Concise review: Oct4 and more: the reprogramming expressway

Effect of Octamer-Binding Transcription Factor 4 Overexpression on the Neural Induction of Human Dental Pulp Stem Cells

Stem cell-based therapy is a potential alternative strategy for brain repair, with neural stem cells (NSC) presenting as the most promising candidates. Obtaining sufficient quantities of NSC for clinical applications is challenging, therefore alternative cell types, such as neural crest-derived dental pulp stem cells (DPSC), may be considered. Human DPSC possess neurogenic potential, exerting positive effects in the damaged brain through paracrine effects. However, a method for conversion of DPSC into NSC has yet to be developed. Here, overexpression of octamer-binding transcription factor 4 (OCT4) in combination with neural inductive conditions was used to reprogram human DPSC along the neural lineage. The reprogrammed DPSC demonstrated a neuronal-like phenotype, with increased expression levels of neural markers, limited capacity for sphere formation, and enhanced neuronal but not glial differentiation. Transcriptomic analysis further highlighted the expression of genes associated with neural and neuronal functions. In vivo analysis using a developmental avian model showed that implanted DPSC survived in the developing central nervous system and respond to endogenous signals, displaying neuronal phenotypes. Therefore, OCT4 enhances the neural potential of DPSC, which exhibited characteristics aligning with neuronal progenitors. This method can be used to standardise DPSC neural induction and provide an alternative source of neural cell types.

OCT4 induces long-lived dedifferentiated kidney progenitors poised to redifferentiate in 3D kidney spheroids

Upscaling of kidney epithelial cells is crucial for renal regenerative medicine. Nonetheless, the adult kidney lacks a distinct stem cell hierarchy, limiting the ability to long-term propagate clonal populations of primary cells that retain renal identity. Toward this goal, we tested the paradigm of shifting the balance between differentiation and stemness in the kidney by introducing a single pluripotency factor, OCT4. Here we show that ectopic expression of OCT4 in human adult kidney epithelial cells (hKEpC) induces the cells to dedifferentiate, stably proliferate, and clonally emerge over many generations. Control hKEpC dedifferentiate, assume fibroblastic morphology, and completely lose clonogenic capacity. Analysis of gene expression and histone methylation patterns revealed that OCT4 represses the HNF1B gene module, which is critical for kidney epithelial differentiation, and concomitantly activates stemness-related pathways. OCT4-hKEpC can be long-term expanded in the dedifferentiated state that is primed for renal differentiation. Thus, when expanded OCT4-hKEpC are grown as kidney spheroids (OCT4-kSPH), they reactivate the HNF1B gene signature, redifferentiate, and efficiently generate renal structures in vivo. Hence, changes occurring in the cellular state of hKEpC following OCT4 induction, long-term propagation, and 3D aggregation afford rapid scale-up technology of primary renal tissue-forming cells.

Exploring the reprogramming potential of B cells and comprehending its clinical and therapeutic perspective

Initiating from multipotent progenitors, the lineages extrapolated from hematopoietic stem cells are determined by transcription factors specific to each of them. The commitment factors assist in the differentiation of progenitor cells into terminally differentiated cells. B lymphocytes constitute a population of cells that expresses clonally diverse cell surface immunoglobulin (Ig) receptors specific to antigenic epitopes. B cells are a significant facet of the adaptive immune system. The secreted antibodies corresponding to the B cell recognize the antigens via the B cell receptor (BCR). Following antigen recognition, the B cell is activated and thereafter undergoes clonal expansion and proliferation to become memory B cells. The essence of 'cellular reprogramming' has aided in reliably altering the cells to desired tissue type. The potential of reprogramming has been harnessed to decipher and find solutions for various genetically inherited diseases and degenerative disorders. B lymphocytes can be reprogrammed to their initial naive state from where they get differentiated into any lineage or cell type similar to a pluripotent stem cell which can be accomplished by the deletion of master regulators of the B cell lineage. B cells can be reprogrammed into pluripotent stem cells and also can undergo transdifferentiation at the midway of cell differentiation to other cell types. Mandated expression of C/EBP in specialized B cells corresponds to their fast and effective reprogramming into macrophages, reversing the cell fate of these lymphocytes and allowing them to differentiate freshly into other types of cells. The co-expression of C/EBPα and OKSM (Oct4, Sox2, Klf4, c-Myc) amplified the reprogramming efficiency of B lymphocytes. Various human somatic cells including the immune cells are compliant to reprogramming which paves a path for opportunities like autologous tissue grafts, blood transfusion, and cancer immunotherapy. The ability to reprogram B cells offers an unprecedented opportunity for developing a therapeutic approach for several human diseases. Here, we will focus on all the proteins and transcription factors responsible for the developmental commitment of B lymphocytes and how it is harnessed in various applications.

Synthetic and immunological studies on the OCT4 immunodominant motif antigen-based anti-cancer vaccine

Objective: Cancer stem cell is one of the important causes of tumorigenesis as well as a drug target in the treatment of malignant tumor. However, at present, there is no immune vaccine targeting these cells. Octamer-binding transcription factor 4 (OCT4), a marker of embryonic stem cells and germ cells, often highly expresses in the early stages of tumorigenesis and is therefore a good candidate for cancer vaccine development.

Methods: To identify the optimal carrier and adjuvant combination, we chemically synthesized and linked three different OCT4 epitope antigens to a carrier protein, keyhole limpet hemocyanin (KLH), combined with Toll-like receptor 9 agonist (TLR9).

Results: Immunization with OCT4-3 + TLR9 produced the strongest immune response in mice. In prevention assays, significant tumor growth inhibition was achieved in BABL/c mice treated with OCT4-3 + TLR9 (P < 0.01). Importantly, the results showed that cytotoxic T lymphocyte activity and the inhibition of tumor growth were enhanced in mice immunized with OCT4-3 combined with TLR9. Meanwhile, multiple cytokines [such as interferon (IFN)-γ (P < 0.05), interleukin (IL)-12 (P < 0.05), IL-2 (P < 0.01), and IL-6 (P < 0.05)] promoting cellular immune responses were shown to be greatly enhanced in mice immunized with OCT4-3 + TLR9. Moreover, we considered safety considerations in terms of the composition of the vaccines to help facilitate the development of effective next-generation vaccines.

Conclusions: Collectively, these experiments demonstrated that combination therapy with TLR9 agonist induced a tumor-specific adaptive immune response, leading to the suppression of primary tumor growth in testis embryonic carcinoma.

