Effects of cobalt chloride on the stem cell marker expression and osteogenic differentiation of stem cells from human exfoliated deciduous teeth

Investigating the effect of Quercetin in the presence of CoCl2 as an inducing hypoxia agent on the biological characteristics of human telomerase reverse transcription-immortalized adipose tissue-derived MSCs

Studying the effect of small chemical molecules on stem cell characteristics under normoxia and hypoxia conditions is crucial to discovering the best conditions for effective biomedical applications. This study aimed to investigate the effect of Quercetin (QC; a flavonoid) in the presence of CoCl2 as a mimicking hypoxia chemical on the biological features of human telomerase reverse transcription-immortalized mesenchymal stem cell (hTERT-MSC) lines. The effect of CoCl2, QC, and their combination on the viability, proliferation, and migration of hTERT-MSCs were evaluated by MTT, Trypan-blue staining and cell counting by hemocytometer, and in vitro wound healing assays, respectively. Moreover, the effect of treatments on the reactive oxygen species (ROS) production, cell cycle, and HIF1a, c-MET, H19, and CASP3 gene expression was assessed by NBT, PI-staining and flow-cytometry, and real-time PCR assays, respectively. We found that CoCl2 and QC have different effects on the viability, proliferation, and migration of hTERT-MSCs in a dose-dependent manner. In addition, CoCl2 and QC affect ROS levels in cells in a dose- and time-dependent manner. While CoCl2 up-regulated HIF1a, QC and CoCl2 down-regulated CASP3 and c-MET in hTERT-MSCs. Moreover, QC reduced HIF1a and lncRNA-H19 expression in cells. Furthermore, in the presence of CoCl2, QC at low concentrations reduced hTERT-MSC survival, proliferation, and migration at 48 h; however, at high concentrations, it induced cell survival and proliferation. The combination treatment also up-regulated ROS levels and down-regulated the investigated genes in cells. Altogether, we conclude that QC at high concentrations under CoCl2-mediated hypoxia and short exposure time induces hTERT-MSCs survival and proliferation.

MiR-143-5p regulates the proangiogenic potential of human dental pulp stem cells by targeting HIF-1α/RORA under hypoxia: A laboratory investigation in pulp regeneration

AIM

Angiogenesis is a key event in the successful healing of pulp injuries, and hypoxia is the main stimulator of pulpal angiogenesis. In this study, we investigated the effect of hypoxia on the proangiogenic potential of human dental pulp stem cells (hDPSCs) and the role of miR-143-5p in the process.

METHODOLOGY

Human dental pulp stem cells were isolated, cultured and characterized in vitro. Cobalt chloride (CoCl2) was used to induce hypoxia in hDPSCs. CCK-8 and Transwell assays were used to determine the effect of hypoxia on hDPSCs proliferation and migration. Quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting (WB) and ELISA were performed to assess the mRNA and protein levels of HIF-1α and angiogenic cytokines in hDPSCs. The effect of hypoxia on hDPSCs proangiogenic potential was measured in vitro using Matrigel tube formation and chick chorioallantoic membrane (CAM) assays. Recombinant lentiviral vectors were constructed to stably overexpress or inhibit miR-143-5p in hDPSCs, and the proangiogenic effects were assessed using qRT-PCR, WB, and tube formation assays. miR-143-5p target genes were identified and verified using bioinformatics prediction tools, dual-luciferase reporter assays and RNA pull-down experiments. Finally, a subcutaneous transplantation model in nude mice was used to determine the effects of hypoxia treatment and miR-143-5p overexpression/inhibition in hDPSCs in dental pulp regeneration.

