Developmental complexity of early mammalian pluripotent cell populations in vivo and in vitro

1998 ◽  
Vol 10 (8) ◽  
pp. 535 ◽  
Author(s):  
T. A. Pelton ◽  
M. D. Bettess ◽  
J. Lake ◽  
J. Rathjen ◽  
P. D. Rathjen

Early mammalian embryogenesis is characterised by the coordinated proliferation, differentiation, migration and apoptosis of a pluripotent cell pool that is able to give rise to extraembryonic lineages and all the cell types of the embryo proper. These cells retain pluripotent differentiation capability, defined in this paper as the ability to form all cell types of the embryo and adult, until differentiation into the three embryonic germ layers at gastrulation. Our understanding of pluripotent cell biology and molecular regulation has been hampered by the difficulties associated with experimental manipulation of these cells in vivo. However, a more detailed understanding of pluripotent cell behaviour is emerging from the application of molecular technologies to early mouse embryogenesis. The construction of mouse mutants by gene targeting, mapping of gene expression in vivo, and modelling of cell decisions in vitro are providing insight into the cellular origin, identity and action of key developmental regulators, and the nature of pluripotent cells themselves. In this review we discuss the properties of early embryonic pluripotent cells in vitro and in vivo, focusing on progression from inner cell mass (ICM) cells in the blastocyst to the onset of gastrulation.

2009 ◽  
Vol 21 (9) ◽  
pp. 63
Author(s):  
L. Ganeshan ◽  
C. O'Neill

The developmental viability of the early embryo requires the formation of the inner cell mass (ICM) at the blastocyst stage. The ICM contributes to all cell lineages within the developing embryo in vivo and the embryonic stem cell (ESC) lineage in vitro. Commitment of cells to the ICM lineage and its pluripotency requires the expression of core transcription factors, including Nanog and Pou5f1 (Oct4). Embryos subjected to culture in vitro commonly display a reduced developmental potential. Much of this loss of viability is due to the up-regulation of TRP53 in affected embryos. This study investigated whether increased TRP53 disrupts the expression of the pluripotency proteins and the normal formation of the ICM lineage. Mouse C57BL6 morulae and blastocysts cultured from zygotes (modHTF media) possessed fewer (p < 0.001) NANOG-positive cells than equivalent stage embryos collected fresh from the uterus. Blocking TRP53 actions by either genetic deletion (Trp53–/–) or pharmacological inhibition (Pifithrin-α) reversed this loss of NANOG expression during culture. Zygote culture also resulted in a TRP53-dependent loss of POU5F1-positive cells from resulting blastocysts. Drug-induced expression of TRP53 (by Nutlin-3) also caused a reduction in formation of pluripotent ICM. The loss of NANOG- and POU5F1-positive cells caused a marked reduction in the capacity of blastocysts to form proliferating ICM after outgrowth, and a consequent reduced ability to form ESC lines. These poor outcomes were ameliorated by the absence of TRP53, resulting in transmission distortion in favour of Trp53–/– zygotes (p < 0.001). This study shows that stresses induced by culture caused TRP53-dependent loss of pluripotent cells from the early embryo. This is a cause of the relative loss of viability and developmental potential of cultured embryos. The preferential survival of Trp53–/– embryos after culture due to their improved formation of pluripotent cells creates a genetic danger associated with these technologies.


2012 ◽  
Vol 24 (1) ◽  
pp. 220
Author(s):  
J. K. Park ◽  
H. S. Kim ◽  
K. J. Uh ◽  
K. H. Choi ◽  
H. M. Kim ◽  
...  

