Core pluripotency factors promote glycolysis of human embryonic stem cells by activating GLUT1 enhancer

Human embryonic stem cells (hESCs) depend on glycolysis for energy and substrates for biosynthesis. To understand the mechanisms governing the metabolism of hESCs, we investigated the transcriptional regulation of glucose transporter 1 (GLUT1, SLC2A1), a key glycolytic gene to maintain pluripotency. By combining the genome-wide data of binding sites of the core pluripotency factors (SOX2, OCT4, NANOG, denoted SON), chromosomal interaction and histone modification in hESCs, we identified a potential enhancer of the GLUT1 gene in hESCs, denoted GLUT1 enhancer (GE) element. GE interacts with the promoter of GLUT1, and the deletion of GE significantly reduces the expression of GLUT1, glucose uptake and glycolysis of hESCs, confirming that GE is an enhancer of GLUT1 in hESCs. In addition, the mutation of SON binding motifs within GE reduced the expression of GLUT1 as well as the interaction between GE and GLUT1 promoter, indicating that the binding of SON to GE is important for its activity. Therefore, SON promotes glucose uptake and glycolysis in hESCs by inducing GLUT1 expression through directly activating the enhancer of GLUT1.

Expression dynamics of lens development-associated transcription factors in human embryonic stem cell-induced lentoid body / 中华实验眼科杂志

Objective To observe the expression dynamics of lens-related transcription factors in human embryonic stem cell (hESC) differentiated into lentoid body(LB).Methods A "three-stage" protocol was used for LB directional differentiation from hESC in vitro.The hESC (D0) and three differentiation stages cells were collected to analyze the expression dynamics of lens development-associated transcription factors by high throughput RNA sequencing technology in hESC-induced LB.Western blot and cell immunofluorescence were used to observe the involved genes at protein level.Results During D0-D6,cells became more round and compact.And during D7-D18,cells morphology gradually changed to spindle.At the end of D35,three-dimensional and transparent structurelentoid body (LB) was obtained.RT-PCR results showed that the stem cell related genes reduced and the lens specific genes increased significantly,and the LB was characterized by the expression of crystallins.According to clustering analysis of high throughput sequencing,a distinct difference in transcription factors gene expression was observed between D0 and D32.Meanwhile,the difference between D6 and D18 was minimum.The expressions of preplacodal genes,including DLX3,DLX5,DLX6,HES1,HES4,OTX2 and EYA1 increased remarkably at the first induction stage and then decreased.Lens-specification gene SOX2 declined gradually and then increased.In addition,the expression of PAX6 increased during all three induction stages.Furthermore,lens-differentiation genes including MAB21L1,CMAF,PROXI and PITX3 had no significant change in the early induction stage,but increased significantly at the third induction stage.Conclusions The expression dynamics of lens development-associated transcription factors in the hESC induced LB corresponded to those in vivo,which indicate that this induction system can recapitulate early lens development well and lay the foundation of studying lens embryonic development andtranscription factor associated congenital lens diseases.

Differential MicroRNA Expression Profile of Human Embryonic Stem Cell-Derived Cardiac Lineage Cells

MicroRNAs (miRNAs) are small non-coding RNA molecules that participate in transcriptional and post-transcriptional regulation of gene expression. miRNAs have numerous roles in cellular function including embryonic development. Human embryonic stem cells (hESCs) are capable of self-renewal and can differentiate into most of cell types including cardiomyocytes (CMs). These characteristics of hESCs make them considered as an important model for studying human embryonic development and tissue specific differentiation. In this study, we tried to demonstrate the profile of miRNA expression in cardiac differentiation from hESCs. To induce differentiation, we differentiated hESCs into CMs by direct differentiation method and characterized differentiated cells. To analyze the expression of miRNAs, we distinguished (days 4, 8, 12, 16, 20, 24, 28) and isolated RNAs from each differentiation stage. miRNA specific RT-qPCR was performed and the expression profile of miR-1, -30d, -133a, -143, -145, -378a, -499a was evaluated. The expression of all miRs was up-regulated at day 8. miR-143 and -145 expression was also up-regulated at the later stage of differentiation. Only miR-378a expression returned to undifferentiated hESC levels at the other stages of differentiation. In conclusion, we elucidated the expression profile of miRNAs during differentiation into cardiomyocytes from hESCs. Our findings demonstrate the expression of miRNAs was stage-dependent during differentiation and suggest that the differentiation into CMs can be regulated by miRNAs through direct or indirect pathway.

