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Results for “Mouse Embryonic Stem Cells”

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PubMed2004

Lentivirus-based gene delivery in mouse embryonic stem cells.

BACKGROUND: Embryonic stem (ES) cells are widely used in therapeutic research as an unlimited source of cell therapy. Therefore, it is of great value to find a way to efficiently manipulate ES cells. HIV-1-derived lentiviral vectors are now considered to be an efficient vehicle for delivering genes into a variety of cells. In this study, we examined the efficacy of lentivirus-based gene delivery into mouse ES (mES) cells. MATERIALS AND METHODS: Recombinant HIV-I-based lentiviral vectors Lt-GFP, expressing green fluorescent protein (GFP), and Lt-LacZ, expressing E. coli LacZ gene in conjunction with neomycin resistance gene, were generated using a FuGENE 6 transduction method and used for transducing ES cells derived from 129Sv mice. Lentiviral transduction efficacy was evaluated by GFP expression assay using flow cytometry and by X-gal staining. The in vivo potential of developing teratoma of such transduced mES cells was examined in severe combined immunodeficiency (SCID) mice. RESULTS: FuGENE 6 showed no considerable transduction-associated cytotoxicity. The expression rate of GFP and LacZ of mES cells increased on a multiplicity of infection (MOI)-dependent manner with the amount of Lt-GFP and Lt-LacZ used. Approximately 42% of mES cells were positive for GFP after infection of Lt-GFP at an MOI of 30. Notably, after G418 selection, nearly 100% of Lt-LacZ-transduced mES cells were positive for LacZ and formed teratomas in SCID mice. CONCLUSIONS: This work demonstrates that HIV-I-based lentiviral vectors are capable of transducing mES cells. Lentiviral vectors may facilitate an advance in the field of gene transfer and expression in various types of ES cells, including human ES cells.

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PubMed2006

Efficient generation of dopaminergic neurons from mouse embryonic stem cells enclosed in hollow fibers.

Transplantation of dopamine neurons is a promising approach to treat Parkinson's disease. Embryonic stem (ES) cells are expected to be a cell source of the dopaminergic neurons. Various difficulties, however, need to be overcome to realize cell therapy of Parkinson's disease using dopaminergic neurons from ES cells. For example, they are highly sensitive to enzymatic treatment and physical dissociation, and the patient's immune system may attack the transplanted cells. In this study, we attempted to induce dopaminergic neurons from mouse ES cells enclosed in hollow fibers using conditioning medium from PA6 cells, the stromal cells derived from skull bone marrow. beta-tubulin type III positive cells and tyrosine hydroxylase positive cells were efficiently derived in hollow fibers after 16 days in culture, and dopamine release was observed when the hollow fibers containing cells were exposed to 56mm KCl for 15min to induce dopamine release through depolarization of the neurons. By our procedure, enclosure of dopaminergic neurons in hollow fibers was easily performed without loss of cells, and the hollow fiber membrane is expected to efficiently protect dopaminergic neurons from mechanical disturbances and attacks by the host immune system. Although there are many issues, especially related to immuno-isolation, that still remain to be addressed, we believe that differentiation of ES cells within hollow fibers is one of the crucial procedures so that cell therapy of Parkinson's disease can be realized.

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PubMedDate not supplied

Transplantation of cardiac-committed mouse embryonic stem cells to infarcted sheep myocardium: a preclinical study.