RESULTS

Hypoxia promotes hDPSCs proliferation, migration and proangiogenic potential. The in vivo experiments showed that hypoxia treatment (50 and 100 μM CoCl2) promoted pulp angiogenesis and dentine formation. In contrast to the levels of proangiogenic factors, miR-143-5p levels decreased with increasing CoCl2 concentration. miR-143-5p inhibition significantly promoted proangiogenic potential of hDPSCs, whereas miR-143-5p overexpression inhibited angiogenesis in vitro. Dual-luciferase reporter assay identified retinoic acid receptor-related orphan receptor alpha (RORA) as an miR-143-5p target gene in hDPSCs. RNA pull-down experiments demonstrated that HIF-1α and RORA were pulled down by biotin-labelled miR-143-5p, and the levels of HIF-1α and RORA bound to miR-143-5p in the hypoxia group were lower than those in the normoxia group. Inhibition of miR-143-5p expression in hDPSCs promoted ectopic dental pulp tissue regeneration.

CONCLUSIONS

CoCl2-induced hypoxia promotes hDPSCs-driven paracrine angiogenesis and pulp regeneration. The inhibition of miR-143-5p upregulates the proangiogenic potential of hDPSCs under hypoxic conditions by directly targeting HIF-1α and RORA.

Role of Hypoxia in Mesenchymal Stem Cells from Dental Pulp: Influence, Mechanism and Application

Mesenchymal stem cells (MSCs) from dental pulp (DP-MSCs), which include dental pulp stem cells (DPSCs) isolated from permanent teeth and stem cells from human exfoliated deciduous teeth (SHED), have emerged as highly promising cell sources for tissue regeneration, due to their high proliferative rate, multi-lineage differentiation capability and non-invasive accessibility. DP-MSCs also exert extensive paracrine effects through the release of extracellular vesicles (EVs) and multiple trophic factors. To be noted, the microenvironment, commonly referred to as the stem cell niche, plays a crucial role in shaping the functionality and therapeutic effects of DP-MSCs, within which hypoxia has garnered considerable attention. Extensive research has demonstrated that hypoxic conditions profoundly impact DP-MSCs. Specifically, hypoxia promotes DP-MSC proliferation, survival, stemness, migration, and pro-angiogenic potential while modulating their multi-lineage differentiation capacity. Furthermore, hypoxia stimulates the paracrine activities of DP-MSCs, leading to an increased production of EVs and soluble factors. Considering these findings, hypoxia preconditioning has emerged as a promising approach to enhance the therapeutic potential of DP-MSCs. In this comprehensive review, we provide a systematic overview of the influence of hypoxia on DP-MSCs, shedding light on the underlying mechanisms involved. Moreover, we also discuss the potential applications of hypoxia-preconditioned DP-MSCs or their secretome in tissue regeneration. Additionally, we delve into the methodologies employed to simulate hypoxic environments. This review aims to promote a comprehensive and systematic understanding of the hypoxia-induced effects on DP-MSCs and facilitate the refinement of regenerative therapeutic strategies based on DP-MSCs.

Hypoxia and Hypoxia Mimetic Agents As Potential Priming Approaches to Empower Mesenchymal Stem Cells

Mesenchymal stem cells (MSC) exhibit self-renewal capacity and multilineage differentiation potential, making them attractive for research and clinical application. The properties of MSC can vary depending on specific micro-environmental factors. MSC resides in specific niches with low oxygen concentrations, where oxygen functions as a metabolic substrate and a signaling molecule. Conventional physical incubators or chemically hypoxia mimetic agents are applied in cultures to mimic the original low oxygen tension settings where MSC originated. This review aims to focus on the current knowledge of the effects of various physical hypoxic conditions and widely used hypoxia-mimetic agents-PHD inhibitors on mesenchymal stem cells at a cellular and molecular level, including proliferation, stemness, differentiation, viability, apoptosis, senescence, migration, immunomodulation behaviors, as well as epigenetic changes.