Development of a new coating substrate for human embryonic stem cell culture / 中国实验动物学报

Objective To reduce the animal component contamination for human embryonic stem cells ( hESCs ) and to simplify hESCs culture process , we develop a new coating substrate which can support the hESCs growth without dif -ferentiation, and is easy to store and use. Methods Mouse embryonic fibroblasts(MEF)were fixed on the surface of plate by methanol.hESCs were cultured on this new substrate and were passaged every 5 to 6 days.After 10 passages, we checked the cell morphology , alkaline phosphatase expression , embryonic specific markers and the differentiation ability in vitro.Results After 10 passages , the hESCs grew well on this new substrate and maintained the typical hESCs morpholo -gy.Alkaline phosphatase staining was positive .Immunofluorescence staining showed that the expressions of Oct 4, SSEA4, Tra-1-60 were positive .The cells formed embryoid body in vitro .Conclusions This methanol-fixed MEF substrate can support the growth of undifferentiated hESCs .The coating material can be produced in large scale and stored for a long time.It provides a new and relatively easy way to amplify hESCs .

Constraining the Pluripotent Fate of Human Embryonic Stem Cells for Tissue Engineering and Cell Therapy – The Turning Point of Cell- Based Regenerative Medicine.

To date, the lack of a clinically-suitable source of engraftable human stem/progenitor cells with adequate neurogenic potential has been the major setback in developing safe and effective cell-based therapies for regenerating the damaged or lost CNS structure and circuitry in a wide range of neurological disorders. Similarly, the lack of a clinically-suitable human cardiomyocyte source with adequate myocardium regenerative potential has been the major setback in regenerating the damaged human heart. Given the limited capacity of the CNS and heart for self-repair, there is a large unmet healthcare need to develop stem cell therapies to provide optimal regeneration and reconstruction treatment options to restore normal tissues and function. Derivation of human embryonic stem cells (hESCs) provides a powerful in vitro model system to investigate molecular controls in human embryogenesis as well as an unlimited source to generate the diversity of human somatic cell types for regenerative medicine. However, realizing the developmental and therapeutic potential of hESC derivatives has been hindered by the inefficiency and instability of generating clinically-relevant functional cells from pluripotent cells through conventional uncontrollable and incomplete multi-lineage differentiation. Recent advances and breakthroughs in hESC research have overcome some major obstacles in bringing hESC therapy derivatives towards clinical applications, including establishing defined culture systems for de novo derivation and maintenance of clinical-grade pluripotent hESCs and lineage-specific differentiation of pluripotent hESCs by small molecule induction. Retinoic acid was identified as sufficient to induce the specification of neuroectoderm direct from the pluripotent state of hESCs and trigger a cascade of neuronal lineage-specific progression to human neuronal progenitors and neurons of the developing CNS in high efficiency, purity, and neuronal lineage specificity by promoting nuclear translocation of the neuronal specific transcription factor Nurr-1. Similarly, nicotinamide was rendered sufficient to induce the specification of cardiomesoderm direct from the pluripotent state of hESCs by promoting the expression of the earliest cardiacspecific transcription factor Csx/Nkx2.5 and triggering progression to cardiac precursors and beating cardiomyocytes with high efficiency. This technology breakthrough enables direct conversion of pluripotent hESCs into a large supply of high purity neuronal cells or heart muscle cells with adequate capacity to regenerate CNS neurons and contractile heart muscles for developing safe and effective stem cell therapies. Transforming pluripotent hESCs into fate-restricted therapy derivatives dramatically increases the clinical efficacy of graft-dependent repair and safety of hESC-derived cellular products. Such milestone advances and medical innovations in hESC research allow generation of a large supply of clinical-grade hESC therapy derivatives targeting for major health problems, bringing cell-based regenerative medicine to a turning point.

