The culture of neural stem cells (NSCs) as floating neurospheres has become widely used as an experimental model to analyse the properties of NSCs. Although the neurosphere model has existed for two decades, there is still no standard protocol to grow NSCs in this way. Thus, we have analysed the consequences of the frequency of growth factor (FGF-2 and EGF) addition to embryonic and adult olfactory bulb stem cells (eOBSCs and aOBSCs) cultures, specifically in terms of proliferation, cell cycle progression, death and differentiation, as well as on global changes in gene expression and signaling pathways. We found that addition of FGF-2 and EGF every two or four days rather than daily significantly reduces the volume of the neurospheres and the total number of cells, changes that were more evident in aOBSC than in eOBSC cultures. The reduction in neurosphere size was mainly due to an increase in cell death and occurs without major changes in the cell cycle parameters tested. Moreover, partial deprivation of FGF-2 and EGF produces a mild increase in aOBSC differentiation during the proliferative phase. Remarkably, these effects were accompanied by a significant upregulation in the expression of genes involved in cell death regulation (Cryab), lipid catabolic processes (Pla2g7), cell adhesion (Dscaml1), cell differentiation (Dscaml1, Gpr17, S100b) and signal transduction (Gpr17, Ndrg2), among others. These findings support that continuous supply of FGF-2 and EGF is critical to maintain the viability/survival of NSCs in culture and reveals novel molecular hallmarks of NSC maintenance/survival and expansion in response to these growth factors.
A global transcriptome analysis reveals molecular hallmarks of neural stem cell death, survival, and differentiation in response to partial FGF-2 and EGF deprivation.
Specimen part
View SamplesAcross life neural stem cells (NSCs) generate new neurons in the mammalian brain through asymmetric neurogenic and self-renewing cell divisions. However, the cellular mechanisms underlying NSC asymmetry remain unknown. Using fluorescence loss in photobleaching (FLIP) we here show that NSCs in vitro and within the developing forebrain generate a lateral diffusion barrier during cell division resulting in asymmetric segregation of cellular components. The strength of the diffusion barrier is dynamically regulated with age and depends on the proper function of lamin-associated nuclear envelope constituents. Strikingly, age-associated or experimental impairment of the diffusion barrier disrupts asymmetric segregation of damaged proteins, a product of aging. Thus, the data presented here identify a mechanism how age is asymmetrically distributed during somatic stem cell division.
A mechanism for the segregation of age in mammalian neural stem cells.
Age, Specimen part
View SamplesThis study compares directed cardiac differentiation time-courses using (i) HuES6 cells with endogenous ISL1 knockout + inducible ISL1 transgene, and (ii) wild-type HuES6 cells.
Revised roles of ISL1 in a hES cell-based model of human heart chamber specification.
Specimen part, Time
View SamplesReprogramming of somatic cells is a valuable tool to understand the mechanisms of regaining pluripotency and further opens up the possibility of generating patient-specific pluripotent stem cells. Reprogramming of mouse and human somatic cells into pluripotent stem cells, designated as induced pluripotent stem (iPS) cells, has been possible with the expression of the transcription factor quartet Oct4 (also known as Pou5f1), Sox2, c-Myc, and Klf4. Considering that ectopic expression of c-Myc causes tumourigenicity in offspring and retroviruses themselves can cause insertional mutagenesis, the generation of iPS cells with a minimal number of factors may hasten the clinical application of this approach. Here, we show that adult mouse neural stem cells express higher endogenous levels of Sox2 and c-Myc than embryonic stem cells, and that exogenous Oct4 together with either Klf4 or c-Myc are sufficient to generate iPS cells from neural stem cells. These two-factor (2F) iPS cells are similar to embryonic stem cells at the molecular level, contribute to development of the germ line, and form chimeras. We propose that, in inducing pluripotency, the number of reprogramming factors can be reduced when using somatic cells that endogenously express appropriate levels of complementing factors.
Pluripotent stem cells induced from adult neural stem cells by reprogramming with two factors.
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View SamplesIn pluripotential reprogramming, a pluripotent state is established within somatic cells. In this study, we have generated induced pluripotent stem (iPS) cells from bi-maternal (uniparental) parthenogenetic neural stem cells (pNSCs) by transduction with four (Oct4, Klf4, Sox2, and c-Myc) or two (Oct4 and Klf4) transcription factors. The parthenogenetic iPS (piPS) cells directly reprogrammed from pNSCs were able to generate germline-competent himeras, and hierarchical clustering analysis showed that piPS cells were clustered more closer to parthenogenetic ES cells than normal female ES cells. Interestingly, piPS cells showed loss of parthenogenetic-specific imprinting patterns of donor cells. Microarray data also showed that the maternally imprinted genes, which were not expressed in pNSCs, were upregulated in piPS cells, indicating that pluripotential reprogramming lead to induce loss of imprinting as well as re-establishment of various features of pluripotent cells in parthenogenetic somatic cells.
Generation of parthenogenetic induced pluripotent stem cells from parthenogenetic neural stem cells.
Sex, Specimen part
View SamplesMany studies have already shown the reprogramming of somatic cells into other cell types such as neural stem cells, blood progenitor cells, and hepatocytes by inducing combinations of transcription factors. One of the recent development in cellular reprogramming is the direct reprogramming, that can change cell fate towards different lineages. This strategy provides an alternative to the use of pluripotent stem cells ruling out the concerns of tumorigenicity caused by undifferentiated cell populations. Here, we generated induced oligodendrocyte progenitor cells (iOPCs) from mouse fibroblasts by direct reprogramming. The generated iOPCs are homogenous, self-renewing, and multipotent. Once differentiated, the somatic stem cells exhibit morphological and molecular characteristics of oligodendrocyte progenitor cells (OPCs). Thus, we demonstrated that terminally differentiated somatic cells can be converted into functional iOPCs by induction of transcription factors offering a new strategies to cure myelin disorders.