Potential of Induced Pluripotent Stem Cells for Use in Gene Therapy: History, Molecular Bases, and Medical Perspectives

Induced pluripotent stem cells (iPSCs) are defined as reprogrammed somatic cells exhibiting embryonic stem cell characteristics. Since their discovery in 2006, efforts have been made to utilize iPSCs in clinical settings. One of the promising fields of medicine, in which genetically patient-specific stem cells may prove themselves useful, is gene therapy. iPSCs technology holds potential in both creating models of genetic diseases and delivering therapeutic agents into the organism via auto-transplants, which reduces the risk of rejection compared to allotransplants. However, in order to safely administer genetically corrected stem cells into patients’ tissues, efforts must be made to establish stably pluripotent stem cells and reduce the risk of insertional tumorigenesis. In order to achieve this, optimal reprogramming factors and vectors must be considered. Therefore, in this review, the molecular bases of reprogramming safe iPSCs for clinical applications and recent attempts to translate iPSCs technology into the clinical setting are discussed.

Expression of Recombinant Human Octamer-Binding Transcription Factor 4 in Rice Suspension Cells

The rice cell suspension culture system is a good way to produce recombinant human proteins, owing to its high biosafety and low production cost. Human Octamer-binding Transcription Factor 4 (Oct4) is a fundamental transcription factor responsible for maintaining human pluripotent embryonic stem cells. Recombinant Oct4 protein has been used to induce pluripotent stem cells. In this study, recombinant Oct4 proteins are produced via a sugar starvation-inducible αAmy3/RAmy3D promoter-signal peptide-based rice recombinant protein expression system. Oct4 mRNAs accumulate in the transgenic rice suspension cells under sugar starvation. The Oct4 recombinant protein is detected in the transgenic rice suspension cells, and its highest yield is approximately 0.41% of total cellular soluble proteins after one day of sugar starvation. The rice cell-synthesized recombinant human Oct4 protein show DNA-binding activity in vitro, which implies that the protein structure is correct for enabling specific binding to the target DNA motif.

Transcription factors β-catenin and Hex in postnatal development of the rat adrenal cortex: implication in proliferation control

Transcriptional regulation of growth, maturation, and cell turnover in adrenal cortex during postnatal development has been significantly less studied than in embryonic period, while elucidation of factors mediating its normal postnatal morphogenesis could clarify mechanisms of tumorigenesis in adrenal cortex. Expression of transcription factors Hex, β-catenin, and Wnt signaling in the adrenal cortex of male pubertal and postpubertal Wistar rats were examined. Adrenal cortex morphology and hormone production during postnatal development were also studied. Adrenocortical zones demonstrated similar reduction of Ki-67-expressing cells, but different patterns of morphological and functional changes. Age-dependent decrease in percentage of cells with membrane localization of β-catenin and stable rate of cells with nuclear β-catenin, indicative of Wnt signaling activation, were revealed in each cortical zone. Nuclear β-catenin was not observed in immature areas of zona fasciculata. No association between Wnt signaling activation and rates of proliferation as well as changes in secretion of adrenocortical hormones was observed in postnatal development of rat adrenal cortex. Hex, known as antiproliferative factor, showed up-regulation of expression after puberty. Strong inverse correlations between ratio of Hex-positive cells and proliferating cells were found in zona glomerulosa and zona fasciculata. Zona reticularis demonstrated moderate correlation. Thus, these findings suggest a role for Hex in proliferation control during postnatal development of the rat adrenal cortex and possible implication of Hex down-regulation in adrenocortical dysplasia and neoplasia, which requires further study. Evaluation of Hex expression may also be considered a potent tool in assessment of cell proliferation in rat adrenal cortex.

Oct4 Regulates the Transition of Cancer Stem-Like Cells to Tumor Endothelial-Like Cells in Human Liver Cancer

Octamer-binding transcription factor 4 (Oct4) has been recently implicated as a proangiogenic regulator in several induced pluripotent stem cells (iPSCs), however, its role in cancer stem-like cells (CSCs) remain unclear. We report here that Oct4 participates in tumor vasculogenesis in liver CSCs (LCSCs). We identify that LCSCs possess the potential of endothelial trans-differentiation under endothelial induction, present endothelial specific markers and their functions in vitro, and participate in neovasculogenesis in vivo. The knockdown of the Oct4A by short hairpin RNA (shRNA) in LCSCs represses endothelial trans-differentiation potential, but induces endothelial lineage-restricted differentiation, the latter is positively regulated by Oct4B1. Furthermore, Oct4 regulates vasculogenesis in LCSCs may be via the AKT-NF-κB-p65 signaling pathway. This work reveals Oct4, which is a crucial regulator, plays a critical role in tumor endothelial-like cells transition of LCSCs through Oct4A and Oct4B1 by different ways. The simultaneous inhibition of both the isoforms of Oct4 is hence expected to help regress neovascularization derived from CSCs. Our findings may provide insights to the possible new mechanisms of tumor vasculogenesis for primary liver cancer.

Reprogramming and transdifferentiation - two key processes for regenerative medicine

Regenerative medicine based on transplants obtained from donors or foetal and new-born mesenchymal stem cells, encounter important obstacles such as limited availability of organs, ethical issues and immune rejection. The growing demand for therapeutic methods for patients being treated after serious accidents, severe organ dysfunction and an increasing number of cancer surgeries, exceeds the possibilities of the therapies that are currently available. Reprogramming and transdifferentiation provide powerful bioengineering tools. Both procedures are based on the somatic differentiated cells, which are easily and unlimitedly available, like for example: fibroblasts. During the reprogramming procedure mature cells are converted into pluripotent cells - which are capable to differentiate into almost any kind of desired cells. Transdifferentiation directly converts differentiated cells of one type into another differentiated cells type. Both procedures allow to obtained patient's dedicated cells for therapeutic purpose in regenerative medicine. In combination with biomaterials, it is possible to obtain even whole anatomical structures. Those patient's dedicated structures may serve for them upon serious accidents with massive tissue damage but also upon cancer surgeries as a replacement of damaged organ. Detailed information about reprogramming and transdifferentiation procedures as well as the current state of the art are presented in our review.

Roles of OCT4 in pathways of embryonic development and cancer progression

Somatic cells may be reprogrammed to pluripotent state by ectopic expression of certain transcription factors; namely, OCT4, SOX2, KLF4 and c-MYC. However, the molecular and cellular mechanisms are not adequately understood, especially for human embryonic development. Studies during the last five years implicated importance of OCT4 in human zygotic genome activation (ZGA), patterns of OCT4 protein folding and role of specialized sequences in binding to DNA for modulation of gene expression during development. Epigenetic modulation of OCT4 gene and post translational modifications of OCT4 protein activity in the context of multiple cancers are important issues. A consensus is emerging that chromatin organization and epigenetic landscape play crucial roles for the interactions of transcription factors, including OCT4 with the promoters and/or regulatory sequences of genes associated with human embryonic development (ZGA through lineage specification) and that when the epigenome niche is deregulated OCT4 helps in cancer progression, and how OCT4 silencing in somatic cells of adult organisms may impact ageing.

