Skin remodeling and wound healing in the Gottingen minipig following exposure to sulfur mustard

Sulfur mustard (SM), a dermal vesicant that has been used in chemical warfare, causes inflammation, edema and epidermal erosions depending on the dose and time following exposure. Herein, a minipig model was used to characterize wound healing following dermal exposure to SM. Saturated SM vapor caps were placed on the dorsal flanks of 3-month-old male Gottingen minipigs for 30 min. After 48 h the control and SM wounded sites were debrided daily for 7 days with wet to wet saline gauze soaks. Animals were then euthanized, and full thickness skin biopsies prepared for histology and immunohistochemistry. Control skin contained a well differentiated epidermis with a prominent stratum corneum. A well-developed eschar covered the skin of SM treated animals, however, the epidermis beneath the eschar displayed significant wound healing with a hyperplastic epidermis. Stratum corneum shedding and a multilayered basal epithelium consisting of cuboidal and columnar cells were also evident in the neoepidermis. Nuclear expression of proliferating cell nuclear antigen (PCNA) was contiguous in cells along the basal epidermal layer of control and SM exposed skin; SM caused a significant increase in PCNA expression in basal and suprabasal cells. SM exposure was also associated with marked changes in expression of markers of wound healing including increases in keratin 10, keratin 17 and loricrin and decreases in E-cadherin. Trichrome staining of control skin showed a well-developed collagen network with no delineation between the papillary and reticular dermis. Conversely, a major delineation was observed in SM-exposed skin including a web-like papillary dermis composed of filamentous extracellular matrix, and compact collagen fibrils in the lower reticular dermis. Although the dermis below the wound site was disrupted, there was substantive epidermal regeneration following SM-induced injury. Further studies analyzing the wound healing process in minipig skin will be important to provide a model to evaluate potential vesicant countermeasures.