bone sialoprotein (BSP) gene expression.

RESULTS

1 μg/ml and 10 μg/ml LPS stimulation for 48 h induced cellular senescence, as shown by remarkable SA-β-gal staining and p16 and p21 gene expression. The percentage of wound closure and mineralized formation was reduced. The co-incubation with ascorbic acid significantly down-regulated the level of SA-β-gal staining. The reduction of senescence-associated gene expressions was observed. Ascorbic acid improved cell migration, mineralized nodule formation, and the expression of DSPP and BSP genes in LPS-treated hAPCs.

CONCLUSIONS

LPS significantly promoted cellular senescence on hAPCs and diminished the cell function capacity. Co-presence of ascorbic acid could impede cellular senescence and possibly improve the regenerative capacity of LPS-induced senescent hAPCs in vitro.

CLINICAL RELEVANCE

The data support the in vitro potential benefit of ascorbic acid on cellular senescence recovery of apical papilla cells.

Influence of Ascorbic Acid as a Growth and Differentiation Factor on Dental Stem Cells Used in Regenerative Endodontic Therapies

BACKGROUND

Vitamin C is one of the major extracellular nonenzymatic antioxidants involved in the biosynthesis of collagen. It promotes the growth of fibroblasts, wound healing processes, and enhances the survival and differentiation of osteoblasts. The potential effects of ascorbic acid on human dental pulp cells (DPC) and the cells of the apical papilla (CAP) used in actual regenerative endodontic procedures remain largely unknown. In this study, we investigated the possible employment of ascorbic acid in the differentiation and regenerative therapies of DPC and CAP.

METHODS

Nine extracted human wisdom teeth were selected for this study. Subpopulations of stem cells within DPC and CAP were sorted with the mesenchymal stem cell marker STRO-1, followed by treatments with different concentrations (0 mM, 0.1 mM, 0.5 mM, and 1.0 mM) of ascorbic acid (AA), RT-PCR, and Western blot analysis.

RESULTS

FACS analysis revealed the presence of cell subpopulations characterized by a strong expression of mesenchymal stem cell marker STRO-1 and dental stem cell markers CD105, CD44, CD146, CD90, and CD29. Treatment of the cells with defined amounts of AA revealed a markedly increased expression of proliferation marker Ki-67, especially in the concentration range between 0.1 mM and 0.5 mM. Further investigations demonstrated that treatment with AA led to significantly increased expression of common stem cell markers OCT4, Nanog, and Sox2. The most potent proliferative and expressional effects of AA were observed in the concentration of 0.1 mM.

CONCLUSIONS

AA might be a novel and potent growth promoter of human dental cells. Increasing the properties of human dental pulp cells and the cells of the apical papilla using AA could be a useful factor for further clinical developments of regenerative endodontic procedures.

Vitamin C stimulates RNA expression of human gingival fibroblasts proliferation and adhesion in cigarette smokers: An in vitro study

Background

Smoking and the severity of periodontal disease have long been associated. In Saudi Arabia, tobacco smoking is rising, contributing to the increased demand for products that counter its detrimental effects. The antioxidant properties of vitamin C (vit C) make it a powerful countermeasure to tobacco toxicity. Observation of these effects on human gingival fibroblasts (hGFs) would suggest use of vitamin C in future dental applications.

Aim

To examine the proliferation, adhesion, and expression of extracellular RNA in human gingival fibroblasts extracted from cigarette smokers when compared to never-smokers, in association with vitamin C.

Materials and Methods

Human gingival fibroblasts were extracted from Periodontal free sites of healthy adult male participants. Group 1; consisted of Heavy cigarette smokers (n = 1) while group 2 was never-smokers (n = 1). Collected cells were cultured and subcultured in supplemented growth medium. Vitamin C was then induced in the medium at the experimental sixth passage. RNA expression analysis using quantitative reverse transcriptase-polymerase chain reaction was performed to analyze the adhesion, proliferation, and extracellular matrix expression.

