The Ability of Inner-Cell-Mass Cells to Self-Renew as Embryonic Stem Cells Is Acquired following Epiblast Specification Researchers present transcriptional and functional data to identify the embryonic counterpart of embryonic stem cells (ESCs). Marker profiling shows that ESCs are distinct from early inner cell mass and closely resemble pre-implantation epiblast. [Nat Cell Biol] Abstract Towards a Clinical Use of Human Embryonic Stem Cell-Derived Cardiac Progenitors: A Translational Experience Data collected by researchers has led to approval by the French regulatory authorities for a first-in-man clinical trial of transplantation of SSEA-1+ progenitors in patients with severely impaired cardiac function. Although several facets of the manufacturing process still need to be improved, these data may yet provide a useful platform for the production of human embryonic stem cell-derived cardiac progenitor cells under safe and cost-effective good manufacturing practice conditions. [Eur Heart J] Abstract Identification of a Large Protein Network Involved in Epigenetic Transmission in Replicating DNA of Embryonic Stem Cells Investigators used a modified version of the iPOND (isolation of proteins at nascent DNA) technology to identify a large protein network enriched at nascent DNA in embryonic stem cells (ESCs). This comprehensive and unbiased proteomic characterization in ESCs reveals that, in addition to the core replication machinery, proteins relevant for pluripotency of ESCs are present at DNA replication sites. [Nucleic Acids Res] Full Article Aberrant DNA Methylation in ES Cells Both mouse and human embryonic stem cells can be differentiated in vitro to produce a variety of somatic cell types. Using a new developmental tracing approach, scientists showed that these cells are subject to massive aberrant CpG island de novo methylation that is exacerbated by differentiation in vitro. [PLoS One] Full Article Derivation of Stable Zebrafish ES-Like Cells in Feeder-Free Culture Zebrafish embryonic stem (ES)-like cells have been produced on a feeder cell layer. Researchers report the derivation of Z428, a zebrafish ES-like cell line, from blastula embryos in feeder-free culture. [Cell Tissue Res] Abstract Evaluation of Human Embryonic Stem Cells and their Differentiated Fibroblastic Progenies as Cellular Models for In Vitro Genotoxicity Screening The DNA damage response of human embryonic stem cells and their differentiated fibroblastic progenies were compared to a fibroblastic cell line and primary cultures of peripheral blood lymphocytes, upon exposure to Mitomycin C, gamma irradiation and H2O2. [J Biotechnol] Abstract Generation of Induced Pluripotent Stem Cell-Derived Mice by Reprogramming of a Mature Natural Killer T Cell Two lines of induced pluripotent stem cell-derived mice were generated by reprogramming of mature natural killer T cells, where one harbors both rearranged Vα14Jα18 and Vβ7 genes and the other carries rearranged Vα14Jα18 on both alleles but germline Vβ loci. [Int Immunol] Abstract Noninvasive Reporter Gene Imaging of Human Oct4 (Pluripotency) Dynamics during the Differentiation of Embryonic Stem Cells in Living Subjects To assess Oct4 activity noninvasively, investigators engineered a mouse embryonic stem cell line which encoded both a pOct4-hrluc (humanized renilla luciferase) reporter and a pUbi-hfluc2-gfp (humanized firefly luciferase 2 fused to green fluorescent protein) reporter. [Mol Imaging Biol] Abstract Directed Differentiation of Human Induced Pluripotent Stem Cells Toward Bone and Cartilage: In Vitro versus In Vivo Assays The ability to differentiate induced pluripotent stem cells (iPSCs) into committed skeletal progenitors could allow for an unlimited autologous supply of such cells for therapeutic uses; therefore, the authors attempted to create novel bone-forming cells from human iPSCs using lines from two distinct tissue sources and methods of differentiation that they previously devised for osteogenic differentiation of human embryonic stem cells, and as suggested by other publications. [Stem Cells Transl Med] Abstract Targeting Polycomb to Pericentric Heterochromatin in Embryonic Stem Cells Reveals a Role for H2AK119u1 in PRC2 Recruitment Building on recent studies that determined a reciprocal relationship between DNA methylation and Polycomb activity, scientists demonstrate that, in methylation-deficient embryonic stem cells, CpG density combined with antagonistic effects of H3K9me3 and H3K36me3 redirects Polycomb group complexes to pericentric heterochromatin and gene-rich domains. [Cell Rep] Full Article | Graphical Abstract |