ULTRASTRUCTURAL CHARACTERIZATION OF SULFUR MUSTARD-INDUCED VESICATIONIN ISOLATED-PERFUSED PORCINE SKIN

The isolated perfused porcine skin flap (IPPSF) is a novel alternative , humane in vitro model consisting of a viable epidermis and dermis wi th a functional microvasculature. For this study, 200 mu l of either 1 0.0, 5.0, 2.5, 1.25, 0.50, or 0.20 mg/ml of bis (2-chloroethyl) sulfid e (HD) in ethanol or ethanol control was topically applied to a 5.0 cm (2) dosing area of the IPPSF and perfused for 8 h with recirculating m edia. HD dermatotoxicity was assessed in the flap by cumulative glucos e utilization (CGU), vascular resistance (VR), light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microsco py (TEM). HD produced a statistically significant dose relationship fo r gross blisters and microvesicles. The HD-treated IPPSFs were also ch aracterized by a decrease in CGU and an increase in VR. Light microsco pic changes included mild intracellular and slight intercellular epide rmal edema, multifocal epidermal-dermal separation, and dark basal cel ls. Ultrastructural alterations consisted of cytoplasmic vacuoles, pyk notic basal cells, nucleolar segregation, and epidermal-dermal separat ion occurring between the lamina lucida and lamina densa of the baseme nt membrane. The severity of these changes increased in a dose-depende nt manner. Morphologically, the IPPSF appeared similar to human skin e xposed to HD with the formation of macroscopic blisters and microscopi c vesicles. In conclusion, the IPPSF appears to be an appropriate in v itro model with which to study the pathogenesis of vesicant-induced to xicity. (C) Wiley-Liss, Inc.