Pharmacological Regulation of Oxidative Stress in Stem Cells

Circular RNA-Mediated Regulation of Oral Tissue-Derived Stem Cell Differentiation: Implications for Oral Medicine and Orthodontic Applications

Circular RNAs (circRNAs) are a novel class of endogenous non-coding RNAs (ncRNAs) which unlike linear RNAs, have a covalently closed continuous loop structure. circRNAs are found abundantly in human cells and their biology is complex. They feature unique expression to different types of cells, tissues, and developmental stages. To the present, the functional roles of circular RNAs are not fully understood. They reportedly act as microRNA (miRNA) sponges, therefore having key regulatory functions in diverse physiological and pathological processes. As for dentistry field, lines of evidence indicate that circRNAs play vital roles in the odontogenic and osteogenic differentiation of dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs). Abnormal expression of circRNAs have been found in other areas of pathology frequently reflected also in the oral environment, such as inflammation or bone and soft tissue loss. Therefore, circRNAs could be of significant importance in various fields in dentistry, especially in bone and soft tissue engineering and regeneration. Understanding the molecular mechanisms occurring during the regulation of oral biological and tissue remodeling processes could augment the discovery of novel diagnostic biomarkers and therapeutic strategies that will improve orthodontic and other oral therapeutic protocols.

Txnip regulates the Oct4-mediated pluripotency circuitry via metabolic changes upon differentiation

Thioredoxin interacting protein (Txnip) is a stress-responsive factor regulating Trx1 for redox balance and involved in diverse cellular processes including proliferation, differentiation, apoptosis, inflammation, and metabolism. However, the biological role of Txnip function in stem cell pluripotency has yet to be investigated. Here, we reveal the novel functions of mouse Txnip in cellular reprogramming and differentiation onset by involving in glucose-mediated histone acetylation and the regulation of Oct4, which is a fundamental component of the molecular circuitry underlying pluripotency. During reprogramming or PSC differentiation process, cellular metabolic and chromatin remodeling occur in order to change its cellular fate. Txnip knockout promotes induced pluripotency but hinders initial differentiation by activating pluripotency factors and promoting glycolysis. This alteration affects the intracellular levels of acetyl-coA, a final product of enhanced glycolysis, resulting in sustained histone acetylation on active PSC gene regions. Moreover, Txnip directly interacts with Oct4, thereby repressing its activity and consequently deregulating Oct4 target gene transcriptions. Our work suggests that control of Txnip expression is crucial for cell fate transitions by modulating the entry and exit of pluripotency.

Characterization of Chilean hot spring-origin Staphylococcus sp. BSP3 produced exopolysaccharide as biological additive

A type of high molecular weight bioactive polymers called exopolysaccharides (EPS) are produced by thermophiles, the extremophilic microbes that thrive in acidic environmental conditions of hot springs with excessively warm temperatures. Over time, EPS became important as natural biotechnological additives because of their noncytotoxic, emulsifying, antioxidant, or immunostimulant activities. In this article, we unravelled a new EPS produced by Staphylococcus sp. BSP3 from an acidic (pH 6.03) San Pedro hot spring (38.1 °C) located in the central Andean mountains in Chile. Several physicochemical techniques were performed to characterize the EPS structure including Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), High-Performance Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR), 1D Nuclear Magnetic Resonance (NMR), and Thermogravimetric analysis (TGA). It was confirmed that the amorphous surface of the BSP3 EPS, composed of rough pillar-like nanostructures, is evenly distributed. The main EPS monosaccharide constituents were mannose (72%), glucose (24%) and galactose (4%). Also, it is a medium molecular weight (43.7 kDa) heteropolysaccharide. NMR spectroscopy demonstrated the presence of a [→ 6)-⍺-D-Manp-(1 → 6)-⍺-D-Manp-(1 →] backbone 2-O substituted with 1-⍺-D-Manp. A high thermal stability of EPS (287 °C) was confirmed by TGA analysis. Emulsification, antioxidant, flocculation, water-holding (WHC), and oil-holding (OHC) capacities are   also studied for biotechnological industry applications. The results demonstrated that BSP3 EPS could be used as a biodegradable material for different purposes, like flocculation and natural additives in product formulation.

Antitumor efficacy of synthesized Ag-Au nanocomposite loaded with PEG and ascorbic acid in human lung cancer stem cells

Lung cancer is the leading cause of mortality worldwide of which non-small cell lung carcinoma constitutes majority of the cases. High mortality is attributed to early metastasis, late diagnosis, ineffective treatment and tumor relapse. Chemotherapy and radiotherapy form the mainstay of its treatment. However, their associated side effects involving kidneys, nervous system, gastrointestinal tract, and liver further adds to dismal outcome. These disadvantages of conventional treatment can be circumvented by use of engineered nanoparticles for improved effectiveness with minimal side effects. In this study we have synthesized silver gold nanocomposite (Ag-Au NC) using polyethylene glycol and l-ascorbic acid as surfactant and reducing agent respectively. Synthesized nanocomposite was characterized by ultraviolet-visible absorption, dynamic light scattering, scanning and transmission electron microscopy. Compositional analysis was carried out by energy dispersive X-ray analysis and average pore diameter was estimated using Barrett-Joyner-Halenda method. In-silico molecular docking analysis of the synthesized NC against active regions of epidermal growth factor receptor revealed good binding energy. Subsequently, we investigated the effect of NC on growth and stem cell attributes of A549 lung cancer cells. Results showed that NC was effective in inhibiting A549 cell proliferation, induced DNA damage, G2/M phase arrest and apoptosis. Further, tumor cell migration and spheroid formation were also negatively affected. NC also enhanced reactive oxygen species generation and mitochondrial depolarization. In addition, the effect of NC on putative cancer stem cells in A549 cells was evaluated. We found that Ag-Au NC at IC50 targeted CD44, CD24, CD166, CD133 and CD326 positive cancer stem cells and induced apoptosis. CD166 positive cells were relatively resistance to apoptosis. Together our results demonstrate the anticancer efficacy of Ag-Au NC mediated by a mechanism involving cell cycle arrest and mitochondrial derangement.

Keratinocyte-Specific SOX2 Overexpression Suppressed Pressure Ulcer Formation after Cutaneous Ischemia-Reperfusion Injury via Enhancement of Amphiregulin Production

Ischemia-reperfusion (I/R) injury is a key player in the pathogeneses of pressure ulcer formation. Our previous work demonstrated that inducing the transcription factor SOX2 promotes cutaneous wound healing through EGFR signaling pathway enhancement. However, its protective effect on cutaneous I/R injury was not well-characterized. We aimed to assess the role of SOX2 in cutaneous I/R injury and the tissue-protective effect of SOX2 induction in keratinocytes (KCs) in cutaneous I/R injury. SOX2 was transiently expressed in KCs after cutaneous I/R injury. Ulcer formation was significantly suppressed in KC-specific SOX2-overexpressing mice. SOX2 in skin KCs significantly suppressed the infiltrating inflammatory cells, apoptotic cells, vascular damage, and hypoxic areas in cutaneous I/R injury. Oxidative stress-induced mRNA levels of inflammatory cytokine expression were suppressed, and antioxidant stress factors and amphiregulin were elevated by SOX2 induction in skin KCs. Recombinant amphiregulin administration suppressed pressure ulcer development after cutaneous I/R injury in mice and suppressed oxidative stress-induced ROS production and apoptosis in vitro. These findings support that SOX2 in KCs might regulate cutaneous I/R injury through amphiregulin production, resulting in oxidative stress suppression. Recombinant amphiregulin can be a potential therapeutic agent for cutaneous I/R injury.

Stem cell-derived paracrine factors by modulated reactive oxygen species to enhance cancer immunotherapy

Herein, we present an approach for manipulating paracrine factors and signaling pathways in adipose-derived stem cells (ADSCs) to achieve highly effective tumor immunotherapy. Our method involves precise control of reactive oxygen species concentration using the CD90-maleimide-pluronic F68-chlorin e6 conjugate (CPFC) to create ACPFC, which is then attached to ADSCs through the CD90 receptor-specific interaction. By regulating the irradiated laser power, ACPFC promotes signaling pathways such as cascade-3, VEGFR2, α2β1, C3AR1, CR1-4, and C5AR1, leading to the secretion of various inflammatory cytokines such as IFN-γ, TGF-β, and IL-6, while inhibiting AKT, ERK, NFkB, PAR1, and PAR3/4 signaling pathways to reduce the secretion of cell growth factors like TIMP-1, TIMP-2, VEGF, Ang-2, FGF-2, and HGF. When ACPFC is injected intravenously into a tumor animal model, it autonomously targets and accumulates at the tumor site, and upon laser irradiation, it generates various anti-inflammatory factors while reducing angiogenesis growth factors. The resulting antitumor response recruits CD3+CD8+ cytotoxic T cells and CD3+CD4+ helper T cells into the tumor and spleen, leading to highly effective melanoma and pancreatic tumor treatment in mice. Our technology for regulating stem cell paracrine factors holds significant promise for the treatment of various diseases.