Embedding the Future of Regenerative Medicine into the Open Epigenomic Landscape of Pluripotent Human Embryonic Stem Cells.

It has been recognized that pluripotent human embryonic stem cells (hESCs) must be transformed into fate-restricted derivatives before use for cell therapy. Realizing the therapeutic potential of pluripotent hESC derivatives demands a better understanding of how a pluripotent cell becomes progressively constrained in its fate options to the lineages of tissue or organ in need of repair. Discerning the intrinsic plasticity and regenerative potential of human stem cell populations reside in chromatin modifications that shape the respective epigenomes of their derivation routes. The broad potential of pluripotent hESCs is defined by an epigenome constituted of open conformation of chromatin mediated by a pattern of Oct-4 global distribution that corresponds genome-wide closely with those of active chromatin modifications. Dynamic alterations in chromatin states correlate with lossof- Oct4-associated hESC differentiation. The epigenomic transition from pluripotence to restriction in lineage choices is characterized by genome-wide increases in histone H3K9 methylation that mediates global chromatin-silencing and somatic identity. Human stem cell derivatives retain more open epigenomic landscape, therefore, more developmental potential for scale-up regeneration, when derived from the hESCs in vitro than from the CNS tissue in vivo. Recent technology breakthrough enables direct conversion of pluripotent hESCs by small molecule induction into a large supply of lineage-specific neuronal cells or heart muscle cells with adequate capacity to regenerate neurons and contractile heart muscles for developing safe and effective stem cell therapies. Nuclear translocation of NAD-dependent histone deacetylase SIRT1 and global chromatin silencing lead to hESC cardiac fate determination, while silencing of pluripotenceassociated hsa-miR-302 family and drastic up-regulation of neuroectodermal Hox miRNA hsa-miR-10 family lead to hESC neural fate determination. These recent studies place global chromatin dynamics as central to tracking the normal pluripotence and lineage progression of hESCs. Embedding lineage-specific genetic and epigenetic developmental programs into the open epigenomic landscape of pluripotent hESCs offers a new repository of human stem cell therapy derivatives for the future of regenerative medicine.

Contralaterally transplanted human embryonic stem cell-derived neural precursor cells (ENStem-A) migrate and improve brain functions in stroke-damaged rats

The transplantation of neural precursor cells (NPCs) is known to be a promising approach to ameliorating behavioral deficits after stroke in a rodent model of middle cerebral artery occlusion (MCAo). Previous studies have shown that transplanted NPCs migrate toward the infarct region, survive and differentiate into mature neurons to some extent. However, the spatiotemporal dynamics of NPC migration following transplantation into stroke animals have yet to be elucidated. In this study, we investigated the fates of human embryonic stem cell (hESC)-derived NPCs (ENStem-A) for 8 weeks following transplantation into the side contralateral to the infarct region using 7.0T animal magnetic resonance imaging (MRI). T2- and T2*-weighted MRI analyses indicated that the migrating cells were clearly detectable at the infarct boundary zone by 1 week, and the intensity of the MRI signals robustly increased within 4 weeks after transplantation. Afterwards, the signals were slightly increased or unchanged. At 8 weeks, we performed Prussian blue staining and immunohistochemical staining using human-specific markers, and found that high percentages of transplanted cells migrated to the infarct boundary. Most of these cells were CXCR4-positive. We also observed that the migrating cells expressed markers for various stages of neural differentiation, including Nestin, Tuj1, NeuN, TH, DARPP-32 and SV38, indicating that the transplanted cells may partially contribute to the reconstruction of the damaged neural tissues after stroke. Interestingly, we found that the extent of gliosis (glial fibrillary acidic protein-positive cells) and apoptosis (TUNEL-positive cells) were significantly decreased in the cell-transplanted group, suggesting that hESC-NPCs have a positive role in reducing glia scar formation and cell death after stroke. No tumors formed in our study. We also performed various behavioral tests, including rotarod, stepping and modified neurological severity score tests, and found that the transplanted animals exhibited significant improvements in sensorimotor functions during the 8 weeks after transplantation. Taken together, these results strongly suggest that hESC-NPCs have the capacity to migrate to the infarct region, form neural tissues efficiently and contribute to behavioral recovery in a rodent model of ischemic stroke.

