Epidermal keratinocytes represent the major cell type of the epidermis, making up about 90％ of the cells. They originate in the stratum basale and undergo gradual differentiation including profound morphological changes during their shift to the stratum corneum. In the stratum corneum, the final barrierlayer of the skin, keratinocytes are found as nucleus-free, flat, and highly keratinized squamous cells. AcceGen offers a range of Normal Human Epidermal Keratinocytes （NHEK） from single donors or pooled donors produced at Promo- Cell's cell culture facility. The cells are isolated from juvenile foreskin or from adult normal human tissue from different locations, e.g. face, breast, abdomen, and thighs. Shortly after isolation, all AcceGen Normal Human Epidermal Keratinocytes are cryopreserved at passage 2 （P2） using AcceGen's proprietary, serum-free freezing medium, Cryo-SFM. Each cryo vial contains more than 500,000 viable cells after thawing. Proliferating cell cultures are made from 500,000 cryopreserved cells that have been thawed and cultured for three days at AcceGen.