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

BACKGROUND/AIM

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Regulation of adult stem cell function by ketone bodies

Adult stem cells play key roles in tissue homeostasis and regeneration. Recent evidence suggests that dietary interventions can significantly impact adult stem cell function. Some of these effects depend on ketone bodies. Adult stem cells could therefore potentially be manipulated through dietary regimens or exogenous ketone body supplementation, a possibility with significant implications for regenerative medicine. In this review we discuss recent findings of the mechanisms by which ketone bodies could influence adult stem cells, including ketogenesis in adult stem cells, uptake and transport of circulating ketone bodies, receptor-mediated signaling, and changes to cellular metabolism. We also discuss the potential effects of ketone bodies on intracellular processes such as protein acetylation and post-transcriptional control of gene expression. The exploration of mechanisms underlying the effects of ketone bodies on stem cell function reveals potential therapeutic targets for tissue regeneration and age-related diseases and suggests future research directions in the field of ketone bodies and stem cells.

Modulation of miR-146b Expression during Aging and the Impact of Physical Activity on Its Expression and Chondrogenic Progenitors

The finding of molecules associated with aging is important for the prevention of chronic degenerative diseases and for longevity strategies. MicroRNAs (miRNAs) are post-transcriptional regulators involved in many biological processes and miR-146b-5p has been shown to be involved in different degenerative diseases. However, miR-146b-5p modulation has not been evaluated in mesenchymal stem cells (MSCs) commitment or during aging. Therefore, the modulation of miR-146b-5p in the commitment and differentiation of mesenchymal cells as well as during maturation and aging in zebrafish model were analyzed. In addition, circulating miR-146b-5p was evaluated in human subjects at different age ranges. Thus, the role of physical activity in the modulation of miR-146b-5p was also investigated. To achieve these aims, RT (real-time)-PCR, Western blot, cell transfections, and three-dimensional (3D) culture techniques were applied. Our findings show that miR-146b-5p expression drives MSCs to adipogenic differentiation and increases during zebrafish maturation and aging. In addition, miR-146b-5p expression is higher in females compared to males and it is associated with the aging in humans. Interestingly, we also observed that the physical activity of walking downregulates circulating miR-146b-5p levels in human females and increases the number of chondroprogenitors. In conclusion, miR-146b-5p can be considered an age-related marker and can represent a useful marker for identifying strategies, such as physical activity, aimed at counteracting the degenerative processes of aging.

Toxicity of bisphenol A (BPA) and its derivatives in divers biological models with the assessment of molecular mechanisms of toxicity

The aim of the study was to determine totoxicity of bisphenol A (BPA) and its derivatives (bisphenol S (BPS), bisphenol F (BPF), and tetrabromobisphenol A (TBBPA)) due to its high accumulation in environment. The performed analysis revealed the toxicity of the BPA, BPF, and BPS against Kurthia gibsoni, Microbacterium sp., and Brevundimonas diminuta as the most sensitive, reaching microbial toxic concentrations in the range of 0.018-0.031 mg ∙ L^-1. Moreover, the genotoxicity assay shows the ability of all tested compounds to increase in the β-galactosidase level at the concentration range 7.81-500 µM (in Escherichia coli, PQ37). In turn, the matbolic activation of tested bishpenols has caused the enhacement of the genotoxicity and cytotoxicity effect. Interestingely, the highest phytotoxicity effect was pointed for BPA and TBBPA at the concentrations of 10 mg ∙ L^-1 and 50 mg ∙ L^-1, which cause the inhibition of root growth by 58% and 45%, respectively (especially for S. alba and S. saccharatum). Furthermore, the cytotoxicity analyses show the ability of BPA, BPS, and TBBPA to significantly decrease the metabolic activity of human keratynoctes in vitro after 24 h of treatment at the micromolar concentrations. Simialry, the impact of the certain bisphenols on proliferation-, apoptosis-, and inflammation-related mRNA expression was shown in tested cell line. Summarizing, the presented results have proved that BPA and its derrivatives are able to show high negative effect on certain living orgnisms such as bacteria, plants, and human cells, which is strict related to pro-apoptotic and genotoxic mechanism of action.

Inhibition of thioredoxin reductase activity reduces the antioxidant defense capacity of human pluripotent stem cells under conditions of mild but not severe oxidative stress

Pro-oxidative shift in redox balance, usually termed as "oxidative stress", can lead to different cell responses depending on its intensity. Excessive accumulation of reactive oxygen species ("oxidative distress") can cause DNA, lipid and protein damage. Physiological oxidative stimulus ("oxidative eustress"), in turn, can favor cell proliferation and differentiation - the processes of paramount importance primarily for stem cells. Functions of antioxidant enzymes in cells is currently a focus of intense research, however the role of different antioxidant pathways in pluripotent cell responses to oxidative distress/eustress is still under investigation. In this study, we assessed the contribution of the thioredoxin reductase (TrxR)-dependent pathways to maintaining the redox homeostasis in human induced pluripotent stem cells and their differentiated progeny cells under basal conditions and under conditions of oxidative stress of varying intensity. Employing the genetically encoded H₂O₂ biosensor cyto-HyPer and two inhibitors of thioredoxin reductase (auranofin and Tri-1), we show that the reduced activity of TrxR-dependent enzymatic systems leads to the non-cytotoxic disruption of thiol-disulfide metabolism in the cytoplasm of both pluripotent and differentiated cells under basal conditions. Quantifying the cytoplasmic concentrations of peroxide establishing in H₂O₂-stressed cells, we demonstrate that TrxR-dependent pathways contribute to the antioxidant activity in the cell cytoplasm under conditions of mild but not severe oxidative stress in both cell lines tested. The observed effects may testify about a conservative role of the TrxR-controlled enzymatic systems manifested as a response to physiological redox stimuli rather than a protection against the severe oxidative stress.

Centella asiatica (L.) Urban. Attenuates Cell Damage in Hydrogen Peroxide-Induced Oxidative Stress in Transgenic Murine Embryonic Stem Cell Line-Derived Neural-Like Cells: A Preliminary Study for Potential Treatment of Alzheimer's Disease

BACKGROUND

Centella asiatica (L.) (C. asiatica) is commonly known in South East and South East Asia communities for its nutritional and medicinal benefits. Besides being traditionally used to enhance memory and accelerate wound healing, its phytochemicals have been extensively documented for their neuroprotective, neuroregenerative, and antioxidant properties.

OBJECTIVE

The present study aims to investigate the effects of a standardized raw extract of C. asiatica (RECA) on hydrogen peroxide (H2O2)-induced oxidative stress and apoptotic death in neural-like cells derived from mouse embryonic stem (ES) cell line.

METHODS

A transgenic mouse ES cell (46C) was differentiated into neural-like cells using 4-/4+ protocol with addition of all-trans retinoic acid. These cells were then exposed to H2O2 for 24 h. The effects of RECA on H2O2-induced neural-like cells were assessed through cell viability, apoptosis, and reactive oxygen species (ROS) assays, as well as neurite length measurement. The gene expression levels of neuronal-specific and antioxidant markers were assessed by RT-qPCR analysis.

RESULTS

Pre-treatment with H2O2 for 24 hours, in a dose-dependent manner, damaged neural-like cells as marked by a decrease in cell viability, substantial increase in intracellular ROS accumulation, and increase in apoptotic rate compared to untreated cells. These cells were used to treat with RECA. Treatment with RECA for 48 h remarkably restored cell survival and promoted neurite outgrowth in the H2O2- damaged neurons by increasing cell viability and decreasing ROS activity. RT-qPCR analysis revealed that RECA upregulated the level of antioxidant genes such as thioredoxin-1 (Trx-1) and heme oxygenase-1 (HO-1) of treated cells, as well as the expression level of neuronal-specific markers such as Tuj1 and MAP2 genes, suggesting their contribution in neuritogenic effect.

