Enhanced apoptosis during early neuronal differentiation in mouse ES cells with autosomal imbalance

Although particular chromosomal syndromes are phenotypicaUy and clinically distinct, the majority of individuals with autosomal imbalance, such as aneuploidy, manifest mental retardation. A common abnormal phenotype of Down syndrome （DS）, the most prevalent autosomal aneuploidy, shows a reduction in both the number and the density of neurons in the brain. As a DS model, we have recently created chimeric mice from ES cells containing a single human chromosome 21. The mice mimicked the characteristic phenotypic features of DS, and ES cells showed a higher incidence of apoptosis during early neuronal differentiation in vitro. In this study, we examined the induction of anomalous early neural development by aneuploidy in mouse ES cells by transferring various human chromosomes or additional mouse chromosomes. Results showed an elevated incidence of apoptosis in all autosome-aneuploid clones examined during early neuronal differentiation in vitro. Further, cDNA microarray analysis revealed a common cluster of down-regulated genes, of which eight known genes are related to cell proliferation, neurite outgrowth and differentiation. Importantly, targeting of these genes by siRNA knockdown in normal mouse ES cells led to enhanced apoptosis during early neuronal differentiation. These findings strongly suggest that autosomal imbalance is associated with general neuronal loss through a common molecular mechanism for apoptosis.

Investigation of VEGF and PDGF signals in vascular formation by 3D culture models using mouse ES cells

Vascular formation in vivo involves several processes and signal cascades subsequently occurring in the embryo. Several models by ES cells have been reported for analysis in vitro. We show here a 3D culture system using collagen gel (AteloCell) as a simple and useful system for investigating vascular formations and analyzing the roles of factors in vivo. Although VEGF and PDGF are growth factors with multi-potentials for vascular formation, their sequential roles have not been elucidated. We investigated the effects of VEGF and PDGF B signals for vascular formation by a 3D culture system that embedded embryoid bodies (EBs) from ES cells into a collagen gel. After embedding EBs in the collagen gel with a medium containing VEGF, EBs gave off CD105 immunopositive vessels as the initial step of vasculogenesis. When the factor in the culture medium for EBs was switched from VEGF to PDGF B after 5 days of culture, the morphological features of vessels varied, suggesting the occurrence of vascular-type differentiation. After 11 days of 3D culture, vessels in both groups cultured with VEGF alone and switching to VEGF B at day 5 showed Flk-1 immunoreactivity. Some blood vessels cultured with PDGF B after day 5 expressed either EphrinB2 (arteriole marker) or Flt-4 (lymphatic marker) immunoreactivity, but vessels cultured with VEGF alone exhibited neither of them. Vessels cultured with these two factors could not differentiate into a venous type. The present study indicates that VEGF is the initial signal for vasculogenesis, and that PDGF B is probably involved in vascular diversification.

Distinct functions of Dnmt3a and Dnmt3b de novo DNA methyltransferases in ES cell proliferation and differentiation

Two de novo DNA methyltransferases, Dnmt3a and Dnmt3b, have been identified in humans and mice to contribute to the methylation of unmodified DNA. We recently showed a transition of de novo DNA methyltransferase expression from Dnmt3b to Dnmt3a during mouse embryogenesis and in tissue-specific stem cells, suggesting distinct functions of Dnmt3a and Dnmt3b during these processes. In this study, to characterize the functions of Dnmt3a and Dnmt3b in pluripotent stem cells, we exogenously transfected ES cells with Dnmt3a and Dnmt3b cDNAs linked to an internal ribosome entry site-green fluorescent protein gene, and then analyzed the effects of expression of these de novo DNA methyltransferases on ES cell growth and differentiation. ES cells expressing Dnmt3b showed specific downregulation of pluripotency marker genes such as Nanog and Oct 3/4. In addition, Dnmt3a-transfected ES cells showed a specific increase in mitotic index, while Dnmt3b-transfected ES cells showed a decrease in mitotic index. These results suggest that Dnmt3b has important physiological roles in the initial process of stem cell differentiation and that Dnmt3a has a function in stem cell proliferation.

