DEVELOPMENT OF A FULL THICKNESS IN VITRO HUMAN SKIN EQUIVALENT (EPIDERM-FT) FOR SULFUR MUSTARD RESEARCH.

This study by scientists at the U.S. Army Medical Research Institute of Chemical Defense and MatTek Corp. demonstrated that MatTek’s EpiDermFT full-thickness in vitro human skin tissue equivalent is an excellent in vitro alternative for studying the effects of human skin exposure to mustard gas. Skin exposure to the chemical warfare agent bis-(â-chloroethyl)sulfide (mustard gas) causes vesication at the basement membrane of the dermal/epidermal junction that is difficult to heal. Efforts to develop prophylactic and/or therapeutic treatments for mustard gas wounds have been hampered by lack of adequate human skin models. Therefore, an in vitro skin model was developed for mustard gas research. Normal human epidermal keratinocytes and dermal fibroblasts were cultured to produce highly differentiated full-thickness skin equivalents (EpiDerm-FT). Histologic examination of EpiDerm-FT shows a collagen dermis populated by viable fibroblasts and an epidermis of stratified keratinocytes including basal, spinous, granular and stratum corneum components. Examination of the dermal/epidermal junction by transmission electron microscopy (TEM) revealed a well-developed basement membrane. Hemidesmosomes exist at the basal membranes of keratinocytes, with associated tonofilaments extending into the cytoplasm. Well-defined lamina densa, lamina lucida and fine anchoring filaments are present beneath the basal keratinocytes. Anchoring fibrils connect the lamina densa to the underlying collagen matrix. Immunohistochemical analysis of basement membrane proteins was also performed. Protein markers of hemidesmosomes (á-6 integrin), lamina lucida (laminin 5), lamina densa (collagen IV) and anchoring fibrils (collagen VII) are localized to the dermal/epidermal junction. EpiDerm-FT was exposed to mustard gas for 8 minutes and evaluated at 6 and 12 hours post-exposure. Histological evaluation revealed typical mustard gas targeting of basal keratinocytes (cytopathology, condensed chromatin, pyknotic nuclei, increased eosinophilia) and epidermal cleavage at the dermal/epidermal junction. TEM show the lamina densa of the basement membrane was largely intact. EpiDerm-FT overcomes shortcomings of previous models in terms of providing a wall-to-wall tissue as well as appropriate in vivo-like basement membrane development. These attributes will enable more realistic in vitro toxicological studies of dermal/epidermal phenomena including mustard gas research.

Anchoring fibril , Basement membrane, Chemical warfare agents, EFT-200, EpiDerm-FT, EpiDermFT, HD pathogenesis , Hemidesmosome, Lamina Densa , Mustard gas (HD), NDHF Normal human dermal fibroblasts, Prophylactic and therapeutic treatments, Tonofilament , Wound healing, bis-(-chloroethyl)sulfide

Mustard gas (MD)