Oct4-induced oligodendrocyte progenitor cells enhance functional recovery in spinal cord injury model.
Specimen part
View SamplesMaintenance and maturation of primordial germ cells is controlled by complex genetic and epigenetic cascades, and disturbances in this network lead to either infertility or malignant aberration. Transcription factor Tcfap2c / TFAP2C has been described to be essential for primordial germ cell maintenance and to be upregulated in several human germ cell cancers. Using global gene expression profiling, we identified genes deregulated upon loss of Tcfap2c in primordial germ cell-like cells. We show that loss of Tcfap2c affects many aspects of the genetic network regulating germ cell biology, such as downregulation maturation markers and induction of markers indicative of somatic differentiation, cell cycle, epigenetic remodeling, and pluripotency associated genes. Chromatin-immunoprecipitation analyses demonstrated binding of Tcfap2c to regulatory regions of deregulated genes (Sfrp1, Dmrt1, Nanos3, c-Kit, Cdk6, Cdkn1a, Fgf4, Klf4, Dnmt3b and Dnmt3l) suggesting that these genes are direct transcriptional targets of Tcfap2c in primordial germ cells. Since Tcfap2c deficient primordial germ cell like cells display cancer related deregulations in epigenetic remodeling, cell cycle and pluripotency control, the Tcfap2c-knockout allele was bred onto 129S2/Sv genetic background. There, mice heterozygous for Tcfap2c develop germ cell cancer with high incidence. Precursor lesions can be observed as early as E16.5 in developing testes displaying persisting expression of pluripotency markers. We further demonstrate, that mice with a heterozygous deletion of the Tcfap2c target gene Nanos3 are also prone to develop teratoma. These data highlight Tcfap2c as a critical and dose-sensitive regulator of germ cell fate.
Transcription factor TFAP2C regulates major programs required for murine fetal germ cell maintenance and haploinsufficiency predisposes to teratomas in male mice.
Specimen part
View SamplesExpression of germ cell nuclear factor (GCNF, Nr6a1), an orphan member of the nuclear receptor gene family of transcription factors, during gastrulation and neurulation is critical for normal embryogenesis in mice. Gcnf represses the expression of the POU domain transcription factor Oct4 (Pou5f1) during mouse post-implantation development. Although Gcnf expression is not critical for the embryonic segregation of the germ cell lineage, we found that sexually dimorphic expression of Gcnf in germ cells correlates with the expression of pluripotency-associated genes, such as Oct4, Sox2, and Nanog, as well as the early meiotic marker gene Stra8. To elucidate the role of Gcnf during mouse germ cell differentiation, we generated an ex vivo Gcnf-knockdown model in combination with a regulated CreLox mutation of Gcnf. Lack of Gcnf impairs normal spermatogenesis and oogenesis in vivo, as well as the derivation of germ cells from embryonic stem cells (ESCs) in vitro. Inactivation of the Gcnf gene in vivo leads to loss of repression of Oct4 expression in both male and female gonads.
Germ cell nuclear factor regulates gametogenesis in developing gonads.
Specimen part
View SamplesGraphene has been selected as a candidate for synthetic feeder-free culture substrate guiding human/mouse multipotent stem cell lineage specification, and culturing pluripotent stem cells in a number of studies. However, conventional graphene is not an ideal biomaterial to maintain the pluripotency of human pluripotent stem cells (hPSC) including hESCs/hiPSCs due to its intrinsic hydrophobicity and relatively flat surface topography. Here, we applied morphology-controlled nanocrystalline graphene (NG) coating onto the culture substrates via diffusion-associated synthesis (DAS) process and cultivated hPSCs. It is found that enhanced hydrophilicity and controlled surface roughness of DAS-NG enabled tight focal adhesion of hPSCs onto the DAS-NG coated culture substrate and retained pluripotency for over 2 weeks. It is also found hPSCs grown on DAS-NG shared comparable global gene expression profile with hPSCs grown on mouse embryonic fibroblast (MEF). Importantly, the similarities in cell adhesion gene expression between hPSCs grown on DAS-NG and hPSCs on MEF suggest DAS-NG may provide comparable physical cues with MEF for sustaining pluripotency. Taken together, our findings show a new reliable method for culturing hPSCs in feeder-free condition using DAS-graphene.
Establishment of feeder-free culture system for human induced pluripotent stem cell on DAS nanocrystalline graphene.
Specimen part, Cell line
View SamplesPluripotency is the differentiation capacity of particular cells exhibited in the early embryo in vivo and embryonic stem (ES) cells have been shown to originate from the inner cell mass (ICM) of an E3.5 blastocyst. Although the potential for ES cells to differentiate into the three germ layers is equated to ICM cells, they differ in the ability to maintain the capacity for self-renewal. Despite several studies on the maintenance of ES cells in the ground state of pluripotency, the precise mechanism of conversion from the ICM to the ES cell remains unclear. Here , we have examined the cell characteristics and expression profile within the intermediate stages of ES cell derivation from the ICM. Gene clustering and ontology (GO) analyses showed a significant change in the expression of epigenetic modifiers and DNA methylation-related genes in the intermediate stages. We have proposed that an epithelial-to-mesenchymal transition (EMT) blockage is required during derivation of mouse ES cells from E3.5 blastocysts. This study suggests a novel mechanistic insight into ES cell derivation and provides a time-course transcriptome profiling resource for the dissection of gene regulatory networks that underlie the transition from ICM to ES cells.
Blockage of the Epithelial-to-Mesenchymal Transition Is Required for Embryonic Stem Cell Derivation.
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