CONCLUSION

Our findings indicate that RECA promotes neuroregenerative effects and exhibits antioxidant properties, suggesting a valuable synergistic activity of its phytochemical constituents, thus, making the extract a promising candidate in preventing or treating oxidative stress-associated Alzheimer's disease.

Pathological implications of metabolic reprogramming and its therapeutic potential in medulloblastoma

Tumor-specific alterations in metabolism have been recognized to sustain the production of ATP and macromolecules needed for cell growth, division and survival in many cancer types. However, metabolic heterogeneity poses a challenge for the establishment of effective anticancer therapies that exploit metabolic vulnerabilities. Medulloblastoma (MB) is one of the most heterogeneous malignant pediatric brain tumors, divided into four molecular subgroups (Wingless, Sonic Hedgehog, Group 3 and Group 4). Recent progresses in genomics, single-cell sequencing, and novel tumor models have updated the classification and stratification of MB, highlighting the complex intratumoral cellular diversity of this cancer. In this review, we emphasize the mechanisms through which MB cells rewire their metabolism and energy production networks to support and empower rapid growth, survival under stressful conditions, invasion, metastasis, and resistance to therapy. Additionally, we discuss the potential clinical benefits of currently available drugs that could target energy metabolism to suppress MB progression and increase the efficacy of the current MB therapies.

Dynamic biological characteristics of human bone marrow hematopoietic stem cell senescence

Hematopoietic stem cells show biological manifestations of aging, diminished hematopoietic function and abnormal differentiation, which can lead to leukemia. It is therefore important to explore the mechanism underlying hematopoietic stem cell aging to develop strategies for delaying the process. Our evaluations revealed that the number of bone marrow hematopoietic cells (BMHCs) started to decrease significantly after 45 years of age, and the number of senescent BMHCs, as determined by senescence-associated beta-galactosidase staining, gradually increased with age. In addition, BMHCs from individuals over 45 years of age presented with notably reduced proliferative capacity, increased G1-phase cell cycle arrest, and significantly decreased generation of mixed colony forming units, which suggests that BMHCs enter senescence during middle age. Furthermore, we observed significantly lower antioxidant capacity and a significant increase in oxidative damage products, a gradual increase in the expression of senescence-associated proteins and genes, and a gradual decrease in the expression of cell cycle related proteins in BMHCs after middle age. Taken together, these findings offer both a theoretical and experimental basis for better understanding of the senescence progression of BMHCs and the optimal timing for anti-senescence drug interventions in clinical practice.

Photobiomodulation isolated or associated with adipose-derived stem cells allograft improves inflammatory and oxidative parameters in the delayed-healing wound in streptozotocin-induced diabetic rats

The single and associated impressions of photobiomodulation (PBM) and adipose-derived stem cells (ADS) on stereological parameters (SP), and gene expression (GE) of some antioxidant and oxidative stressors of repairing injured skin at inflammation and proliferation steps (days 4 and 8) of a delayed healing, ischemic, and infected wound model (DHIIWM) were examined in type one diabetic (DM1) rats. DM1 was induced by administration of streptozotocin (40 mg/kg) in 48 rats. The DHIIWM was infected by methicillin-resistant Staphylococcus aureus (MRSA). The study comprised 4 groups (each, n = 6): Group 1 was the control group (CG). Group 2 received allograft human (h) ADSs transplanted into the wound. In group 3, PBM (890 nm, 80 Hz, 0.2 J/cm²) was emitted, and in group 4, a combination of PBM+ADS was used. At both studied time points, PBM+ADS, PBM, and ADS significantly decreased inflammatory cell count (p < 0.05) and increased granulation tissue formation compared to CG (p < 0.05). Similarly, there were lower inflammatory cells, as well as higher granulation tissue in the PBM+ADS compared to those of alone PBM and ADS (all, p < 0.001). At both studied time points, the GE of catalase (CAT) and superoxide dismutase (SOD) was remarkably higher in all treatment groups than in CG (p < 0.05). Concomitantly, the outcomes of the PBM+ADS group were higher than the single effects of PBM and ADS (p < 0.05). On day 8, the GE of NADPH oxidase (NOX) 1 and NOX4 was substantially less in the PBM+ADS than in the other groups (p < 0.05). PBM+ADS, PBM, and ADS treatments significantly accelerated the inflammatory and proliferative stages of wound healing in a DIIWHM with MRSA in DM1 rats by decreasing the inflammatory response, and NOX1 and 4 as well; and also increasing granulation tissue formation and SOD and CAT. The associated treatment of PBM+ADS was more effective than the individual impacts of alone PBM and ADS because of the additive anti-inflammatory and proliferative effects of PBM plus ADS treatments.

Melatonin: Regulation of Viral Phase Separation and Epitranscriptomics in Post-Acute Sequelae of COVID-19

The relentless, protracted evolution of the SARS-CoV-2 virus imposes tremendous pressure on herd immunity and demands versatile adaptations by the human host genome to counter transcriptomic and epitranscriptomic alterations associated with a wide range of short- and long-term manifestations during acute infection and post-acute recovery, respectively. To promote viral replication during active infection and viral persistence, the SARS-CoV-2 envelope protein regulates host cell microenvironment including pH and ion concentrations to maintain a high oxidative environment that supports template switching, causing extensive mitochondrial damage and activation of pro-inflammatory cytokine signaling cascades. Oxidative stress and mitochondrial distress induce dynamic changes to both the host and viral RNA m6A methylome, and can trigger the derepression of long interspersed nuclear element 1 (LINE1), resulting in global hypomethylation, epigenetic changes, and genomic instability. The timely application of melatonin during early infection enhances host innate antiviral immune responses by preventing the formation of "viral factories" by nucleocapsid liquid-liquid phase separation that effectively blockades viral genome transcription and packaging, the disassembly of stress granules, and the sequestration of DEAD-box RNA helicases, including DDX3X, vital to immune signaling. Melatonin prevents membrane depolarization and protects cristae morphology to suppress glycolysis via antioxidant-dependent and -independent mechanisms. By restraining the derepression of LINE1 via multifaceted strategies, and maintaining the balance in m6A RNA modifications, melatonin could be the quintessential ancient molecule that significantly influences the outcome of the constant struggle between virus and host to gain transcriptomic and epitranscriptomic dominance over the host genome during acute infection and PASC.

Conditioned medium from human uterine cervical stem cells regulates oxidative stress and angiogenesis of retinal pigment epithelial cells

INTRODUCTION

Retinal homeostasis is essential to avoid retinal pigment epithelium (RPE) damage resulting in photoreceptor death and blindness. Mesenchymal stem cells-based cell therapy could contribute to the maintenance of the retinal homeostasis. We have explored the effect of human uterine cervical stem cells (hUCESCs) conditioned medium (hUCESC-CM) on RPE cells under oxidative stress condition.

METHODS

ARPE-19 cells were treated with hydrogen peroxide (H2O2) in presence or absence of hUCESC-CM. qRT-PCR and Western blot were used to evaluate the expression of oxidative stress (HO-1, GCLC and HSPB1) and vasculogenesis (VEGFA, PDGFA and PDGFB) related factors. Also, we assessed in vitro effects of hUCESC-CM on endothelial cells (HUVEC) tube formation.

RESULTS

mRNA expression of HO-1, GCLC, HSPB1, VEGFA, PDGFA and PDGFB were significantly increased in ARPE-19 cells treated with H2O2 + hUCESC-CM compared to cells treated with H2O2 only. Regarding the tube formation assay, HUVEC treated with supernatant from ARPE-19 cells treated with H2O2 + hUCESC-CM showed a significant increase in average vessel length, number of capillary-like junctions and average of vessels area compared with HUVEC treated with supernatant from ARPE-19 cells treated with H2O2 only.

CONCLUSION

Our results show potential therapeutic effects of hUCESC-CM on RPE, such as protection from damage by oxidative stress, stimulation of detoxifying genes and a better vascularization.