BACKGROUND: Heart failure develops after myocardial infarction and is a major cause of morbidity and mortality. The ability to direct differentiation of embryonic stem cells (ESC) towards a cardiomyogenic phenotype makes them an attractive therapeutic option for cardiac repair, but species-specific and individual-specific immunological imprinting remains a hurdle. Our aim was to ascertain whether the purported immune privilege of ESC allows for their cross-species engraftment in a clinically relevant large-animal model. METHODS: We studied engraftment and differentiation of cardiac-committed mouse ESC in 18 sheep in which a myocardial infarction had been induced; nine controls received medium and nine sheep (five of which were immunosuppressed) received ESC. The gain in myocardial function was measured by echocardiography 1 month after cell transplantation. FINDINGS: Cardiac-committed murine ESC engrafted in infarcted myocardium of immunosuppressed and immunocompetent sheep, and differentiated into mature cardiomyocytes that expressed connexins. Colonisation of the scar area by ESC was accompanied by a functional benefit of the damaged myocardium. Left-ventricular ejection fraction deteriorated in the control group by a median of 9.9% (range -20 to 0.3) relative to baseline (p=0.011) whereas in the treated group it improved by 6.6% (-5.7 to 50.8; comparison between groups p=0.002). INTERPRETATION: These findings obtained in a clinically relevant large-animal model of heart failure strengthen the potential therapeutic use of ESC to regenerate the severely dysfunctional myocardium and bring additional evidence for an immune privilege of these cells.

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PubMed2005

Differentiation and lineage selection of mouse embryonic stem cells in a stirred bench scale bioreactor with automated process control.

It is well established that embryonic stem (ES) cells can differentiate into functional cardiomyocytes in vitro. ES-derived cardiomyocytes could be used for pharmaceutical and therapeutic applications, provided that they can be generated in sufficient quantity and with sufficient purity. To enable large-scale culture of ES-derived cells, we have developed a robust and scalable bioprocess that allows direct embryoid body (EB) formation in a fully controlled, stirred 2 L bioreactor following inoculation with a single cell suspension of mouse ES cells. Utilizing a pitched-blade-turbine, parameters for optimal cell expansion as well as efficient ES cell differentiation were established. Optimization of stirring conditions resulted in the generation of high-density suspension cultures containing 12.5 x 10(6) cells/mL after 9 days of differentiation. Approximately 30%-40% of the EBs formed in this process vigorously contracted, indicating robust cardiomyogenic induction. An ES cell clone carrying a recombinant DNA molecule comprised of the cardiomyocyte-restricted alpha myosin heavy chain (alphaMHC) promoter and a neomycin resistance gene was used to establish the utility of this bioprocess to efficiently generate ES-derived cardiomyocytes. The genetically engineered ES cells were cultured directly in the stirred bioreactor for 9 days, followed by antibiotic treatment for another 9 days. The protocol resulted in the generation of essentially pure cardiomyocyte cultures, with a total yield of 1.28 x 10(9) cells in a single 2 L bioreactor run. This study thus provides an important step towards the large-scale generation of ES-derived cells for therapeutic and industrial applications.

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PubMedDate not supplied

Proliferation and differentiation of mouse embryonic stem cells in APA microcapsule: A model for studying the interaction between stem cells and their niche.

Embryonic stem (ES) cells hold promise either as an in vitro model recapitulating early embryonic development or as a renewable source of therapeutically useful cells. Certain aspects of the microenvironment (or niche) play critical roles in determining the fate of ES cells. Here, we reported the feasibility of using the technique of microencapsulation to study the interaction between ES cells and their tissue niche. ES cells' growth, viability, and differentiation in vitro were evaluated when they were enclosed in solid or liquefied core APA microcapsules. In comparison with those microcapsules with solid cores, the liquefied capsules provided a more suitable culture environment for the growth of ES cells. In addition, behavior of encapsulated ES cells in vivo was observed after their being implanted into mouse peritoneal cavities. In contrast to the prolonged lag phase in vitro, ES cells encapsulated grew much faster in vivo. Typical markers for the undifferentiated ES cells, such as AP, SSEA-1, and Oct-4 gene, were also tracked by immunochemistry and RT-PCR. Results showed that expression of markers remained high over 2 weeks of culture in vitro. However, decreased expression of markers was found in those samples in vivo with time passage. These findings implied that it was the combination of the intrinsic characteristics of ES cells and their microenvironment that regulated their fate. The APA-ES cells system may provide an optimal model to study the interaction between stem cells and their tissue niches.

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PubMed2005

Hematopoietic and endothelial development of mouse embryonic stem cells in culture.

