Embryonic stem cell differentiation models: cardiogenesis, myogenesis, neurogenesis, epithelial and vascular smooth muscle cell differentiation in vitro

Complex regulation of Eomes levels mediated through distinct functional features of the Meteor long non-coding RNA locus

Long non-coding RNAs (lncRNAs) are implicated in a plethora of cellular processes, but an in-depth understanding of their functional features or their mechanisms of action is currently lacking. Here we study Meteor, a lncRNA transcribed near the gene encoding EOMES, a pleiotropic transcription factor implicated in various processes throughout development and in adult tissues. Using a wide array of perturbation techniques, we show that transcription elongation through the Meteor locus is required for Eomes activation in mouse embryonic stem cells, with Meteor repression linked to a change in the subpopulation primed to differentiate to the mesoderm lineage. We further demonstrate that a distinct functional feature of the locus-namely, the underlying DNA element-is required for suppressing Eomes expression following neuronal differentiation. Our results demonstrate the complex regulation that can be conferred by a single locus and emphasize the importance of careful selection of perturbation techniques when studying lncRNA loci.

Embryonic Stem Cells Can Generate Oral Epithelia under Matrix Instruction

We aimed to investigate whether molecular clues from the extracellular matrix (ECM) can induce oral epithelial differentiation of pluripotent stem cells. Mouse embryonic stem cells (ESC) of the feeder-independent cell line E14 were used as a model for pluripotent stem cells. They were first grown in 2D on various matrices in media containing vitamin C and without leukemia inhibitory factor (LIF). Matrices investigated were gelatin, laminin, and extracellular matrices (ECM) synthesized by primary normal oral fibroblasts and keratinocytes in culture. Differentiation into epithelial lineages was assessed by light microscopy, immunocytochemistry, and flow cytometry for cytokeratins and stem cell markers. ESC grown in 2D on various matrices were afterwards grown in 3D organotypic cultures with or without oral fibroblasts in the collagen matrix and examined histologically and by immunohistochemistry for epithelial (keratin pairs 1/10 and 4/13 to distinguish epidermal from oral epithelia and keratins 8,18,19 to phenotype simple epithelia) and mesenchymal (vimentin) phenotypes. ECM synthesized by either oral fibroblasts or keratinocytes was able to induce, in 2D cultures, the expression of cytokeratins of the stratified epithelial phenotype. When grown in 3D, all ESC developed into two morphologically distinct cell populations on collagen gels: (i) epithelial-like cells organized in islands with occasional cyst- or duct-like structures and (ii) spindle-shaped cells suggestive of mesenchymal differentiation. The 3D culture on oral fibroblast-populated collagen matrices was necessary for further differentiation into oral epithelia. Only ESC initially grown on 2D keratinocyte or fibroblast-synthesized matrices reached full epithelial maturation. In conclusion, ESC can generate oral epithelia under matrix instruction.

Direct Cardiac Reprogramming: Current Status and Future Prospects

Advances in cellular reprogramming articulated the path for direct cardiac lineage conversion, bypassing the pluripotent state. Direct cardiac reprogramming attracts major attention because of the low or nil regenerative ability of cardiomyocytes, resulting in permanent cell loss in various heart diseases. In the field of cardiology, balancing this loss of cardiomyocytes was highly challenging, even in the modern medical world. Soon after the discovery of cell reprogramming, direct cardiac reprogramming also became a promising alternative for heart regeneration. This review mainly focused on the various direct cardiac reprogramming approaches (integrative and non-integrative) for the derivation of induced autologous cardiomyocytes. It also explains the advancements in cardiac reprogramming over the decade with the pros and cons of each approach. Further, the review highlights the importance of clinically relevant (non-integrative) approaches and their challenges for the prospective applications for personalized medicine. Apart from direct cardiac reprogramming, it also discusses the other strategies for generating cardiomyocytes from different sources. The understanding of these strategies could pave the way for the efficient generation of integration-free functional autologous cardiomyocytes through direct cardiac reprogramming for various biomedical applications.

p57 Suppresses the Pluripotency and Proliferation of Mouse Embryonic Stem Cells by Positively Regulating p53 Activation

Embryonic stem cells (ESCs) are pluripotent stem cells that have indefinite self-renewal capacities under appropriate culture conditions in vitro. The pluripotency maintenance and proliferation of these cells are delicately governed by the concert effect of a complex transcriptional regulatory network. Herein, we discovered that p57^Kip2 (p57), a cyclin-dependent kinase inhibitor canonically inhibiting cell proliferation, played a role in suppressing the pluripotency state of mouse ESCs (mESCs). p57 knockdown significantly stimulated the expressions of core pluripotency factors NANOG, OCT4, and SOX2, while p57 overexpression inhibited the expressions of these factors in mESCs. In addition, consistent with its function in somatic cells, p57 suppressed mESC proliferation. Further analysis showed that p57 could interact with and contribute to the activation of p53 in mESCs. In conclusion, the present study showed that p57 could antagonize the pluripotency state and the proliferation process of mESCs. This finding uncovers a novel function of p57 and provides new evidence for elucidating the complex regulatory of network of mESC fate.

