EPIDERM™ FULL THICKNESS (EPIDERM-FT™), A DERMAL-EPIDERMAL SKIN MODEL WITH A FULLY DEVELOPED BASEMENT MEMBRANE.

Paracrine signaling between dermal fibroblasts (FB) and epidermal keratinocytes (KC) is believed to modulate skin responses during contact irritant or allergic reactions. Dermal FB also play an important role in photo-aging and photo-damage, wound healing and cancer progression. To enable in vitro study of these and other dermal phenomena in which FB-KC interactions are important, a full thickness skin model composed of a FB-containing dermis/KC-containing epidermis was developed. Normal human epidermal KC and dermal FB were cultured to produce highly differentiated full-thickness tissues extending wall-to-wall in cell culture inserts. Histologic examination of the tissue shows a collagen dermis populated by numerous viable FB and an epidermis consisting of stratified KC including basal, spinous, granular and stratum corneum components. The ultrastructure of the dermal/epidermal junction was examined by transmission electron microscopy. A well-developed basement membrane was evident. Hemidesmosomes were observed at the basal membranes of KC, with associated tonofilaments extending into the cytoplasm. Well-defined, continuous lamina lucida and lamina densa and fine anchoring filaments were present beneath the basal KC. Anchoring fibrils with characteristic striated structure connected the lamina densa to the underlying collagen matrix. Tissue responses to ultraviolet irradiation (UVR) were also evaluated. Twenty-four hours after irradiation with 40 J/cm2 of UVR, tissues were examined histologically, and culture media was assayed for pro-MMP-1 secretion by ELISA. Irradiation produced numerous sunburn cells and disruption of basal KC organization compared to control tissues. Also, pro-MMP-1 secretion was significantly increased compared to controls. 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.

Allergic reactions, Anchoring fibrils, Anchoring filaments, Basement membrane, Cancer, Collagen, Collagen dermis, Collagen matrix, Contact irritant reaction, Dermal fibroblasts (FB), Dermal phenomena, Dermal/epidermal junction, Dermal/epidermal phenomena, ELISA, EpiDerm-FT, EpiDermFT, Epidermal keratinocytes (KC), Epidermis, FB-KC interactions, FB-containing dermis, Fine anchoring filaments, Full thickness, Hemidesmosomes, In vitro toxicological studies, In vivo-like basement membrane, KC-containing epidermis, Lamina densa, Lamina lucida, MMP, MMP-1, Paracrine signaling, Photo-aging, Photo-damage, Pro-MMP-1, Stratified KC, Stratum corneum, Sunburn cells, TEM, Tonofilaments, Transmission electron microscopy, UVA, UVB, Ultrastructure, Ultraviolet irradiation (UVR), Wound healing