Surface Marker Epithelial Cell Adhesion Molecule and E-cadherin Facilitate the Identification and Selection of Induced Pluripotent Stem Cells

The derivation of induced pluripotent stem cells (iPSCs) requires not only efficient reprogramming methods, but also reliable markers for identification and purification of iPSCs. Here, we demonstrate that surface markers, epithelial cells adhesion molecule (EpCAM) and epithelial cadherin (E-cadherin) can be used for efficient identification and/or isolation of reprogrammed mouse iPSCs. By viral transduction of Oct4, Sox2, Klf4 and n- or c-Myc into mouse embryonic fibroblasts, we observed that the conventional mouse embryonic stem cell (mESC) markers, alkaline phosphatase (AP) and stage-specific embryonic antigen 1 (SSEA1), were expressed in incompletely reprogrammed cells that did not express all the exogenous reprogramming factors or failed to acquire pluripotent status even though exogenous reprogramming factors were expressed. EpCAM and E-cadherin, however, remained inactivated in these cells. Expression of EpCAM and E-cadherin correlated with the activation of Nanog and endogenous Oct4, and was only seen in the successfully reprogrammed iPSCs. Furthermore, purification of EpCAM-expressing cells at late reprogramming stage by FACS enriched the Nanog-expressing cell population suggesting the feasibility of selecting successful reprogrammed mouse iPSCs by EpCAM expression. We have thus identified new surface markers that can efficiently identify successfully reprogrammed iPSCs and provide an effective means for iPSC isolation.