Properties of four human embryonic stem cell lines maintained in a feeder-free culture system.

Several laboratories have begun evaluating human ES (hES) cell lines; however, direct comparisons between different hES cell lines have not been performed. We have characterized the properties of four human cell lines maintained in feeder-free culture conditions. Quantitative assessment of surface markers, microarray analysis of gene expression patterns, expression of SOX-2, UTF-1, Rex-1, OCT3/4, CRIPTO, and telomerase activity demonstrated similar patterns in all hES cell lines examined. Undifferentiated hES cells do not respond to neurotransmitters such as acetylcholine, glutamate, and gamma-aminobutyric acid. In addition, the undifferentiated hES cells possess gap junctions. Although similarities in marker expression were observed, allotyping showed that all four lines have a distinct HLA profile, predicting differences in transplantation responses. These data provide the first detailed comparison of different hES cell lines and demonstrate remarkable similarities among lines maintained in identical culture conditions.     

低氧对人胚胎干细胞多能性维持及印迹基因表达稳定性的影响

目的 研究低氧对人胚胎干细胞(hESC)生物学特性维持及印迹基因表达状态的影响.方法 在低氧(5％O2)条件下持续培养FY-hES-7细胞并采用细胞免疫荧光染色、RT-PCR等方法对其胚胎干细胞特性进行鉴定.运用全基因组基因表达谱芯片技术及实时荧光定量PCR方法检测FY-hES-7早期(第32代)和晚期(第52代)细胞的55个印迹基因表达状态.所有检测同时以常氧(21％ O2)培养作为对照.结果 低氧条件下长期培养的FY-hES-7细胞具有和常氧条件下培养相似的生物学特性,阳性表达干细胞表面标志SSEA-3、SSEA-4、TRA- 1-60、TRA-1-81及碱性磷酸酶(AKP),但细胞克隆形态较常氧培养下典型,且未分化状态保持时间较常氧条件下更长.低氧长期培养后FY-hES-7细胞的55个印迹基因中,有15个印迹基因(27.27％)表达发生了变化(上调8个,下调7个),而常氧培养后则有39个印迹基因表达水平有变化(70.91％)(上调21个,下调18个),氧浓度对印迹的影响差异具有统计学意义(P＜0.05).结论 低氧更有利于hESC生物学特性的维持.长期培养能对hESC的印迹表达产生影响,但低氧培养条件下hESC的印迹稳定性要明显好于常氧培养.     

Cytotrophoblast stem cell lines derived from human embryonic stem cells and their capacity to mimic invasive implantation events

BACKGROUND: An effective embryonic-maternal interaction is crucial for successful human pregnancy. Failure of this process is a major cause of infertility and can lead to placental dysfunction resulting in recurrent miscarriage, fetal retardation and pre-eclampsia. Research is severely constrained by ethical and practical considerations; therefore, we aimed to generate cytotrophoblast stem (CTBS) cell lines from human embryonic stem cells (HESCs). METHOD: Beta-HCG was used as a marker of viable trophoblast cells. In defined culture, embryoid bodies were generated from HESCs and selected for trophoblast enrichment by rounds of cellular aggregation and disaggregation. Distinct CTBS cell lines were isolated and characterized. Spheroid cytotrophoblast bodies were generated and their interaction with luteal-phase endometrial stroma was analysed by real-time image analysis. RESULTS: Three CTBS cell lines were derived, which were maintained in the absence of residual HESCs, fibroblast feeder cells or extracellular matrix. CTBS cells displayed typical cytotrophoblast and syncytiotrophoblast characteristics and exhibited further differentiation to invasive endovascular cell phenotype. One cell line was generated with constitutive expression of enhanced green fluorescent protein (eGFP). Spheroid trophoblast bodies mimicked closely the early invasive stages of implantation when incubated with human endometrial stromal preparations in vitro. CONCLUSION: These human CTBS cell lines are a significant new model for investigating human placentation and may have considerable potential in cell therapy applications.     

MicroRNA and gene expression patterns in the differentiation of human embryonic stem cells

Background  

The unique features of human embryonic stem (hES) cells make them the best candidate resource for both cell replacement therapy and development research. However, the molecular mechanisms responsible for the simultaneous maintenance of their self-renewal properties and undifferentiated state remain unclear. Non-coding microRNAs (miRNA) which regulate mRNA cleavage and inhibit encoded protein translation exhibit temporal or tissue-specific expression patterns and they play an important role in development timing.     