Since pluripotent cells were first derived from the inner cell mass (ICM) of mouse blastocysts, tremendous efforts have been made to establish embryonic stem cell (ESC) lines in several domestic species including the pig; however, authentic porcine ESCs have not yet been established. It has proven difficult to derive pluripotent cells of naïve state that represents full pluripotency, due to the frequent occurrence of spontaneous differentiation into an EpiSC-like state during culture in pigs. We have been able to derive EpiSC-like porcine embryonic stem cell (pESC) lines of a differentiated non-ES cell state from blastocyst stage porcine embryos of various origins, including in vitro fertilized (IVF), in vivo derived, IVF aggregated and parthenogenetic embryos. In addition, we have generated induced pluripotent stem cells (piPSCs) via plasmid transfection of reprogramming factors (Oct4, Sox2, Klf4 and c-Myc) into porcine fibroblast cells. In this study, we analysed characteristics such as marker expression, pluripotency and the X chromosome inactivation (XCI) status of our EpiSC-like pESC lines along with our piPSC line. Our results show that these cell lines demonstrate the expression of genes associated with the Activin/Nodal and FGF2 pathways along with the expression of pluripotent markers Oct4, Sox2, Nanog, SSEA4, TRA 1-60 and TRA 1-81. Furthermore all of these cell lines showed in vitro differentiation potential; female XCI activity and a normal karyotype. Here we provide preliminary results that suggest that, as a nonpermissive species, the porcine species undergoes reprogramming into a primed state during the establishment of pluripotent stem cell lines. This work was supported by the BioGreen 21 Program (#20070401034031, PJ0081382011), Rural Development Administration, Republic of Korea.


2002 ◽  
Vol 115 (2) ◽  
pp. 329-339 ◽  
Author(s):  
T. A. Pelton ◽  
S. Sharma ◽  
T. C. Schulz ◽  
J. Rathjen ◽  
P. D. Rathjen

Formation and differentiation of a pluripotent cell population is central to mammalian development, and the isolation, identification and manipulation of human pluripotent cells is predicted to be of therapeutic use. Within the early mammalian embryo, two distinct populations of pluripotent cells have been described: the inner cell mass (ICM), which differentiates to form a second pluripotent cell populations, the primitive ectoderm. Indirect evidence suggests the existence of temporally distinct intermediate pluripotent cell populations as primitive ectoderm is formed. We coupled an in vitro model of primitive ectoderm formation (the transition of embryonic stem cells to early primitive ectoderm-like (EPL) cells) with ddPCR-based techniques to identify three novel genes, Psc1, CRTR-1 and PRCE, that were expressed differently during pluripotent cell progression. Detailed mapping of these genes with Oct4, Rex1 and Fgf5 on pregastrulation embryos provided the first molecular evidence for the existence of successive, temporally distinct pluripotent cell populations in the embryo between the ICM and primitive ectoderm. No evidence was found for spatial heterogeneity within the Oct4+ pool. The transition between populations correlated with morphological or developmental alterations in pluripotent cells in vivo. Genes that are temporally expressed during pluripotent cell progression may provide an opportunity for molecular discrimination of pluripotent cells at different stages of maturation in vivo and an understanding of the cellular origins and properties of pluripotent cell lines isolated from diverse sources. Furthermore, the strong correlation of gene expression demonstrated between EPL cell formation in vitro and primitive ectoderm formation in vivo validates EPL cells as a model for primitive ectoderm, thereby providing a model system for the investigation of pluripotent differentiation and an opportunity for directed differentiation of pluripotent cells to therapeutically useful cell populations.


1995 ◽  
Vol 43 (1) ◽  
pp. 304 ◽  
Author(s):  
D. Rath ◽  
H. Niemann ◽  
T. Tao ◽  
M. Boerjan

Development ◽  
1988 ◽  
Vol 102 (4) ◽  
pp. 793-803 ◽  
Author(s):  
V.E. Papaioannou ◽  
K.M. Ebert

Total cell number as well as differential cell numbers representing the inner cell mass (ICM) and trophectoderm were determined by a differential staining technique for preimplantation pig embryos recovered between 5 and 8 days after the onset of oestrus. Total cell number increased rapidly over this time span and significant effects were found between embryos of the same chronological age from different females. Inner cells could be detected in some but not all embryos of 12–16 cells. The proportion of inner cells was low in morulae but increased during differentiation of ICM and trophectoderm in early blastocysts. The proportion of ICM cells then decreased as blastocysts expanded and hatched. Some embryos were cultured in vitro and others were transferred to the oviducts of immature mice as a surrogate in vivo environment and assessed for morphology and cell number after several days. Although total cell number did not reach in vivo levels, morphological development and cell number increase was sustained better in the immature mice than in vitro. The proportion of ICM cells in blastocysts formed in vitro was in the normal range.