Research progress in feeder layers of human embryonic stem cells / 国际生物医学工程杂志

Human embryonic stem cell (hES cells) lines can be derived from the inner cell mass (ICM) of preimplantation blastocysts.hES cells are commonly defined as undifferentiated pluripotent cells that can proliferate and have the capacity of both self-renewal and differentiation into one or more types of specialized cells.hES cells remain undifferentiated when culture on feeder layers,such as murine embryonic fibroblasts (MEFs).It is believed that various factors secreted from feeder layers are necessary to prevent hES cell from differentiation.In this review,we will summarize the advantages and disadvantages of various types of feeder cells by which a reference for future research will be provided.

Effect of VEGF on Neural Differentiation of Human Embryonic Stem Cells in vitro / 华中科技大学学报（医学）（英德文版）

The effects of vascular endothelial growth factor (VEGF) on neural differentiation of human embryonic stem cells (hESCs) in vitro and the possible mechanism were observed. The hESCs lines,TJMU1 and TJMU2, were established and stored by our laboratory, hESCs differentiated into neuronal cells through embryonic body formation. In this induction process, hESCs were divided into three groups: group A, routine induction; group B, routine induction+10 ng/mL VEGF; group C, routine in-duction+10 ng/mL VEGF+10 ng/mL VEGFR2/Fc. OCT4, Nestin and GFAP in each group were de-tected by RT-PCR, and the cells expressing Nestin and GFAP were counted by immunofluorescence.The percentage of Nestin positive cells in group B was significantly higher than in groups A and C,while the percentage of GFAP positive cells in group B was significantly lower than in groups A and C (P<0.01). There was no significant difference between groups A and C (P>0.05). It was concluded that VEGF, via VEGFR2, stimulated the neural differentiation of hESCs in vitro.

Efficient gene delivery in differentiated human embryonic stem cells

Human embryonic stem (hES) cells are capable of differentiating into pluralistic cell types, however, spontaneous differentiation generally gives rise to a limited number of specific differentiated cell types and a large degree of cell heterogeneity. In an effort to increase the efficiency of specified hES cell differentiation, we performed a series of transient transfection of hES cells with EGFP expression vectors driven by different promoter systems, including human cellular polypeptide chain elongation factor 1 alpha (hEF1alpha), human cytomegalo-virus, and chicken beta-actin. All these promoters were found to lead reporter gene expression in undifferentiated hES cells, but very few drug-selectable transfectants were obtained and failed to maintain stable expression of the transgene with either chemical or electroporation methods. In an attempt to increase transfection efficiency and obtain stable transgene expression, differentiated hES cells expressing both mesodermal and ectodermal markers were derived using a defined medium. Differentiated hES cells were electroporated with a hEF1alpha promoter-driven EGFP or human noggin expression vector. Using RT-PCR, immunocytochemistry and fluorescence microscopy, the differentiated hES cells transfected with foreign genes were confirmed to retain stable gene and protein expression during prolonged culture. These results may provide a new tool for introducing exogenous genes readily into hES cells, thereby facilitating more directed differentiation into specific and homogenous cell populations.