Effects of vitamin A and retinoic acid on mouse embryonic stem cells and their differentiating progeny

Embryonic development is controlled by retinoids, and one approach that has been used to investigate the mechanisms for retinoid actions in developmental processes has been to study the effects of adding retinoids to cultures of pluripotent embryonic stem cells (ESC). To date, most in vitro retinoid research has been directed at deciphering the actions of all-trans retinoic acid (atRA). atRA is a derivative of all-trans retinol (a.k.a. vitamin A, VA), which mammals can generate via an enzyme-catalyzed pathway. atRA's effects on development result from its (1) activation of receptor complexes (RARs and RXRs) in the nucleus which then bind to and activate RA response elements (RAREs) in genes and (2) its interactions with processes that are initiated in the cytoplasm. While much work has focused on the impact of atRA on cell differentiation, VA, itself, has been shown to exert effects on the maintenance of ESC identity that are not dependent upon classic RA-signaling pathways. In this chapter, we present results from our laboratory and others using well-documented approaches for investigating the effects of retinoids on the differentiation of ESC in vitro and introduce a novel method that uses chemically-defined growth conditions. The merits of each approach are discussed.

Thick Filament Protein Network, Functions, and Disease Association

Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018.

Gene expression signatures after ethanol exposure in differentiating embryoid bodies

During the differentiation process, various epigenetic factors regulate the precise expression of important genes and control cellular fate. During this stage, the differentiating cells become vulnerable to external stimuli. Here, we used an early neural differentiation model to observe ethanol-mediated transcriptional alterations. Our objective was to identify important molecular regulators of ethanol-related alterations in the genome during differentiation. A transcriptomic analysis was performed to profile the mRNA expression in differentiating embryoid bodies with or without ethanol treatment. In total, 147 differentially expressed genes were identified in response to 50mM ethanol. Of these differentially expressed genes, 78 genes were up-regulated and 69 genes were down-regulated. Our analysis revealed a strong association among the transcript signatures of the important modulators which were involved in protein modification, protein synthesis and gene expression. Additionally, ethanol-mediated activation of DNA transcription was observed. We also profiled ethanol-responsive transcription factors (TFs), upstream transcriptional regulators and TF-binding motifs in the differentiating embryoid bodies. In this study, we established a platform that we hope will help other researchers determine the ethanol-mediated changes that occur during cellular differentiation.

Making muscle: skeletal myogenesis in vivo and in vitro

Skeletal muscle is the largest tissue in the body and loss of its function or its regenerative properties results in debilitating musculoskeletal disorders. Understanding the mechanisms that drive skeletal muscle formation will not only help to unravel the molecular basis of skeletal muscle diseases, but also provide a roadmap for recapitulating skeletal myogenesis in vitro from pluripotent stem cells (PSCs). PSCs have become an important tool for probing developmental questions, while differentiated cell types allow the development of novel therapeutic strategies. In this Review, we provide a comprehensive overview of skeletal myogenesis from the earliest premyogenic progenitor stage to terminally differentiated myofibers, and discuss how this knowledge has been applied to differentiate PSCs into muscle fibers and their progenitors in vitro.

Efficient neural differentiation of mouse pluripotent stem cells in a serum-free medium and development of a novel strategy for enrichment of neural cells

Pluripotent stem cells (PSCs) offer an excellent model to study neural development and function. Although various protocols have been developed to direct the differentiation of PSCs into desired neural cell types, many of them suffer from limitations including low efficiency, long duration of culture, and the use of expensive, labile, and undefined growth supplements. In this study, we achieved efficient differentiation of mouse PSCs to neural lineage, in the absence of exogenous molecules, by employing a serum-free culture medium containing knockout serum replacement (KSR). Embryoid bodies (EBs) cultured in this medium predominantly produced neural cells which included neural progenitors (15-18%), immature neurons (8-24%), mature neurons (10-26%), astrocytes (27-61%), and oligodendrocytes (∼1%). Different neuronal subtypes including glutamatergic, GABAergic, cholinergic, serotonergic, and dopaminergic neurons were generated. Importantly, neurons generated in the KSR medium were electrically active. Further, the EB scooping strategy, involving the removal of the EB core region from the peripheral EB outgrowth, resulted in the enrichment of PSC-derived neural cells. Taken together, this study provides the evidence that the KSR medium is ideal for the rapid and efficient generation of neural cells, including functional neurons, from PSCs without the requirement of any other additional molecule.

Oral mucosal progenitor cell clones resist in vitro myogenic differentiation

Progenitor cells derived from the oral mucosa lamina propria (OMLP-PCs) demonstrate an ability to differentiate into tissue lineages removed from their anatomical origin. This clonally derived population of neural-crest cells have demonstrated potential to differentiate along mesenchymal and neuronal cell lineages.

OBJECTIVE

Significant efforts are being made to generate functioning muscle constructs for use in research and clinical tissue engineering. In this study we aimed to determine the myogenic properties of clonal populations of expanded OMLP-PCs.

DESIGN

PCs were subject to several in vitro culture conditions in an attempt to drive myogenic conversion. Methodologies include use of demethylation gene-modifying reagents, mechanical conditioning of tissue culture substrates, tuneable polyacrylamide gels and a 3-dimensional construct as well as published myogenic media compositions. PCR and immunostaining for the muscle cell markers Desmin and MyoD1 were used to assess muscle differentiation.

RESULTS

The clones tested did not intrinsically express myogenic lineage markers. Despite use of two and 3-dimensional pre-published in vitro culture protocols OMLP clones could not be differentiated down a myogenic lineage.