Which stem cells will eventually translate to the clinics for treatment of diabetes?

Human embryonic stem (hES) cells have been around for more than two decades now. It was expected that hES/iPS (induced pluripotent stem) cells will quickly translate to the clinics to treat diabetic patients and to obtain gametes in vitro for infertile couples. However, there is no breakthrough yet in either of the fields although considerable progress has been made. Research efforts are ongoing to obtain an insight into the gene expression changes associated with directed differentiation of hES/iPS cells. Autologous bone marrow/cord blood mononuclear cells' therapy has also failed to show any regenerative potential and only remains as a standard method of care for blood diseases. Only mesenchymal stem cells (MSCs) have shown promise in the clinics to alleviate diabetic symptoms. But MSCs are stromal cells with no regenerative properties; rather "paracrine providers", pericytes/stromal cells, better known for their trophic, immuno-modulatory, and anti-inflammatory properties and thus best termed as mesenchymal stromal cells (MSCs). Autologus bone marrow cells enriched for hematopoietic stem cells have no potential to cross boundaries and transdifferentiate into other lineages including endodermal pancreatic cells. Endogenous, pluripotent, very small embryonic-like stem cells (VSELs) emerge as the most likely endogenous stem cell candidates to regenerate adult diabetic pancreas. Transplanted MSCs provide a healthy paracrine support required for endogenous/ resident VSELs to differentiate into acinar cells and islets in a diabetic pancreas to enable restoration of homeostasis. Our recently published study shows that VSELs exist and can be enriched from intact mouse pancreas as well as from the islets and increase in numbers in diabetic pancreas. Providing "regenerative pressure" by subjecting diabetic mice to partial pancreatectomy stimulated the VSELs to undergo differentiation into various cell types in an attempt to restore homeostasis. Double-blinded, placebo controlled clinical trials need to be undertaken to evaluate the efficacy of transplanting MSCs in diabetic patients with conviction since now underlying fine play of endogenous VSELs and niche providing MSCs has emerged.

Oct4 plays a role in 2, 3, 7, 8 - tetrachlorobenzo-p-dioxin (TCDD) inducing cleft palate and inhibiting mesenchymal proliferation

As a common birth defect, Cleft palate can be caused by the disturbance during the developmental process of the palatal shelves. The 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) is a well-known environmental teratogenic agent for cleft palate and Aryl hydrocarbon receptor (AhR) pathway can be activated by dioxins. Oct4 as a pluripotent stem cell transcription factor is also involved in the process of embryonic development. The AHR and retinoid receptors have cross-talk at CYP1A1 (cytochrome P450, family 1, subfamily A, polypeptide 1) promoter. There are also bidirectional talk between AhR and Oct4. In this study, we used C57/BL6 N mice and TCDD (64 μg/Kg body weight) to establish a model of fetal cleft palate to observe the effects of dioxin on fetal mesenchymal proliferation and apoptosis, and explore the role of Oct4 in inducing cleft palate. The results showed that dioxin inhibited mesenchymal proliferation and promoted apoptosis. In addition, dioxin inhibited Oct4 expression, and preliminary data suggest that hypermethylation of the Oct4 promoter may be a putative mechanism, suggesting that TCDD might induce cleft palate by inhibiting the proliferation of palatal mesenchymal cells mediated by Oct4.

In Vitro Generation of Oocyte Like Cells and Their In Vivo Efficacy: How Far We have been Succeeded

In the last few decades, stem cell therapy has grown as a boon for many pathological complications including female reproductive disorders. In this review, a brief description of available strategies that are related to stem cell-based in vitro oocyte-like cell (OLC) development are given. We have tried to cover all the aspects and latest updates of the in vitro OLC developmental methodologies, marker profiling, available disease models, and in vivo efficacies, with a special focus on mesenchymal stem cells (MSCs), induced pluripotent stem cells (iPSCs), and embryonic stem cells (ESCs) usage. The differentiation abilities of both the ovarian and non-ovarian stem cell sources under various induction conditions have shown different effects on morphological alterations, proliferation- and size-associated developments, hormonal secretions under gonadotropic stimulations, and their neo-oogenesis or folliculogenesis abilities after in vivo transplantations. The attainment of characters like oocyte-like morphology, size expansion, and meiosis initiation have been found to be major obstacles during in vitro oogenesis. A number of reports have either lacked in vivo studies or have shown their functional incapability to produce viable and healthy offspring. Though researchers have gained many valuable insights regarding in vitro gametogenesis, still there are many things to do to make stem cell-derived OLCs fully functional.

Transcriptional co-repressor CtBP2 orchestrates epithelial-mesenchymal transition through a novel transcriptional holocomplex with OCT1

The epithelial to mesenchymal transition (EMT) is a cell intrinsic program controlling cellular morphological and phenotypic remodeling in a wide range of biological processes. Despite the accumulating evidence, the transcriptional networks regulating EMT still remain to be elucidated. In this study, we demonstrate that C-terminal binding protein 2 (CtBP2), a critical transcriptional co-repressor harboring pyridine nucleotide sensing capability, orchestrates the EMT program at least in part through a novel transcriptional interaction with an octamer transcription factor, OCT1 (POU2F1, POU class 2 homeobox 1). We identified novel interactions of CtBP2 with several octamer transcription factors, and CtBP2 exhibits a direct interaction with OCT1 in particular. OCT1 accelerates the EMT program as reported, which is diminished by the mutation of the CtBP-binding motif in OCT1, suggesting OCT1 represses epithelial gene expression through recruiting the co-repressor CtBP2. In accordance with these findings, a canonical EMT activator transforming growth factor-β (TGF-β) promotes the formation of the CtBP2/OCT1 complex. Our observations illustrate the role of CtBP2 to orchestrate the EMT program through the interaction with OCT1 and highlight the potential of therapeutic exploitation of this new transcriptional system for a wide range of diseases.

Natural Compounds as a Strategy to Optimize "In Vitro" Expansion of Stem Cells

The efficient use of stem cells for transplantation is often limited by the relatively low number of stem cells collected. The ex vivo expansion of human stem cells for clinical use is a potentially valuable approach to increase stem cell number. Currently, most of the procedures used to expand stem cells are carried out using a 21% oxygen concentration, which is about 4- to 10-fold greater than the concentration characteristic of their natural niches. Hyperoxia might cause oxidative stress with a deleterious effect on the physiology of cultured stem cells. In this review, we investigate and critically examine the available information on the ability of natural compounds to counteract hyperoxia-induced damage in different types of stem cells ex vivo. In particular, we focused on proliferation and stemness maintenance in an attempt to draw up useful indications to define new culture media with a promoting activity on cell expansion in vitro.

