Project description:Assessing relevant molecular differences between human-induced pluripotent stem cells (hiPSCs) and human embryonic stem cells (hESCs) is important, given that such differences may impact their potential therapeutic use. Controversy surrounds recent gene expression studies comparing hiPSCs and hESCs. Here, we present an in-depth quantitative mass spectrometry-based analysis of hESCs, two different hiPSCs and their precursor fibroblast cell lines. Our comparisons confirmed the high similarity of hESCs and hiPSCS at the proteome level as 97.8% of the proteins were found unchanged. Nevertheless, a small group of 58 proteins, mainly related to metabolism, antigen processing and cell adhesion, was found significantly differentially expressed between hiPSCs and hESCs. A comparison of the regulated proteins with previously published transcriptomic studies showed a low overlap, highlighting the emerging notion that differences between both pluripotent cell lines rather reflect experimental conditions than a recurrent molecular signature. See the Data Processing section of the published paper concerning the bioinformatics pipeline used. PMCID: PMC3261715 PMID: 22108792 Mol Syst Biol. 2011 Nov 22;7:550. doi: 10.1038/msb.2011.84. The quantitative proteomes of human-induced pluripotent stem cells and embryonic stem cells. Munoz J, Low TY, Kok YJ, Chin A, Frese CK, Ding V, Choo A, Heck AJ. Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
Project description:The equivalency of human induced pluripotent stem cells (hiPSCs) with human embryonic stem cells (hESCs) remains controversial. Here, we devised a strategy to assess the contribution of clonal growth, reprogramming method and genetic background to transcriptional patterns in hESCs and hiPSCs. Surprisingly, transcriptional variation originating from two different genetic backgrounds was dominant over variation due to the reprogramming method or cell type of origin of pluripotent cell lines. Moreover, the few differences we detected between isogenic hESCs and hiPSCs neither predicted functional outcome, nor distinguished an independently derived, larger set of unmatched hESC/hiPSC lines. We conclude that hESCs and hiPSCs are transcriptionally and functionally highly similar and cannot be distinguished by a consistent gene expression signature. Our data further imply that genetic background variation is a major confounding factor for transcriptional comparisons of pluripotent cell lines, explaining some of the previously observed expression differences between unmatched hESCs and hiPSCs. Expression profiling of human embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and fibroblasts, mostly in triplicates.
Project description:The equivalency of human induced pluripotent stem cells (hiPSCs) with human embryonic stem cells (hESCs) remains controversial. Here, we devised a strategy to assess the contribution of clonal growth, reprogramming method and genetic background to transcriptional patterns in hESCs and hiPSCs. Surprisingly, transcriptional variation originating from two different genetic backgrounds was dominant over variation due to the reprogramming method or cell type of origin of pluripotent cell lines. Moreover, the few differences we detected between isogenic hESCs and hiPSCs neither predicted functional outcome, nor distinguished an independently derived, larger set of unmatched hESC/hiPSC lines. We conclude that hESCs and hiPSCs are transcriptionally and functionally highly similar and cannot be distinguished by a consistent gene expression signature. Our data further imply that genetic background variation is a major confounding factor for transcriptional comparisons of pluripotent cell lines, explaining some of the previously observed expression differences between unmatched hESCs and hiPSCs.
Project description:It remains controversial whether human induced pluripotent stem cells (hiPSCs) are distinct from human embryonic stem cells (hESCs) in their molecular signatures and differentiation properties. We examined the gene expression and DNA methylation of 49 hiPSC and 10 hESC lines and identified no molecular signatures that distinguished hiPSCs from hESCs. Comparisons of the in vitro directed neural differentiation of 40 hiPSC and four hESC lines showed that most hiPSC clones were comparable to hESCs. However, in seven hiPSC clones, significant amount of undifferentiated cells persisted even after neural differentiation and resulted in teratoma formation when transplantated into mouse brains. These differentiation-defective hiPSC clones were marked by higher expression of several genes, including those expressed from long terminal repeats of human endogenous retroviruses. These data demonstrated that many hiPSC clones are indistinguishable from hESCs, while some defective hiPSC clones need to be eliminated prior to their application for regenerative medicine. Bisulphite converted DNA from 10 hESCs, 49 hiPSCs, 2 hECCs, 6 somatic cells and 3 cancer cell lines were hybridized to the Illumina Infinium 27k Human Methylation Beadchip.