Results

Expression of the adhesion gene (CD44) in the smoker group was significantly downregulated than never-smoker group (p-value = 0.024). After the induction of vitamin C, the smoker samples showed a significant improvement in their gene expression levels. The extracellular genes involved in this study (COL1A1, LAMA3, and TGFB3) were significantly affected by the smoking status. In addition, the proliferation of MK167 and CCNB1 genes in smokers and never-smokers was increased.

Conclusion

Cigarette smoking affects the overall properties of human gingival fibroblasts’ adhesion, proliferation, and extra-cellular matrix formation. Furthermore, the addition of vitamin C affects these cellular properties in a positive manner.

Allotransplantation of ascorbic acid-treated fibroblasts improves healing of excisional cutaneous wound in diabetic rats

The purpose of this study was to evaluate the effects of ascorbic acid (AA)-treated fibroblasts transplantation on excisional diabetic wound healing. An excisional wound was created between the shoulders of streptozotocin-induced diabetic rats. On day three, 1 ml of PBS, ‎1 × 10⁶ ‎intact homologous fibroblasts, and ‎1 × 10⁶ ‎ fibroblasts treated with 50 μM AA were injected subcutaneously around the wound edges in control, treatment-1 and treatment-2 groups, respectively. In the sham group, the wound was left intact. Wound area was measured by planimetry. On day 15, samples were harvested for histopathological examination and hydroxyproline content. Wound area in treatment-1 and - 2 groups was ‎significantly decreased compared to other groups, on days 11 and 15. The hydroxyproline content was significantly lower in the control group compared to the other groups. Histopathology revealed significant increases in the number of neovessels, macrophages, lymphocytes and fibroblasts in the treatment-2 group compared to the other groups. Trichrome staining showed the highest level of collagen deposition and orientation in the treatment-2 group. In conclusion, allotransplantation of ‎50 μM ‎ AA-treated fibroblasts ‎could result in progressive healing and improved reparative indices of excisional dermal wound in diabetic rats.

Ascorbic Acid/Retinol and/or Inflammatory Stimuli's Effect on Proliferation/Differentiation Properties and Transcriptomics of Gingival Stem/Progenitor Cells

The present study explored the effects of ascorbic-acid (AA)/retinol and timed inflammation on the stemness, the regenerative potential, and the transcriptomics profile of gingival mesenchymal stem/progenitor cells' (G-MSCs). STRO-1 (mesenchymal stem cell marker) immuno-magnetically sorted G-MSCs were cultured in basic medium (control group), in basic medium with IL-1β (1 ng/mL), TNF-α (10 ng/mL) and IFN-γ (100 ng/mL, inflammatory-medium), in basic medium with AA (250 µmol/L) and retinol (20 µmol/L) (AA/retinol group) or in inflammatory medium with AA/retinol (inflammatory/AA/retinol group; n = 5/group). The intracellular levels of phosphorylated and total β-Catenin at 1 h, the expression of stemness genes over 7 days, the number of colony-forming units (CFUs) as well as the cellular proliferation aptitude over 14 days, and the G-MSCs' multilineage differentiation potential were assessed. Next-generation sequencing was undertaken to elaborate on up-/downregulated genes and altered intracellular pathways. G-MSCs demonstrated all mesenchymal stem/progenitor cells characteristics. Controlled inflammation with AA/retinol significantly elevated NANOG (p < 0.05). The AA/retinol-mediated reduction in intracellular phosphorylated β-Catenin was restored through the effect of controlled inflammation (p < 0.05). Cellular proliferation was highest in the AA/retinol group (p < 0.05). AA/retinol counteracted the inflammation-mediated reduction in G-MSCs' clonogenic ability and CFUs. Amplified chondrogenic differentiation was observed in the inflammatory/AA/retinol group. At 1 and 3 days, the differentially expressed genes were associated with development, proliferation, and migration (FOS, EGR1, SGK1, CXCL5, SIPA1L2, TFPI2, KRATP1-5), survival (EGR1, SGK1, TMEM132A), differentiation and mineral absorption (FOS, EGR1, MT1E, KRTAP1-5, ASNS, PSAT1), inflammation and MHC-II antigen processing (PER1, CTSS, CD74) and intracellular pathway activation (FKBP5, ZNF404). Less as well as more genes were activated the longer the G-MSCs remained in the inflammatory medium or AA/retinol, respectively. Combined, current results point at possibly interesting interactions between controlled inflammation or AA/retinol affecting stemness, proliferation, and differentiation attributes of G-MSCs.