OCT4 Silencing Triggers Its Epigenetic Repression and Impairs the Osteogenic and Adipogenic Differentiation of Mesenchymal Stromal Cells

Mechanisms mediating mesenchymal stromal/stem cells’ (MSCs) multipotency are unclear. Although the expression of the pluripotency factor OCT4 has been detected in MSCs, whether it has a functional role in adult stem cells is still controversial. We hypothesized that a physiological expression level of OCT4 is important to regulate MSCs’ multipotency and trigger differentiation in response to environmental signals. Here, we specifically suppressed OCT4 in MSCs by using siRNA technology before directed differentiation. OCT4 expression levels were reduced by 82% in siOCT4-MSCs, compared with controls. Interestingly, siOCT4-MSCs also presented a hypermethylated OCT4 promoter. OCT4 silencing significantly impaired the ability of MSCs to differentiate into osteoblasts. Histologic and macroscopic analysis showed a lower degree of mineralization in siOCT4-MSCs than in controls. Moreover, OCT4 silencing prevented the up-regulation of osteoblast lineage-associated genes during differentiation. Similarly, OCT4 silencing resulted in decreased MSC differentiation potential towards the adipogenic lineage. The accumulation of lipids was reduced 3.0-fold in siOCT4-MSCs, compared with controls. The up-regulation of genes engaged in the early stages of adipogenesis was also suppressed in siOCT4-MSCs. Our findings provide evidence of a functional role for OCT4 in MSCs and indicate that a basal expression of this transcription factor is essential for their multipotent capacity.

Human mid-trimester amniotic fluid (stem) cells lack expression of the pluripotency marker OCT4A

Expression of OCT4A is one of the hallmarks of pluripotency, defined as a stem cell's ability to differentiate into all the lineages of the three germ layers. Despite being defined as non-tumorigenic cells with high translational potential, human mid-trimester amniotic fluid stem cells (hAFSCs) are often described as sharing features with embryonic stem cells, including the expression of OCT4A, which could hinder their clinical potential. To clarify the OCT4A status of hAFSCs, we first undertook a systematic review of the literature. We then performed extensive gene and protein expression analyses to discover that neither frozen, nor fresh hAFSCs cultivated in multipotent stem cell culture conditions expressed OCT4A, and that the OCT4A positive results from the literature are likely to be attributed to the expression of pseudogenes or other OCT4 variants. To address this issue, we provide a robust protocol for the assessment of OCT4A in other stem cells.

Integrative analyses of triple negative dysregulated transcripts compared with non-triple negative tumors and their functional and molecular interactions

Triple-negative (TN) tumors are a subtype of breast cancer with aggressive behaviors and limited targeted therapies. Microarray studies were not concerned with interactions and functional relations of dysregulated transcripts. Here, we aimed to conduct integrative strategy to analyze gene and miRNA available microarray data as well as bioinformatic analyses to catch a more inclusive picture of pivotal dysregulated transcripts and their interactions in TN tumors. Several online datasets and offline bioinformatic tools were used to detect differentially expressed (DE) transcripts, both protein and nonprotein coding, in TN compared with non-TN tumors and their functional and molecular interactions. Sixteen upregulated and 58 downregulated genes with a log fold change higher or equal to | 2 | were identified, including nine transcription factors. Coexpression network revealed EN1 as a hub gene, moreover Kaplan-Meier plotter survival analysis indicated that it was an appropriate prognostic marker for TN patients with breast cancer. Functional annotation analysis of protein-protein interaction network showed FOXM1 as an upexpressed and ESR1 as a downexpressed hub genes are suitable targets as far as antitumor protein therapy is concerned in TN breast cancers. The consensus analysis of two microRNA datasets revealed seven DE miRNAs. The gene-transcriptional factor (TF)-miRNA network revealed mir-135b and mir-29b are the hub nodes and involved in feedback loops with GATA3. This study suggests that dysregulated TFs and miRNAs have pivotal roles in regulation of TN oncotranscriptomic profile and might become both biomarkers and therapeutic targets.

Using Dental Pulp Stem Cells for Stroke Therapy

Stroke is a leading cause of permanent disability world-wide, but aside from rehabilitation, there is currently no clinically-proven pharmaceutical or biological agent to improve neurological disability. Cell-based therapies using stem cells, such as dental pulp stem cells, are a promising alternative for treatment of neurological diseases, including stroke. The ischaemic environment in stroke affects multiple cell populations, thus stem cells, which act through cellular and molecular mechanisms, are promising candidates. The most common stem cell population studied in the neurological setting has been mesenchymal stem cells due to their accessibility. However, it is believed that neural stem cells, the resident stem cell of the adult brain, would be most appropriate for brain repair. Using reprogramming strategies, alternative sources of neural stem and progenitor cells have been explored. We postulate that a cell of closer origin to the neural lineage would be a promising candidate for reprogramming and modification towards a neural stem or progenitor cell. One such candidate population is dental pulp stem cells, which reside in the root canal of teeth. This review will focus on the neural potential of dental pulp stem cells and their investigations in the stroke setting to date, and include an overview on the use of different sources of neural stem cells in preclinical studies and clinical trials of stroke.

The involvement of mitochondrial fission in maintenance of the stemness of bone marrow mesenchymal stem cells

IMPACT STATEMENT

How to maintain the stemness of bone marrow mesenchymal stem cells (BMSCs) in cultures is a long-standing question. The present study found that mitochondrial dynamics affects the stemness of BMSCs in cultures and the retaining of mitochondrial fission enhances the stemness of BMSCs. This work thus provides a novel insight into strategic approaches to maintain the stemness of BMSCs in cultures in relation to the clinical application of bone-marrow stem cells.

Role of OCT4 in the Regulation of FSH-Induced Granulosa Cells Growth in Female Mice

As a member of the POU (Pit-Oct-Unc) transcription factor family, OCT4 (Octamer-binding transcription factor 4) is associated with the cellular proliferative. However, the roles of OCT4 in regulating the transition from preantral follicle to early antral follicle are still remains unclear. To evaluate the effect of OCT4 on cellular development in ovary, mice were injected with eCG in vivo or granulosa cells were co-cultured with FSH in vitro. The results showed that eCG up-regulated ovarian OCT4 expression. Meanwhile, OCT4 expression in granulosa cells was also up-regulated by FSH, and knockdown of OCT4 by siRNA significantly decreased FSH-induced cellular viability. Moreover, gonadotropin increased p-GSK3β (Glycogen synthase kinase 3-beta) level, β-catenin expression and its translocation to nuclear in ovarian cells. In addition, the inhibition of GSK3β activity by CT99021 significantly increased the expression of β-catenin and OCT4 in granulosa cells. And knockdown β-catenin by siRNA dramatically abolished FSH-induced OCT4 expression and cellular development. Furthermore, FSH-induced the phosphorylation of GSK3β, expression of β-catenin and OCT4, and translocation of β-catenin were mediated by the PI3K/Akt pathway. Taken together, the present study demonstrates that FSH regulated OCT4 expression via GSK3β/β-catenin pathway, which was mediated by the PI3K/Akt pathway. And these regulations are involved in ovarian cell development.