CONCLUSIONS

Within the confines of these experimental parameters it was not possible to generate identifiable muscle using the clonal populations. When reviewing the previously successful reports of myogenic conversion, cells utilised have either been derived from tissues that are already 'primed' with the requisite myogenic genetic potential or have undergone specific genetic reprogramming to enhance the myogenic conversion rate. This, along with as yet unidentified stromal interplay, may therefore be required for positive myogenic differentiation to be realised.

T-2 toxin inhibits murine ES cells cardiac differentiation and mitochondrial biogenesis by ROS and p-38 MAPK-mediated pathway

OBJECTIVE

To investigate the effect of T-2 toxin on murine embryonic stem cells (ESCs) cardiac differentiation and mitochondrial biogenesis in vitro.

METHODS

Cardiac differentiation of the mouse ESCs was initiated by embryoid bodies (EBs) formation in hanging drops. EBs were exposed to 0.5ng/ml T-2 toxin for 24, 72 and 120h. Cultures were observed daily for the appearance of contracting clusters, and cardiac-specific protein (α-actiniin) were measured by Western blot and immunocytochemistry. Mitochondrial ultrastructure was observed by confocal laser scanning microscopy and transmission EM photography. Reactive oxygen species (ROS) was monitored by H2-dichlorofluorescein-diacetate (H2DCF-DA). The phosphorylation of the p38 (p-p38) and p38 mitogen-activated protein kinase (MAPK) and the expression of mitochondrial biogenesis proteins, including peroxisome proliferator activated receptor coactivator-1 alpha (PGC-1α), nuclear respiratory factor 1 (NRF-1), mitochondrial transcription factor A (mtTFA), and mitochondrial respiratory chain complex IV (COXIV) were analyzed using Western blot. In some experiments, mESCs were pre-treated with the antioxidant Trolox (200μM) for 30min, then exposed to Trolox (200μM) and T-2 toxin (0.5ng/ml) for 72h.

RESULTS

Contracting clusters were observed under the microscope light and cardiac-specific protein (α-actinin) expressed positively indicated mESCs directly differentiated in cardiomyocytes. However, the cardiac differentiation was inhibited by T-2 toxin treatment 72 and 120h. ROS accumulated in murine ES cells in a time-dependent manner. The expression of p-p38 significantly increased in 24h group and decrease in 72 and 120h groups. The decrease of mitochondrial number and the mitochondrial biogenesis-related proteins expression, including PGC-1α, NRF-1, mtTFA, and COXIV decreased in a time-dependent manner with T-2 toxin treatment. However, the inhibition of mitochondrial biogenesis by T-2 toxin in differentiated mESCs was recovered significantly in the presence of the antioxidant Trolox.

CONCLUSION

Taken together, T-2 toxin decreased the expression of PGC-1α, NRF-1, and mtTFA, inhibited mitochondrial biogenesis, and then inhibited the cardiac differentiation of murine ES cells, and the effect was partly responsible for the p38 MAPK mediated by ROS.

Differential effects of high and low strength magnetic fields on mouse embryonic development and vasculogenesis of embryonic stem cells

Man-made magnetic fields (MFs) may exert adverse effects on mammalian embryonic development. Herein, we analysed the effect of 10mT 50Hz sinusoidal (AC) or static (DC) MFs versus 1mT MFs on embryonic development of mice. Exposure for 20days during gestation to 10mT MFs increased resorptions and dead fetuses, decreased crown-rump length and fresh weight, reduced blood vessel differentiation and caused histological changes, accompanied with diminished vascular endothelial growth factor (VEGF) protein expression in several organs. In embryonic stem (ES) cell-derived embryoid bodies exposure towards 10mT MFs increased reactive oxygen species (ROS), decreased vascular marker as well as VEGF expression and enhanced apoptosis. In conclusion, our combined data from in vivo and in vitro experiments identified VEGF as an important mediator during embryonic development that can be influenced by high strength MFs, which in consequence leads to severe abnormalities in fetus organs and blood vessel formation.

RNA Sequencing Reveals the Alteration of the Expression of Novel Genes in Ethanol-Treated Embryoid Bodies

Fetal alcohol spectrum disorder is a collective term representing fetal abnormalities associated with maternal alcohol consumption. Prenatal alcohol exposure and related anomalies are well characterized, but the molecular mechanism behind this phenomenon is not well characterized. In this present study, our aim is to profile important genes that regulate cellular development during fetal development. Human embryonic carcinoma cells (NCCIT) are cultured to form embryoid bodies and then treated in the presence and absence of ethanol (50 mM). We employed RNA sequencing to profile differentially expressed genes in the ethanol-treated embryoid bodies from NCCIT vs. EB, NCCIT vs. EB+EtOH and EB vs. EB+EtOH data sets. A total of 632, 205 and 517 differentially expressed genes were identified from NCCIT vs. EB, NCCIT vs. EB+EtOH and EB vs. EB+EtOH, respectively. Functional annotation using bioinformatics tools reveal significant enrichment of differential cellular development and developmental disorders. Furthermore, a group of 42, 15 and 35 transcription factor-encoding genes are screened from all of the differentially expressed genes obtained from NCCIT vs. EB, NCCIT vs. EB+EtOH and EB vs. EB+EtOH, respectively. We validated relative gene expression levels of several transcription factors from these lists by quantitative real-time PCR. We hope that our study substantially contributes to the understanding of the molecular mechanism underlying the pathology of alcohol-mediated anomalies and ease further research.