In vitro evaluation of the effect of the electronic cigarette aerosol, Cannabis smoke, and conventional cigarette smoke on the properties of gingival fibroblasts/gingival mesenchymal stem cells

OBJECTIVE

The current study aimed to evaluate the effect of electronic cigarette (EC) aerosol, Cannabis, and conventional cigarettes smoke on gingival fibroblast/gingival mesenchymal stem cells' (GF/G-MSCs) of never smokers.

MATERIAL AND METHODS

Human GF/G-MSCs (n = 32) were isolated and characterized using light microscopy, flow cytometry, and multilineage differentiation ability. Following the application of aerosol/smoke extracts, GF/G-MSCs were evaluated for cellular proliferation; colony-forming units (CFU-F) ability; cellular viability (using the MTT assay); mitochondrial depolarization using JC-1 dye; and genes' expression of ATM, p21, Oct4, and Nanog.

RESULTS

Colony-forming units and viability (OD 450 nm) were significantly reduced upon exposure to Cannabis (mean ± SD; 5.5 ± 1.5; p < .00001, 0.47 ± 0.21; p < .05) and cigarettes smoke (2.3 ± 1.2 p < .00001, 0.59 ± 0.13, p < .05), while EC aerosol showed no significant reduction (10.8 ± 2.5; p = .05, 1.27 ± 0.47; p > .05) compared to the control group (14.3 ± 3, 1.33 ± 0.12). Significantly upregulated expression of ATM, Oct4, and Nanog (gene copies/GADPH) was noticed with Cannabis (1.5 ± 0.42, 0.82 ± 0.44, and 1.54 ± 0.52, respectively) and cigarettes smoke (1.52 ± 0.75, 0.7 ± 0.14, and 1.48 ± 0.79, respectively; p < .05), whereas EC aerosol caused no statistically significant upregulation of these genes compared to the control group (0.63 ± 0.1, 0.31 ± 0.12, and 0.64 ± 0.46, respectively; p > .05). The p21 gene was not significantly downregulated in EC aerosol (1.22 ± 0.46), Cannabis (0.71 ± 0.24), and cigarettes smokes (0.83 ± 0.54) compared to the control group (p = .053, analysis of variance).

CONCLUSION

Cannabis and cigarettes smoke induce DNA damage and cellular dedifferentiation and negatively affect the cellular proliferation and viability of GF/G-MSCs of never smokers, whereas EC aerosol showed a significantly lower impact on these properties.

Key Markers and Epigenetic Modifications of Dental-Derived Mesenchymal Stromal Cells

As a novel research hotspot in tissue regeneration, dental-derived mesenchymal stromal cells (MSCs) are famous for their accessibility, multipotent differentiation ability, and high proliferation. However, cellular heterogeneity is a major obstacle to the clinical application of dental-derived MSCs. Here, we reviewed the heterogeneity of dental-derived MSCs firstly and then discussed the key markers and epigenetic modifications related to the proliferation, differentiation, immunomodulation, and aging of dental-derived MSCs. These messages help to control the composition and function of dental-derived MSCs and thus accelerate the translation of cell therapy into clinical practice.

Gingiva-Derived Mesenchymal Stem Cells: Potential Application in Tissue Engineering and Regenerative Medicine - A Comprehensive Review

A unique subpopulation of mesenchymal stem cells (MSCs) has been isolated and characterized from human gingival tissues (GMSCs). Similar to MSCs derived from other sources of tissues, e.g. bone marrow, adipose or umbilical cord, GMSCs also possess multipotent differentiation capacities and potent immunomodulatory effects on both innate and adaptive immune cells through the secretion of various types of bioactive factors with immunosuppressive and anti-inflammatory functions. Uniquely, GMSCs are highly proliferative and have the propensity to differentiate into neural cell lineages due to the neural crest-origin. These properties have endowed GMSCs with potent regenerative and therapeutic potentials in various preclinical models of human disorders, particularly, some inflammatory and autoimmune diseases, skin diseases, oral and maxillofacial disorders, and peripheral nerve injuries. All types of cells release extracellular vesicles (EVs), including exosomes, that play critical roles in cell-cell communication through their cargos containing a variety of bioactive molecules, such as proteins, nucleic acids, and lipids. Like EVs released by other sources of MSCs, GMSC-derived EVs have been shown to possess similar biological functions and therapeutic effects on several preclinical diseases models as GMSCs, thus representing a promising cell-free platform for regenerative therapy. Taken together, due to the easily accessibility and less morbidity of harvesting gingival tissues as well as the potent immunomodulatory and anti-inflammatory functions, GMSCs represent a unique source of MSCs of a neural crest-origin for potential application in tissue engineering and regenerative therapy.

