The panel of surface markers used to characterize undifferentiated hES cells recognize specific proteins or carbohydrates expressed on the cell surface. Common markers of undifferentiated hES cells include the globoseries glycolipid antigens designated stage-specific antigen-1 (SSEA-1), SSEA-3, and SSEA-4 [Kannagi et al., 1983] and the keratin sulfate-related antigens (Trafalgar antigens) TRA-1-60 and TRA-1-81 [Andrews et al., 1984]. Other markers such as the POU transcription factor OCT-4 are also expressed in pluripotent cell populations including undifferentiated hES cells [Rosner et al., 1990]. Furthermore, it has been shown that OCT-4 expression is necessary to maintain pluripo-tency in ES cells [Nichols et al., 1998; Boyer et al., 2005], and therefore the loss of OCT-4 expression can be used as a marker of differentiation [Loh et al., 2006].
Stem cell markers can be identified by immunocytochemical (ICC) staining using chromogenic or fluorescent antibodies and microscopy or flow cytometry. Protocol 2.11 outlines the use of ICC as a simple screening method as it is a relatively inexpensive and rapid way of characterizing of hES cells and can be performed without the need of a flow cytometer.
Was this article helpful?