Interpenetrating gallol functionalized tissue adhesive hyaluronic acid hydrogel polarizes macrophages to an immunosuppressive phenotype

Innovative scaffold designs that modulate the local inflammatory microenvironment through favorable macrophage polarization and suppressing oxidative stress are needed for successful clinical translation of regenerative cell therapies and graft integration. We herein report derivation of a hydrazone-crosslinked gallol functionalized hyaluronic acid (HA-GA)-based hydrogel that displayed outstanding viscoelastic properties and immunomodulatory characteristics. Grafting of 6% gallol (GA) to a HA-backbone formed an interpenetrative network by promoting an additional crosslink between the gallol groups in addition to hydrazone crosslinking. This significantly enhanced the mechanical stability and displayed shear-thinning/self-healing characteristics, facilitated tissue adhesive properties to porcine tissue and also displayed radical scavenging properties, protecting encapsulated fibroblasts from peroxide challenge. The THP-1 human macrophage cell line or primary bone-marrow-derived murine macrophages cultured within HA-GA gels displayed selective polarization to a predominantly anti-inflammatory phenotype by upregulating IL4ra, IL-10, TGF-β, and TGF-βR1 expression when compared with HA-HA gels. Conversely, culturing of pro-inflammatory activated primary murine macrophages in HA-GA gels resulted in a significant reduction of pro-inflammatory TNF-α, IL-1β, SOCS3 and IL-6 marker expression, and upregulated expression of anti-inflammatory cytokines including TGF-β. Finally, when the gels were implanted subcutaneously into healthy mice, we observed infiltration of pro-inflammatory myeloid cells in HA-HA gels, while immunosuppressive phenotypes were observed within the HA-GA gels. Taken together these data suggest that HA-GA gels are an ideal injectable scaffold for viable immunotherapeutic interventions. STATEMENT OF SIGNIFICANCE: Host immune response against the implanted scaffolds that are designed to deliver stem cells or therapeutic proteins in vivo significantly limits the functional outcome. For this reason, we have designed immunomodulatory injectable scaffolds that can favorably polarize the recruited macrophages and impart antioxidant properties to suppress oxidative stress. Specifically, we have tailored a hyaluronic acid-based extracellular matrix mimetic injectable scaffold that is grafted with immunomodulatory gallol moiety. Gallol functionalization of hydrogel not only enhanced the mechanical properties of the scaffold by forming an interpenetrating network but also induced antioxidant properties, tissue adhesive properties, and polarized primary murine macrophages to immunosuppressive phenotype. We believe such immunoresponsive implants will pave the way for developing the next-generation of biomaterials for regenerative medicine applications.

Cellular and Molecular Mechanisms Involved in Hematopoietic Stem Cell Aging as a Clinical Prospect

There is a hot topic in stem cell research to investigate the process of hematopoietic stem cell (HSC) aging characterized by decreased self-renewal ability, myeloid-biased differentiation, impaired homing, and other abnormalities related to hematopoietic repair function. It is of crucial importance that HSCs preserve self-renewal and differentiation ability to maintain hematopoiesis under homeostatic states over time. Although HSC numbers increase with age in both mice and humans, this cannot compensate for functional defects of aged HSCs. The underlying mechanisms regarding HSC aging have been studied from various perspectives, but the exact molecular events remain unclear. Several cell-intrinsic and cell-extrinsic factors contribute to HSC aging including DNA damage responses, reactive oxygen species (ROS), altered epigenetic profiling, polarity, metabolic alterations, impaired autophagy, Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway, nuclear factor- (NF-) κB pathway, mTOR pathway, transforming growth factor-beta (TGF-β) pathway, and wingless-related integration site (Wnt) pathway. To determine how deficient HSCs develop during aging, we provide an overview of different hallmarks, age-related signaling pathways, and epigenetic modifications in young and aged HSCs. Knowing how such changes occur and progress will help researchers to develop medications and promote the quality of life for the elderly and possibly alleviate age-associated hematopoietic disorders. The present review is aimed at discussing the latest advancements of HSC aging and the role of HSC-intrinsic factors and related events of a bone marrow niche during HSC aging.

Activation of the Hippo Pathway in Rana sylvatica: Yapping Stops in Response to Anoxia

Wood frogs (Rana sylvatica) display well-developed anoxia tolerance as one component of their capacity to endure prolonged whole-body freezing during the winter months. Under anoxic conditions, multiple cellular responses are triggered to efficiently cope with stress by suppressing gene transcription and promoting activation of mechanisms that support cell survival. Activation of the Hippo signaling pathway initiates a cascade of protein kinase reactions that end with phosphorylation of YAP protein. Multiple pathway components of the Hippo pathway were analyzed via immunoblotting, qPCR or DNA-binding ELISAs to assess the effects of 24 h anoxia and 4 h aerobic recovery, compared with controls, on liver and heart metabolism of wood frogs. Immunoblot results showed significant increases in the relative levels of multiple proteins of the Hippo pathway representing an overall activation of the pathway in both organs under anoxia stress. Upregulation of transcript levels further confirmed this. A decrease in YAP and TEAD protein levels in the nuclear fraction also indicated reduced translocation of these proteins. Decreased DNA-binding activity of TEAD at the promoter region also suggested repression of gene transcription of its downstream targets such as SOX2 and OCT4. Furthermore, changes in the protein levels of two downstream targets of TEAD, OCT4 and SOX2, established regulated transcriptional activity and could possibly be associated with the activation of the Hippo pathway. Increased levels of TAZ in anoxic hearts also suggested its involvement in the repair mechanism for damage caused to cardiac muscles during anoxia. In summary, this study provides the first insights into the role of the Hippo pathway in maintaining cellular homeostasis in response to anoxia in amphibians.

The effect of photobiomodulation therapy on antioxidants and oxidative stress profiles of adipose derived mesenchymal stem cells in diabetic rats

We studied the effects of photobiomodulation therapy (PBMT) on adipose-derived mesenchymal stem cells (ADSCs) which were extracted from streptozotocin (STZ) induced diabetic rats. Adipose tissue was extracted from the hypodermis of diabetic rats, and diabetic ADSCs were extracted, characterized, and cultured. There were two in vitro groups: control-diabetic ADSCs, and PBMT-diabeticADSCs. We used 630 nm and 810 nm laser at 1.2 J/cm² with 3 applications 48 h apart. We measured cell viability, apoptosis, population doubling time (PDT), and reactive oxygen species (ROS) by flow cytometry. Gene expression of antioxidants, including cytosolic copper-zinc superoxide dismutase (SOD1), catalase (CAT), total antioxidant capacity (TAC), and oxidative stress biomarkers (NADPH oxidase 1 and 4) by quantitative real time (qRT) - PCR. In this study, data were analyzed using t-test. Viability of PBMT-diabetic- ADSC group was higher than control- diabetic-ADSC (p = 0.000). PDT and apoptosis of PBMT- diabetic-ADSC group were lower than control-diabetic -ADSC (p = 0.001, p = 0.02). SOD1 expression and TAC of PBMT- diabetic-ADSC group were higher than control -diabetic -ADSC (p = 0.018, p = 0.005). CAT of PBMT -diabetic-ADSC group was higher than control-diabetic -ADSC. ROS, NOX1, and NOX4 of PBMT- diabetic -ADSC group were lower than control-diabetic-ADSC (p = 0.002, p = 0.021, p = 0.017). PBMT may improve diabetic- ADSC function in vitro by increasing levels of cell viability, and gene expression of antioxidant agents (SOD1, CAT, and TAC), and significantly decreasing of levels of PDT, apoptosis, ROS, and gene expression of oxidative stress biomarkers (NOX1 and NOX4).

Camphorquinone Promotes the Antisenescence Effect via Activating AMPK/SIRT1 in Stem Cells and D-Galactose-Induced Aging Mice

Terpenoids are a wide class of secondary metabolites with geroprotective properties that can alter the mechanism of aging and aging-related diseases. Camphorquinone (CQ) is a bicyclic monoterpenoid compound that can be efficiently synthesized through the continuous bromination and oxidation reaction of camphor. The purpose of this study is to investigate the effects of CQ on oxidative-stress-induced senescence and its underlying mechanisms. To generate oxidative stress in human bone marrow mesenchymal stem cells (hBM-MSCs) and mice, we used hydrogen peroxide (200 μM twice) and D-galactose (D-Gal) (150 mg/kg for 10 weeks), respectively. Our findings suggest that CQ potentially reduces senescence in hBM-MSCs and mouse heart tissue. In addition, we found that CQ boosted AMPK/SIRT1 activation and autophagy in both models. These results were subsequently verified in hBM-MSCs using compound C (an AMPK inhibitor) but AMPK inhibition by CC did not significantly reduce the SIRT1 and the autophagy markers. CQ treatment also reduced the gene expression of inflammation markers in D-Gal-induced aging mouse heart tissue. Furthermore, we determined that CQ fits all of the pharmacological parameters using the freely available SwissADME Web tool. Collectively, our findings demonstrate that CQ possesses antisenescence and cardioprotective properties, and that oxidative-stress-induced senescence could be suppressed by AMPK/SIRT1 and autophagy mechanisms.