Development of cobalt-incorporated chitosan scaffold for regenerative potential in human dental pulp stem cells: An in vitro study

The aim of the study was to comparatively evaluate chitosan and Cobalt incorporated chitosan (CoCH) scaffold at varying concentrations in terms of their material characteristics, cytotoxicity and cell adhesion potential. In the present study, cobalt incorporated chitosan scaffolds at varying concentrations were prepared and dried. The synthesised scaffolds were characterised using XRD, FTIR, SEM-EDX and BET which revealed amorphous, porous surface of CoCH scaffolds and FTIR analysis showed the complexation confirming the chelation of cobalt with chitosan. The experimental scaffolds proved to be non-cytotoxic when compared to chitosan scaffolds on XTT analysis. Cell-seeding assay revealed enhanced adherence of hDPSCs to CoCH scaffold at 1:1 ratio in the concentration of 100 mL of 100 μmol/L cobalt chloride solution in 100mL of 2% chitosan solution, when compared to other groups. The results highlighted that 100 μmol/L concentration of cobalt chloride when incorporated in 1:1 ratio into 2 % CH solution yields a promising porous, biocompatible scaffold with enhanced cellular adhesion for dentin-pulp regeneration.

Erythroid Cells as Full Participants in the Tumor Microenvironment

The tumor microenvironment is an important factor that can determine the success or failure of antitumor therapy. Cells of hematopoietic origin are one of the most important mediators of the tumor-host interaction and, depending on the cell type and functional state, exert pro- or antitumor effects in the tumor microenvironment or in adjacent tissues. Erythroid cells can be full members of the tumor microenvironment and exhibit immunoregulatory properties. Tumor growth is accompanied by the need to obtain growth factors and oxygen, which stimulates the appearance of the foci of extramedullary erythropoiesis. Tumor cells create conditions to maintain the long-term proliferation and viability of erythroid cells. In turn, tumor erythroid cells have a number of mechanisms to suppress the antitumor immune response. This review considers current data on the existence of erythroid cells in the tumor microenvironment, formation of angiogenic clusters, and creation of optimal conditions for tumor growth. Despite being the most important life-support function of the body, erythroid cells support tumor growth and do not work against it. The study of various signaling mechanisms linking tumor growth with the mobilization of erythroid cells and the phenotypic and functional differences between erythroid cells of different origin allows us to identify potential targets for immunotherapy.

High-Throughput Drug Screening Revealed That Ciclopirox Olamine Can Engender Gastric Cancer Stem-like Cells

Cancer stem cells (CSCs) are relevant therapeutic targets for cancer treatment. Still, the molecular circuits behind CSC characteristics are not fully understood. The low number of CSCs can sometimes be an obstacle to carrying out assays that explore their properties. Thus, increasing CSC numbers via small molecule-mediated cellular reprogramming appears to be a valid alternative tool. Using the SORE6-GFP reporter system embedded in gastric non-CSCs (SORE6-), we performed a high-throughput image-based drug screen with 1200 small molecules to identify compounds capable of converting SORE6- to SORE6+ (CSCs). Here, we report that the antifungal agent ciclopirox olamine (CPX), a potential candidate for drug repurposing in cancer treatment, is able to reprogram gastric non-CSCs into cancer stem-like cells via activation of SOX2 expression and increased expression of C-MYC, HIF-1α, KLF4, and HMGA1. This reprogramming depends on the CPX concentration and treatment duration. CPX can also induce cellular senescence and the metabolic shift from oxidative phosphorylation (OXPHOS) to glycolysis. We also disclose that the mechanism underlying the cellular reprogramming is similar to that of cobalt chloride (CoCl2), a hypoxia-mimetic agent.