Embryonic stem (ES) cells differentiate efficiently in vitro and give rise to many different somatic cell types. Hematopoietic progenitors present within differentiated ES cells (embryoid bodies, EBs) can be identified by replating EB cells into semisolid media with hematopoietic growth factors. The developmental kinetics of various hematopoietic lineage precursors within EBs and molecular and cellular studies of these cells have suggested that the sequence of events leading to the onset of hematopoiesis within EBs is similar to that found within the mouse embryo. Thus, the in vitro differentiation model of ES cells provides a unique opportunity to study onset mechanisms involved in hematopoietic development.

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PubMed2001

Specific double-stranded RNA interference in undifferentiated mouse embryonic stem cells.

Specific mRNA degradation mediated by double-stranded RNA (dsRNA) interference (RNAi) is a powerful way of suppressing gene expression in plants, nematodes, and fungal, insect, and protozoan systems. However, only a few cases of RNAi have been reported in mammalian systems. Here, we investigated the feasibility of the RNAi strategy in several mammalian cells by using the enhanced green fluorescent protein gene as a target, either by in situ production of dsRNA from transient transfection of a plasmid harboring a 547-bp inverted repeat or by direct transfection of dsRNA made by in vitro transcription. Several mammalian cells including differentiated embryonic stem (ES) cells did not exhibit specific RNAi in transient transfection. This long dsRNA, however, was capable of inducing a sequence-specific RNAi for the episomal and chromosomal target gene in undifferentiated ES cells. dsRNA at 8.3 nM decreased the cognate gene expression up to 70%. However, RNAi activity was not permanent because it was more pronounced in early time points and diminished 5 days after transfection. Thus, undifferentiated ES cells may lack the interferon response, similar to mouse embryos and oocytes. Regardless of their apparent RNAi activity, however, cytoplasmic extracts from mammalian cells produced a small RNA of 21 to 22 nucleotides from the long dsRNA. Our results suggest that mammalian cells may possess RNAi activity but nonspecific activation of the interferon response by longer dsRNA may mask the specific RNAi. The findings offer an opportunity to use dsRNA for inhibition of gene expression in ES cells to study differentiation.

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PubMed2004

Partial hepatectomy and subsequent radiation facilitates engraftment of mouse embryonic stem cells in the liver.

For liver-targeted regenerative medicine, embryonic stem (ES) cell-derived hepatocyte-like cells proffer great expectation. In vitro exposure to a combination of various growth factors, such as hepatocyte growth factor and fibroblast growth factor-4, as well as cytokines, leads to differentiation of ES cells into hepatocyte-like cells. We sought to determine the in vivo environment that allowed engraftment of ES cells transplanted to the liver. Thus, we examined the effect of partial hepatectomy (50%) (PHT) and subsequent radiation (RT) of the male Balb/c mouse host liver on ES cell engraftment. ES cells (5 x 10(6)) derived from 129Sv mice were transplanted into the residual liver. The controls were ES cells transplanted into a normal liver. Bromo-deoxy-residine (BrdU)-uptake was performed to evaluate the effect of hepatectomy and RT on hepatocyte regeneration. Mouse ES cells engrafted, forming teratomas in the normal liver without showing any mononuclear infiltration. A liver modified by PHT and RT facilitated engraftment of mouse ES cells compared with a normal liver. Hepatic RT significantly suppressed hepatocytic uptake of BrdU.

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PubMed2005

Transient inhibition of BMP signaling by Noggin induces cardiomyocyte differentiation of mouse embryonic stem cells.

Embryonic stem (ES) cells are a promising source of cardiomyocytes, but clinical application of ES cells has been hindered by the lack of reliable selective differentiation methods. Differentiation into any lineage is partly dependent on the regulatory mechanisms of normal early development. Although several signals, including bone morphogenetic protein (BMP), Wnt and FGF, are involved in heart development, scarce evidence is available about the exact signals that mediate cardiomyocyte differentiation. While investigating the involvement of BMP signaling in early heart formation in the mouse, we found that the BMP antagonist Noggin is transiently but strongly expressed in the heart-forming region during gastrulation and acts at the level of induction of mesendoderm to establish conditions conducive to cardiogenesis. We applied this finding to develop an effective protocol for obtaining cardiomyocytes from mouse ES cells by inhibition of BMP signaling.

