Embryonic Stem Cells Expressing Both Platelet Endothelial Cell Adhesion Molecule-1 and Stage-Specific Embryonic Antigen-1 Differentiate Predominantly

We examined the expression of cell-surface markers on sub-populations of mouse embryonic stem (ES) cells to identify those that were associated with cells that had the highest pluripoten-cy. Flow cytometry analysis revealed a wide variation in the ex-pression of platelet endothelial cell adhesion molecule 1 (PE-CAM-1) and stage-specific embryonic antigen (SSEA)-1 in ES cells. Almost all SSEA-11 cells expressed a high level of PECAM-1, and reversible repopulation was observed between PECAM-11SSEA-11 and PECAM-11SSEA-12 cells. The ES cells carrying the lacZ gene were sorted into three subpopulations: PECAM-12SSEA-12, PECAM-11SSEA-12, and PECAM-11SSEA-11. Quan-titative reverse transcription–polymerase chain reaction re-vealed a low level of Oct3/4 mRNA expression and an elevation in differentiation maker gene expression in PECAM-12 cells. T