Translating Dosage Compensation to Trisomy 21 Scientists tested the concept that gene imbalance across an extra chromosome can be de facto corrected by manipulating a single gene, XIST (the X-inactivation gene). Using genome editing with zinc finger nucleases, they inserted a large, inducible XIST transgene into the DYRK1A locus on chromosome 21, in Down’s syndrome pluripotent stem cells. [Nature] Abstract | Press Release Photoreceptor Precursors Derived from Three-Dimensional Embryonic Stem Cell Cultures Integrate and Mature within Adult Degenerate Retina To isolate photoreceptor precursors fit for transplantation, investigators adapted a recently reported three-dimensional differentiation protocol that generates neuroretina from mouse embryonic stem cells. They showed that rod precursors derived by this protocol and selected via a GFP reporter under the control of a Rhodopsin promoter integrate within degenerate retinas of adult mice and mature into outer segment-bearing photoreceptors. [Nat Biotechnol] Abstract | Press Release Reprogramming of Human Fibroblasts to Pluripotency with Lineage Specifiers Through a combination of transcriptome and bioinformatic analysis researchers have identified factors previously characterized as being lineage specifiers that are able to replace OCT4 and SOX2 in the reprogramming of human fibroblasts. [Cell Stem Cell] Abstract | Press Release Jmjd3 Controls Mesodermal and Cardiovascular Differentiation of Embryonic Stem Cells Researchers showed that ablation of Jmjd3 in mouse embryonic stem cells did not affect the maintenance of pluripotency and self-renewal, but compromised mesoderm and subsequent endothelial and cardiac differentiation. [Circ Res] Abstract The p53–PUMA Axis Suppresses iPSC Generation Scientists examined the role of PUMA, a pro-apoptotic mediator of p53, during somatic reprogramming in comparison to p21 in the p53 pathway. Using mouse strains deficient in these molecules, they demonstrated that PUMA is an independent mediator of the negative effect of p53 on induced pluripotent stem cell (iPSC) induction. [Nat Commun] Abstract Integration-Deficient Lentivectors: An Effective Strategy to Purify and Differentiate Human ES Cell Derived Hepatic Progenitors Scientists used lentivectors encoding GFP driven by the liver-specific apolipoprotein A-II promoter to purify human hepatic progenitors. They evaluated both integrating and integration-defective lentivectors in combination with an inhibitor of HIV integrase. A human ES cell line was differentiated into hepatic progenitors using a chemically-defined protocol. [BMC Biol] Abstract | Full Article MRAS GTPase Is a Novel Stemness Marker that Impacts Mouse Embryonic Stem Cell Plasticity and Xenopus Embryonic Cell Fate To characterize the effects of muscle ras oncogene homolog (Mras) on cell pluripotency and differentiation, investigators used gain- and loss-of-function strategies in mouse embryonic stem cells and in the Xenopus laevis embryo, in which Mras gene structure and protein sequence are conserved. [Development] Abstract Drug Metabolizing Enzyme and Transporter Protein Profiles of Hepatocytes Derived from Human Embryonic and Induced Pluripotent Stem Cells The expression and function of important drug metabolizing cytochrome P450 enzymes and transporter proteins in human embryonic and induced pluripotent stem cell-derived hepatocytes were compared to cryopreserved human primary hepatocytes and HepG2 cells. [Biochem Pharmacol] Abstract The Self-Renewal of Mouse Embryonic Stem Cells Is Regulated by Cell-Substratum Adhesion and Cell Spreading Using E14 and R1 mouse embryonic stem cells (mESC) lines, the authors restricted cell spreading in the absence of leukemia inhibitory factor by either culturing mESCs on chemically defined, weakly adhesive biomaterial substrates, or by manipulating the cytoskeleton. They demonstrated that by restricting the degree of spreading by either method, mESCs can be maintained in an undifferentiated and pluripotent state. [Int J Biochem Cell Biol] Abstract |