The Role of Trace Elements and Minerals in Osteoporosis: A Review of Epidemiological and Laboratory Findings

The objective of the present study was to review recent epidemiological and clinical data on the association between selected minerals and trace elements and osteoporosis, as well as to discuss the molecular mechanisms underlying these associations. We have performed a search in the PubMed-Medline and Google Scholar databases using the MeSH terms "osteoporosis", "osteogenesis", "osteoblast", "osteoclast", and "osteocyte" in association with the names of particular trace elements and minerals through 21 March 2023. The data demonstrate that physiological and nutritional levels of trace elements and minerals promote osteogenic differentiation through the up-regulation of BMP-2 and Wnt/β-catenin signaling, as well as other pathways. miRNA and epigenetic effects were also involved in the regulation of the osteogenic effects of trace minerals. The antiresorptive effect of trace elements and minerals was associated with the inhibition of osteoclastogenesis. At the same time, the effect of trace elements and minerals on bone health appeared to be dose-dependent with low doses promoting an osteogenic effect, whereas high doses exerted opposite effects which promoted bone resorption and impaired bone formation. Concomitant with the results of the laboratory studies, several clinical trials and epidemiological studies demonstrated that supplementation with Zn, Mg, F, and Sr may improve bone quality, thus inducing antiosteoporotic effects.

Ameliorative Effects of Extracellular Vesicles Derived from Mesenchymal Stem Cells on Apoptosis and Differentiation of Osteoblasts Treated with CoCl2

Severe osteoporotic fracture occurring in sites with inadequate blood supply can cause irreversible damage to cells, particularly osteoblasts, with current drug and surgical interventions exhibiting limitations for elderly individuals. As participants mediating intercellular communication, extracellular vesicles (EVs) are rarely reported to play functional roles in osteoblasts under hypoxia. Our study mainly investigated the effects of bone marrow mesenchymal stem cells-derived EVs (BMSCs-EVs) on apoptosis and differentiation of osteoblasts treated with CoCl2. Primary rat BMSCs and osteoblasts were extracted as required for the following experiments. Cell counting kit 8 assay was used to explore the concentration of CoCl2 for treating osteoblasts, and we found that 100 μM CoCl2 was appropriate to treat osteoblasts for 48 hours. The analysis of flow cytometer showed that CoCl2-treated osteoblasts apoptosis can be ameliorated when cocultured with BMSCs-EVs. Further findings revealed that reactive oxygen species (ROS) was related to CoCl2-induced apoptosis. In addition, our results demonstrated that EVs exerted an important role in increasing expression levels of ALP, BMP-2, OCN, and OSTERIX under hypoxia. Similarly, the functional effects of BMSCs-EVs were observed on the osteoblasts mineralization. In summary, these findings provide insight that BMSCs-EVs might decrease the effect of CoCl2-induced apoptosis through inhibiting ROS, and promote osteogenic differentiation under hypoxia.

[Hypoxia promotes differentiation of human induced pluripotent stem cells into embryoid bodies in vitro]

OBJECTIVE

To investigate effects of physiological hypoxic conditions on suspension and adherence of embryoid bodies (EBs) during differentiation of human induced pluripotent stem cells (hiPSCs) and explore the underlying mechanisms.

METHODS

EBs in suspension culture were divided into normoxic (21% O₂) and hypoxic (5% O₂) groups, and those in adherent culture were divided into normoxic, hypoxic and hypoxia + HIF-1α inhibitor (echinomycin) groups. After characterization of the pluripotency with immunofluorescence assay, the hiPSCs were digested and suspended under normoxic and hypoxic conditions for 5 days, and the formation and morphological changes of the EBs were observed microscopically; the expressions of the markers genes of the 3 germ layers in the EBs were detected. The EBs were then inoculated into petri dishes for further culture in normoxic and hypoxic conditions for another 2 days, after which the adhesion and peripheral expansion rate of the adherent EBs were observed; the changes in the expressions of HIF-1α, β-catenin and VEGFA were detected in response to hypoxic culture and echinomycin treatment.