Oxidative Stress Enhances Autophagy-Mediated Death Of Stem Cells Through Erk1/2 Signaling Pathway - Implications For Neurotransplantations

Stem cell therapies are becoming increasingly popular solutions for neurological disorders. However, there is a lower survival rate of these cells after transplantation. Oxidative stress is linked to brain damage, and it may also impact transplanted stem cells. To better understand how transplanted cells respond to oxidative stress, the current study used H₂O₂. We briefly illustrated that exogenous H₂O₂ treatment exaggerated oxidative stress in the human dental pulp and mesenchymal stem cells. 2',7'-Dichlorofluorescin diacetate (DCFDA), MitoSOX confirms the reactive oxygen species (ROS) involvement, which was remarkably subsided by the ROS inhibitors. The findings showed that H₂O₂ activates autophagy by enhancing pro-autophagic proteins, Beclin1 and Atg7. Increased LC3II/I expression (which co-localized with lysosomal proteins, LAMP1 and Cathepsin B) showed that H₂O₂ treatment promoted autophagolysosome formation. In the results, both Beclin1 and Atg7 were observed co-localized in mitochondria, indicating their involvement in mitophagy. The evaluation of Erk1/2 in the presence and absence of Na-Pyruvate, PEG-Catalase, and PD98059 established ROS-Erk1/2 participation in autophagy regulation. Further, these findings showed a link between apoptosis and autophagy. The results conclude that H₂O₂ acts as a stressor, promoting autophagy and mitophagy in stem cells under oxidative stress. The current study may help understand better cell survival and death approaches for transplanted cells in various neurological diseases. The current study uses human Dental Pulp and Mesenchymal Stem cells to demonstrate the importance of H₂O₂-driven autophagy in deciding the fate of these cells in an oxidative microenvironment. To summarise, we discovered that exogenous H₂O₂ treatment causes oxidative stress. Exogenous H₂O₂  treatment also increased ROS production, especially intracellular H₂O₂. H₂O₂ stimulated the ErK1/2 signaling pathway and autophagy. Erk1/2 was found to cause autophagy. Further, the function of mitophagy appeared to be an important factor in the H₂O₂-induced regulation of these two human stem cell types. In a nutshell, by engaging in autophagy nucleation, maturation, and terminal phase proteins, we elucidated the participation of autophagy in cell dysfunction and death.

Biofunction of Polydopamine Coating in Stem Cell Culture

High levels of reactive oxygen species (ROS) during stem cell expansion often lead to replicative senescence. Here, a polydopamine (PDA)-coated substrate was used to scavenge extracellular ROS for mesenchymal stem cell (MSC) expansion. The PDA-coated substrate could reduce the oxidative stress and mitochondrial damage in replicative senescent MSCs. The expression of senescence-associated β-galactosidase of MSCs from three human donors (both bone marrow- and adipose tissue-derived) was suppressed on PDA. The MSCs on the PDA-coated substrate showed a lower level of interleukin 6 (IL-6), one of the senescence-associated inflammatory components. Cellular senescence-specific genes, such as p53 and p21, were downregulated on the PDA-coated substrate, while the stemness-related gene, OCT4, was upregulated. The PDA-coated substrate strongly promoted the proliferation rate of MSCs, while the stem cell character and differentiation potential were retained. Large-scale expansion of stem cells would greatly benefit from the PDA-coated substrate.

Cell therapy for the treatment of heart disease: Renovation work on the broken heart is still in progress

Cardiovascular disease (CVD) continues to be the number one killer in the aging population. Heart failure (HF) is also an important cause of morbidity and mortality in patients with congenital heart disease (CHD). Novel therapeutic approaches that could restore stable heart function are much needed in both paediatric and adult patients. Regenerative medicine holds promises to provide definitive solutions for correction of congenital and acquired cardiac defects. In this review article, we recap some important aspects of cardiovascular cell therapy. First, we report quantifiable data regarding the scientific advancements in the field and how this has been translated into tangible outcomes according clinical studies and related meta-analyses. We then comment on emerging trends and technologies, such as the use of second-generation cell products, including pericyte-like vascular progenitors, and reprogramming of cells by different approaches including modulation of oxidative stress. The more affordable and feasible strategy of repurposing clinically available drugs to awaken the intrinsic healing potential of the heart will be discussed in the light of current social, financial, and ethical context. Cell therapy remains a work in progress field. Uncertainty in the ability of the experts and policy makers to solve urgent medical problems is growing in a world that is significantly influenced by them. This is particularly true in the field of regenerative medicine, due to great public expectations, polarization of leadership and funding, and insufficient translational vision. Cardiovascular regenerative medicine should be contextualized in a holistic program with defined priorities to allow a complete realization. Reshaping the notion of medical expertise is fundamental to fill the current gap in translation.

α-Tocopherol Acetate Attenuates Mitochondrial Oxygen Consumption and Maintains Primitive Cells within Mesenchymal Stromal Cell Population

We present here the data showing, in standard cultures exposed to atmospheric O₂ concentration, that alpha-tocopherol acetate (α-TOA) has a positive impact on primitive cells inside mesenchymal stromal cell (MstroC) population, by maintaining their proliferative capacity. α-TOA decreases the O₂ consumption rate of MStroC probably by impacting respiratory chain complex II activity. This action, however, is not associated with a compensatory increase in glycolysis activity, in spite of the fact that the degradation of HIF-1α was decreased in presence of α-TOA. This is in line with a moderate enhancement of mtROS upon α-TOA treatment. However, the absence of glycolysis stimulation implies the inactivity of HIF-1α which might - if it were active - be related to the maintenance of stemness. It should be stressed that α-TOA might act directly on the gene expression as well as the mtROS themselves, which remains to be elucidated. Alpha-tocopherol acetate (α-TOA), a synthetic vitamin E ester, attenuates electron flow through electron transport chain (ETC) which is probably associated with a moderate increase in mtROS in Mesenchymal Stromal Cells. α-TOA action results in enhancement of the proliferative capacity and maintenance of the differentiation potential of the mesenchymal stem and progenitor cells.

Selenium Nanoparticles by Moderating Oxidative Stress Promote Differentiation of Mesenchymal Stem Cells to Osteoblasts

Purpose

Redox homeostasis plays an important role in the osteogenic differentiation of human mesenchymal stem cells (hMSCs) for bone engineering. Oxidative stress (OS) is believed to induce osteoporosis by changing bone homeostasis. Selenium nanoparticles (SeNPs), an antioxidant with pleiotropic pharmacological activity, prevent bone loss. However, the molecular mechanism underlying the osteogenic activity during hMSC–SeNP interaction is unclear.

Methods

This study assessed the effects of different concentrations (25, 50, 100, and 300 ng/mL) of SeNPs on the cell viability and differentiation ability of human embryonic stem cell-derived hMSCs. In addition, we analyzed OS markers and their effect on mitogen-activated protein kinase (MAPK) and Forkhead box O3 (FOXO3) during osteogenesis.

Results

SeNPs increased the cell viability of hMSCs and induced their differentiation toward an osteogenic over an adipogenic lineage by enhancing osteogenic transcription and mineralization, while inhibiting Nile red staining and adipogenic gene expression. By preventing excessive reactive oxygen species accumulation, SeNPs increased antioxidant levels in hMSCs undergoing osteogenesis compared to untreated cells. In addition, SeNPs significantly upregulated the gene and protein expression of phosphorylated c-Jun N-terminal kinase (JNK) and FOXO3a, with no significant change in the expression levels of extracellular signal-related kinase (ERK) and p38 MAPK.

Conclusion

The results approved that low concentrations of SeNPs might enhance the cell viability and osteogenic potential of hMSCs by moderating OS. Increased JNK and FOXO3a expression shows that SeNPs might enhance osteogenesis via activation of the JNK/FOXO3 pathway. In addition, SeNP co-supplementation might prevent bone loss by enhancing osteogenesis and, thus, can be an effective candidate for treating osteoporosis through cell-based therapy.

