We have derived hESC from biopsied blastomeres of cleavage stage embryos under virtually the same conditions we used for the derivation of hESC lines from inner cell mass of blastocyst stage embryos. Blastomere-derived hESC lines exhibited all the standard characteristics of hESC including undifferentiated proliferation, genomic stability, expression of pluripotency markers and the ability to differentiate into the cells of all three germ layers both in vitro and in vivo. To examine whether hESC lines derived from two developmental stages of the embryo differ in gene expression, we have subjected three blastomere-derived hESC lines and two ICM-derived hESC lines grown under identical culture conditions to transcriptome analysis using gene expression arrays. Unlike previously reported comparisons of hESC lines which demonstrated, apart from core hESC-associated pluripotency signature, significant variations in gene expression profiles of different lines, our data show that hESC lines derived and grown under well-controlled defined culture conditions adopt nearly identical gene expression profiles. Moreover, blastomere-derived and ICM-derived hESC exhibited very similar transcriptional profiles independent of the developmental stage of the embryo from which they originated. Furthermore, this profile was evident in very early passages of the cells and did not appear to be affected by extensive passaging. These results suggest that during derivation process cells which give rise to hESC acquire virtually identical stable phenotype and are not affected by the developmental stage of the starting cell population.
Human embryonic stem cells derived from embryos at different stages of development share similar transcription profiles.
Specimen part, Disease, Cell line
View SamplesDuplication of the genome in mammalian cells occurs in a defined temporal order referred as its replication-timing program (RT). RT is regulated in units of 400-800 Kb referred as replication domains (RDs) and changes dynamically during development. Changes in RT are generally coordinated with transcriptional competence and changes in sub-nuclear position. We generated genome-wide RT profiles for 29 distinct human cell types including embryonic stem cell (hESC)-derived, primary cells and established cell lines representing intermediate stages of endoderm, mesoderm, ectoderm and neural crest (NC) development. We identified clusters of RDs that replicate at unique times in each stage (RT signatures). Surprisingly, transcriptome data revealed that, despite an overall correlation between early replication and transcriptional activity, most genes that switched RT during differentiation can be expressed when late replicating. Intriguingly, this class of genes was nonetheless induced to high expression levels prior to a late to early RT switch and down-regulated after the switch back to late replication. These results clarify the complex relationship between transcription and RT and identify classes of genes that behave as potential drivers of the RT switch vs. those that may depend upon an RT switch for transcriptional induction.
Human stem cells from single blastomeres reveal pathways of embryonic or trophoblast fate specification.
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