RESULTS

The EBs cultured in normoxic and hypoxic conditions were all capable of differentiation into the 3 germ layers. The EBs cultured in hypoxic conditions showed reduced apoptotic debris around them with earlier appearance of cystic EBs and more uniform sizes as compared with those in normoxic culture. Hypoxic culture induced more adherent EBs than normoxic culture (P < 0.05) with also a greater outgrowth rate of the adherent EBs (P < 0.05). The EBs in hypoxic culture showed significantly up-regulated mRNA expressions of β-catenin and VEGFA (P < 0.05) and protein expressions of HIF-1 α, β-catenin and VEGFA (P < 0.05), and their protein expresisons levels were significantly lowered after treatment with echinomycin (P < 0.05).

CONCLUSION

Hypoxia can promote the formation and maturation of suspended EBs and enhance their adherence and post-adherent proliferation without affecting their pluripotency for differentiation into all the 3 germ layers. Our results provide preliminary evidence that activation of HIF-1α/β-catenin/VEGFA signaling pathway can enhance the differentiation potential of hiPSCs.

Hypoxia-Mimetic CoCl2 Agent Enhances Pro-Angiogenic Activities in Ovine Amniotic Epithelial Cells-Derived Conditioned Medium

Amniotic epithelial stem cells (AECs) are largely studied for their pro-regenerative properties. However, it remains undetermined if low oxygen (O₂) levels that AECs experience in vivo can be of value in maintaining their biological properties after isolation. To this aim, the present study has been designed to evaluate the effects of a hypoxia-mimetic agent, cobalt chloride (CoCl₂), on AECs’ stemness and angiogenic activities. First, a CoCl₂ dose-effect was performed to select the concentration able to induce hypoxia, through HIF-1α stabilization, without promoting any cytotoxicity effect assessed through the analysis of cell vitality, proliferation, and apoptotic-related events. Then, the identified CoCl₂ dose was evaluated on the expression and angiogenic properties of AECs’ stemness markers (OCT-4, NANOG, SOX-2) by analysing VEGF expression, angiogenic chemokines’ profiles, and AEC-derived conditioned media activity through an in vitro angiogenic xeno-assay. Results demonstrated that AECs are sensitive to the cytotoxicity effects of CoCl₂. The unique concentration leading to HIF-1α stabilization and nuclear translocation was 10 µM, preserving cell viability and proliferation up to 48 h. CoCl₂ exposure did not modulate stemness markers in AECs while progressively decreasing VEGF expression. On the contrary, CoCl₂ treatment promoted a significant short-term release of angiogenic chemokines in culture media (CM). The enrichment in bio-active factors was confirmed by the ability of CoCl₂-derived CM to induce HUVEC growth and the cells’ organization in tubule-like structures. These findings demonstrate that an appropriate dose of CoCl₂ can be adopted as a hypoxia-mimetic agent in AECs. The short-term, chemical-induced hypoxic condition can be targeted to enhance AECs’ pro-angiogenic properties by providing a novel approach for stem cell-free therapy protocols.

Stem Cells from Human Exfoliated Deciduous Teeth and their Promise as Preventive and Therapeutic Strategies for Neurological Diseases and Injuries

Stem cells from human exfoliated deciduous teeth (SHEDs) are relatively easy to isolate from exfoliated deciduous teeth, which are obtained via dental therapy as biological waste. SHEDs originate from the embryonic neural crest and therefore have considerable potential for neurogenic differentiation. Currently, an increasing amount of research attention is focused on the therapeutic applications of SHEDs in neurological diseases and injuries. In this article, we summarize the biological characteristics of SHEDs and the potential role of SHEDs and their derivatives, including conditioned medium from SHEDs and the exosomes they secrete, in the prevention and treatment of neurological diseases and injuries.