Impaired expression of the COSMOC/MOCOS gene unit in ASD patient stem cells

Autism spectrum disorders (ASD) are complex neurodevelopmental disorders with a very large number of risk loci detected in the genome. However, at best, each of them explains rare cases, the majority being idiopathic. Genomic data on ASD derive mostly from post-mortem brain analyses or cell lines derived from blood or patient-specific induced pluripotent stem cells (iPSCS). Therefore, the transcriptional and regulatory architecture of the nervous system, particularly during early developmental periods, remains highly incomplete. To access the critical disturbances that may have occurred during pregnancy or early childhood, we recently isolated stem cells from the nasal cavity of anesthetized patients diagnosed for ASD and compared them to stem cells from gender-matched control individuals without neuropsychiatric disorders. This allowed us to discover MOCOS, a non-mutated molybdenum cofactor sulfurase-coding gene that was under-expressed in the stem cells of most ASD patients of our cohort, disturbing redox homeostasis and synaptogenesis. We now report that a divergent transcription upstream of MOCOS generates an antisense long noncoding RNA, to which we coined the name COSMOC. Surprisingly, COSMOC is strongly under-expressed in all ASD patients of our cohort with the exception of a patient affected by Asperger syndrome. Knockdown studies indicate that loss of COSMOC reduces MOCOS expression, destabilizes lipid and energy metabolisms of stem cells, but also affects neuronal maturation and splicing of synaptic genes. Impaired expression of the COSMOC/MOCOS bidirectional unit might shed new lights on the origins of ASD that could be of importance for future translational studies.

Reflections of an aging free radical

In this mini-reflection, I explain how during my doctoral work in a Botany Department I first became interested in H2O2 and later in my career in other reactive oxygen species, especially the role of "catalytic" iron and haem compounds (including leghaemoglobin) in promoting oxidative damage. The important roles that H2O2, other ROS and dietary plants play in respect to humans are discussed. I also review the roles of diet-derived antioxidants in relation to human disease, presenting reasons why clinical trials using high doses of natural antioxidants have generally given disappointing results. Iron chelators and ergothioneine are reviewed as potential cytoprotective agents with antioxidant properties that may be useful therapeutically. The discovery of ferroptosis may also lead to novel agents that can be used to treat certain diseases.

Rejuvenation of mesenchymal stem cells by extracellular vesicles inhibits the elevation of reactive oxygen species

Aging induces numerous cellular disorders, such as the elevation of reactive oxygen species (ROS), in a number type of cells, including mesenchymal stem cells (MSCs). However, the correlation of ROS and impaired healing abilities as well as whether or not the inhibition of elevating ROS results in the rejuvenation of elderly MSCs is unclear. The rejuvenation of aged MSCs has thus recently received attention in the field of regenerative medicine. Specifically, extracellular vesicles (EVs) act as a novel tool for stem cell rejuvenation due to their gene transfer ability with systemic effects and safety. In the present study, we examined the roles of aging-associated ROS in the function and rejuvenation of elderly MSCs by infant EVs. The data clearly showed that elderly MSCs exhibited the downregulation of superoxide dismutase (SOD)1 and SOD3, which resulted in the elevation of ROS and downregulation of the MEK/ERK pathways, which are involved in the impairment of the MSCs’ ability to decrease necrotic area in the skin flap model. Furthermore, treatment with the antioxidant Edaravone or co-overexpression of SOD1 and SOD3 rescued elderly MSCs from the elevation of ROS and cellular senescence, thereby improving their functions. Of note, infant MSC-derived EVs rejuvenated elderly MSCs by inhibiting ROS production and the acceleration of cellular senescence and promoting the proliferation and in vivo functions in both type 1 and type 2 diabetic mice.

Pro-Aging Effects of Xanthine Oxidoreductase Products

The senescence process is the result of a series of factors that start from the genetic constitution interacting with epigenetic modifications induced by endogenous and environmental causes and that lead to a progressive deterioration at the cellular and functional levels. One of the main causes of aging is oxidative stress deriving from the imbalance between the production of reactive oxygen (ROS) and nitrogen (RNS) species and their scavenging through antioxidants. Xanthine oxidoreductase (XOR) activities produce uric acid, as well as reactive oxygen and nitrogen species, which all may be relevant to such equilibrium. This review analyzes XOR activity through in vitro experiments, animal studies and clinical reports, which highlight the pro-aging effects of XOR products. However, XOR activity contributes to a regular level of ROS and RNS, which appears essential for the proper functioning of many physiological pathways. This discourages the use of therapies with XOR inhibitors, unless symptomatic hyperuricemia is present.

Serum deprivation initiates adaptation and survival to oxidative stress in prostate cancer cells

Inadequate nutrient intake leads to oxidative stress disrupting homeostasis, activating signaling, and altering metabolism. Oxidative stress serves as a hallmark in developing prostate lesions, and an aggressive cancer phenotype activating mechanisms allowing cancer cells to adapt and survive. It is unclear how adaptation and survival are facilitated; however, literature across several organisms demonstrates that a reversible cellular growth arrest and the transcription factor, nuclear factor-kappaB (NF-κB), contribute to cancer cell survival and therapeutic resistance under oxidative stress. We examined adaptability and survival to oxidative stress following nutrient deprivation in three prostate cancer models displaying varying degrees of tumorigenicity. We observed that reducing serum (starved) induced reactive oxygen species which provided an early oxidative stress environment and allowed cells to confer adaptability to increased oxidative stress (H₂O₂). Measurement of cell viability demonstrated a low death profile in stressed cells (starved + H₂O₂), while cell proliferation was stagnant. Quantitative measurement of apoptosis showed no significant cell death in stressed cells suggesting an adaptive mechanism to tolerate oxidative stress. Stressed cells also presented a quiescent phenotype, correlating with NF-κB nuclear translocation, suggesting a mechanism of tolerance. Our data suggests that nutrient deprivation primes prostate cancer cells for adaptability to oxidative stress and/or a general survival mechanism to anti-tumorigenic agents.

Regulation of Hematopoietic Stem Cell Fate and Malignancy

The regulation of hematopoietic stem cell (HSC) fate decision, whether they keep quiescence, self-renew, or differentiate into blood lineage cells, is critical for maintaining the immune system throughout one’s lifetime. As HSCs are exposed to age-related stress, they gradually lose their self-renewal and regenerative capacity. Recently, many reports have implicated signaling pathways in the regulation of HSC fate determination and malignancies under aging stress or pathophysiological conditions. In this review, we focus on the current understanding of signaling pathways that regulate HSC fate including quiescence, self-renewal, and differentiation during aging, and additionally introduce pharmacological approaches to rescue defects of HSC fate determination or hematopoietic malignancies by kinase signaling pathways.

Mechanisms and rejuvenation strategies for aged hematopoietic stem cells

Hematopoietic stem cell (HSC) aging, which is accompanied by reduced self-renewal ability, impaired homing, myeloid-biased differentiation, and other defects in hematopoietic reconstitution function, is a hot topic in stem cell research. Although the number of HSCs increases with age in both mice and humans, the increase cannot compensate for the defects of aged HSCs. Many studies have been performed from various perspectives to illustrate the potential mechanisms of HSC aging; however, the detailed molecular mechanisms remain unclear, blocking further exploration of aged HSC rejuvenation. To determine how aged HSC defects occur, we provide an overview of differences in the hallmarks, signaling pathways, and epigenetics of young and aged HSCs as well as of the bone marrow niche wherein HSCs reside. Notably, we summarize the very recent studies which dissect HSC aging at the single-cell level. Furthermore, we review the promising strategies for rejuvenating aged HSC functions. Considering that the incidence of many hematological malignancies is strongly associated with age, our HSC aging review delineates the association between functional changes and molecular mechanisms and may have significant clinical relevance.

