KnockOut™ ESC/iPSC Media Kit - FAQs

Human ES cells are generally characterized by their typical morphology (they grow as tightly packed clusters of small cells with high ratio of nucleus to cytoplasm); surface marker expression; RT-PCR detection of stem cell-specific gene expression (such as Oct3/4, Sox2, and Nanog); alkaline phosphatase staining, and telomerase activity assay. The most commonly used ES specific surface markers include stage-specific embryonic antigens SSEA-3 and SSEA-4 for human ES cells. Other ES-specific surface antigens also include TRA-1-60 and TRA-1-81. (Science 282:1145 (1998).

Human ES cells are derived from human blastocyst inner cell masses, isolated by immunosurgery with rabbit antiserum to BeWO cells (a human trophoblast cell line) (Science 282:1145 (1998)).

Embryonic stem (ES) cells are derived from the early mammalian embryo and are capable of unlimited, undifferentiated proliferation in vitro while maintaining their potential to differentiate into a wide of range of adult tissues including germ cells. The pluripotency of the ES cells is normally demonstrated in vitro by inducing ES cells to differentiate into embryoid bodies and checking lineage-specific markers for differentiated cells in three body layers (endo, meso, and ectoderm), or injecting them into immunodeficient mice and determining the cell types produced in the teratomas.