Question

Transformation of human embryonic stem cells

Answer 1

Human embryonic stem cells (HESCs) are the in vitro descendants of the pluripotent inner cell mass (ICM) of human blastocyst stage embryos. HESCs can be kept undifferentiated in culture or be differentiated to tissues representing all three germ layers, both in vivo and in vitro.

Answer 2

Answer:

Human cells have two control points that regulate their life span in vitro, the senescence and crisis phases. Senescence is associated with moderate telomere shortening and is characterized by cell cycle arrest and positive β-galactosidase staining at pH 6 ( 4). If cells bypass this stage, they continue to grow until telomeres become critically short and cells enter crisis phase, characterized by generalized chromosome instability that provokes mass apoptosis ( 5). Human cells immortalize at low frequency and seem resistant to spontaneous transformation