Gene-specific vulnerability to imprinting variability in human embryonic stem cell lines

Disregulation of imprinted genes can be associated with tumorigenesis and altered cell differentiation capacity and so could provide adverse outcomes for stem cell applications. Although the maintenance of mouse and primate embryonic stem cells in a pluripotent state has been reported to disrupt the monoallelic expression of several imprinted genes, available data have suggested relatively higher imprint stability in the human equivalents. Identification of 202 heterozygous loci allowed us to examine the allelic expression of 22 imprinted genes in 22 human embryonic stem cell lines. Half of the genes examined (IPW, H19, MEG3, MEST isoforms 1 and 2, PEG10, MESTIT1, NESP55, ATP10A, PHLDA2, IGF2) showed variable allelic expression between lines, indicating vulnerability to disrupted imprinting. However, seven genes showed consistent monoallelic expression (NDN, MAGEL2, SNRPN, PEG3, KCNQ1, KCNQ1OT1, CDKN1C). Furthermore, four genes known to be monoallelic or to exhibit polymorphic imprinting in later-developing human tissues (TP73, IGF2R, WT1, SLC22A18) were always biallelic in hESCs. MEST isoform 1, PEG10, and NESP55 showed an association between the variability observed in interline allelic expression status and the DNA methylation of previously identified regulatory regions. Our results demonstrate gene-specific differences in the stability of imprinted loci in human embryonic stem cells and identify disrupted DNA methylation as one potential mechanism. We conclude the prudence of including comprehensive imprinting analysis in the continued characterization of human embryonic stem cell lines.     

Comparative evaluation of human embryonic stem cell lines derived from zygotes with normal and abnormal pronuclei

Human embryonic stem (hES) cell lines have been derived from normally or abnormally fertilized zygotes. However, the similar and different properties of these two types of hES cell lines are not well‐known. To address this question, we generated nine hES cell lines from zygotes containing normal (2PN) and abnormal (0PN, 1PN, 3PN) pronuclei. A side‐by‐side comparison showed that all cell lines exhibited distinct identity and karyotypical stability. They expressed similar “stemness” markers and alkaline phosphatase activity and differentiated into three embryonic germ lineages in embryoid bodies and teratomas. Under neural differentiation‐promoting conditions, they were directed into neural progenitors and neurons. However, a variation in cell cycle and the relative abundance of gene expression of undifferentiated and differentiated markers were observed. These variations were also seen among individually derived normal hES cell lines. Thus, normal hES cell lines can be developed from fertilized zygotes with abnormal pronuclei usually excluded from clinical use. Developmental Dynamics 239:425–438, 2010. © 2009 Wiley‐Liss, Inc.     

Derivation of three clones from human embryonic stem cell lines by FACS sorting and their characterization

Here we describe the first report of three human embryonic stem cell (hESC) clones, hES 3.1, 3.2, and 3.3, derived from the parent line hES3 by sorting of single-cell preparations by flow cytometry. The viability of single-cell preparations before and after cell sorting remained >98%. The hESC were selected by size gating and forward-angle light scatter and were dispersed directly as single cell/ well into 96-well plates containing human fetal fibroblasts as feeder layers. Single stem cell dispersion into 96-well plates was confirmed by using cells from a hES3 line that constitutively expressed green fluorescence protein (eGFP) under similar conditions of flow cytometry. Three clones were obtained from the parent line hES3 -- hES3.1, 3.2, and 3.3 -- and they have been in continuous culture for more than 1 year. The cloning efficiency was less than <0.5%. These hESC clones show normal stem cell characteristics, such as undifferentiated growth, high nucleocytoplasmic ratio, the same karyotype as that of the parent line (46 XX), stem cell surface markers (i.e., SSEA3, SSEA4, OCT4, TRA-1-60, and TRA-1-81), and gene expression for pluripotency (Oct-4 and nanog). They all formed embryoid bodies in suspension cultures, and after seeding in culture plates they showed pluripotency in vitro by forming cell lineages derived from all three germ layers as indicated by expression of the ectodermal marker nestin, the mesodermal marker renin, and the endodermal markers alpha-fetoprotein and GATA6. All clones showed normal expression of alkaline phosphatase activity, a marker of in vitro pluripotency. When hESC clones (1-2 x 10(6) total) were injected into nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice under the kidney capsule, all formed teratomas within 6-8 weeks. Analysis of the stem cell surface marker TRA-1-160 by flow cytometry showed nonsignificant (p < 0.05) differences between the clones and the parent line. The clones also differed in their expression of genes, with only one, hES 3.2, expressing the endodermal markers, i.e., alpha-fetoprotein and GATA6. The ability to produce clones from a parent hESC line rapidly by FACS sorting will help provide a homogeneous population of cells for achieving uniformed lineage specifications for future transplantation therapies and biomedical research.     