Recent Advances in Human Embryonic Stem Cell Research

The 21st century is considered as the era of Biotechnology (BT). Recently, the regenerative medicine using stem cells has been recognized as the future medicine, especially for the devastating diseases such as neurodegenerative diseases, heart disease, diabetes, infertility and liver diseases. Human embryonic stem cells (hESCs) are at the center of the stem cell research due to its ability to proliferate unlimitedly without differentiation (self-renewal) and to differentiate into the derivatives of all three germ layers including germ cells with appropriate treatments (pluripotency). A total of 173 hESC lines have been derived since the first derivation by Thomson et al. in 1998, and 70 hESC lines are currently available for distribution including hESC line (Miz-hES1) established at the MizMedi Hospital. The major goal of hESC research is to provide basic and clinical clues for cell replacement therapy, whose targets are aforementioned incurable diseases. One of the landmarks in hESC research is the derivation of a hESC line from a cloned human blastocyst, which has recently been done by Korean scientists. This made it possible to overcome the issue of immune-mediated rejection following cell replacement therapy using hESCs. Guided differentiation of hESCs into specific cell types by treating growth factors and drugs or by genetic manipulation by using overexpression or an RNAi knockdown system is one of the most active research areas. Combined efforts towards the guided differentiation of hESC into specific cell types and the cloning of hESC from a cloned human blastocyst will overcome a list of diseases hitherto considered to be incurable.

Effects of Neurotrophic Factors on the Generation of Functional Dopamine Secretory Neurons Derived from in vitro Differentiated Human Embryonic Stem Cells / 대한불임학회지

OBJECTIVE: This study was to examine the in vitro neural cell differentiation patterns of human embryonic stem (hES) cells following treatment of various neurotrophic factors [basic fibroblast growth factor (bFGF), retinoic acid (RA), brain derived neurotrophic factor (BDNF) and transforming growth factor (TGF)-alpha], particulary in dopaminergic neuron formation. METHODS: The hES cells were induced to differentiate by bFGF and RA. Group I) In bFGF induction method, embryoid bodies (EBs, for 4 days) derived from hES were plated onto gelatin dish, selected for 8 days in ITSFn medium and expanded at the presence of bFGF (10 ng/ml) for another 6 days followed by a final differentiation in N2 medium for 7, 14 and 21 days. Group II) For RA induction, EBs were exposed of RA (10-6 M) for 4 days and allowed to differentiate in N2 medium for 7, 14 and 21 days. Group III) To examine the effects of additional neurotrophic factors, bFGF or RA induced cells were exposed to either BDNF (10 ng/ml) or TGF-alpha (10 ng/ml) during the 21 days of final differentiation. Neuron differentiation and dopamine secretion were examined by indirect immunocytochemistry and HPLC, respectively. RESULTS: The bFGF or RA treated hES cells were resulted in similar neural cell differentiation patterns at the terminal differentiation stage, specifically, 75% neurons and 11% glial cells. Additionally, treatment of hES cells with BDNF or TGF-alpha during the terminal differentiation stage led to significantly increased tyrosine hydroxylase (TH) expression of a dopaminergic neuron marker, compared to control (p<0.05). In contrast, no effect was observed on the rate of mature neuron (NF-200) or glutamic acid decarboxylase-positive neurons. Immunocytochemistry and HPLC analyses revealed the higher levels of TH expression (20.3%) and dopamine secretion (265.5+/-62.8 pmol/mg) in bFGF and TGF-alpha sequentially treated hES cells than those in RA or BDNF treated hES cells. CONCLUSION: These results indicate that the generation of dopamine secretory neurons from in vitro differentiated hES cells can be improved by TGF-alpha addition in the bFGF induction protocol.

A New Efficient Cryopreservation of Human Embryonic Stem Cells by a Minimum Volume Cooling Method / 대한불임학회지

No abstract available.

In vitro Neural Cell Differentiation of Genetically Modified Human Embryonic Stem Cells Expressing Tyrosine Hydroxylase / 대한불임학회지