Factors supporting long-term culture of bovine male germ cells

Spermatogonial stem cells (SSCs) are unipotent in nature, but mouse SSCs acquire pluripotency under the appropriate culture conditions. Although culture systems are available for rodent and human germ-cell lines, no proven culture system is yet available for livestock species. Here, we examined growth factors, matrix substrates and serum-free supplements to develop a defined system for culturing primitive germ cells (gonocytes) from neonatal bovine testis. Poly-L-lysine was a suitable substrate for selective inhibition of the growth of somatic cells and made it possible to maintain a higher gonocyte : somatic cell ratio than those maintained with gelatin, collagen or Dolichos biflorus agglutinin (DBA) substrates. Among the serum-free supplements tested in our culture medium, knockout serum replacement (KSR) supported the proliferation and survival of gonocytes better than the supplements B-27 and StemPro-SFM after sequential passages of colonies. Under our optimised culture conditions consisting of 15% KSR supplement on poly-L-lysine-coated dishes, the stem-cell and germ-cell potentials of the cultured gonocytes were maintained with normal karyotype for more than 2 months (over 13 passages). The proposed culture system, which can maintain a population of proliferating bovine germ stem cells, could be useful for studying SSC biology and germline modifications in livestock animals.

From pluripotency to myogenesis: a multistep process in the dish

Pluripotent stem cells (PSCs), such as embryonic stem cells or induced pluripotent stem cells are a promising source of cells for regenerative medicine as they can differentiate into all cell types building a mammalian body. However, protocols leading to efficient and safe in vitro generation of desired cell types must be perfected before PSCs can be used in cell therapies or tissue engineering. In vivo, i.e. in developing mouse embryo or teratoma, PSCs can differentiate into skeletal muscle, but in vitro their spontaneous differentiation into myogenic cells is inefficient. Numerous attempts have been undertaken to enhance this process. Many of them involved mimicking the interactions occurring during embryonic myogenesis. The key regulators of embryonic myogenesis, such as Wnts proteins, fibroblast growth factor 2, and retinoic acid, have been tested to improve the frequency of in vitro myogenic differentiation of PSCs. This review summarizes the current state of the art, comparing spontaneous and directed myogenic differentiation of PSCs as well as the protocols developed this far to facilitate this process.

Fluoxetine-induced regulation of heat shock protein 90 and 14-3-3ε in human embryonic carcinoma cells

Fluoxetine, a serotonin-selective reuptake inhibitor, exerts antidepressant and antianxiety effects on major depressive and anxiety disorders. Previous studies suggest that treatment with fluoxetine influences the expression of various proteins that are involved in proliferation, differentiation, and apoptosis in the neuronal cells of the brain. However, many aspects of the molecular pathways that modulate antidepressant action are not well understood. Here, with the aim of identifying proteins involved in antidepressant action, we examined the protein expression profile of human embryonic carcinoma (NCCIT) cells in response to fluoxetine treatment using proteomic techniques such as two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). We found several upregulated and downregulated proteins in fluoxetine-treated NCCIT cells, and then biochemically confirmed the increased expression of heat shock protein 90 and 14-3-3ε, which play an essential role in many cellular mechanisms including cell cycle control and other signaling pathways. Our data suggest that the regulated expression of heat shock protein 90, 14-3-3ε, and other identified proteins may be associated with the therapeutic action of fluoxetine.

Neural Commitment of Embryonic Stem Cells through the Formation of Embryoid Bodies (EBs)

An embryonic stem cell (ESC) is a good tool to generate neurons in vitro and can be used to mimic neural development in vivo. It has been widely used in research to examine the role of cell signalling during neuronal development, test the effects of drugs on neurons, and generate a large population of functional neurons. So far, a number of protocols have been established to promote the differentiation of ESCs, such as direct and indirect differentiation. One of the widely used protocols to generate neurons is through the spontaneous formation of multicellular aggregates known as embryonic bodies (EBs). However, for some, it is not clear why EB protocol could be the protocol of choice. EB also is known to mimic an early embryo; hence, knowing the similarities between EB and an early embryo is essential, particularly the information on the players that promote the formation of EBs or the aggregation of ESCs. This review paper focuses on these issues and discusses further the generation of neural cells from EBs using a well-known protocol, the 4-/4+ protocol.

Optimization of culture condition of human bone marrow stromal cells in terms of purification, proliferation, and pluripotency

Human bone marrow stromal cells (hBMSCs) possess multilineage differentiation potential and play an important role in modern tissue engineering. However, the development of culture media to maintain hBMSCs in an undifferentiated, self-renewing state during their robust proliferation remains a challenge. We developed and tested modified growth medium [medium 1: epidermal growth factor (EGF), platelet-derived growth factor (PDGF), low glucose, 2% fetal calf serum (FCS)] on hBMSCs by comparing primary cell isolation, multipassage expansion, culture morphology, proliferation, and cellular phenotype, and performing an expression analysis of intrinsic-regulated genes to other two media. Cell morphology, proliferation, and phenotype varied among the media, while cells cultured in medium 1 displayed small, spindle-shaped morphology with the highest rate of growth capacities and the expected phenotype. RT-PCR analysis showed that medium 1 displayed the lowest expression levels of osteogenic genes, chondrogenic genes (osteonectin, runt-related transcription factor 2, cartilage oligo matrix protein, and SOX9), and adipogenic genes (lipoprotein lipase). The expression of another adipogenic gene, peroxisome proliferator-activator receptor-γ2, was higher in medium 1 but did not reach significance. In addition, hBMSCs expanded in medium 1 showed the highest expression ratio of self-renewing-related genes Krüppel-like factor 2 (KLF2) and KLF5. In conclusion, medium 1 allows for better expansion and pluripotency maintenance of hBMSCs and serves as a preferred alternative to traditional serum-containing media for research applications and future clinical use.