Embryonic stem cells generated by nuclear transfer of human somatic nuclei into rabbit oocytes

To solve the problem of immune incompatibility, nuclear transplantation has been envisaged as a means to produce cells or tissues for human autologous transplantation. Here we have derived embryonic stem cells by the transfer of human somatic nuclei into rabbit oocytes. The number of blastocysts that developed from the fused nuclear transfer was comparable among nuclear donors at ages of 5, 42, 52 and 60 years, and nuclear transfer (NT) embryonic stem cells (ntES cells) were subsequently derived from each of the four age groups. These results suggest that human somatic nuclei can form ntES cells independent of the age of the donor. The derived ntES cells are human based on karyotype, isogenicity, in situ hybridization, PCR and immunocytochemistry with probes that distinguish between the various species. The ntES cells maintain the capability of sustained growth in an undifferentiated state, and form embryoid bodies, which, on further induction, give rise to cell types such as neuron and muscle, as well as mixed cell populations that express markers representative of all three germ layers. Thus, ntES cells derived from human somatic cells by NT to rabbit eggs retain phenotypes similar to those of conventional human ES cells, including the ability to undergo multilineage cellular differentiation.

Establishment of Embryonic Stem Cell Lines Derived from Outbred Mouse Embryos and Production of Chimeras

The aim of the present investigation was to determine if embryonic stem (ES) cells could be isolated from outbred mouse embryos (KM) and if chimeras could be producedly using outbred ES cells. Three ES cell lines,designated KE1, KE2, and KE5,were isolated from 5 Kunming albino blastocysts. Normal diploid composition of these cell lines was above 70%. By using C57BL/6J and 615 blastocysts as host embryos, one chimera was obtained in living pups. It was shown for the first time that chimeras can be produced by using outhred ES cells. This work implies that to establish ES cell lines from other animal embryos is possible. More interestingly, white color dots from ES cells on the coat of this chimeric mouse enlarged a lot after half a year, indicated that ES cells were inhibited by cells from outbred mouse or the cells of outbred mouse grew vigiously.

LincRNA1230 inhibits the differentiation of mouse ES cells towards neural progenitors

In vitro, mouse embryonic stem （ES） cells can differentiate into many somatic cell types, including neurons and glial cells. When cultured in serum-free medium, ES cells convert spontaneously and efficiently to a neural fate. Previous studies have shown that the neural conversion of mouse ES cells includes both the participation of neural-specific transcription factors and the regulation of epigenetic modifications. However, the intracellular mechanism underlying this intrinsic transition still re- mains to be further elucidated. Herein, we describe a long intergenic non-coding RNA, LincRNA1230, which participates in the regulation of the neural lineage specification of mouse ES cells. The ectopic forced expression of LincRNAI230 dramatically inhibited mouse ES cells from adopting a neural cell fate, while LincRNA1230 knockdown promoted the conversion of mouse ES cells towards neural progenitors. Mechanistic studies have shown that LincRNA1230 inhibits the activation of early neural genes, such as Pax6 and Soxl, through the modulation of bivalent modifications （tri-methylation of histone3 lysine4 and his- tone3 lysine27） at the promoters of these genes. The interaction of LincRNA1230 with Wdr5 blocked the localization of Wdr5 at the promoters of early neural genes, thereby inhibiting the enrichment of H3K4me3 modifications at these loci. Collectively, these findings revealed a crucial role for LincRNA1230 in the regulation of the neural differentiation of mouse ES cells.

Establishment of Embryonic Stem Cell Lines from C57BL/6J Mice and Generation of Chimeras

Four embryonic stem (ES) cell lines, designated CE1, CE2, CE3 and CE4, were isolated from C57BL/6J blastocysts. The ratio of normal diploid composition of these cell lines is above 70%. To examine the differentiation potential of the ES cells, the CE2 cells were injected subcutaneously into syngenic mice, and many kinds of differentiated cells were observed on the sections of the teratoma derived from this ES cell line. On the other hand, to test the chimeric ability of the ES cells, the CE2 cells were microinjected into the blastocysts of ICR mice, and a chimera was obtained among living pups. These results show that CE2 ES cells are pluripotent stem cells, which can differentiate into many kinds of cell types, and can be used as a cell system for further research.

