![]() ![]() iPS cells have many advantages and the ethical concerns regarding the use of fertilized eggs are eliminated. Induced pluripotent stem (iPS) cells can be generated from adult human somatic cells by introducing factors such as Oct3/4, Sox2, Klf-4, and c-Myc (the four so-called Yamanaka factors), and like ES cells, iPS cells are able to self-renew and differentiate into cells representative of all three germ layers. While they are expected to contribute to cell-based therapy due to their ability to differentiate into a great variety of cells, ethical considerations relating to the use of fertilized eggs pose limitations for their practical use. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist.Įmbryonic stem (ES) cells derived from the inner cell mass of blastocysts are able to self-renew and differentiate into cells representative of all three germ layers, indicating that they are pluripotent stem cells. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.įunding: This study was supported by a Grant-in-Aid for Scientific Research (23390060) from the Ministry of Education, Culture Sports, Science, and Technology, Japan. Received: JAccepted: SeptemPublished: December 13, 2012Ĭopyright: © 2012 Wakao et al. (2012) Morphologic and Gene Expression Criteria for Identifying Human Induced Pluripotent Stem Cells. Our findings indicate that morphologic parameters and the expression of endogenous Sox2 and Cdx2 can be used to accurately identify iPS cells.Ĭitation: Wakao S, Kitada M, Kuroda Y, Ogura F, Murakami T, Niwa A, et al. Most importantly, gene expression analysis revealed for the first time that endogenous Sox2 and Cdx2 were expressed specifically in iPS cells, whereas Oct3/4 and Nanog, popularly used markers for identifying iPS cells, are expressed in colonies other than iPS cells, suggesting that Sox2 and Cdx2 are reliable markers for identifying iPS cells. The essential qualifications for iPS cells were: cells with a single nucleolus nucleus to nucleolus (N/Nls) ratio ∼2.19: cell size ∼43.5 µm 2: a nucleus to cytoplasm (N/C) ratio ∼0.87: cell density in a colony ∼5900 cells/mm 2: and number of cell layer single. Here we demonstrate that the morphologic features of emerged colonies can be categorized based on six parameters, and all generated colonies that could be passaged were classified into seven subtypes in colonies transfected with four retroviral vectors and six subtypes with a single polycistronic retroviral vector, both including iPS cell colonies. ![]() Therefore, we exhaustively analyzed the morphology and gene expression of all the colonies generated from human fibroblasts after transfection with four retroviral vectors encoding individual factors (192 and 203 colonies in two experiments) and with a single polycistronic retroviral vector encoding all four factors (199 and 192 colonies in two experiments). Researchers currently use visual observation to identify iPS cells and select colonies resembling embryonic stem (ES) cells, and there are no established objective criteria. ![]() While a great variety of colonies grow during induction, only a few of them develop into iPS cells. Induced pluripotent stem (iPS) cells can be generated from somatic cells by the forced expression of four factors, Oct3/4, Sox2, Klf4, and c-Myc. ![]()
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