Therapeutic efficacy of catalpol against apoptosis in cardiomyocytes derived from human induced pluripotent stem cells

Cardiac arrhythmia is an irregular heart rhythm that can lead to serious heart conditions and various organ disorders, and may cause sudden cardiac death. Catalpol belongs to the iridoid glycoside family and is highly abundant in Rehmannia glutinosa Libosch. The study included five groups such as group I (normal control), group II (treatment control), group III (low-dose treatment), group IV (medium-dose treatment) and group V (high-dose treatment). We investigated the therapeutic effects of catalpol on cardiac arrhythmia in human-induced pluripotent stem cells (iPSCs). Cell viability, lactate dehydrogenase (LDH) levels, lipid peroxidation, antioxidant activity, and caspase-3 and caspase-9 activities and protein levels were measured in normal control, treatment control, and treated (1, 10, and 100 µM) iPSC groups. Compared with the treatment control group, catalpol supplementation (1, 10, and 100 µM) increased iPSC cell viability by 7.5, 27.3, and 65.8%, respectively; reduced the LDH levels by 10.4, 31.3, and 75.2%, respectively; and reduced the lipid peroxidation levels by 7.7, 33.0, and 62.6%, respectively. The antioxidant levels were significantly higher in the treatment control group than in the normal control group. Catalpol (100 µM) reduced the caspase-3 and caspase-9 activities by more than 30% and increased expression of the corresponding proteins by more than 50%. These findings suggest that the naturally occurring iridoid glycoside catalpol is effective against aconitine-induced cardiac arrhythmia in iPSCs.

Oxidative stress regulates progenitor behavior and cortical neurogenesis

Orderly division of radial glial progenitors (RGPs) in the developing mammalian cerebral cortex generates deep and superficial layer neurons progressively. However, the mechanisms that control RGP behavior and precise neuronal output remain elusive. Here, we show that the oxidative stress level progressively increases in the developing mouse cortex and regulates RGP behavior and neurogenesis. As development proceeds, numerous gene pathways linked to reactive oxygen species (ROS) and oxidative stress exhibit drastic changes in RGPs. Selective removal of PRDM16, a transcriptional regulator highly expressed in RGPs, elevates ROS level and induces expression of oxidative stress-responsive genes. Coinciding with an enhanced level of oxidative stress, RGP behavior was altered, leading to abnormal deep and superficial layer neuron generation. Simultaneous expression of mitochondrially targeted catalase to reduce cellular ROS levels significantly suppresses cortical defects caused by PRDM16 removal. Together, these findings suggest that oxidative stress actively regulates RGP behavior to ensure proper neurogenesis in the mammalian cortex.

Stem cell therapy for chronic skin wounds in the era of personalized medicine: From bench to bedside

With the significant financial burden of chronic cutaneous wounds on the healthcare system, not to the personal burden mention on those individuals afflicted, it has become increasingly essential to improve our clinical treatments. This requires the translation of the most recent benchtop approaches to clinical wound repair as our current treatment modalities have proven insufficient. The most promising potential treatment options rely on stem cell-based therapies. Stem cell proliferation and signaling play crucial roles in every phase of the wound healing process and chronic wounds are often associated with impaired stem cell function. Clinical approaches involving stem cells could thus be utilized in some cases to improve a body's inhibited healing capacity. We aim to present the laboratory research behind the mechanisms and effects of this technology as well as current clinical trials which showcase their therapeutic potential. Given the current problems and complications presented by chronic wounds, we hope to show that developing the clinical applications of stem cell therapies is the rational next step in improving wound care.

Recombinant Klotho Protects Human Periodontal Ligament Stem Cells by Regulating Mitochondrial Function and the Antioxidant System during H2O2-Induced Oxidative Stress

Human periodontal ligament stem cells (hPDLSCs) are a favourable source for tissue engineering, but oxidative stress conditions during cell culture and transplantation could affect stem cell viability and stemness, leading to failed regeneration. The aim of this study was to evaluate the antioxidant and protective effects of Klotho, an antiageing protein, against cell damage and the loss of osteogenesis in hPDLSCs in H₂O₂-induced oxidative environments. H₂O₂ was used as an exogenous reactive oxygen species (ROS) to induce oxidative stress. Recombinant human Klotho protein was administered before H₂O₂ treatment. Multitechniques were used to assess antioxidant activity, cell damage, and osteogenic ability of hPDLSCs in oxidative stress and the effects of Klotho on hPDLSCs. Mitochondrial function was analyzed by an electron microscopy scan of cellular structure, mitochondrial DNA copy number, and cellular oxygen consumption rate (OCR). Furthermore, we explored the pathway by which Klotho may function to regulate the antioxidant system. We found that pretreatment with recombinant human Klotho protein could enhance SOD activity and reduce intracellular oxidative stress levels. Klotho reduced H₂O₂-induced cellular damage and eventually maintained the osteogenic differentiation potential of hPDLSCs. Notably, Klotho promoted mitochondrial function and activated antioxidants by negatively regulating the PI3K/AKT/FoxO1 pathway. The findings suggest that Klotho protein enhanced the antioxidative ability of hPDLSCs and protected stem cell viability and stemness from H₂O₂-induced oxidative stress by restoring mitochondrial functions and the antioxidant system.

Dnmt3a-Mediated DNA Methylation Changes Regulate Osteogenic Differentiation of hMSCs Cultivated in the 3D Scaffolds under Oxidative Stress

Oxidative stress (OS) caused by multiple factors occurs after the implantation of bone repair materials. DNA methylation plays an important role in the regulation of osteogenic differentiation. Moreover, recent studies suggest that DNA methyltransferases (Dnmts) are involved in bone formation and resorption. However, the effect and mechanism of DNA methylation changes induced by OS on bone formation after implantation still remain unknown. Three-dimensional (3D) cell culture systems are much closer to the real situation than traditional monolayer cell culture systems in mimicking the in vivo microenvironment. We have developed porous 3D scaffolds composed of mineralized collagen type I, which mimics the composition of the extracellular matrix of human bone. Here, we first established a 3D culture model of human mesenchymal stem cells (hMSCs) seeded in the biomimetic scaffolds using 160 μM H₂O₂ to simulate the microenvironment of osteogenesis after implantation. Our results showed that decreased methylation levels of ALP and RUNX2 were induced by H₂O₂ treatment in hMSCs cultivated in the 3D scaffolds. Furthermore, we found that Dnmt3a was significantly downregulated in a porcine anterior lumbar interbody fusion model and was confirmed to be reduced by H₂O₂ treatment using the 3D in vitro model. The hypomethylation of ALP and RUNX2 induced by H₂O₂ treatment was abolished by Dnmt3a overexpression. Moreover, our findings demonstrated that the Dnmt inhibitor 5-AZA can enhance osteogenic differentiation of hMSCs under OS, evidenced by the increased expression of ALP and RUNX2 accompanied by the decreased DNA methylation of ALP and RUNX2. Taken together, these results suggest that Dnmt3a-mediated DNA methylation changes regulate osteogenic differentiation and 5-AZA can enhance osteogenic differentiation via the hypomethylation of ALP and RUNX2 under OS. The biomimetic 3D scaffolds combined with 5-AZA and antioxidants may serve as a promising novel strategy to improve osteogenesis after implantation.

Psychological Stress and Cellular Aging in Cancer: A Meta-Analysis

BACKGROUND

Epidemiological evidence continues to accumulate on the effect of psychosocial and behavioral factors in relation to cancer risk, progression, and mortality.

MATERIAL AND METHODS

This article presents the current evidence on the relationship between psychological stress and the risk of cancer and cellular aging process. Ten databases were searched to identify publications up to September 2019. References from retrieved articles were also reviewed. We included nine review papers and 26 cohort or case-control studies based on inclusion/exclusion criteria.

RESULTS

Results of previously published review articles did not show consistent evidence for the association between cancer risk and psychological stress, while previous evidence is stronger regarding the role of chronic psychological stress on cancer growth and metastasis and aging. In seven observational studies, severe life events, anxiety, depression, insufficient social support perception, or avoiding coping strategy were significantly associated with breast cancer risk. For other specific types of cancer, 11 studies reported increased risk factors for stressful life events, and two others found increased mortality or a decline in treatment adherence.

CONCLUSIONS

Recent epidemiological evidence generally suggests psychosocial factors may be considered risk factors for specific types of cancer and play a key role in the cellular aging process. Understanding molecular mechanisms of the stress interaction is important in cancer management and prevention. The psychological stressors should be considered when developing or evaluating change in psychosocial practice.