The signal transduction pathways and molecules for ES cells self-renewal

Embryonic stem cells (ES cells) are derived from the inner cell mass (ICM) of blastocysts. ES cells can divide and produce identical copies of them over and over again (self-renewal) in vitro for a long time, and retain the capability of differentiating into all cell types when induced by appropriate signals. Their capability of multilineage dif- ferentiation might be exploited for cell-based therapies. Therefore, ES cells have a broad prospect in many clinical applications. To achieve success in the clinical applications, we have to understand how ES cells propagate and differen- tiate into specific cell types. The cytokine LIF can sustain the self-renewal of certain mouse ES cells (mES cells) through activation of the signal transduction pathway LIF/gp130/ STAT3. In this pathway the transcription factor STAT3 is a crucial factor. Furthermore, Oct-3/4 plays a very important role in maintaining the ES cell pluripotency. Oct-3/4 regu- lates embryo development through its co-factor Sox2 and Rox-1. Recently nanog, a new homeodomain gene, was found and it has been shown to be crucial for the renewal and pluripotency of ES cells. Three other signals BMP, Wnt and ERK also can influence differentiation and propagation of ES cells. This review article summarizes recent progress in this area, mainly focusing on the LIF signaling pathway and the transcription factors Oct-3/4 and Nanog. Although it is still unclear how these components cooperate, a model is presented here to provide a design for solving this problem.

In vitro differentiation of mouse ES cells into hepatocytes with coagulation factors VIII and IX expression profiles

Coagulation factors II, V, VII, VIII, IX and X are produced by hepatocytes.So factors VIII and IX deficiencies, which result in hemophilia A and B, have the potential torespond to cellular replacement therapy. Embryonic stem (ES) cells provide a unique source fortherapeutic applications. Here, E14 mouse ES cells have been induced into hepatocytes in vitro.Morphology revealed that ES-derived hepatic-like cells were round or polyhedral shaped with distinctboundary of individual cells, and some arranged in trabeculae. These cells expressed endodermal- orliver-specific mRNA---transthyretin (TTR), alpha 1-anti-trypsin (AAT), alpha-fetoprotein (AFP),albumin (ALB), glucose-6-phoshpatase (G6P) and tyrosine aminotransferase (TAT). Approximately(85.1±0.5)% of the ES-derived cells was stained positive green with ICG uptake. These cells werealso stained magenta as a result of PAS reaction. In this paper, expression of coagulation factorsVIII and IX mRNA in the ES-derived cells is documented. Therefore, ES cells might be developed assubstitute donor cells for the therapy of coagulation factor deficiencies.

The xenotropic microRNA gene information for stem cell researches and clinical applications

MicorRNA (miRNA) is a small noncoding RNA and a miRNA is the gene. The identification of the human miRNA gene and its application have been performed and then it has been proceeding to explain about functioning of miRNAs in miRNA-messenger RNA targeting, profiling of miRNAs for diseases, transduction of the miRNA gene expression, production of human-induced pluripotent stem (iPS) cells by miRNA, embryonic stem (ES) cells and cancer development upon miRNA. The RNA information supplied by the miRNA gene, and the RNA gene information could expand to intracellular, intercellular, intraorgan, interorgan, intraspecies and interspecies. Therefore, the implantation of ES and iPS cells from donors would deliver xenotropic miRNAs to the acceptor. The therapeutic efficacy for treatment of iPS-derived cell implantation is the most important for clinical development of the stem cell researches but the xenotropic miRNA gene assessment with iPS-derived cells should substantially be completed for a safe and an exact application of the stem cell researches.

The N-terminal domain is a transcriptional activation domain required for Nanog to maintain ES cell self-renewal

Nanog is a transcription factor identified by its ability to maintain the self-renewal of ES cells in the absence of leukemia inhibitory factor (LIF). Nanog protein contains an N-terminal domain (ND), a DNA-binding homeobox domain (HD) and a C-terminal domain (CD). We previously reported that the CD in Nanog is a transcriptional activation domain essential for the in vivo function of Nanog. Here we demonstrated that the ND in Nanog is also functionally important. Deletion of the ND reduces the transcriptional activity of Nanog on either artificial reporters or native Nanog promoters. This truncated Nanog is also less effective in regulating the endogenous Nanog target genes. Furthermore, the ND truncation disrupted the ability of Nanog to maintain ES cell self-renewal as well. We found that the ND is not required for the nuclear localization of Nanog. These results suggest that the regulation of endogenous pluripotent genes such as oct3/4 and rex-1 is required for the in vivo function of Nanog.