Clinical and radiographic effects of ascorbic acid-augmented platelet-rich fibrin versus platelet-rich fibrin alone in intra-osseous defects of stage-III periodontitis patients: a randomized controlled clinical trial

Aim

To assess platelet-rich fibrin (PRF) with ascorbic acid (AA) versus PRF in intra-osseous defects of stage-III periodontitis patients.

Methodology

Twenty stage-III/grade C periodontitis patients, with ≥ 3 mm intra-osseous defects, were randomized into test (open flap debridement (OFD)+AA/PRF; n = 10) and control (OFD+PRF; n = 10). Clinical attachment level (CAL; primary outcome), probing pocket depth (PPD), gingival recession depth (RD), full-mouth bleeding scores (FMBS), full-mouth plaque scores (FMPS), radiographic linear defect depth (RLDD) and radiographic defect bone density (RDBD) (secondary-outcomes) were examined at baseline, 3 and 6 months post-surgically.

Results

OFD+AA/PRF and OFD+PRF demonstrated significant intragroup CAL gain and PPD reduction at 3 and 6 months (p < 0.001). OFD+AA/PRF and OFD+PRF showed no differences regarding FMBS or FMPS (p > 0.05). OFD+AA/PRF demonstrated significant RD reduction of 0.90 ± 0.50 mm and 0.80 ± 0.71 mm at 3 and 6 months, while OFD+PRF showed RD reduction of 0.10 ± 0.77 mm at 3 months, with an RD-increase of 0.20 ± 0.82 mm at 6 months (p < 0.05). OFD+AA/PRF and OFD+PRF demonstrated significant RLDD reduction (2.29 ± 0.61 mm and 1.63 ± 0.46 mm; p < 0.05) and RDBD-increase (14.61 ± 5.39% and 12.58 ± 5.03%; p > 0.05). Stepwise linear regression analysis showed that baseline RLDD and FMBS at 6 months were significant predictors of CAL reduction (p < 0.001).

Conclusions

OFD+PRF with/without AA significantly improved periodontal parameters 6 months post-surgically. Augmenting PRF with AA additionally enhanced gingival tissue gain and radiographic defect fill.

Clinical relevance

PRF, with or without AA, could significantly improve periodontal parameters. Supplementing PRF with AA could additionally augment radiographic linear defect fill and reduce gingival recession depth.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-021-03929-1.

Vitamin C deficient reduces proliferation in a human periventricular tumor stem cell-derived glioblastoma model

Glioblastoma multiforme (GBM) is the most common and aggressive brain tumor with a median survival of 14.6 months. GBM is highly resistant to radio- and chemotherapy, and remains without a cure; hence, new treatment strategies are constantly sought. Vitamin C, an essential micronutrient and antioxidant, was initially described as an antitumor molecule; however, several studies have shown that it can promote tumor progression and angiogenesis. Thus, considering the high concentrations of vitamin C present in the brain, our aim was to study the effect of vitamin C deficiency on the progression of GBM using a GBM model generated by the stereotactic injection of human GBM cells (U87-MG or HSVT-C3 cells) in the subventricular zone of guinea pig brain. Initial characterization of U87-MG and HSVT-C3 cells showed that HSVT-C3 are highly proliferative, overexpress p53, and are resistant to ferroptosis. To induce intraperiventricular tumors, animals received control or a vitamin C-deficient diet for 3 weeks, after which histopathological and confocal microscopy analyses were performed. We demonstrated that the vitamin C-deficient condition reduced the glomeruloid vasculature and microglia/macrophage infiltration in U87-MG tumors. Furthermore, tumor size, proliferation, glomeruloid vasculature, microglia/macrophage infiltration, and invasion were reduced in C3 tumors carried by vitamin C-deficient guinea pigs. In conclusion, the effect of the vitamin C deficiency was dependent on the tumor cell used for GBM induction. HSVT-C3 cells, a cell line with stem cell features isolated from a human subventricular GBM, showed higher sensitivity to the deficient condition; however, vitamin C deficiency displayed an antitumor effect in both GBM models analyzed.