Efficient generation of hepatic cells from multipotent adult mouse germ-line stem cells using an OP9 co-culture system

On the basis of their self-renewal capacity and their ability to differentiate into derivatives of all three germ layers, germ line-derived multipotent adult stem cells (maGSCs) from mouse testis might serve as one of preferable sources for pluripotent stem cells in regenerative medicine. In our study, we aimed for an efficient hepatic differentiation protocol that is applicable for both maGSCs and embryonic stem cells (ESCs). We attempted to accomplish this goal by using a new established co-culture system with OP9 stroma cells for direct differentiation of maGSCs and ESCs into hepatic cells. We found that the hepatic differentiation of maGSCs was induced by the OP9 co-culture system in comparison to the gelatin culture. Furthermore, we showed that the combination of OP9 co-culture with activin A resulted in the increased expression of endodermal and early hepatic markers Gata4, Sox17, Foxa2, Hnf4, Afp, and Ttr compared to differentiated cells on gelatin or on OP9 alone. Moreover, the hepatic progenitors were capable of differentiating further into mature hepatic cells, demonstrated by the expression of liver-specific markers Aat, Alb, Tdo2, Krt18, Krt8, Krt19, Cps1, Sek, Cyp7a1, Otc, and Pah. A high percentage of maGSC-derived hepatic progenitors (51% AFP- and 61% DLK1-positive) and mature hepatic-like cells (26% ALB-positive) were achieved using this OP9 co-culture system. These generated hepatic cells successfully demonstrated in vitro functions associated with mature hepatocytes, including albumin and urea secretion, glycogen storage, and uptake of low-density lipoprotein. The established co-culture system for maGSCs into functional hepatic cells might serve as a suitable model to delineate the differentiation process for the generation of high numbers of mature hepatocytes in humans without genetic manipulations and make germ line-derived stem cells a potential autologous and alternative cell source for hepatic transplants in metabolic liver disorders.

The key enzyme of the sialic acid metabolism is involved in embryoid body formation and expression of marker genes of germ layer formation

The bi-functional enzyme UDP-N-acetyl-2-epimerase/N-acetylmannosamine kinase (GNE) is the key enzyme of the sialic acid biosynthesis. Sialic acids are negatively charged nine carbon amino sugars and are found on most glycoproteins and many glycolipids in terminal positions, where they are involved in a variety of biological important molecular interactions. Inactivation of the GNE by homologous recombination results in early embryonic lethality in mice. Here, we report that GNE-deficient embryonic stem cells express less differentiation markers compared to wild-type embryonic stem cells. As a result, GNE-deficient embryonic stem cells fail to form proper embryoid bodies (EB) within the first day of culture. However, when culturing these cells in the presence of sialic acids for three days, also GNE-deficient embryonic stem cells form normal EBs. In contrast, when culturing these cells in sialic acid reduced medium, GNE-deficient embryonic stem cells proliferate faster and form larger EBs without any change in the expression of markers of the germ layers.

Functions of huntingtin in germ layer specification and organogenesis

Huntington’s disease (HD) is a neurodegenerative disease caused by abnormal polyglutamine expansion in the huntingtin protein (Htt). Although both Htt and the HD pathogenic mutation (mHtt) are implicated in early developmental events, their individual involvement has not been adequately explored. In order to better define the developmental functions and pathological consequences of the normal and mutant proteins, respectively, we employed embryonic stem cell (ESC) expansion, differentiation and induction experiments using huntingtin knock-out (KO) and mutant huntingtin knock-in (Q111) mouse ESC lines. In KO ESCs, we observed impairments in the spontaneous specification and survival of ectodermal and mesodermal lineages during embryoid body formation and under inductive conditions using retinoic acid and Wnt3A, respectively. Ablation of BAX improves cell survival, but failed to correct defects in germ layer specification. In addition, we observed ensuing impairments in the specification and maturation of neural, hepatic, pancreatic and cardiomyocyte lineages. These developmental deficits occurred in concert with alterations in Notch, Hes1 and STAT3 signaling pathways. Moreover, in Q111 ESCs, we observed differential developmental stage-specific alterations in lineage specification and maturation. We also observed changes in Notch/STAT3 expression and activation. Our observations underscore essential roles of Htt in the specification of ectoderm, endoderm and mesoderm, in the specification of neural and non-neural organ-specific lineages, as well as cell survival during early embryogenesis. Remarkably, these developmental events are differentially deregulated by mHtt, raising the possibility that HD-associated early developmental impairments may contribute not only to region-specific neurodegeneration, but also to non-neural co-morbidities.

