Mol. Hum. Reprod. Advance Access originally published online on February 7, 2008
Molecular Human Reproduction 2008 14(3):169-179; doi:10.1093/molehr/gan001
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GSK-3-specific inhibitor-supplemented hESC medium prevents the epithelial–mesenchymal transition process and the up-regulation of matrix metalloproteinases in hESCs cultured in feeder-free conditions
1Department of Embryology and Genetics, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, 1090 Brussels, Belgium 2Laboratory of Developmental and Tumour Biology, Université de Liège, Belgium
3Correspondence address. E-mail: urielle.ullmann{at}uzbrussel.be
Feeder-free culture induces spontaneous differentiation of human embryonic stem cells (hESCs), identified as an epithelial to mesenchymal transition (EMT). The maintenance of pluripotency of hESCs in feeder-free cultures through the activation of the WNT pathway using a glycogen synthase kinase (GSK)-3-specific inhibitor (BIO) was reported. The aim of this study was to determine the effect of BIO on the EMT process. In contrast with those grown in feeder-free conditions with control medium, hESC colonies cultured with BIO-supplemented hESC medium did not show any fibroblast-like cells at the periphery. Transmission electron microscopy, relative quantitative real-time RT–PCR and immunostaining analyses showed the presence of epithelial features and a diminution of mesenchymal features in the BIO-treated hESCs such as a strong E-cadherin expression, the down-regulation of Vimentin, Snail and Slug expressions and a cytoplasmic β-catenin expression. An up-regulation of matrix metalloproteinases (MMP) MMP-2, MMP-9, MT-1MMP (membrane-type 1 MMP) and EMMPRIN (extracellular MMP inducer) expression was also found associated with the EMT occurring in feeder-free hESCs cultures using mouse embryonic fibroblasts conditioned medium (MEF CM). The presence of BIO clearly down-regulated the expression of these MMPs. This study showed that BIO, a GSK-3-specific inhibitor, prevents the EMT process which is associated with the feeder-free hESC culture. Nevertheless, BIO was not sufficient to expand hESCs in a long-term culture system.
Key words: epithelial–mesenchymal transition/GSK-3 inhibitor/human embryonic stem cells/feeder-free culture/matrix metalloproteinases
This study was presented orally at the 23rd Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE) in Lyon (1–4 July 2007) (abstract O-166).
Submitted on July 31, 2007; resubmitted on December 28, 2007; accepted on January 3, 2008.