Ultrastructural and Immunohistochemical Characterization of an in Vitro Model of Human Epidermis: Its Potential for Sulfur Mustard Study

Abstract

The morphopathology of sulfur mustard dermal toxicity has been studied largely with in vivo models such as the hairless guinea pig and domestic weanling pig. Although these models have provided useful clues toward the understanding of mechanisms of sulfur mustard-induced dermal lesions, the correlation with human skin is not exact and the continuing availability of any animal model is problematic. In the interest of reducing research dependence on animal models, and to provide a laboratory model for sulfur mustard study with some level of correlation to human skin, we are evaluating an in vitro human epidermal model developed by Rhoads. The model was generated by seeding human keratinocytes onto Millipore Milli-Cm inserts precoated with type I collagen. The model, grown in culture for 7 days, presented a replicate display of epidermal structural components typically found in vivo. There was evidence of organotypic differentiation and stratification with characteristic cell types recognized to each epidermal stratum. Well-defined desmosomes, tonofilaments, human-type keratohyaline granules, and complete hemidesmosomes at the basement membrane zone were present. Im-munohistochemical investigations revealed the generation of the epidermal proteins, bullous pemphigoid antigen (BPA), and hemides-mosomal anchoring filament protein (GB3), both of which have been shown to be altered following dermal exposure to sulfur mustard. These characteristics, as well as the in-house availability of the model, may lead to its increasing facility as an appropriate in vitro human epidermal model for the replicate study of sulfur mustard-induced skin lesions.