Cell-based screening of traditional Chinese medicines for proliferation enhancers of mouse embryonic stem cells

A high-throughput cell-based method was developed for screening traditional Chinese herbal medicines (TCHMs) for potential stem cell growth promoters. Mouse embryonic stem (mES) cells expressing enhanced green fluorescent protein (EGFP) were cultured in growth media supplemented with various TCHM extracts. The dosage-dependent effects of TCHM extracts on cell growth, including proliferation and cytotoxicity, were assessed via EGFP fluorescence measurement. Seven TCHMs were investigated, and among them Panax notoginseng (PN), Rhizoma Atractylodis macrocephalae, Rhizoma chuanxiong, and Ganoderma lucidum spores (GLS) showed potential to improve mES cell proliferation. Eleven mixtures of these four TCHMs were then studied, and the results showed that the mixture of PN and GLS had the strongest growth promoting effect, increasing the specific growth rate of mES cells by 29.5% at a low dosage of 0.01% (wt/vol) PN/GLS (P<0.01) and 34.2% at 0.1% (wt/vol) PN/GLS (P<0.05) compared to the control. The growth promoting effect of PN/GLS was further confirmed with ES cells cultured in spinner flasks. A 29.3-fold increase in the total cell number was achieved in the medium supplemented with 0.01% PN/GLS after 5 days, while the control culture only gave a 16.8-fold increase. This cell-based screening method thus can provide an efficient and high-throughput way to explore potential stem cell growth promoters from TCHMs.

Susceptibility of neuron-like cells derived from bovine Wharton's jelly to bovine herpesvirus type 5 infections

Background

Bovine herpesvirus type 5 (BoHV-5), frequently lethal in cattle, is associated with significant agricultural economic losses due to neurological disease. Cattle and rabbits are frequently used as models to study the biology and pathogenesis of BoHV-5 infection. In particular, neural invasion and proliferation are two of the factors important in BoHV-5 infection. The present study investigated the potential of bovine Wharton’s jelly mesenchymal stromal cells (bWJ-MSCs) to differentiate into a neuronal phenotype and support robust BoHV-5 replication.

Results

Upon inducing differentiation within a defined neuronal specific medium, most bWJ-MSCs acquired the distinctive neuronal morphological features and stained positively for the neuronal/glial markers MAP2 (neuronal microtubule associated protein 2), N200 (neurofilament 200), NT3 (neutrophin 3), tau and GFAP (glial fibrillary acidic protein). Expression of nestin, N200, β-tubulin III (TuJI) and GFAP was further demonstrated by reverse transcriptase polymerase chain reaction (RT-PCR). Following BoHV-5 inoculation, there were low rates of cell detachment, good cell viability at 96 h post-infection (p.i.), and small vesicles developed along neuronal branches. Levels of BoHV-5 antigens and DNA were associated with the peak in viral titres at 72 h p.i. BoHV-5 glycoprotein C mRNA expression was significantly correlated with production of progeny virus at 72 h p.i. (p < 0.05).

Conclusion

The results demonstrated the ability of bWJ-MSCs to differentiate into a neuronal phenotype in vitro and support productive BoHV-5 replication. These findings constitute a remarkable contribution to the in vitro study of neurotropic viruses. This work may pave the way for bWJ-MSCs to be used as an alternative to animal models in the study of BoHV-5 biology.

Selective development of myogenic mesenchymal cells from human embryonic and induced pluripotent stem cells

Human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells are promising sources for the cell therapy of muscle diseases and can serve as powerful experimental tools for skeletal muscle research, provided an effective method to induce skeletal muscle cells is established. However, the current methods for myogenic differentiation from human ES cells are still inefficient for clinical use, while myogenic differentiation from human iPS cells remains to be accomplished. Here, we aimed to establish a practical differentiation method to induce skeletal myogenesis from both human ES and iPS cells. To accomplish this goal, we developed a novel stepwise culture method for the selective expansion of mesenchymal cells from cell aggregations called embryoid bodies. These mesenchymal cells, which were obtained by dissociation and re-cultivation of embryoid bodies, uniformly expressed CD56 and the mesenchymal markers CD73, CD105, CD166, and CD29, and finally differentiated into mature myotubes in vitro. Furthermore, these myogenic mesenchymal cells exhibited stable long-term engraftment in injured muscles of immunodeficient mice in vivo and were reactivated upon subsequent muscle damage, increasing in number to reconstruct damaged muscles. Our simple differentiation system facilitates further utilization of ES and iPS cells in both developmental and pathological muscle research and in serving as a practical donor source for cell therapy of muscle diseases.

Generation of skeletal muscle cells from embryonic and induced pluripotent stem cells as an in vitro model and for therapy of muscular dystrophies

Muscular dystrophies (MDs) are a heterogeneous group of inherited disorders characterized by progressive muscle wasting and weakness likely associated with exhaustion of muscle regeneration potential. At present, no cures or efficacious treatments are available for these diseases, but cell transplantation could be a potential therapeutic strategy. Transplantation of myoblasts using satellite cells or other myogenic cell populations has been attempted to promote muscle regeneration, based on the hypothesis that the donor cells repopulate the muscle and contribute to its regeneration. Embryonic stem cells (ESCs) and more recently induced pluripotent stem cells (iPSCs) could generate an unlimited source of differentiated cell types, including myogenic cells. Here we review the literature regarding the generation of myogenic cells considering the main techniques employed to date to elicit efficient differentiation of human and murine ESCs or iPSCs into skeletal muscle. We also critically analyse the possibility of using these cellular populations as an alternative source of myogenic cells for cell therapy of MDs.

Isolation and characterization of Wharton's jelly-derived multipotent mesenchymal stromal cells obtained from bovine umbilical cord and maintained in a defined serum-free three-dimensional system

Background

The possibility for isolating bovine mesenchymal multipotent cells (MSCs) from fetal adnexa is an interesting prospect because of the potential for these cells to be used for biotechnological applications. Bone marrow and adipose tissue are the most common sources of MSCs derived from adult animals. However, little knowledge exists about the characteristics of these progenitors cells in the bovine species. Traditionally most cell cultures are developed in two dimensional (2D) environments. In mammalian tissue, cells connect not only to each other, but also support structures called the extracellular matrix (ECM). The three-dimensional (3D) cultures may play a potential role in cell biotechnology, especially in tissue therapy. In this study, bovine-derived umbilical cord Wharton’s jelly (UC-WJ) cells were isolated, characterized and maintained under 3D-free serum condition as an alternative of stem cell source for future cell banking.