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PubMed2006

Genomewide gain-of-function genetic screen identifies functionally active genes in mouse embryonic stem cells.

Embryonic stem (ES) cells hold great promise for the future of medicine. To elucidate the molecular mechanisms that control ES cell self-renewal and differentiation, a comprehensive knowledge of the molecules involved in these processes is required. Here we describe an effective approach for genomewide identification of functionally active genes in ES cells. This approach combines genetic screens based on cDNA libraries with microarray detection methods to permit high-throughput functional analyses. We implement this strategy to identify genes whose overexpression can maintain phenotypic properties of undifferentiated mouse ES cells under differentiation-inducing conditions, specifically in the absence of leukemia inhibitory factor. The identified genes encode a variety of regulatory proteins whose function in ES cells was previously unknown. Moreover, our approach is capable of detecting genes whose overexpression promote differentiation or cell death. Overall, our studies establish a methodology for highly sensitive identification of genes that confer particular phenotypes on ES cells.

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PubMed2004

Directed differentiation and mass cultivation of pure erythroid progenitors from mouse embryonic stem cells.

Differentiating embryonic stem (ES) cells are an increasingly important source of hematopoietic progenitors, useful for both basic research and clinical applications. Besides their characterization in colony assays, protocols exist for the cultivation of lymphoid, myeloid, and erythroid cells. With the possible exception of mast cells, however, long-term expansion of pure hematopoietic progenitors from ES cells has not been possible without immortalization caused by overexpression of exogenous genes. Here, we describe for the first time an efficient yet easy strategy to generate mass cultures of pure, immature erythroid progenitors from mouse ES cells (ES-EPs), using serum-free medium plus recombinant cytokines and hormones. ES-EPs represent long-lived, adult, definitive erythroid progenitors that resemble immature erythroid cells expanding in vivo during stress erythropoiesis. When exposed to terminal differentiation conditions, ES-EPs differentiated into mature, enucleated erythrocytes. Importantly, ES-EPs injected into mice did not exhibit tumorigenic potential but differentiated into normal erythrocytes. Both the virtually unlimited supply of cells and the defined culture conditions render our system a valuable tool for the analysis of factors influencing proliferation and maturation of erythroid progenitors. In addition, the system allows detailed characterization of processes during erythroid proliferation and differentiation using wild-type (wt) and genetically modified ES cells.

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PubMed2004

Differentiation of human and mouse embryonic stem cells along a hepatocyte lineage.

Embryonic stem (ES) cells may differentiate along a hepatocyte lineage; however, currently there are no reports of culture conditions yielding high levels of hepatocyte-specific gene expression in these cells. We investigated culture conditions for differentiating ES cells into hepatocyte-like cells in vitro. Various combinations of culture media, growth and differentiation factors, and substratum precoatings were evaluated, and it was determined that a combination of Iscove's modified Dulbecco's medium with 20% fetal bovine serum, human insulin, dexamethasone. and collagen type I precoating was optimal for directing mouse ES cells along a hepatocyte lineage. Treatment of mouse ES cell with the optimal condition led to prealbumin gene expression 20% as high, and albumin synthesis 7% as high, as in mouse liver. The optimal culture condition also induced albumin gene expression in differentiated human ES cells 1% as high as in normal human hepatocytes as shown by Western blot analysis, and cells were positive for human albumin by immunocytochemistry. In addition, our optimal condition led to high levels of albumin gene expression in primary mouse hepatocytes after 35 days of culture, levels 10-fold higher than with other hepatocyte differentiation media. In conclusion, our optimal condition directed both mouse and human ES cells along a hepatocyte lineage. This represents the initial step in establishing cell lines that can be employed in cell-based therapeutics in humans and for toxicology and pharmacology studies.

Albumins↗

PubMed2005

Curcumin prevents methylglyoxal-induced oxidative stress and apoptosis in mouse embryonic stem cells and blastocysts.