Establishment of Germ-line Competent C57BL/6J Embryonic Stem Cell Lines

Objective To establish C57BL/6J embryonic stem （ES） cell lines with potential germ- line contribution Methods ES cells were isolated from blastocyst inner cell mass of C5 7BL/6J mice, and cultured for 15 passages, and then injected into blastococels of ICR mice blastocysts to establish chimeric mice. Results Three ES cell lines （mC57ES1,mC57ES3, mC57ES7） derived from the inner cell mass of C57BL/6J mice blastocysts were established. They were characteristic of undifferentiated state, including normal XY karyotype, expression of a specific cell surface marker “stage-specific embryonic antigen-I” and alkaline phosphatase in continuous passage. When injected into immunodeficient mice, mC57ES1 cells consistently differentiated into derivatives of all three embryonic germ layers. When mC57ES1 cells were transferred into ICR mice blastocysts, 4 chimeric mice have been obtained. One male of them revealed successful germ-line transmission. Conclussion We have obtained C57BL/6J ES cell lines with a potential germ-line contribution, which can be used to generate transgenic and gene knock-out mice.

TGF-β receptors in mouse ES-5 cells and their differentiated derivatives

By radioreceptor binding studies with iodinated TGF-β1, it has been shown that an undifferentiated ES-5 cell expresses approximately 3270 receptors with a dissociation constant Kd=130pM, but after the induction of differenti-ation by retinoic acid and dBcAMP, the receptor number of a differentiated RA-ES-5 cell was increased about 80% and the Kd was also increased to 370 pM. Furthermore,more direct evidence supporting the expression of TGF-βtype Ⅰand type Ⅱ receptors in both ES-5 and RA-ES-5 cells has come from dot blot hybridization of cellular mRNA with cDNA probes for type Ⅰ and type Ⅱ recep-tors. Meanwhile, mRNA expression level of types Ⅰ and Ⅱreceptors in RA-ES-5 cells were higher than that in ES-5 cells. Down regulation of TGF-β receptors with a signifi-cant decrease in the rate of cell proliferation in both cells, was found by employing a pretreatment with neutralizing antibody to TGF-β1. The possible role of receptors for TGF-β in cen differentiation is discussed here.

大鼠心脏细胞条件培养基对小鼠ES细胞特性的维持

以C1 9- 2和MESPU - 1 3为供试细胞 ,用克隆测试、传代培养等方法对 1 7种细胞的条件培养基进行了筛选 ,结果表明 ,大鼠心脏细胞的条件培养基 (RH -CM)具有显著抑制小鼠ES细胞分化、维持其二倍体核型、促进ES细胞贴壁生长的作用。经RH -CM培养 1 0代和 2 0代的小鼠ES细胞在体内外分化能力上仍保留了原ES细胞的多方向分化潜能和特征 ;RH -CM也可作为小鼠ES细胞培养基的添加物 ,用含 70 %RH -CM的ES细胞培养基和小鼠胚胎原代成纤维细胞饲养层 (PMEF)培养ES细胞 ,可长期有效地维持其未分化状态和二倍体核型。RT

饲养层对维持新建ES细胞系的影响

以ＳＴＯ细胞和鼠胚原代成纤维细胞（ＰＭＥＦ）为饲养层建立了１１个小鼠胚胎于细胞系（ＥＳ细胞系）。两种饲养层细胞都可以维持ＥＳ细胞的正常形态和体外分化能力，但ＳＴＯ细胞不能维持ＥＳ细胞的正常二倍体核型，ＰＭＥＦ的效果比ＳＴＯ为佳，但也仅能短期内维持二倍体状态，１０代后染色体数目逐渐发生偏离。分离出１０个ＥＳ细胞克隆。讨论了两种饲养层的不同和影响核型发生偏离的若干可能的原因。

小鼠胚胎干细胞(ES细胞)建系和维持过程中的问题及对策

总结了十多年来我们从事ES细胞建系和培养工作的经验和教训 ,提出了研究工作中存在的问题以及解决这些问题的方法和对策 ,并对一些常规性的操作步骤进行了改进。同时 ,对某些尚不明确的问题进行了讨论 ,提出了我们的看法和建议。研究工作表明 ,我们采取的对策和方法是可行。