Results

Bovine-derived UC-WJ cells, collected individually from 5 different umbilical cords sources, were successfully cultured under serum-free conditions and were capable to support 60 consecutive passages using commercial Stemline® mesenchymal stem cells expansion medium. Moreover, the UC-WJ cells were differentiated into osteocytes, chondrocytes, adipocytes and neural-like cells and cultured separately. Additionally, the genes that are considered important embryonic, POU5F1 and ITSN1, and mesenchymal cell markers, CD105⁺, CD29⁺, CD73⁺ and CD90⁺ in MSCs were also expressed in five bovine-derived UC-WJ cultures. Morphology of proliferating cells typically appeared fibroblast-like spindle shape presenting the same viability and number. These characteristics were not affected during passages. There were 60 chromosomes at the metaphase, with acrocentric morphology and intense telomerase activity. Moreover, the proliferative capacity of T cells in response to a mitogen stimulus was suppressed when bovine-derived UC-WJ cells was included in the culture which demonstrated the immunossupression profile typically observed among isolated mesenchymal cells from other species. After classified the UC-WJ cells as mesenchymal stromal phenotype the in vitro 3D cultures was performed using the AlgiMatrix® protocol. Based on the size of spheroids (283,07 μm ± 43,10 μm) we found that three weeks of culture was the best period to growth the UC-WJ cells on 3D dimension. The initial cell density was measured and the best value was 1.5 × 10⁶ cells/well.

Conclusions

We described for the first time the isolation and characterization of UC-WJ cells in a serum-free condition and maintenance of primitive mesenchymal phenotype. The culture was stable under 60 consecutive passages with no genetic abnormalities and proliferating ratios. Taken together all results, it was possible to demonstrate an easy way to isolate and culture of bovine-derived UC-WJ cells under 2D and 3D serum-free condition, from fetal adnexa with a great potential in cell therapy and biotechnology.

Analysis of altered gene expression specific to embryotoxic chemical treatment during embryonic stem cell differentiation into myocardiac and neural cells

Embryonic stem cells (ES cells), pluripotent cells derived from the inner cell mass of blastocysts, differentiate in vitro into a variety of cell types representing all three germ layers. They therefore constitute one of the most promising in vitro tools for developmental toxicology. To assess the developmental toxicity of chemicals using ES cells easily, identification of effective marker genes is a high priority. We report here altered gene expression during ES cell differentiation into myocardiac and neural cells on treatment with some embryotoxic and non-embryotoxic chemicals. Decreases in several undifferentiated markers such as Oct3/4 and Nanog, and elevated expression of genes associated with heart development or the central nervous system, respectively, were found on microarray analysis. Under differentiation of ES cells into myocardic cells, 107 genes were substantially up-regulated. Decrease in the expression of 13 genes of these (Hand1, Pim2, Tbx20, Myl4, Myl7, Hbb-bh1, Hba-a1, Col1a2, Hba-x, Cmya1, Pitx2, Smyd1 and Adam19) was observed specifically by embryotoxic chemicals. Of the 107 genes up-regulated under differentiation into neurons, 22 genes (Map2, Cpe, Marcks, Ptbp2, Sox11, Tubb2b, Vim, Arx, Emx2, Pax6, Basp1, Ddr1, Ndn, Sfrp, Ttc3, Ubqln2, Six3, Dcx, L1cam, Reln, Wnt1 and Nnat) showed reduced expression specifically by embryotoxic chemicals. Almost all gene sets identified in this study are known to be indispensable for differentiation and development of heart and brain tissues, and thus may serve in early detection or prediction of embryotoxicity of chemicals in vitro.

Chondrocytes derived from mouse embryonic stem cells

Our knowledge of cellular differentiation processes during chondro- and osteogenesis, in particular the complex interaction of differentiation factors, is still limited. We used the model system of embryonic stem (ES) cell differentiation in vitro via cellular aggregates, so called embryoid bodies (EBs), to analyze chondrogenic and osteogenic differentiation. ES cells differentiated into chondrocytes and osteocytes throughout a series of developmental stages resembling cellular differentiation events during skeletal development in vivo. A lineage from pluripotent ES cells via mesenchymal, prechondrogenic cells, chondrocytes and hypertrophicchondrocytes up to osteogenic cells was characterized. Furthermore, we found evidence for another osteogenic lineage, bypassing the chondrogenic stage. Together our results suggest that this in vitro system will be helpful to answer so far unacknowledged questions regarding chondrogenic and osteogenic differentiation. For example, we isolated an as yet unknown cDNA fragment from ES cell-derived chondrocytes, which showed a developmentally regulated expression pattern during EB differentiation. Considering ES cell differentiation as an alternative approach for cellular therapy, we used two different methods to obtain pure chondrocyte cultures from the heterogenous EBs. First, members of the transforming growth factor (TGF)-beta family were applied and found to modulate chondrogenic differentiation but were not effective enough to produce sufficient amounts of chondrocytes. Second, chondrocytes were isolated from EBs by micro-manipulation. These cells initially showed dedifferentiation into fiboblastoid cells in culture, but later redifferentiated into mature chondrocytes. However, a small amount of chondrocytes isolated from EBs transdifferentiated into other mesenchymal cell types, indicating that chondrocytes derived from ES cells posses a distinct differentiation plasticity.