Stem Cell Therapy in Cerebrovascular Disease

PURPOSE OF REVIEW

The purpose of this article is to provide a review of state-of-the-art cellular therapy in cerebrovascular diseases by discussing published and ongoing clinical trials.

RECENT FINDINGS

In spite of the challenge in translating the success of cellular therapy in acute strokes from preclinical models to clinical trials, early phase clinical trial have recently shown promise in overcoming these challenges. Various stem cell types and doses are being studied, different routes of administration are under investigation, as well as defining the optimal time window to intervene. In addition, experimental methods to enhance cellular therapy, such as ischemic preconditioning, are evolving. After the failure of neuroprotectants in cerebrovascular diseases, researchers have been keen to provide a way of replacement of damaged brain tissue and to promote recovery in order to achieve better outcomes. The field has progressed from intravenous delivery in the 24- to 36-h time window to later intracerebral administration in chronic stroke in clinical trials. New optimism in acute stroke care fostered by the success of mechanical thrombectomy will hopefully extend into cell therapy to promote recovery.

Multiplexed CRISPR/Cas9 Targeting of Genes Implicated in Retinal Regeneration and Degeneration

Thousands of genes have been implicated in retinal regeneration, but only a few have been shown to impact the regenerative capacity of Müller glia—an adult retinal stem cell with untapped therapeutic potential. Similarly, among nearly 300 genetic loci associated with human retinal disease, the majority remain untested in animal models. To address the large-scale nature of these problems, we are applying CRISPR/Cas9-based genome modification strategies in zebrafish to target over 300 genes implicated in retinal regeneration or degeneration. Our intent is to enable large-scale reverse genetic screens by applying a multiplexed gene disruption strategy that markedly increases the efficiency of the screening process. To facilitate large-scale phenotyping, we incorporate an automated reporter quantification-based assay to identify cellular degeneration and regeneration-deficient phenotypes in transgenic fish. Multiplexed gene targeting strategies can address mismatches in scale between “big data” bioinformatics and wet lab experimental capacities, a critical shortfall limiting comprehensive functional analyses of factors implicated in ever-expanding multiomics datasets. This report details the progress we have made to date with a multiplexed CRISPR/Cas9-based gene targeting strategy and discusses how the methodologies applied can further our understanding of the genes that predispose to retinal degenerative disease and which control the regenerative capacity of retinal Müller glia cells.

OCT4 expression mediates partial cardiomyocyte reprogramming of mesenchymal stromal cells

Mesenchymal stem/stromal cells (MSCs) are in numerous cell therapy clinical trials, including for injured myocardium. Acquisition of cardiomyocyte characteristics by MSCs may improve cardiac regeneration but the mechanisms regulating this process are unclear. Here, we investigated whether the pluripotency transcription factor OCT4 is involved in the activation of cardiac lineage genetic programs in MSCs. We employed our established co-culture model of MSCs with rat embryonic cardiomyocytes showing co-expression of cardiac markers on MSCs independent of cell fusion. Bone marrow-derived MSCs were isolated from transgenic mice expressing GFP under the control of the cardiac-specific α-myosin heavy chain promoter. After 5 days of co-culture, MSCs expressed cardiac specific genes, including Nkx2.5, atrial natriuretic factor and α-cardiac actin. The frequency of GFP+ cells was 7.6±1.9%, however, these cells retained the stromal cell phenotype, indicating, as expected, only partial differentiation. Global OCT4 expression increased 2.6±0.7-fold in co-cultured MSCs and of interest, 87±5% vs 79±4% of MSCs expressed OCT4 by flow cytometry in controls and after co-culture, respectively. Consistent with the latter observation, the GFP+ cells did not express nuclear OCT4 and showed a significant increase in OCT4 promoter methylation compared with undifferentiated MSCs (92% vs 45%), inferring that OCT4 is regulated by an epigenetic mechanism. We further showed that siRNA silencing of OCT4 in MSCs resulted in a reduced frequency of GFP+ cells in co-culture to less than 1%. Our data infer that OCT4 expression may have a direct effect on partial cardiomyocyte reprogramming of MSCs and suggest a new mechanism(s) associated with MSC multipotency and a requirement for crosstalk with the cardiac microenvironment.

Expression of markers for germ cells and oocytes in cow dermal fibroblast treated with 5-azacytidine and cultured in differentiation medium containing BMP2, BMP4 or follicular fluid

This study aims to investigate the effect 5-azacytidine (5-Aza) during induction of pluripotency in bovine fibroblasts and to evaluate the effects of BMP2, BMP4 or follicular fluid in the differentiation of reprogrammed fibroblasts in primordial germ cells and oocytes. It also analysis the mRNA levels for OCT4, NANOG, REX, SOX2, VASA, DAZL, cKIT, SCP3, ZPA and GDF9 after culturing 5-Aza treated fibroblasts in the different tested medium. Dermal fibroblasts were cultured and exposed to 0.5, 1.0 or 2.0 μM of 5-Aza for 18 h, 36 h or 72 h. Then, the cells were cultured in DMEM/F12 supplemented with 10 ng/ml BMP2, 10 ng/ml BMP4 or 5% follicular fluid. After culture, morphological characteristics, viability and gene expression were evaluated by qPCR. Treatment of skin fibroblasts with 2.0 μM 5-Aza for 72 h significantly increased expression of mRNAs for SOX2, OCT4, NANOG and REX. The culture in medium supplemented with BMP2, BMP4 or follicular fluid for 7 or 14 days induced formation of oocyte-like cells, as well as the expression of markers for germ cells and oocyte. In conclusion, treatment of bovine skin-derived fibroblasts with 2.0 μM 5-Aza for 72 h induces the expression of pluripotency factors. Culturing these cells in differentiation medium supplemented with BMP2, BMP4 or follicular fluid induces morphological changes and promotes expression of markers for germ cells, meiosis and oocyte.