大鼠心肌条件培养基对形成小鼠ES细胞集落的影响

报道一种新的从小鼠囊胚中培养和分离出ＥＳ细胞集落的方法。取出生２～３周龄大鼠的心肌组织制备单层培养物，收集６代以内的条件培养基（ＲＨＣＭ）。以ＲＨＣＭ培养Ｃ５７ＢＬ／６Ｊ小鼠的囊胚（无饲养层），对照组以小鼠胚胎原代成纤维细胞（ＭＥ）为饲养层，并补加ＬＩＦ因子。经过１９０个胚的实验证明，以ＲＨＣＭ为培养基培养小鼠囊胚时，胚胎贴壁率、ＩＣＭ增殖率和ＥＳ细胞集落的出现率与对照组没有显著性差异，分别为６７％、９３％和１３％。这种新的方法为简便而有效地建立与培养小鼠ＥＳ细胞系提供了有益的资料。

ES细胞体外定向分化为成熟肝细胞的实验研究

探讨了肝细胞在胚胎干细胞 (EScell)体外诱导分化系统中成熟分化的条件、机制及其鉴定方法 .利用TGF ,bFGF、HGF等细胞生长因子进行BALB/c小鼠ES细胞向肝细胞方向的定向诱导 .利用反转录聚合酶链反应 (RT PCR)、免疫细胞化学 (ICC)和放射免疫法 (RIA)动态检测肝细胞特异性基因和蛋白AFP ,ALB ,G6P ,TAT ,CK8,CK18等在培养体系中的表达 ,并测定肝细胞的尿素合成功能 ,最后测定肝细胞分化率 .结果 ,肝细胞特异基因AFP ,ALB ,G6P和TAT最早分别于第 3、 9、 11、 13天表达 ,肝细胞特异蛋白AFP ,CK8,CK18和ALB最早分别于第 7、 9、 9和 11天开始表达 .第 12天开始检测到尿素出现 ,浓度为 8 3μmol/L ,并随培养时间延长而浓度逐渐增加 .最后 ,测得生长因子诱导组肝细胞的分化率为 32 % ,对照组肝细胞分化率为 8% .说明肝细胞可以在ES细胞体外诱导分化系统中出现并成熟分化 ,bFGF、HGF、OSM等可以明显提高细胞分化率和成熟度 ,有望成为解决肝功能替代疗法中细胞来源问题的新希望 .

山羊PGCs用于分离与克隆类ES细胞

选择健康成年本地白山羊 ,自然发情、配种后 4 4 d取胎儿 ,以传统的原始生殖细胞 (PGCs)分离与克隆的方法和PGCs与其胎儿生殖嵴周围组织细胞共同培养的方法获得类胚胎干细胞 (类 ES细胞 ) ,并对山羊类 ES细胞在不同饲养层上进行培养。结果表明 ,采用传统方法和共培养的方法并添加细胞因子均能分离获得类 ES细胞。分离获得的类ES细胞在同源 (山羊 )胎儿细胞饲养层上生长效果较好 ,可传 4代或 5代 ,而在小鼠原代成纤维细胞饲养层上类 ES细胞仅传 3代。另外 ,共培养不添加细胞因子组仅获 1个类 ES细胞集落 。

ES细胞（MESPU13）嵌合体小鼠的GPI分析

为了评判小鼠ＥＳ细胞系ＭＥＳＰＵ１３的分化潜能，我们对１９只嵌合小鼠的心、肝、脾、肺、肾、胰腺、生殖腺、肌肉和血液的ＧＰＩ（磷酸葡萄糖异构酶）进行了分析。在这些样品中，来源于ＥＳ细胞的Ａ型条带的检出情况和小鼠的毛色嵌合率成正比关系。当毛色嵌合率低于４０％时，除了少数小鼠的肾脏外，没有看到Ａ型的条带。当毛色嵌合率大于８５％时，几乎所有的器官组织都检测到Ａ型条带，显示了ＥＳ细胞在发育形成内、中、外胚层的细胞方面具有很高的分化潜能。另外，在毛色嵌合率大于８５％的其中的６只嵌合鼠的肌肉中，只观察到Ａ型的条带，表明这些肌肉只单独来源于ＥＳ细胞。