Dental mesenchymal stromal/stem cells in different microenvironments— implications in regenerative therapy

Current research data reveal microenvironment as a significant modifier of physical functions, pathologic changes, as well as the therapeutic effects of stem cells. When comparing regeneration potential of various stem cell types used for cytotherapy and tissue engineering, mesenchymal stem cells (MSCs) are currently the most attractive cell source for bone and tooth regeneration due to their differentiation and immunomodulatory potential and lack of ethical issues associated with their use. The microenvironment of donors and recipients selected in cytotherapy plays a crucial role in regenerative potential of transplanted MSCs, indicating interactions of cells with their microenvironment indispensable in MSC-mediated bone and dental regeneration. Since a variety of MSC populations have been procured from different parts of the tooth and tooth-supporting tissues, MSCs of dental origin and their achievements in capacity to reconstitute various dental tissues have gained attention of many research groups over the years. This review discusses recent advances in comparative analyses of dental MSC regeneration potential with regards to their tissue origin and specific microenvironmental conditions, giving additional insight into the current clinical application of these cells.

Salidroside promotes the osteogenic and odontogenic differentiation of human dental pulp stem cells through the BMP signaling pathway

Regenerative endodontics, as an alternative approach, aims to regenerate dental pulp-like tissues and is garnering the attention of clinical dentists. This is due to its reported biological benefits for dental therapeutics. Stem cells and their microenvironment serve an important role in the process of pulp regeneration. Regulation of the stem cell microenvironment and the directed differentiation of stem cells is becoming a topic of intensive research. Salidroside (SAL) is extracted from the root of Rhodiola rosea and it has been reported that SAL exerts antiaging, neuroprotective, hepatoprotective, cardioprotective and anticancer effects. However, the ability of SAL to regulate the osteo/odontogenic differentiation of hDPSCs remains to be elucidated. In the present study, the effect of SAL on the proliferation and osteogenic/odontogenic differentiation of human dental pulp stem cells (hDPSCs) was investigated. This was achieved by performing CCK-8 ARS staining assay, reverse transcription-quantitative PCR to detect mRNA of ALP, OSX, RUNX2, OCN, DSPP and BSP, western blotting to detect the protein of MAPK, Smad1/5/8, OSX, RUNX2, BSP and GAPDH and immunofluorescence assays to detect DSPP. The results indicated that SAL promoted the cell viability and the osteogenic/odontogenic differentiation of hDPSCs whilst increasing the expression of genes associated with osteogenic/odontogenic differentiation by ARS staining assay. In addition, SAL promoted osteogenic and odontogenic differentiation by activating the phosphorylation of Smad1/5/8. Collectively, these findings suggest that SAL promoted the osteogenic and odontogenic differentiation of hDPSCs activating the BMP signaling pathway.

Chondrogenic Potential of Dental-Derived Mesenchymal Stromal Cells

The field of tissue engineering has revolutionized the world in organ and tissue regeneration. With the robust research among regenerative medicine experts and researchers, the plausibility of regenerating cartilage has come into the limelight. For cartilage tissue engineering, orthopedic surgeons and orthobiologists use the mesenchymal stromal cells (MSCs) of various origins along with the cytokines, growth factors, and scaffolds. The least utilized MSCs are of dental origin, which are the richest sources of stromal and progenitor cells. There is a paradigm shift towards the utilization of dental source MSCs in chondrogenesis and cartilage regeneration. Dental-derived MSCs possess similar phenotypes and genotypes like other sources of MSCs along with specific markers such as dentin matrix acidic phosphoprotein (DMP) -1, dentin sialophosphoprotein (DSPP), alkaline phosphatase (ALP), osteopontin (OPN), bone sialoprotein (BSP), and STRO-1. Concerning chondrogenicity, there is literature with marginal use of dental-derived MSCs. Various studies provide evidence for in-vitro and in-vivo chondrogenesis by dental-derived MSCs. With such evidence, clinical trials must be taken up to support or refute the evidence for regenerating cartilage tissues by dental-derived MSCs. This article highlights the significance of dental-derived MSCs for cartilage tissue regeneration.