STELLA collaborates in distinct mesendodermal cell subpopulations at the fetal-placental interface in the mouse gastrula

The allantois-derived umbilical component of the chorio-allantoic placenta shuttles fetal blood to and from the chorion, thereby ensuring fetal-maternal exchange. The progenitor populations that establish and supply the fetal-umbilical interface lie, in part, within the base of the allantois, where the germ line is claimed to segregate from the soma. Results of recent studies in the mouse have reported that STELLA (DPPA-3, PGC7) co-localizes with PRDM1 (BLIMP1), the bimolecular signature of putative primordial germ cells (PGCs) throughout the fetal-placental interface. Thus, if PGCs form extragonadally within the posterior region of the mammal, they cannot be distinguished from the soma on the basis of these proteins. We used immunohistochemistry, immunofluorescence, and confocal microscopy of the mouse gastrula to co-localize STELLA with a variety of gene products, including pluripotency factor OCT-3/4, mesendoderm-associated T and MIXl1, mesendoderm- and endoderm-associated FOXa2 and hematopoietic factor Runx1. While a subpopulation of cells localizing OCT-3/4 was always found independently of STELLA, STELLA always co-localized with OCT-3/4. Despite previous reports that T is involved in specification of the germ line, co-localization of STELLA and T was detected only in a small subset of cells in the base of the allantois. Slightly later in the hindgut lip, STELLA+/(OCT-3/4+) co-localized with FOXa2, as well as with RUNX1, indicative of definitive endoderm and hemangioblasts, respectively. STELLA was never found with MIXl1. On the basis of these and previous results, we conclude that STELLA identifies at least five distinct cell subpopulations within the allantois and hindgut, where they may be involved in mesendodermal differentiation and hematopoiesis at the posterior embryonic-extraembryonic interface. These data provide a new point of departure for understanding STELLA's potential roles in building the fetal-placental connection.

Phenotype switching through epigenetic conversion

Different cell types have been suggested as candidates for use in regenerative medicine. Embryonic pluripotent stem cells can give rise to all cells of the body and possess unlimited self-renewal potential. However, they are unstable, difficult to control and have a risk of neoplastic transformation. Adult stem cells are safe but have limited proliferation and differentiation abilities and are usually not within easy access. In recent years, induced pluripotent stem (iPS) cells have become a new promising tool in regenerative medicine. However, the use of transgene vectors, commonly required for the induction of iPS cells, seriously limits their use in therapy. The same problem arising from the use of retroviruses is associated with the use of cells obtained through transdifferentiation. Developing knowledge of the mechanisms controlling epigenetic regulation of cell fate has boosted the use of epigenetic modifiers that drive cells into a 'highly permissive' state. We recently set up a new strategy for the conversion of an adult mature cell into another cell type. We increased cell plasticity using 5-aza-cytidine and took advantage of a brief window of epigenetic instability to redirect cells to a different lineage. This approach is termed 'epigenetic conversion'. It is a simple, direct and safe way to obtain both cells for therapy avoiding gene transfection and a stable pluripotent state.

The pioneer factor OCT4 requires the chromatin remodeller BRG1 to support gene regulatory element function in mouse embryonic stem cells

Pioneer transcription factors recognise and bind their target sequences in inaccessible chromatin to establish new transcriptional networks throughout development and cellular reprogramming. During this process, pioneer factors establish an accessible chromatin state to facilitate additional transcription factor binding, yet it remains unclear how different pioneer factors achieve this. Here, we discover that the pluripotency-associated pioneer factor OCT4 binds chromatin to shape accessibility, transcription factor co-binding, and regulatory element function in mouse embryonic stem cells. Chromatin accessibility at OCT4-bound sites requires the chromatin remodeller BRG1, which is recruited to these sites by OCT4 to support additional transcription factor binding and expression of the pluripotency-associated transcriptome. Furthermore, the requirement for BRG1 in shaping OCT4 binding reflects how these target sites are used during cellular reprogramming and early mouse development. Together this reveals a distinct requirement for a chromatin remodeller in promoting the activity of the pioneer factor OCT4 and regulating the pluripotency network.

DOI:http://dx.doi.org/10.7554/eLife.22631.001

All cells in your body contain the same genetic information in the form of genes encoded within DNA. Yet, cells use this information in different ways so that the activities of individual genes within that DNA can vary from cell to cell. This allows identical cells to become different to each other and to adapt to changing circumstances.

A group of proteins called transcription factors control the activity of certain genes by binding to specific sites on DNA. However, this isn’t a straightforward process because DNA in human and other animal cells is usually associated with structures called nucleosomes that can block access to the DNA. Pioneer transcription factors, such as OCT4, are a specific group of transcription factors that can attach to DNA in spite of the nucleosomes, but it’s not clear how this is possible. Once pioneer transcription factors attach to DNA they can help other transcription factors to bind alongside them.

King et al. studied OCT4 in stem cells from mouse embryos to investigate how it is able to act as a pioneer transcription factor and control gene activity. The experiments show that several other transcription factors lose the ability to bind to DNA when OCT4 is absent. This leads to widespread changes in gene activity in the cells, which seems to be due to other transcription factors being unable to get past the nucleosomes to attach to the DNA.

Further experiments showed that OCT4 needs a protein called BRG1 in order to act as a pioneer transcription factor. BRG1 is an enzyme that is able to move and remove (remodel) nucleosomes attached to DNA, suggesting that normal transcription factor binding requires this activity. The next challenge is to investigate whether BRG1, or similar enzymes, are also needed by other pioneer transcription factors that are required for normal gene activity and cell identity. This will be important because many enzymes that remodel nucleosomes are disrupted in human diseases like cancer where cells lose their normal identity.

DOI:http://dx.doi.org/10.7554/eLife.22631.002

Beneficial effects of diazepin-quinazolin-amine derivative (BIX-01294) on preimplantation development and molecular characteristics of cloned mouse embryos

Somatic cell nuclear transfer is frequently associated with abnormal epigenetic modifications that may lead to the developmental failure of cloned embryos. BIX-01294 (a diazepine–quinazoline–amine derivative) is a specific inhibitor of the histone methyltransferase G9a. The aim of the present study was to investigate the effects of BIX-01294 on development, dimethylation of histone H3 at lysine 9 (H3K9), DNA methylation and the expression of imprinted genes in cloned mouse preimplantation embryos. There were no significant differences in blastocyst rates of cloned embryos treated with or without 0.1 μM BIX-01294. Relative to clone embryos treated without 0.1 μM BIX-01294, exposure of embryos to BIX-01294 decreased histone H3K9 dimethylation and DNA methylation in cloned embryos to levels that were similar to those of in vivo-fertilised embryos at the 2-cell and blastocyst stages. Cloned embryos had lower expression of octamer-binding transcription factor 4 (Oct4) and small nuclear ribonucleoprotein N (Snrpn), but higher expression of imprinted maternally expressed transcript (non-protein coding) (H19) and growth factor receptor-bound protein 10 (Grb10) compared with in vivo-fertilised counterparts. The addition of 0.1 μM BIX-01294 to the activation and culture medium resulted in lower H19 expression and higher cyclin dependent kinase inhibitor 1C (Cdkn1c) and delta-like 1 homolog (Dlk1) expression, but had no effect on the expression of Oct4, Snrpn and Grb10. The loss of methylation at the Grb10 cytosine–phosphorous–guanine (CpG) islands in cloned embryos was partially corrected by BIX-01294. These results indicate that BIX-01294 treatment of cloned embryos has beneficial effects in terms of correcting abnormal epigenetic modifications, but not on preimplantation development.