Ascorbic Acid, Inflammatory Cytokines (IL-1β/TNF-α/IFN-γ), or Their Combination's Effect on Stemness, Proliferation, and Differentiation of Gingival Mesenchymal Stem/Progenitor Cells

Objective

Ascorbic acid (AA) and controlled inflammatory stimuli are postulated to possess the ability to independently exert positive effects on a variety of proliferative, pluripotency, and differentiation attributes of gingival mesenchymal stem/progenitor cells (G-MSCs). The current study's objective was to explore and compare for the first time the impact of the major inflammatory cytokines (IL-1β/TNF-α/IFN-γ), AA, or their combination on multipotency/pluripotency, proliferative, and differentiation characteristics of G-MSCs.

Design

Human G-MSCs (n = 5) were isolated and cultured in basic medium (control group), in basic medium with major inflammatory cytokines; 1 ng/ml IL-1β, 10 ng/ml TNF-α, and 100 ng/ml IFN-γ (inflammatory group), in basic medium with 250 μmol/l AA (AA group) and in inflammatory medium supplemented by AA (inflammatory/AA group). All media were renewed three times per week. In stimulated G-MSCs intracellular β-catenin at 1 hour, pluripotency gene expression at 1, 3, and 5 days, as well as colony-forming units (CFUs) ability and cellular proliferation over 14 days were examined. Following a five-days stimulation in the designated groups, multilineage differentiation was assessed via qualitative and quantitative histochemistry as well as mRNA expression.

Results

β-Catenin significantly decreased intracellularly in all experimental groups (p = 0.002, Friedman). AA group exhibited significantly higher cellular counts on days 3, 6, 7, and 13 (p < 0.05) and the highest CFUs at 14 days [median-CFUs (Q25/Q75); 40 (15/50), p = 0.043]. Significantly higher Nanog expression was noted in AA group [median gene-copies/PGK1 (Q25/Q75); 0.0006 (0.0002/0.0007), p < 0.01, Wilcoxon-signed-rank]. Significant multilineage differentiation abilities, especially into osteogenic and chondrogenic directions, were further evident in the AA group.

Conclusions

AA stimulation enhances G-MSCs' stemness, proliferation, and differentiation properties, effects which are associated with a Wnt/β-catenin signaling pathway activation. Apart from initially boosting cellular metabolism as well as Sox2 and Oct4A pluripotency marker expression, inflammation appeared to attenuate these AA-induced positive effects. Current results reveal that for AA to exert its beneficial effects on G-MSCs' cellular attributes, it requires to act in an inflammation-free microenvironment.

On the physiological and cellular homeostasis of ascorbate

Recent interest in the role of ascorbate in crucial metabolic processes is driven by the growing number of medical reports that show beneficial effects of ascorbate supplementation for maintaining general well-being and recovery from a variety of medical conditions. The effect of ascorbate on the local body environment highly depends on its local concentration; at low concentrations it can cause the reduction of reactive oxygen and facilitate activities of enzymes, while at high concentrations it generates free radicals by reducing ferric ions. Ascorbate serving as an electron donor assists the iron-containing proteins and the iron transfer between various aqueous compartments. These functions require effective and adjustable mechanisms responsible for ascorbate biodistribution. In the paper we propose a new biophysical model of ascorbate redistribution between various aqueous body compartments. It combines recent experimental evidence regarding the ability of ascorbate to cross the lipid bilayer by unassisted diffusion, with active transport by well-characterized sodium vitamin C transporter (SVCT) membrane proteins. In the model, the intracellular concentration of ascorbate is maintained by the balance of two opposing fluxes: fast active and slow passive transport. The model provides a mechanistic understanding of ascorbate flux across the epidermal barrier in the gut as well as the role of astrocytes in ascorbate recycling in the brain. In addition, ascorbate passive diffusion across biological membranes, which depends on membrane electric potentials and pH gradients, provides the rationale for the correlation between ascorbate distribution and the transfer of iron ions inside a cell. The proposed approach provides, for the first time, a mechanistic account of processes leading to ascorbate physiological and cellular distribution, which helps to explain numerous experimental and clinical observations.