Development ◽  
1980 ◽  
Vol 60 (1) ◽  
pp. 405-418
Author(s):  
E. B. Ilgren

The growth of mouse trophectoderm depends upon the presence of the inner cell mass. Whether this applies to other species of mammals is not known. To investigate this problem, the guinea pig was selected for two reasons. Firstly, the growth of guinea-pig trophoblast resembles that of man. Secondly, earlier studies suggest that the proliferation of guinea-pig trophectoderm may not be under ICM control. Therefore, in the present study, the guinea-pig blastocyst was cut microsurgically to yield two tissue fragments. These contained roughly equal numbers of trophectodermal cells, one fragment being composed only of trophectoderm and the other containing ICM tissue as well. Subsequently, the growth of these mural and polar fragments was followed in vitro since numerous technical difficulties make an in vivo analysis of this problem impracticable. In a manner similar to the mouse, the isolated mural trophectoderm of the guinea pig stopped dividing and became giant. In contrast, guinea-pig polar fragments formed egg-cylinder-like structures. The latter contained regions structurally similar to two presumptive polar trophectodermal derivatives namely the ectoplacental and extraembryonic ectodermal tissues. These findings suggest that guinea-pig trophectodermal growth may occur in a manner similar to the mouse and thus be under ICM control.


2000 ◽  
Vol 113 (3) ◽  
pp. 555-566 ◽  
Author(s):  
J. Lake ◽  
J. Rathjen ◽  
J. Remiszewski ◽  
P.D. Rathjen

We have undertaken an in vitro differentiation analysis of two related, interconvertible, pluripotent cell populations, ES and early primitive ectoderm-like (EPL) cells, which are most similar in morphology, gene expression, cytokine responsiveness and differentiation potential in vivo to ICM and early primitive ectoderm, respectively. Pluripotent cells were differentiated in vitro as aggregates (embryoid bodies) and the appearance and abundance of cell lineages were assessed by morphology and gene expression. Differentiation in EPL cell embryoid bodies recapitulated normal developmental progression in vivo, but was advanced in comparison to ES cell embryoid bodies, with the rapid establishment of late primitive ectoderm specific gene expression, and subsequent loss of pluripotent cell markers. Nascent mesoderm was formed earlier and more extensively in EPL cell embryoid bodies, and resulted in the appearance of terminally differentiated mesodermal cell types prior to and at higher levels than in ES cell embryoid bodies. Nascent mesoderm in EPL cell embryoid bodies was not specified but could be programmed to alternative fates by the addition of exogenous factors. EPL cells remained competent to form primitive endoderm even though this is not the normal fate of primitive ectoderm in vivo. The establishment of primitive ectoderm-like gene expression and inability to participate in embryogenesis following blastocyst injection is therefore not directly associated with restriction in the ability to form extra-embryonic lineages. However, the EPL cell embryoid body environment did not support differentiation of primitive endoderm to visceral endoderm, indicating the lack of an inductive signal for visceral endoderm formation deduced to originate from the pluripotent cells. Similarly, the inability of EPL cells to form neurons when differentiated as embryoid bodies was attributable to perturbation of the differentiation environment and loss of inductive signals rather than a restricted differentiation potential. Reversion of EPL cells to ES cells was accompanied by restoration of ES cell-like differentiation potential. These results demonstrate the ability of pluripotent cells to adopt developmentally distinct, stable cell states with altered differentiation potentials.


Development ◽  
1995 ◽  
Vol 121 (7) ◽  
pp. 2069-2077
Author(s):  
E.D. Newman-Smith ◽  
Z. Werb

Mouse embryos containing only maternal chromosomes (parthenotes) develop abnormally in vivo, usually failing at the peri-implantation stage. We have analyzed the development of parthenote embryos by using an inner cell mass (ICM) outgrowth assay that mimics peri-implantation development. ICMs from normal embryos maintained undifferentiated stem cells positive for stage-specific embryonic antigen-1 and Rex-1 while differentiating into a variety of cell types, including visceral endoderm-like cells and parietal endoderm cells. In contrast, ICMs from parthenotes failed to maintain undifferentiated stem cells and differentiated almost exclusively into parietal endoderm. This suggests that parthenote ICMs have a defect that leads to differentiation, rather than maintenance, of the stem cells, and a defect that leads to a parietal endoderm fate for the stem cells. To test the hypothesis that the ICM population is not maintained owing to a lack of proliferation of the stem cells, we investigated whether mitogenic agents were able to maintain the ICM population in parthenotes. When parthenote blastocysts were supplied with the insulin-like growth factor-1 receptor (Igf-1r) and insulin-like growth factor-2 (Igf-2), two genes not detectable in parthenote blastocysts by in situ hybridization, the ICM population was maintained. Similarly, culture of parthenote blastocysts in medium conditioned by embryonic fibroblasts and supplemented with the maternal factor leukemia inhibitory factor maintained the ICM population. However, once this growth factor-rich medium was removed, the parthenote ICM cells still differentiated predominantly into parietal endoderm.(ABSTRACT TRUNCATED AT 250 WORDS)