Regulation of Zygotic Genome and Cellular Pluripotency

Events, manifesting transition from maternal to zygotic period of development are studied for more than 100 years, but underlying mechanisms are not yet clear. We provide a brief historical overview of development of concepts and explain the specific terminology used in the field. We further discuss differences and similarities between the zygotic genome activation and in vitro reprogramming process. Finally, we envision the future research directions within the field, where biochemical methods will play increasingly important role.

Nonsyndromic cleft lip with or without cleft palate and cancer: Evaluation of a possible common genetic background through the analysis of GWAS data

Previous research suggests a genetic overlap between nonsyndromic cleft lip with or without cleft palate (NSCL/P) and cancer. The aim of the present study was to identify common genetic risk loci for NSCL/P and cancer entities that have been reported to co-occur with orofacial clefting. This was achieved through the investigation of large genome-wide association study datasets. Investigations of 12 NSCL/P single nucleotide polymorphisms (SNPs) in 32 cancer datasets, and 204 cancer SNPs in two NSCL/P datasets, were performed. The SNPs rs13041247 (20q12) and rs6457327 (6p21.33) showed suggestive evidence for an association with both NSCL/P and a specific cancer entity. These loci harbor genes of biological relevance to oncogenesis (MAFB and OCT4, respectively). This study is the first to characterize possible pleiotropic risk loci for NSCL/P and cancer in a systematic manner. The data represent a starting point for future research by identifying a genetic link between NSCL/P and cancer.

Overexpression of Oct4 in porcine ovarian stem/stromal cells enhances differentiation of oocyte-like cells in vitro and ovarian follicular formation in vivo

Background

Recent findings have revealed that the female gonad may have regenerative activity with having germ line stem cells in juveniles and adults. Application of these germ line stem cells could be an alternative therapy for reproductive disorders in regenerative medicine.

Methods

To enhance the potency of differentiation into oocyte-like cells (OLCs) and folliculogenesis, we overexpressed Oct4 in ovarian stem/stromal cell (OvSCs) and examined the cellular properties related to stemness and self-renewal ability and finally demonstrated the ability of in vitro differentiation and folliculogenesis.

Results

Ovarian cortex included putative stem cells in terms of AP activity, cell cycle status, cell proliferation, expression of mesenchymal lineage surface markers and pluripotent transcriptional markers. Further, Oct4 transfected OvSCs (Oct4-OvSCs) were enhanced their AP activity and cell proliferation compared to OvSCs. The potential on in vitro differentiation into OLCs and in vivo folliculogenesis was also evaluated in OvSCs and Oct4-OvSCs, respectively. Oct4-OvSCs possessed higher oogenesis potential in vitro than OvSCs, in terms of expression of germ cell markers by RT-PCR and the number of OLCs. When OvSCs and Oct4-OvSCs were xeno-transplanted into infertile mice ovaries, the OvSCs transplantation induced new primary follicle formation and hormonal levels of estradiol and FSH remained similar to that of normal mice. However, Oct4-OvSCs possessed higher ability for folliculogenesis based on inducing developing follicles with thecal layer and granulosa cells and more similar estradiol level to normal mice.

Conclusions

These findings demonstrated that putative stem cells were present in ovarian cortex and exhibited differentiation ability into OLCs and folliculogenesis in vivo, and Oct4-overexpression enhanced these ability, suggesting their cellular models based on gene therapy in understanding the mechanisms of oogenesis and folliculogenesis, and finally in view of reproductive cell therapy.

The role of pluripotency factors to drive stemness in gastrointestinal cancer

A better molecular understanding of gastrointestinal cancers arising either from the stomach, the pancreas, the intestine, or the liver has led to the identification of a variety of potential new molecular therapeutic targets. However, in most cases surgery remains the only curative option. The intratumoral cellular heterogeneity of cancer stem cells, bulk tumor cells, and stromal cells further limits straightforward targeting approaches. Accumulating evidence reveals an intimate link between embryonic development, stem cells, and cancer formation. In line, a growing number of oncofetal proteins are found to play common roles within these processes. Cancer stem cells share features with true stem cells by having the capacity to self-renew in a de-differentiated state, to generate heterogeneous types of differentiated progeny, and to give rise to the bulk tumor. Further, various studies identified genes in cancer stem cells, which were previously shown to regulate the pluripotency circuitry, particularly the so-called "Yamanaka-Factors" (OCT4, KLF4, SOX2, and c-MYC). However, the true stemness potential of cancer stem cells and the role and expression pattern of such pluripotency genes in various tumor cell types remain to be explored. Here, we summarize recent findings and discuss the potential mechanisms involved, and link them to clinical significance with a particular focus on gastrointestinal cancers.

Molecular evidence for OCT4-induced plasticity in adult human fibroblasts required for direct cell fate conversion to lineage specific progenitors

Here we characterize the molecular and biological requirements for OCT4 plasticity induction in human skin derived fibroblasts (hFibs) that allows direct conversion of cell fate without iPSC formation. Our results indicate that adult hFibs not only require OCT4 but also short-term exposure to reprogramming media (RM) to successfully undergo direct conversion to early hematopoietic and neural progenitor fates. RM was found to be essential in this process and allowed for unique changes in global gene expression specific to the combined effects of OCT4 and treatment with reprogramming media to establish a plastic state. This molecular state of hFib plasticity was distinct from transient expression of a full complement of iPSC reprogramming factors consistent with a lack in molecular hallmarks of iPSC formation. Human Fib-derived OCT4 plastic cells display elevated levels of developmentally related genes associated with multiple lineages, but not those associated with pluripotency. In response to changes in the extracellular environment, plastic OCT4-expressing hFibs further activate genes involved in hematopoietic as well as tripotent neural progenitor biology that allow cell fate conversion. Our study provides a working definition of hFib-induced plasticity using OCT4 and a deconvoluted system to elucidate the process of direct cell fate reprogramming.

