LIPID AND ULTRASTRUCTURAL CHARACTERIZATION OF A NEW EPIDERMAL MODEL SHOWS GOOD CORRESPONDENCE TO NORMAL HUMAN EPIDERMIS.

A model of the human epidermis, EpiDerm, based on neonatal foreskin-derived normal human epidermal keratinocytes (NHEK), has recently been characterized by scientists at the University of Iowa College of Dentistry in terms of stratum corneum (SC) lipids and ultrastructure. Cultured using serum free media, the model allows determination of the effects of defined media additives on SC lipids, intercellular lamellae, and epidermal barrier properties. Using quantitative thin layer chromatography, all lipid species normally present in epidermis were identified in proportions remarkably similar to those of native epidermis. Although RuO4 stained thin sections of these cultures showed infrequent clusters of abnormal lamellar fragments and intercellular lamellae that were not as uniform as those observed in vivo, these cultures do show evenly spread and alternating broad-narrow-broad lamellar patterns characteristic of the intercellular lamellae of normal epidermis SC. The permeability of optimized cultures to tritiated water was not significantly different from that of human skin (p < 0.05). These results, along with others showing normal epidermal structure, biochemistry, and function, provide the theoretical basis for use of this model to study dermal irritation and skin penetration in vitro.

Barrier properties formation, Ceramides, Cutaneous irritancy, Cutaneous irritation, Cutaneous toxicity, Dermal irritancy, Dermal irritancy testing, Dermal irritation, Dermal penetration, EpiDerm, Lamellar sheets, Lipids, ceramides, Percutaneous absorption, Skin irritancy, Skin irritation, Ultrastructural Characteristics