Insight into Hypoxia Stemness Control

Recently, the research on stemness and multilineage differentiation mechanisms has greatly increased its value due to the potential therapeutic impact of stem cell-based approaches. Stem cells modulate their self-renewing and differentiation capacities in response to endogenous and/or extrinsic factors that can control stem cell fate. One key factor controlling stem cell phenotype is oxygen (O₂). Several pieces of evidence demonstrated that the complexity of reproducing O₂ physiological tensions and gradients in culture is responsible for defective stem cell behavior in vitro and after transplantation. This evidence is still worsened by considering that stem cells are conventionally incubated under non-physiological air O₂ tension (21%). Therefore, the study of mechanisms and signaling activated at lower O₂ tension, such as those existing under native microenvironments (referred to as hypoxia), represent an effective strategy to define if O₂ is essential in preserving naïve stemness potential as well as in modulating their differentiation. Starting from this premise, the goal of the present review is to report the status of the art about the link existing between hypoxia and stemness providing insight into the factors/molecules involved, to design targeted strategies that, recapitulating naïve O₂ signals, enable towards the therapeutic use of stem cell for tissue engineering and regenerative medicine.

Modulation of the Dental Pulp Stem Cell Secretory Profile by Hypoxia Induction Using Cobalt Chloride

The action of stem cells is mediated by their paracrine secretions which comprise the secretory profile. Various approaches can be used to modify the secretory profile of stem cells. Creating a hypoxic environment is one method. The present study aims to demonstrate the influence of CoCl₂ in generating hypoxic conditions in a dental pulp stem cell (DPSCs) culture, and the effect of this environment on their secretory profile. DPSCs that were isolated from human permanent teeth were characterized and treated with different concentrations of CoCl₂ to assess their viability by an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and proliferation by a cell counting kit (CCK)-8 assay. The gene expression level of hypoxia-inducible factor 1-alpha (HIF-1α) was analyzed by quantitative real time polymerase chain reaction (qRT-PCR) to demonstrate a hypoxic environment. Comparative evaluation of the growth factors and cytokines were done by cytometric bead array. Gene expression levels of transcription factors OCT4 and SOX2 were analyzed by qRT-PCR to understand the effect of CoCl₂ on stemness in DPSCs. DPSCs were positive for MSC-specific markers. Doses of CoCl_2, up to 20 µM, did not negatively affect cell viability; in low doses (5 µM), it promoted cell survival. Treatment with 10 µM of CoCl₂ significantly augmented the genetic expression of HIF-1α. Cells treated with 10 µM of CoCl₂ showed changes in the levels of growth factors and cytokines produced. It was very evident that CoCl₂ also increased the expression of OCT4 and SOX2, which is the modulation of stemness of DPSCs. A CoCl₂ treatment-induced hypoxic environment modulates the secretory profile of DPSCs.

Unlocking mammalian regeneration through hypoxia inducible factor one alpha signaling

Historically, the field of regenerative medicine has aimed to heal damaged tissue through the use of biomaterials scaffolds or delivery of foreign progenitor cells. Despite 30 years of research, however, translation and commercialization of these techniques has been limited. To enable mammalian regeneration, a more practical approach may instead be to develop therapies that evoke endogenous processes reminiscent of those seen in innate regenerators. Recently, investigations into tadpole tail regrowth, zebrafish limb restoration, and the super-healing Murphy Roths Large (MRL) mouse strain, have identified ancient oxygen-sensing pathways as a possible target to achieve this goal. Specifically, upregulation of the transcription factor, hypoxia-inducible factor one alpha (HIF-1α) has been shown to modulate cell metabolism and plasticity, as well as inflammation and tissue remodeling, possibly priming injuries for regeneration. Since HIF-1α signaling is conserved across species, environmental or pharmacological manipulation of oxygen-dependent pathways may elicit a regenerative response in non-healing mammals. In this review, we will explore the emerging role of HIF-1α in mammalian healing and regeneration, as well as attempts to modulate protein stability through hyperbaric oxygen treatment, intermittent hypoxia therapy, and pharmacological targeting. We believe that these therapies could breathe new life into the field of regenerative medicine.