Endometriosis: a role for stem cells

Endometriosis is a complex gynecologic condition affecting 6-10% of reproductive aged women and is a major cause of chronic pain and infertility. Mechanisms of disease pathogenesis are poorly understood. Considerable evidence supports the existence of a stem cell population in the endometrium which provides a physiologic source of regenerative endometrial cells, and multiple lines of evidence now support a key role for stem cells in the pathogenesis of endometriosis. In addition, new blood vessel formation is critical for the establishment and maintenance of endometriotic implants, a process in which endothelial progenitor cells may play an integral role. These new insights into disease pathogenesis present exciting opportunities to develop targeted and more effective therapeutic options in the management of this common and challenging disease.

Gene Signature of Human Oral Mucosa Fibroblasts: Comparison with Dermal Fibroblasts and Induced Pluripotent Stem Cells

Oral mucosa is a useful material for regeneration therapy with the advantages of its accessibility and versatility regardless of age and gender. However, little is known about the molecular characteristics of oral mucosa. Here we report the first comparative profiles of the gene signatures of human oral mucosa fibroblasts (hOFs), human dermal fibroblasts (hDFs), and hOF-derived induced pluripotent stem cells (hOF-iPSCs), linking these with biological roles by functional annotation and pathway analyses. As a common feature of fibroblasts, both hOFs and hDFs expressed glycolipid metabolism-related genes at higher levels compared with hOF-iPSCs. Distinct characteristics of hOFs compared with hDFs included a high expression of glycoprotein genes, involved in signaling, extracellular matrix, membrane, and receptor proteins, besides a low expression of HOX genes, the hDFs-markers. The results of the pathway analyses indicated that tissue-reconstructive, proliferative, and signaling pathways are active, whereas senescence-related genes in p53 pathway are inactive in hOFs. Furthermore, more than half of hOF-specific genes were similarly expressed to those of hOF-iPSC genes and might be controlled by WNT signaling. Our findings demonstrated that hOFs have unique cellular characteristics in specificity and plasticity. These data may provide useful insight into application of oral fibroblasts for direct reprograming.

Epigenetic silencing of Oct4 by a complex containing SUV39H1 and Oct4 pseudogene lncRNA

Pseudogene-derived, long non-coding RNAs (lncRNAs) act as epigenetic regulators of gene expression. Here we present a panel of new mouse Oct4 pseudogenes and demonstrate that the X-linked Oct4 pseudogene Oct4P4 critically impacts mouse embryonic stem cells (mESCs) self-renewal. Sense Oct4P4 transcription produces a spliced, nuclear-restricted lncRNA that is efficiently upregulated during mESC differentiation. Oct4P4 lncRNA forms a complex with the SUV39H1 HMTase to direct the imposition of H3K9me3 and HP1α to the promoter of the ancestral Oct4 gene, located on chromosome 17, leading to gene silencing and reduced mESC self-renewal. Targeting Oct4P4 expression in primary mouse embryonic fibroblasts causes the re-acquisition of self-renewing features of mESC. We demonstrate that Oct4P4 lncRNA plays an important role in inducing and maintaining silencing of the ancestral Oct4 gene in differentiating mESCs. Our data introduces a sense pseudogene–lncRNA-based mechanism of epigenetic gene regulation that controls the cross-talk between pseudogenes and their ancestral genes.

Pseudogene derived long non-coding RNAs (lncRNAs) can regulate the expression of their ancestral genes. Here, the authors show that the Oct4 pseudogene OctP4 lncRNA plays an important role in inducing and maintaining silencing of the ancestral Oct4 gene in differentiating mouse embryonic stem cells.

SRY and OCT4 Are Required for the Acquisition of Cancer Stem Cell-Like Properties and Are Potential Differentiation Therapy Targets

The acquisition of stemness is a hallmark of aggressive human hepatocellular carcinoma (hHCC). The stem cell marker OCT4 is frequently expressed in HCCs, and its expression correlates with those of putative cancer stem cell (CSC) markers and CSC properties. Here, we describe a novel mechanism of CSC maintenance by SRY through OCT4. We previously reported that Sry is involved in tumor malignancy in rodent HCCs. However, the oncogenic function of SRY in hHCCs is poorly understood. Ectopic expression of SRY increased multiple stem cell factors, including OCT4 and CD13. The OCT4 promoter contained SRY-binding sites that were directly activated by SRY. In HCC-derived cells, SRY knockdown decreased OCT4 expression and cancer stem-like phenotypes such as self-renewal, chemoresistance, and tumorigenicity. Conversely, OCT4 and SRY overexpression promoted cancer stem-like phenotypes. OCT4 knockdown in SRY clones downregulated the self-renewal capacity and chemoresistance. These data suggest that SRY is involved in the maintenance of cancer stem-like characteristics through OCT4. Moreover, CSCs of HCC-derived cells differentiated into Tuj1-positive neuron-like cells by retinoic acid. Noteworthily, SRY was highly expressed in some hHCC patients. Taken together, our findings imply a novel therapeutic strategy against CSCs of hHCCs.

Application of iPS cells in dental bioengineering and beyond

The stem-cell-based tissue-engineering approaches are widely applied in establishing functional organs and tissues for regenerative medicine. Successful generation of induced pluripotent stem cells (iPS cells) and rapid progress of related technical platform provide great promise in the development of regenerative medicine, including organ regeneration. We have previously reported that iPS cells could be an appealing stem cells source contributing to tooth regeneration. In the present paper, we mainly review the application of iPS technology in dental bioengineering and discuss the challenges for iPS cells in the whole tooth regeneration.

Epigenetic biomarker to support classification into pluripotent and non-pluripotent cells

Quality control of human induced pluripotent stem cells (iPSCs) can be performed by several methods. These methods are usually relatively labor-intensive, difficult to standardize, or they do not facilitate reliable quantification. Here, we describe a biomarker to distinguish between pluripotent and non-pluripotent cells based on DNA methylation (DNAm) levels at only three specific CpG sites. Two of these CpG sites were selected by their discriminatory power in 258 DNAm profiles – they were either methylated in pluripotent or non-pluripotent cells. The difference between these two β-values provides an Epi-Pluri-Score that was validated on independent DNAm-datasets (264 pluripotent and 1,951 non-pluripotent samples) with 99.9% specificity and 98.9% sensitivity. This score was complemented by a third CpG within the gene POU5F1 (OCT4), which better demarcates early differentiation events. We established pyrosequencing assays for the three relevant CpG sites and thereby correctly classified DNA of 12 pluripotent cell lines and 31 non-pluripotent cell lines. Furthermore, DNAm changes at these three CpGs were tracked in the course of differentiation of iPSCs towards mesenchymal stromal cells. The Epi-Pluri-Score does not give information on lineage-specific differentiation potential, but it provides a simple, reliable, and robust biomarker to support high-throughput classification into either pluripotent or non-pluripotent cells.