In vitro development and characterization of canine epidermis on a porcine acellular dermal matrix

The aim of this study was to develop and to characterize a canine skin epidermal model able to form a proper epidermis on a porcine acellular dermal matrix (PADM). In addition, the role of fibroblasts in skin barrier formation was studied by incorporating or omitting canine dermal fibroblasts in the PADM. Canine epidermal composites were developed by seeding keratinocytes onto the surface of PADM that were previously seeded or non-seeded with dermal fibroblasts. After 14 days of culture under air-exposed conditions and in a special growth medium, skin composites were histologically processed and immunohistochemically characterized to determine the expression of cytokeratins and of vimentin and the presence of basement membrane. In all composites, keratinocytes underwent differentiation to a multilayer epidermis with 5-7 viable cell layers. The stratum basalis, stratum spinosum, stratum granulosum and stratum corneum were identified. The expression of cytokeratins was similar to that described in healthy canine epidermis. Laminin and collagen IV immunostaining revealed a homogeneous layer in the epidermal-dermal junction only when the matrix had been seeded by canine dermal fibroblasts. The model may become a simple, useful and cost-effective tool to investigate the biology and pathology of canine epidermis and could partially replace animal testing in several areas of dermatological research.