Rutin promotes the formation and osteogenic differentiation of human periodontal ligament stem cell sheets in vitro

Cell sheet technology is a novel tissue engineering technology that has been rapidly developed in recent years. As a novel technology, cell sheet technology is expected to become one of the preferred methods for cell transplantation. The present study investigated the biological effects of rutin on the formation of periodontal ligament stem cell (PDLSC) sheets and their resultant osteogenic properties. The results of Cell Counting Kit-8 (CCK-8) assay demonstrated that a concentration of 1×10⁻⁶ mol/l rutin promoted the proliferation of PDLSCs more effectively compared with other designed concentrations. Rutin-modified cell sheets could be induced by complete medium supplemented with 20 µg/ml vitamin C (VC) and 1×10⁻⁶ mol/l rutin. Rutin-modified cell sheets appeared thicker and more compact compared with the VC-induced PDLSC sheets, demonstrating more layers of cells (3 or 4 layers), which secreted a richer extracellular matrix (ECM). Furthermore, the improved cell sheets exhibited varying degrees of increases in the mRNA and protein expression of collagen type I (COL1), alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX2) and osteopontin (OPN). Combined treatment with VC and rutin promoted the formation of PDLSC sheets and enhanced the osteogenic differentiation potential of the cell sheets. Therefore, rutin-modified cell sheets of PDLSCs are expected to play an important role in the treatment of periodontal tissue regeneration by stem cells.

Reactive Oxygen Species, Superoxide Dimutases, and PTEN-p53-AKT-MDM2 Signaling Loop Network in Mesenchymal Stem/Stromal Cells Regulation

Mesenchymal stromal/stem cells (MSCs) are multipotent cells that can differentiate to various specialized cells, which have the potential capacity to differentiate properly and accelerate recovery in damaged sites of the body. This stem cell technology has become the fundamental element in regenerative medicine. As reactive oxygen species (ROS) have been reported to adversely influence stem cell properties, it is imperative to attenuate the extent of ROS to the promising protective approach with MSCs’ regenerative therapy. Oxidative stress also affects the culture expansion and longevity of MSCs. Therefore, there is great need to identify a method to prevent oxidative stress and replicative senescence in MSCs. Phosphatase and tensin homologue deleted on chromosome 10/Protein kinase B, PKB (PTEN/AKT) and the tumor suppressor p53 pathway have been proven to play a pivotal role in regulating cell apoptosis by regulating the oxidative stress and/or ROS quenching. In this review, we summarize the current research and our view of how PTEN/AKT and p53 with their partners transduce signals downstream, and what the implications are for MSCs’ biology.

Applications of inflammation-derived gingival stem cells for testing the biocompatibility of dental restorative biomaterials

BACKGROUND

Normal or inflamed gingival tissues are regarded as a source of mesenchymal stem cells (MSCs) abundant and easily accessible through minimally invasive dental procedures. Due to the proximity of dental resin composites to gingival tissues and to the possible local cytotoxic effect of the eluted components, gingiva-derived MSCs could be used to investigate the biocompatibility of dental biomaterials.

PURPOSE

The present research aimed to isolate (MSCs) from inflamed and normal gingiva, to fully characterize them and to observe their behavior in relation with some commercial resin composite materials and one experimental material.