Alterations in Blood Metabolic Parameters of Immature Mice After Subchronic Exposure to Cobalt Chloride

The wide use of cobalt (Co) in food, industry, and medical devices requires full elucidation of its biological effects on tissues and organs. The aim was to assess serum metabolic alterations in immature mice after subchronic exposure to CoCl₂. Pregnant ICR mice were subjected to a daily dose of 75 mg cobalt chloride/kg body weight (CoCl₂x6H₂O) 2-3 days before they gave birth, and treatment continued until days 25 and 30 after delivery. The compound was dissolved in and obtained with regular tap water. ICP-DRC-MS analysis showed significantly elevated serum Co²⁺ and diverse alterations in metabolic parameters of 25- and 30-day-old pups after exposure to CoCl₂. Cholesterol and urea levels were significantly elevated in day 25 mice while HDL-C and LDL-C were reduced. In day 30, Co-exposed mice LDL-C and triglycerides were significantly increased while the total cholesterol level remained unchanged. Alkaline phosphatase was significantly reduced in day 25 Co-exposed mice. Blood glucose level of Co-exposed mice remained close to the untreated controls. Total protein content was slightly increased in day 30 mice. Co-exposure reduced albumin content and albumin/globulin ratio but increased significantly globulin content. Co administration showed strong correlation with cholesterol, urea, and HDL-C in both day 25 and 30 mice. Inverse correlation was found with alkaline phosphatase and albumin for day 25 and with triglycerides, globulin, and total protein content in day 30 Co-exposed mice. Subchronic CoCl₂ exposure of immature mice induced significant changes in key metabolic parameters suggesting possible further disturbances in energy metabolism, osteogenesis, and reproduction.

Protective Effects of Adiponectin against Cobalt Chloride-Induced Apoptosis of Smooth Muscle Cells via cAMP/PKA Pathway

Adiponectin (APN) is an adipokine secreted from adipose tissue and exhibits biological functions such as microcirculation-regulating, hearing-protective, and antiapoptotic. However, the effect of APN on the apoptosis of spiral arterial smooth muscle cells (SMCs) under hypoxic conditions in vitro is not clear. We used cobalt chloride (CoCl₂) to simulate chemical hypoxia in vitro, and the SMCs were pretreated with APN and then stimulated with CoCl₂. The viability of cells and apoptosis were assessed by CCK-8 and flow cytometry, respectively. Superoxide dismutase (SOD) activity, malondialdehyde (MDA) levels, cAMP level, and the activity of PKA were detected by ELISA. Protein expression and localization were studied by Western blot and immunofluorescence analysis. In the present study, we found that APN exhibits antiapoptosis effects. CoCl₂ exhibited decreased cell viability, increased apoptosis and MDA levels, and decreased SOD activity in a concentration-dependent manner, compared with the control group. Moreover, CoCl₂ upregulated the expression levels of Bax and cleaved caspase-3 and then downregulated Bcl-2 levels in a time-dependent manner. Compared with the CoCl₂ group, the group pretreated with APN had increased cell viability, SOD activity, PKA activity, cAMP level, and PKA expression, but decreased MDA levels and apoptosis. Lastly, the protective effect of APN was blocked by cAMP inhibitor SQ22536 and PKA inhibitor H 89. These results showed that APN protected SMCs against CoCl₂-induced hypoxic injury via the cAMP/PKA signaling pathway.

Multi-lineage differentiation and clinical application of stem cells from exfoliated deciduous teeth

Stem cells from human exfoliated deciduous teeth (SHED) have now been considered one of the most promising sources of stem cells for tissue engineering and stem cell therapies due to their stemness and potential to differentiate into other cell lines. The high proliferation rate, the differentiation capacity, the easy access and less ethical concerns make SHED a brilliant solution for many diseases. The purpose of this review is to describe current knowledge of SHED's capability of differentiation, applications and immune status and to draw attention to further research on the mechanism and the dependability of stem cell therapy with SHED.