Asiatic acid supplementation during the in vitro culture period improves early embryonic development of porcine embryos produced by parthenogenetic activation, somatic cell nuclear transfer and in vitro fertilization

Asiatic acid is a pentacyclic triterpene enriched in the medicinal herb Centella asiatica, and it has been suggested to possess free radical scavenging and anti-apoptotic properties. The purpose of the current study was to explore the effects of asiatic acid on porcine early-stage embryonic development and the potential mechanisms for any observed effects. The results showed that 10 μM asiatic acid supplementation during the in vitro culture period dramatically improved developmental competence in porcine embryos derived from parthenogenetic activation (PA), somatic cell nuclear transfer (SCNT) and in vitro fertilization (IVF). Further analysis revealed that asiatic acid attenuated H₂O₂-induced intracellular reactive oxygen species (ROS) generation. Notably, asiatic acid not only enhanced intracellular GSH levels but also attenuated mitochondrial dysfunction. Gene expression analysis revealed that asiatic acid upregulated expression of the antioxidant-related gene Sod-1 and the blastocyst formation related gene Cox-2, while downregulating expression of the apoptosis-related gene Caspase-9 in SCNT blastocysts. These results suggest that asiatic acid exerts beneficial effects on early embryonic development in porcine embryos and that asiatic acid may be useful for improving the in vitro production of porcine embryos.

O-cyclic phytosphingosine-1-phosphate stimulates HIF1α-dependent glycolytic reprogramming to enhance the therapeutic potential of mesenchymal stem cells

O-cyclic phytosphingosine-1-phosphate (cP1P) is a novel chemically synthesized sphingosine metabolite derived from phytosphingosine-1-phosphate. Although structurally similar to sphingosine-1-phosphate (S1P), its biological properties in stem cells remain to be reported. We investigated the effect of cP1P on the therapeutic potential of mesenchymal stem cells (MSCs) and their regulatory mechanism. We found that, under hypoxia, cP1P suppressed MSC mitochondrial dysfunction and apoptosis. Metabolic data revealed that cP1P stimulated glycolysis via the upregulation of glycolysis-related genes. cP1P-induced hypoxia-inducible factor 1 alpha (HIF1α) plays a key role for MSC glycolytic reprogramming and transplantation efficacy. The intracellular calcium-dependent PKCα/mammalian target of the rapamycin (mTOR) signaling pathway triggered by cP1P regulated HIF1α translation via S6K1, which is critical for HIF1 activation. Furthermore, the cP1P-activated mTOR pathway induced bicaudal D homolog 1 expression, leading to HIF1α nuclear translocation. In conclusion, cP1P enhances the therapeutic potential of MSC through mTOR-dependent HIF1α translation and nuclear translocation.

Reactive Oxygen Species (ROS), Intimal Thickening, and Subclinical Atherosclerotic Disease

Arteriosclerosis causes significant morbidity and mortality worldwide. Central to this process is the development of subclinical non-atherosclerotic intimal lesions before the appearance of pathologic intimal thickening and advanced atherosclerotic plaques. Intimal thickening is associated with several risk factors, including oxidative stress due to reactive oxygen species (ROS), inflammatory cytokines and lipid. The main ROS producing systems in-vivo are reduced nicotinamide dinucleotide phosphate (NADPH) oxidase (NOX). ROS effects are context specific. Exogenous ROS induces apoptosis and senescence, whereas intracellular ROS promotes stem cell differentiation, proliferation, and migration. Lineage tracing studies using murine models of subclinical atherosclerosis have revealed the contributory role of medial smooth muscle cells (SMCs), resident vascular stem cells, circulating bone-marrow progenitors and endothelial cells that undergo endothelial-mesenchymal-transition (EndMT). This review will address the putative physiological and patho-physiological roles of ROS in controlling vascular cell fate and ROS contribution to vascular regeneration and disease progression.

Short Overview of ROS as Cell Function Regulators and Their Implications in Therapy Concepts

The importance of reactive oxygen species (ROS) has been gradually acknowledged over the last four decades. Initially perceived as unwanted products of detrimental oxidative stress, they have been upgraded since, and now ROS are also known to be essential for the regulation of physiological cellular functions through redox signaling. In the majority of cases, metabolic demands, along with other stimuli, are vital for ROS formation and their actions. In this review, we focus on the role of ROS in regulating cell functioning and communication among themselves. The relevance of ROS in therapy concepts is also addressed here.

Protein Kinases and Their Inhibitors in Pluripotent Stem Cell Fate Regulation

Protein kinases modulate the reversible postmodifications of substrate proteins to their phosphorylated forms as an essential process in regulating intracellular signaling transduction cascades. Moreover, phosphorylation has recently been shown to tightly control the regulatory network of kinases responsible for the induction and maintenance of pluripotency, defined as the particular ability to differentiate pluripotent stem cells (PSCs) into every cell type in the adult body. In particular, emerging evidence indicates that the balance between the self-renewal and differentiation of PSCs is regulated by the small molecules that modulate kinase signaling pathways. Furthermore, new reprogramming technologies have been developed using kinase modulators, which have provided novel insight of the mechanisms underlying the kinase regulatory networks involved in the generation of induced pluripotent stem cells (iPSCs). In this review, we highlight the recent progress made in defining the roles of protein kinase signaling pathways and their small molecule modulators in regulating the pluripotent states, self-renewal, reprogramming process, and lineage differentiation of PSCs.

Cold atmospheric plasma and silymarin nanoemulsion synergistically inhibits human melanoma tumorigenesis via targeting HGF/c-MET downstream pathway

BACKGROUND

Recent studies claimed the important role of cold atmospheric plasma (CAP) with nanotechnology in cancer treatments. In this study, silymarin nanoemulsion (SN) was used along with air CAP as therapeutic agent to counter human melanoma.

METHODS

In this study, we examined the combined treatment of CAP and SN on G-361 human melanoma cells by evaluating cellular toxicity levels, reactive oxygen and nitrogen species (RONS) levels, DNA damage, melanoma-specific markers, apoptosis, caspases and poly ADP-ribose polymerase-1 (PARP-1) levels using flow cytometer. Dual-treatment effects on the epithelial-mesenchymal transition (EMT), Hepatocyte growth factor (HGF/c-MET) pathway, sphere formation and the reversal of EMT were also assessed using western blotting and microscopy respectively. SN and plasma-activated medium (PAM) were applied on tumor growth and body weight and melanoma-specific markers and the mesenchymal markers in the tumor xenograft nude mice model were checked.

RESULTS

Co-treatment of SN and air CAP increased the cellular toxicity in a time-dependent manner and shows maximum toxicity at 200 nM in 24 h. Intracellular RONS showed significant generation of ROS (< 3 times) and RNS (< 2.5 times) in dual-treated samples compared to control. DNA damage studies were assessed by estimating the level of γ-H2AX (1.8 times), PD-1 (> 2 times) and DNMT and showed damage in G-361 cells. Increase in Caspase 8,9,3/7 (> 1.5 times), PARP level (2.5 times) and apoptotic genes level were also observed in dual treated group and hence blocking HGF/c-MET pathway. Decrease in EMT markers (E-cadherin, YKL-40, N-cadherin, SNAI1) were seen with simultaneously decline in melanoma cells (BRAF, NAMPT) and stem cells (CD133, ABCB5) markers. In vivo results showed significant reduction in SN with PAM with reduction in tumor weight and size.

CONCLUSIONS

The use of air CAP using μ-DBD and the SN can minimize the malignancy effects of melanoma cells by describing HGF/c-MET molecular mechanism of acting on G-361 human melanoma cells and in mice xenografts, possibly leading to suitable targets for innovative anti-melanoma approaches in the future.

Inhibition of Osteoclastogenesis by Thioredoxin-Interacting Protein-Derived Peptide (TN13)

Overactivated osteoclasts lead to many bone diseases, including osteoporosis and rheumatoid arthritis. The p38 MAPK (p38) is an essential regulator of the receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclastogenesis and bone loss. We previously reported TAT conjugated thioredoxin-interacting protein-derived peptide (TAT-TN13) as an inhibitor of p38 in hematopoietic stem cells (HSCs). Here, we examined the role of TAT-TN13 in the differentiation and function of osteoclasts. TAT-TN13 significantly suppressed RANKL-mediated differentiation of RAW 264.7 cells and bone marrow macrophages (BMMs) into osteoclasts. TAT-TN13 also inhibited the RANKL-induced activation of NF-κB and nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), leading to the decreased expression of osteoclast-specific genes, including tartrate-resistant acid phosphatase (TRAP) and Cathepsin K. Additionally, TAT-TN13 treatment protected bone loss in ovariectomized (OVX) mice. Taken together, these results suggest that TAT-TN13 inhibits osteoclast differentiation by regulating the p38 and NF-κB signaling pathway; thus, it may be a useful agent for preventing or treating osteoporosis.