MATERIAL AND METHODS

Following their isolation, putative MSCs from both gingival sources were grown under the same culture conditions and characterized by immunophenotyping of cell surface antigens by flow-cytometry and transcription factors by immunocytochemical staining. Moreover, stemness gene expression was evaluated by RT-PCR analysis. Multipotent mesenchymal differentiation potential was investigated. Osteogenic and neurogenic differentiated cells were highlighted by immunocytochemical staining, chondrogenic cells by cytochemical staining, and adipocytes by cytochemical staining and spectrophotometry, respectively. Resin composite cytotoxicity was evaluated by cell membrane fluorescent labeling with PKH 26 and MTT assay. The results of PKH labeling were statistically analysed using two-way RM ANOVA with Bonferroni post-tests. For MTT assay, two-way RM ANOVA with Bonferroni post-tests and unpaired t test with Welch's correction were used.

RESULTS

A similar expression pattern of surface markers was observed. The cells were positive for CD105, CD73, CD90, CD49e, CD29, CD44 and CD166 and negative for CD45, CD34, CD14, CD79, HLA-DR and CD117 indicating a mesenchymal stem cell phenotype. The qRT-PCR analysis revealed a low gene expression for NOG, BMP4 and Oct3/4 and an increased expression for Nanog in both cells lines. Immunocytochemical analysis highlighted a more intense protein expression for Nanog, Oct3/4 and Sox-2 in MSCs derived from normal gingiva than from inflamed gingiva. Multipotent differentiation capacity of MSCs isolated from both sources was highlighted. The tested materials had no hazardous effect on MSCs as the two cell lines developed well onto resin composite substrates. Cell counting revealed some significant differences in the number of PKH-labeled MSCs at some experimental moments. Also, some differences in cell viability were recorded indicating better developmental conditions offered by some of the tested biomaterials.

CONCLUSIONS

The experimental resin composite behaved like the most biocompatible commercial material. Inflamed gingiva-derived MSCs retain their stem cell properties and could be used as a valuable cell line for testing dental biomaterials.

Stem Cells from Dental Pulp: What Epigenetics Can Do with Your Tooth

Adult stem cells have attracted scientific attention because they are able to self-renew and differentiate into several specialized cell types. In this context, human dental tissue-derived mesenchymal stem cells (hDT-MSCs) have emerged as a possible solution for repairing or regenerating damaged tissues. These cells can be isolated from primary teeth that are naturally replaced, third molars, or other dental tissues and exhibit self-renewal, a high proliferative rate and a great multilineage potential. However, the cellular and molecular mechanisms that determine lineage specification are still largely unknown. It is known that a change in cell fate requires the deletion of existing transcriptional programs, followed by the establishment of a new developmental program to give rise to a new cell lineage. Increasing evidence indicates that chromatin structure conformation can influence cell fate. In this way, reversible chemical modifications at the DNA or histone level, and combinations thereof can activate or inactivate cell-type-specific gene sequences, giving rise to an alternative cell fates. On the other hand, miRNAs are starting to emerge as a possible player in establishing particular somatic lineages. In this review, we discuss two new and promising research fields in medicine and biology, epigenetics and stem cells, by summarizing the properties of hDT-MSCs and highlighting the recent findings on epigenetic contributions to the regulation of cellular differentiation.

Redox Homeostasis Plays Important Roles in the Maintenance of the Drosophila Testis Germline Stem Cells

Oxidative stress influences stem cell behavior by promoting the differentiation, proliferation, or apoptosis of stem cells. Thus, characterizing the effects of reactive oxygen species (ROS) on stem cell behavior provides insights into the significance of redox homeostasis in stem cell-associated diseases and efficient stem cell expansion for cellular therapies. We utilized the Drosophila testis as an in vivo model to examine the effects of ROS on germline stem cell (GSC) maintenance. High levels of ROS induced by alteration in Keap1/Nrf2 activity decreased GSC number by promoting precocious GSC differentiation. Notably, high ROS enhanced the transcription of the EGFR ligand spitz and the expression of phospho-Erk1/2, suggesting that high ROS-mediated GSC differentiation is through EGFR signaling. By contrast, testes with low ROS caused by Keap1 inhibition or antioxidant treatment showed an overgrowth of GSC-like cells. These findings suggest that redox homeostasis regulated by Keap1/Nrf2 signaling plays important roles in GSC maintenance.