Methylglyoxal (MG) is a reactive dicarbonyl compound endogenously produced mainly from glycolytic intermediates. Elevated MG levels in diabetes patients are believed to contribute to diabetic complications. MG is cytotoxic through induction of apoptosis. Curcumin, the yellow pigment of Curcuma longa, is known to have antioxidant and anti-inflammatory properties. In the present study, we examined the effect of curcumin on apoptotic biochemical events caused by incubation of ESC-B5 cells with MG. Curcumin inhibited the MG-induced DNA fragmentation, caspase-3 activation, cleavage of PARP, mitochondrial cytochrome c release, and JNK activation. Importantly, curcumin also inhibited the MG-stimulated increase of reactive oxygen species (ROS) in these cells. In addition, we demonstrated that curcumin prevented the MG-induced apoptosis of mouse blastocysts isolated from pregnant mice. Moreover, curcumin significantly reduced the MG-mediated impairment of blastocyst development from mouse morulas. The results support the hypothesis that curcumin inhibits MG-induced apoptosis in mouse ESC-B5 cells and blastocysts by blocking ROS formation and subsequent apoptotic biochemical events.

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PubMed2004

Influence of in vitro manipulation on the stability of methylation patterns in the Snurf/Snrpn-imprinting region in mouse embryonic stem cells.

Recent work on embryonic stem (ES) cells showed that stem cell-derived tissues and embryos, cloned from ES cell nuclei, often fail to maintain epigenetic states of imprinted genes. This deregulation is frequently associated with in vitro manipulations and culture conditions which might affect the cells potential to develop into normal fetuses. Usually, epigenetic instability is reported in differentially methylated regions of mostly growth-related imprinted genes. However, little is known about the epigenetic stability of genes that function late in organogenesis. Hence, we set out to investigate the epigenetic stability of neuronal genes and analyzed DNA methylation patterns in the Snurf/Snrpn imprinted cluster in several cultured mouse ES cell lines. We also determined the effects of in vitro stress factors such as consecutive passaging, trypsination, mechanical handling, single cell cloning, centrifugation, staurosporine-induced neurogenesis and the insertion of viral (foreign) DNA into the host genome. Intriguingly, none of these in vitro manipulations interfered with the stability of the methylation patterns in the analyzed neuronal genes. These data imply that, in contrast to growth-related genes like Igf2, H19, Igf2r or Grb10, the methylation imprints of the analyzed neuronal genes in the Snurf/Snrpn cluster may be particularly stable in manipulated ES cells.

Adenoviridae↗

PubMed2000

Efficient generation of midbrain and hindbrain neurons from mouse embryonic stem cells.

Embryonic stem (ES) cells are clonal cell lines derived from the inner cell mass of the developing blastocyst that can proliferate extensively in vitro and are capable of adopting all the cell fates in a developing embryo. Clinical interest in the use of ES cells has been stimulated by studies showing that isolated human cells with ES properties from the inner cell mass or developing germ cells can provide a source of somatic precursors. Previous studies have defined in vitro conditions for promoting the development of specific somatic fates, specifically, hematopoietic, mesodermal, and neurectodermal. In this study, we present a method for obtaining dopaminergic (DA) and serotonergic neurons in high yield from mouse ES cells in vitro. Furthermore, we demonstrate that the ES cells can be obtained in unlimited numbers and that these neuron types are generated efficiently. We generated CNS progenitor populations from ES cells, expanded these cells and promoted their differentiation into dopaminergic and serotonergic neurons in the presence of mitogen and specific signaling molecules. The differentiation and maturation of neuronal cells was completed after mitogen withdrawal from the growth medium. This experimental system provides a powerful tool for analyzing the molecular mechanisms controlling the functions of these neurons in vitro and in vivo, and potentially for understanding and treating neurodegenerative and psychiatric diseases.

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PubMed2005

WNT/beta-catenin pathway up-regulates Stat3 and converges on LIF to prevent differentiation of mouse embryonic stem cells.