Variations of clonal marrow stem cell lines established from human bone marrow in surface epitopes, differentiation potential, gene expression, and cytokine secretion

Bone marrow has been considered to contain many different types of progenitor or stem cells. This study aims to establish a new strategy that provides for the rapid establishment of human clonal marrow stem cell (hcMSC) lines with a relatively small amount of bone marrow aspirate and to characterize newly generated hcMSC lines for their cell phenotype, differentiation potential, lineage-specific gene expression, and cytokine secretion. Human cMSC lines were generated with human bone marrow aspirates using a new protocol, called the subfractionation culturing method. The newly established hcMSC lines were analyzed for their cell surface epitopes by fluorescence-activated cell sorting (FACS), differentiation potential by in vitro differentiation assays, lineage-specific gene expression by RT-PCR, and cytokine secretion by enzyme-linked immunoassay (ELISA). The overall profile of the cell-surface epitopes of the newly established hcMSC lines was similar to those of the known MSCs. These hcMSC lines were capable of differentiating into multilineages with some differences in differentiation capability. In addition, these hcMSC lines secrete high levels of transforming growth factor-beta1 (TGF-beta1), leukemia inhibitory factor (LIF), TGF-alpha, and interleukein-10 (IL-10), again with some variation in each cell line. The newly designed protocol may be an efficient method to establish hcMSC lines rapidly with a relatively small amount of bone marrow sample, and these newly established hcMSC lines possess stem cell characteristics and exhibit some differences in cell-surface epitopes, differentiation potential, lineage-specific gene expression, and cytokine secretion.     

Serum-free medium cultivation to improve efficacy in establishment of human embryonic stem cell lines

BACKGROUND: Serum-containing and serum-free media were used to derive human embryonic stem (HES) cells from donated oocytes and embryos. METHODS and RESULTS: Inner cell masses (ICM) were isolated by immunosurgery. The HES cells were found to be easily obtained and expanded in a serum-free medium. The efficacy in establishing human embryonic stem cell lines improved in a serum-free medium compared with that in serum-containing media. Four HES cell lines were derived from 13 isolated ICM on mouse embryonic fibroblast feeder layers. All four cell lines possess the same characteristics and differentiating potency: normal 46, XX or 46, XY karyotype; and expressing a series of surface markers such as APase, SSEA-3, SSEA-4, TRA-1-60, TRA-1-81, but not SSEA-1. They can form embryoid bodies in suspension culture and develop teratomas comprising derivatives of three embryonic germ layers when injected into severe combined immunodeficient mice. CONCLUSION: These preliminary results suggest that serum-free cultivation may be superior to serum-containing cultivation for deriving human embryonic stem cells.     

Enhancement of NF-kappaB expression and activity upon differentiation of human embryonic stem cell line SNUhES3

NF-kappaB is involved in many biological processes including proliferation, survival, and differentiation. Because human embryonic stem (ES) cells have the potential to differentiate to various lineages, understanding mechanisms involved in stemness and lineage differentiation is an important issue. We investigated expression of NF-kappaB in the human ES cell lines SNUhES3 and MizhES4 and found that expression of NF-kappaB mRNA and protein in these two cell lines was significantly lower compared to those of other adult cell lines. However, when SNUhES3 cells were induced to differentiate by retinoic acid, expression levels of NF-kappaB significantly increased compared to undifferentiated SNUhES3 cells. As the components of tumor necrosis factor-alpha (TNF-alpha) signaling are expressed comparably in undifferentiated and differentiated SNUhES3 cells, we examined the responsiveness of SNUhES3 cells to treatment with TNF-alpha, an agonist of NF-kappaB signaling. Nuclear localization of NF-kappaB in response to TNF-alpha was evident in differentiated, but not undifferentiated, SNUhES3 cells. In agreement with this observation, induction of interleukin-8 (IL-8) in response to TNF-alpha was seen only in differentiated SNUhES3 cells. On the basis of an IkappaB kinase (IKK) inhibitor study, expression of IL-8 induced by TNF-alpha was dependent on NF-kappaB activity. Taken together, our results suggest that expression and activity of NF-kappaB is comparatively low in undifferentiated human ES cells, but increases during differentiation of the ES cells.