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Germline stem cell homeostasis in the Drosophila testis is susceptible to ROS levels

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Oxidative stress decreases germline stem cell number by promoting differentiation

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EGFR signaling is involved in precocious GSC differentiation caused by high ROS levels

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Low levels of ROS can promote a growth of germline stem cells

Valproic Acid Induces Decreased Expression of H19 Promoting Cell Apoptosis in A549 Cells

It has been suggested that the imprinted gene, H19, plays a crucial role in the development of cancer. In the present study, we attempted to treat the abnormal expression and methylation status of H19 in A549 cells using valproic acid (VPA), ascorbic acid (Vc), and 5-aza-Cytidine (5-Aza). The results suggested that VPA administration could alter the expression pattern of H19, while the hypomethylation status of H19 DMR was unchanged. Furthermore, overexpression of HDAC1 and DNMT1 was associated with decreased expression of H19 in VPA-treated cells. Western blot results showed that the expression of p53 protein was increased following treatment with VPA. In addition, we also investigated cellular apoptosis and the cell cycle of treated cells. Flow cytometry data indicated that VPA could increase the occurrence of cell apoptosis in A549 cells. Taken together, our results suggest that H19 expression was suppressed by VPA through HDAC1 and DNMT1 and decreased H19 expression correlated with cell apoptosis in A549 cells.

Ascorbic Acid Promotes the Stemness of Corneal Epithelial Stem/Progenitor Cells and Accelerates Epithelial Wound Healing in the Cornea

High concentration of ascorbic acid (vitamin C) has been found in corneal epithelium of various species. However, the specific functions and mechanisms of ascorbic acid in the repair of corneal epithelium are not clear. In this study, it was found that ascorbic acid accelerates corneal epithelial wound healing in vivo in mouse. In addition, ascorbic acid enhanced the stemness of cultured mouse corneal epithelial stem/progenitor cells (TKE2) in vitro, as shown by elevated clone formation ability and increased expression of stemness markers (especially p63 and SOX2). The contribution of ascorbic acid on the stemness enhancement was not dependent on the promotion of Akt phosphorylation, as concluded by using Akt inhibitor, nor was the stemness found to be dependent on the regulation of oxidative stress, as seen by the use of two other antioxidants (GMEE and NAC). However, ascorbic acid was found to promote extracellular matrix (ECM) production, and by using two collagen synthesis inhibitors (AzC and CIS), the increased expression of p63 and SOX2 by ascorbic acid was decreased by around 50%, showing that the increased stemness by ascorbic acid can be attributed to its regulation of ECM components. Moreover, the expression of p63 and SOX2 was elevated when TKE2 cells were cultured on collagen I coated plates, a situation that mimics the in vivo situation as collagen I is the main component in the corneal stroma. This study shows direct therapeutic benefits of ascorbic acid on corneal epithelial wound healing and provides new insights into the mechanisms involved. Stem Cells Translational Medicine2017;6:1356–1365

Gingival Mesenchymal Stem/Progenitor Cells: A Unique Tissue Engineering Gem

The human gingiva, characterized by its outstanding scarless wound healing properties, is a unique tissue and a pivotal component of the periodontal apparatus, investing and surrounding the teeth in their sockets in the alveolar bone. In the last years gingival mesenchymal stem/progenitor cells (G-MSCs), with promising regenerative and immunomodulatory properties, have been isolated and characterized from the gingival lamina propria. These cells, in contrast to other mesenchymal stem/progenitor cell sources, are abundant, readily accessible, and easily obtainable via minimally invasive cell isolation techniques. The present review summarizes the current scientific evidence on G-MSCs' isolation, their characterization, the investigated subpopulations, the generated induced pluripotent stem cells- (iPSC-) like G-MSCs, their regenerative properties, and current approaches for G-MSCs' delivery. The review further demonstrates their immunomodulatory properties, the transplantation preconditioning attempts via multiple biomolecules to enhance their attributes, and the experimental therapeutic applications conducted to treat multiple diseases in experimental animal models in vivo. G-MSCs show remarkable tissue reparative/regenerative potential, noteworthy immunomodulatory properties, and primary experimental therapeutic applications of G-MSCs are very promising, pointing at future biologically based therapeutic techniques, being potentially superior to conventional clinical treatment modalities.