Human embryonic stem cells (hESCs) are derived from the inner cell mass cells of blastocyst-stage human embryos. Cells have a prolonged undifferentiated proliferation potential with the ability to differentiate into cells of all the three germ layers.
Cells exhibit high levels of telomerase activity and express a distinctive class of surface antigens and markers: TRA-1-60, TRA-1-61, SSEA-3, SSEA-4, alkaline phosphatase, OCT-3/4, and Nanog.