OBJECTIVE: This study was to examine in vitro neural cell differentiation pattern of the genetically modified human embryonic stem cells expressing tyrosine hydroxylase (TH). MATERIALS AND METHODS: Human embryonic stem (hES, MB03) cell was transfected with cDNAs cording for TH. Successful transfection was confirmed by western immunoblotting. Newly transfected cell line (TH#2/MB03) was induced to differentiate by two neurogenic factors retinoic acid (RA) and b-FGF. Exp. I) Upon differentiation using RA, embryoid bodies (EB, for 4 days) derived from TH#2/MB03 cells were exposed to RA (10-6 M)/AA (5x10-2 mM) for 4 days, and were allowed to differentiate in N2 medium for 7, 14 or 21 days. Exp. II) When b-FGF was used, neuronal precursor cells were expanded at the presence of b-FGF (10 ng/ml) for 6 days followed by a final differentiation in N2 medium for 7, 14 or 21 days. Neuron differentiation was examined by indirect immunocytochemistry using neuron markers (NF160 & NF200). RESULTS: After 7 days in N2 medium, approximately 80% and 20% of the RA or b-FGF induced Th#2/MB03 cells were immunoreactive to anti-NF160 and anti-NF200 antibodies, respectively. As differentiation continued, NF200 in RA treated cells significantly increased to 73.0% on 14 days compared to that in b-FGF treated cells (53.0%, p<0.05), while the proportion of cells expressing NF160 was similarly decreased between two groups. However, throughout the differentiation, expression of TH was maintained (~90%). HPLC analyses indicated the increased levels of L-DOPA in RA treated genetically modified hES cells with longer differentiation time. CONCLUSION: These results suggested that a genetically modified hES cells (TH#2/MB03) could be efficiently differentiated in vitro into mature neurons by RA induction method.

Establishment and characteristics of clonal human embryonic stem cell lines / 中华妇产科杂志

Objective To establish clonal human embryonic stem cell lines and investigate their biological characteristics. Methods Cells were derived from one inner cell mass of human blastocyst, multiplied for 20 passages, and then dissociated into single cell suspension by digestion with 0.5% trypsin. Single cell was picked up and plated into individual well of a 96-well plate containing feeder-layers directly under a dissection microscope. The outgrowth clones were passed by treatment with collagenase. Surface markers were detected by cytochemistry and histoimmunochemistry. Karyotypes were tested using standard G-banding techniques. The pluripotency was analyzed by inoculating cells into severe combined immunodeficient (SCID) mice. Results Two clonal human embryonic stem cell lines were established. Cells of these two lines possess the characteristics and differentiating potencies: normal 46 XX karyotypes; expressing a series of surface markers such as: alkaline phosphotase, stage-specific embryonic antigen (SSEA)-4, tumor recognition antigen (TRA)-1-60, TRA-1-81 etc; and forming teratomas comprising derivatives of three embryonic germ layers such as neural tissue, cartilage, squamous epithelium and columlar epithelium when injected into SCID mice. Conclusions The two single cell-cloned human embryonic stem (hES) cell lines were derived in our laboratory. The cells possess stable biological characteristics of undifferentiated hES cells.

RESEARCH ON SPONTANEOUS DIFFERENTIATION OF STEM CELLS AND RELATED GENE EXPRESSION PROFILE / 解剖学报

Objective To investigate the expression of endometrial developing-related genes,the endometrium-like structure and cells during spontaneous differentiation of hESCs. Methods (1) Embryoid bodies were cultured in suspension for 14 days,fixed in 10% neutral-buffered formalin and embedded in paraffin.Estrogen receptor(ER) was detected by immunocytochemical staining.(2) hESCs were cultured in a 35 mm plastic dish and differentiated spontaneously for 10 days.The expression of ER and Vimentin/Keratin was detected by double immunofluorescence histochemistry.(3) hESCs were cultured in a 35 mm plastic dish and differentiated for 5 days.The expressions of endometrial developing-related genes including Wnt4,Wnt7a,Wnt5a,Hoxa10,Hoxa11 and ER were detected by RT-PCR. Results (1) The endometrium-like structures were detected in 14-day-old EBs and some were positive for ER staining.(2) Some spontaneously differentiated cells from hESCs for 10 days were positive for ER together with Vimentin/Keratin.(3)Wnt7a,Wnt4,Hoxa10,Hoxa11 and ER were detected by RT-PCR in hESCs which were differentiated spontaneously for 5 days.Conclusion During the spontaneous differentiation of hESCs,some cells are liable to differentiate into endometrial stem cells and endometrium-like cells.However,further identifications of the whole development process are needed to be done in the future.