Chicken embryonic stem cells as a non‐mammalian embryonic stem cell model

Abstract

Embryonic stem cells (ESCs) were isolated in the early 1980s from mouse and in the late 1990s from primate and human. These cells present the unique property of self-renewal and the ability to generate differentiated progeny in all embryonic lineages both in vitro and in vivo. The mESCs (mouse embryonic stem cells) can contribute to both somatic and germinal lineages once re-injected into a recipient embryo at the blastocyst stage. In avian species, chicken embryonic stem cells (cESCs) have been isolated from the in vitro culture of early chicken blastodermal cells (cBCs) taken from stage X embryo (EG&K) These cESCs can be maintained under specific culture conditions and have been characterized on the basis of their morphology, biochemical features, in vitro differentiation potentialities and in vivo morphogenetic properties. The relationship between these cESCs and some of the chicken germ cells identified and grown under specific culture conditions are still under debate, in particular with the identification of the Cvh gene as a key factor for germ cell determination. Moreover, by cloning the avian homologue of the Oct4 mammalian gene, we have demonstrated that this gene, as well as the chicken Nanog gene, was involved in the characterization and maintenance of the chicken pluripotency. These first steps toward the understanding of pluripotency control in a non-mammalian species opens the way for the development and characterization of putative new cell types such as chicken EpiSC and raises the question of the existence of reprogramming in avian species. These different points are discussed.Key words: blastoderm, chicken, germ cells, Nanog, Oct4, stem cells. Totipotency and pluripotency in animal cellsPioneer works carried out both in invertebrates (sea urchin) and vertebrates (newt) demonstrated as early as the last decade of the 19th century the existence of totipotent and pluripotent cells in early embryos. Indeed, Driesch (1891) demonstrated that a small sea urchin blastoderm dice will develop and form two independent animals whose size will be smaller than the parental one. This phenomenon is known as blastomere totipotency. Spemann replicated these results in 1902 with newt blastomeres taken at a two-cell stage and demonstrated that a newt larva could be split in two equal parts at 4, 8 or 16 blastomeres and regenerate two complete embryos. At this stage, the blastomeres are considered as pluripotent, that is, they are able to participate in the development of different embryonic tissues but not to reconstitute autonomously a whole organism.The development of mammalian embryos takes place exclusively in the mother's body. After fertilization, the egg will enter into division and form a small cluster of cells called the morula. It will be compacted and the most outer cells will form the trophectoderm annexes, which will give rise to extra-embryonic tissues while the inner cell mass (ICM), derived from the inner part of the morula will form the future embryo. During this expansion process a cavity will b...

Pluripotency and lineages in the mammalian blastocyst: An evolutionary view

“…Cells from the blastoderm of EGK-X stage chick embryos have been isolated and maintained in culture, and shown to contribute to chimeric embryos, and in some cases to the germ line. 30,49 Our results do not contradict the possibility that these cells are genuine multipotent cells, as they could be derivatives of PGCs (as we have argued before; Fernandez-Tresguerres et al 2010), or might even represent a cell type more akin to EpiS cells. 50,51 This would explain both the expression of the chick homologs of Oct4 and Nanog, and the particular growth factor requirements of these cells in culture (for example, the need for Fgfs).…”

Nonviral Minicircle Generation of Induced Pluripotent Stem Cells Compatible with Production of Chimeric Chickens

“…It was not determined whether these ciPSCs were present in hatched animals. Reports have regularly shown that cPGCs and cESCs have limited ability to form chimeric animals, with the number of chimeric animals ranging from 3% to 20%, with early passage cells and rates decreasing for late passage cells (Carsience et al, 1993;Lavial and Pain, 2010;Park et al, 2003). Techniques such as magnetic-activated cell sorting (MACS) and FACS based on specific markers, bisulfite treatments, and coring of the zona pellucida have increased chimera generation in chickens (Kim et al, 2010;Song et al, 2005;van de Lavoir et al, 2006b).…”

“…Chicken pluripotent stem cell culture conditions have remained elusive, with culture systems only being able to maintain cells for short time periods before changes in plasticity, proliferation, and phenotype of cells occurs (Carsience et al, 1993;Lavial and Pain, 2010;Park et al, 2003). These culture systems are typically complex, even beyond what is used for standard mouse and human pluripotent cells, requiring feeder cells, specialized media, and the use of animal products that have shown significant lotto-lot variability (Chaudhry et al, 2008;Pesce et al, 1993;Shamblott et al, 2001;Turnpenny et al, 2003).…”

Use of pluripotent stem cells for reproductive medicine: are we there yet?

“…Since the first report of chicken ESC derivation, it has been possible to develop recombinant chicken LIF (cLIF) which alone with serum was found to be sufficient to maintain chicken ESCs in their undifferentiated state (Horiuchi et al 2004). Despite the ability of cLIF to maintain undifferentiated chicken ESCs, their capacity to contribute successfully to chimeras was not studied yet (Lavial & Pain 2010). More recently, chicken chimeras were obtained by injecting ESCs into the subgerminal cavity of chicken embryos, proving their germline transmission capacity (Zhang et al 2013).…”