Embryonic stem (ES) cells rely on growth factors provided by feeder cells or exogenously to maintain their pluripotency. In order to identify such factors, we have established sub-lines of STO feeder cells which exhibit variable ability in supporting ES cell self-renewal. Functional screening identifies WNT5A and WNT6 as STO cell-produced factors that potently inhibit ES cell differentiation in a serum-dependent manner. Furthermore, direct activation of beta-catenin without disturbing the upstream components of the WNT/beta-catenin pathway fully recapitulates the effect of WNTs on ES cells. Importantly, the WNT/beta-catenin pathway up-regulates the mRNA for Stat3, a known regulator of ES cell self-renewal in the mouse. Finally, LIF is able to mimic the serum effect to act synergistically with WNT proteins to inhibit ES cell differentiation. Therefore, our study reveals part of the molecular mechanisms by which the WNT/beta-catenin pathway acts to prevent ES cell differentiation through convergence on the LIF/JAK-STAT pathway at the level of STAT3.

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PubMed2004

VIP and PACAP induce selective neuronal differentiation of mouse embryonic stem cells.

The capacity of embryonic stem cells (ES cells) to differentiate into neuronal cells represents a potential source for neuronal replacement and a model for studying factors controlling early stages of neuronal differentiation. Various molecules have been used to induce such differentiation but so far neuropeptides acting via functional G-protein-coupled receptors (GPCRs) have not been investigated. Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are neuropeptides expressed in early development which affect neuronal precursor proliferation and neuronal differentiation. VIP and PACAP share two common receptors (VPAC1 and VPAC2 receptors) while only PACAP binds with high affinity to PAC1 receptors. The aim of the study was to determine whether VIP and PACAP could produce functional neuronal differentiation of ES cells. Mouse ES cells were allowed to aggregate in embryoid bodies (EBs) in the presence or not of VIP and PACAP for 1 week. VIP and PACAP potently increased the proportion of EB-derived cells expressing specifically a neuronal phenotype shown by immunocytochemistry and neurite outgrowth without altering glial cell number. Binding and RT-PCR analyses demonstrated the presence of VPAC2 and PAC1 receptors on ES cells. Accordingly, both peptides increased cyclic AMP and intracellular calcium. In contrast, EB-derived cells only expressed a functional PAC1 receptor, suggesting a switch in GPCR phenotype during ES cell differentiation. These original data demonstrate that functional GPCRs for VIP and PACAP are present on ES cells and that these neuropeptides may induce their differentiation into a neuronal phenotype. It opens an exciting new field for neuropeptide regulation of tissue ontogenesis.

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PubMed2004

Characterization of in vitro gutlike organ formed from mouse embryonic stem cells.

Using an embryoid body (EB) culture system, we have made a functional organlike cluster: the "gut" from embryonic stem (ES) cells (ES gut). There are many types of ES clusters, because ES cells have a pluripotent ability to develop into a wide range of cell types. Before inducing specific differentiation by exogenously added factors, we characterized comprehensive physiological and morphological properties of ES guts. Each ES gut has a hemispherical (or cystic) structure and exhibits spontaneous contractions [mean frequency: 13.5 +/- 8.8 cycles per min (cpm)]. A dense distribution of interstitial cells of Cajal (ICC) was identified by c-Kit immunoreactivity, and specific subcellular structures of ICC and smooth muscle cells were identified with electron microscopy. ICC frequently formed close contacts with the neighboring smooth muscle cells and occasionally formed gap junctions with other ICC. Widely propagating intracellular Ca(2+) concentration oscillations were generated in the ES gut from the aggregates of c-Kit immunopositive cells. Plateau potentials, possibly pacemaker potentials in ICC, and electrical slow waves were recorded for the first time. These events were nifedipine insensitive, as in the mouse gut. Our present results indicate that the rhythmic pacemaker activity generated in ICC efficiently spreads to smooth muscle cells and drives spontaneous rhythmic contractions of the ES gut. The present characterization of physiological and morphological properties of ES gut paves the way for making appropriate models to investigate the origin of rhythmicity in the gut.

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