A pure population of ectodermal cells derived from human embryonic stem cells.

Embryonic stem (ES) cells represent a unique cellular model to recapitulate in vitro early steps of embryonic development and an unlimited cellular source in therapy for many diseases, as well as targets for drug discovery and toxicology screens. Although previous studies have reported epidermal differentiation of mouse and human embryonic stem (huES) cells, the heterogeneity of the resulting cell culture impairs the evaluation of differentiated cells for cell therapy. We report here the reproducible isolation of a homogenous ectodermal cell population, IT1, from human ES cells. Like primary cells, IT1 cells remain homogenous over 15 passages, expand up to 60 population doublings, and then die through senescence. Accordingly, IT1 cells display a normal karyotype and a somatic cell cycle kinetics and do not produce teratoma in nude mice. The production of K14-expressing epithelial cells driven by p63 expression strengthens the ectodermal nature of IT1 cells. Since IT1 can be isolated from different huES cell lines, it may provide a ready source of ectodermal progenitors for the development of a toxicology cell model, new-drug-screening strategies, and cell therapy transplantation.