Messenger RNA and microRNA profiling during early mouse EB formation

Embryonic stem (ES) cells can be induced to differentiate into embryoid bodies (EBs) in a synchronised manner when plated at a fixed density in hanging drops. This differentiation procedure mimics post-implantation development in mouse embryos and also serves as the starting point of protocols used in differentiation of stem cells into various lineages. Currently, little is known about the potential influence of microRNAs (miRNAs) on mRNA expression patterns during EB formation. We have measured mRNA and miRNA expression in developing EBs plated in hanging drops until day 3, when discrete structural changes occur involving their differentiation into three germ layers. We observe significant alterations in mRNA and miRNA expression profiles during this early developmental time frame, in particular of genes involved in germ layer formation, stem cell pluripotency and nervous system development. Computational target prediction using Pictar, TargetScan and miRBase Targets reveals an enrichment of binding sites corresponding to differentially and highly expressed miRNAs in stem cell pluripotency genes and a neuroectodermal marker, Nes. We also find that members of let-7 family are significantly down-regulated at day 3 and the corresponding up-regulated genes are enriched in let-7 seed sequences. These results depict how miRNA expression changes may affect the expression of mRNAs involved in EB formation on a genome-wide scale. Understanding the regulatory effects of miRNAs during EB formation may enable more efficient derivation of different cell types in culture.

Bi-allelic gene targeting in mouse embryonic stem cells

The EUCOMM and KOMP programs have generated targeted conditional alleles in mouse embryonic stem cells for nearly 10,000 genes. The availability of these stem cell resources will greatly accelerate the functional analysis of genes in mice and in cultured cells. We present a method for conditional ablation of genes in ES cells using vectors and targeted clones from the EUCOMM and KOMP conditional resources. Inducible homozygous cells described here provide a precisely controlled experimental system to study gene function in a model cell.

The effect of bone morphogenetic protein 4 on the differentiation of mouse embryonic stem cell to erythroid lineage in serum free and serum supplemented media

This study was done to compare the effects of bone morphogenetic protein-4 (BMP-4) on mouse embryonic stem cells (ESC) differentiation to erythroid lineage in serum free and serum supplemented media. The embryoid bodies (EBs) cells were seeded in semisolid serum free and serum supplemented media in the presence of different concentrations of BMP-4. The erythroid colonies were assessed morphologically, ultrastructurally and by benzidine staining. The expression of the epsilon (ε), βH1 and βmajor globins, Runx1 and β2m genes was evaluated by Real time PCR. The colony size and the percent of benzidine-positive colonies increased in both BMP-4 supplementd groups but the number of colonies were lower in these groups than control. Erythropoiesis related genes were expressed in both serum free and serum supplemented groups. There were not significant differences between the ratios of genes expression to β2m in these groups except the ratio of Runx1 was significantly higher in serum free group (P<0.05). The ratio of ε and βH1 to β2m in EBs was higher than both BMP-4 containing groups (P<0.05) and βmajor was not expressed in EB cells. These findings showed in serum free condition the effects of BMP-4 on the erythroid differentiation was prominent than serum supplemented group.

The Production and Characteristics of a Mouse's Embryonic Stem Cell Lineage, Transfected by the Glia Neurotrophic Factor and Gene Fused with the Green Fluorescent Protein Gene

The influence that the expression of the human (glial-derived neurotrophic factor (GDNF)) neurotrophic factor has on the morphology and proliferative activity of embryonic stem cells (SC) of a mouse with R1 lineage, as well as their ability to form embroid bodies (EB), has been studied. Before that, using a PCR (polymerase chain reaction) coupled with reverse transcription, it was shown that, in this very lineage of the embryonic SC, the expression of the receptors' genes is being fulfilled for the neurotropfic RET and GFRα1 glia factor. The mouse's embryonic SC lineage has been obtained, transfected by the human GDNF gene, and has been fused with the "green" fluorescent protein (GFP) gene. The presence of the expression of the human GDNF gene in the cells was shown by northern hybridization and the synthesis of its albuminous product by immunocitochemical coloration with the use of specific antibodies. The reliable slowing-down of the embriod-body formation by the embryonic SC transfected by the GDNF gene has been shown. No significant influence of the expression of the GDNF gene on the morphology and the proliferative activity of the transfected embryonic SCs has been found when compared with the control ones.

A two-stage perfusion fibrous bed bioreactor system for mass production of embryonic stem cells

BACKGROUND

Embryonic stem cells (ESCs) have unlimited proliferation potential and can differentiate into all cell and tissue types, and thus are ideal sources for cell therapy and drug screening. Current supplies of ESCs are limited by the available cell sources and inefficient culture methods that grow ESCs on surfaces coated with expensive extracellular matrix (ECM) proteins and in media containing expensive growth factors.

OBJECTIVE

To meet the demand for ESCs, it is necessary to develop an economical process for their mass production.

METHODS

We review the latest development in in vitro ESC culture and introduce a two-stage perfusion bioreactor system that uses 3-D fibrous matrices and conditioned media for production of ESCs.

RESULTS/CONCLUSION

The two-stage process can produce billions of ESCs in a small bioreactor without using ECM proteins and growth factors, and is promising for further scale-up for clinical applications.