2010 ◽  
Vol 88 (3) ◽  
pp. 479-490 ◽  
Author(s):  
Guoliang Meng ◽  
Shiying Liu ◽  
Xiangyun Li ◽  
Roman Krawetz ◽  
Derrick E. Rancourt

Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of the blastocyst. Because of their ability to differentiate into a variety of cell types, human embryonic stem cells (hESCs) provide an unlimited source of cells for clinical medicine and have begun to be used in clinical trials. Presently, although several hundred hESC lines are available in the word, only few have been widely used in basic and applied research. More and more hESC lines with differing genetic backgrounds are required for establishing a bank of hESCs. Here, we report the first Canadian hESC lines to be generated from cryopreserved embryos and we discuss how we navigated through the Canadian regulatory process. The cryopreserved human zygotes used in this study were cultured to the blastocyst stage, and used to isolate ICM via microsurgery. Unlike previous microsurgery methods, which use specialized glass or steel needles, our method conveniently uses syringe needles for the isolation of ICM and subsequent hESC lines. ICM were cultured on MEF feeders in medium containing FBS or serum replacer (SR). Resulting outgrowths were isolated, cut into several cell clumps, and transferred onto fresh feeders. After more than 30 passages, the two hESC lines established using this method exhibited normal morphology, karyotype, and growth rate. Moreover, they stained positively for a variety of pluripotency markers and could be differentiated both in vitro and in vivo. Both cell lines could be maintained under a variety of culture conditions, including xeno-free conditions we have previously described. We suggest that this microsurgical approach may be conducive to deriving xeno-free hESC lines when outgrown on xeno-free human foreskin fibroblast feeders.


Reproduction ◽  
2007 ◽  
Vol 133 (1) ◽  
pp. 231-242 ◽  
Author(s):  
Craig Smith ◽  
Debbie Berg ◽  
Sue Beaumont ◽  
Neil T Standley ◽  
David N Wells ◽  
...  

During somatic cell nuclear transfer (NT), the transcriptional status of the donor cell has to be reprogrammed to reflect that of an embryo. We analysed the accuracy of this process by comparing transcript levels of four developmentally important genes (Oct4,Otx2,Ifitm3,GATA6), a gene involved in epigenetic regulation (Dnmt3a) and three housekeeping genes (β-actin, β-tubulinandGAPDH) in 21 NT blastocysts with that in genetically half-identicalin vitroproduced (IVP,n=19) andin vivo(n=15) bovine embryos. We have optimised an RNA-isolation and SYBR-green-based real-time RT-PCR procedure allowing the reproducible absolute quantification of multiple genes from a single blastocyst. Our data indicated that transcript levels did not differ significantly between stage and grade-matched zona-free NT and IVP embryos except for Ifitm3/Fragilis, which was expressed at twofold higher levels in NT blastocysts.Ifitm3expression is confined to the inner cell mass at day 7 blastocysts and to the epiblast in day 14 embryos. No ectopic expression in the trophectoderm was seen in NT embryos. Gene expression in NTand IVP embryos increased between two- and threefold for all eight genes from early to late blastocyst stages. This increase exceeded the increase in cell number over this time period indicating an increase in transcript number per cell. Embryo quality (morphological grading) was correlated to cell number for NT and IVP embryos with grade 3 blastocysts containing 30% fewer cells. However, only NT embryos displayed a significant reduction in gene expression (50%) with loss of quality. Variability in gene expression levels was not significantly different in NT, IVP orin vivoembryos but differed among genes, suggesting that the stringency of regulation is intrinsic to a gene and not affected by culture or nuclear transfer.Oct4levels exhibited the lowest variability. Analysing the total variability of all eight genes for individual embryos revealed thatin vivoembryos resembled each other much more than did NT and IVP blastocysts. Furthermore,in vivoembryos, consisting of 1.5-fold more cells, generally contained two- to fourfold more transcripts for the eight genes than did their cultured counterparts. Thus, culture conditions (in vivoversusin vitro) have greater effects on gene expression than does nuclear transfer when minimising genetic heterogeneity.


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