WOUND HEALING RESPONSE OF THE EPIDERM FULL THICKNESS (EPIDERM-FT™) IN VITRO HUMAN SKIN EQUIVALENT AFTER SOLAR UV IRRADIATION: COMPARISON TO EXCISED HUMAN SKIN.
Normal human epidermal keratinocytes (KC) and dermal fibroblasts (FB) were cultured to produce full-thickness skin equivalents consisting of FB-containing dermal and stratified epidermal components with a fully developed basement membrane at the dermal/epidermal junction (EpiDerm-FT 200, EFT). The wound healing response of EFT after solar UV-irradiation was compared to excised human skin. H&E stained paraffin sections of EFT displayed a dose-dependent increase in apoptotic sunburn cells at 24 h post-irradiation. After 48 h, high dose (61 J/cm2, metal halide lamp) samples showed extensive epidermal damage and some dermal damage. After 72 h, sunburn cells still persisted in mid dose samples (40 J/cm2), which were thinner than controls (indicating a major decrease in KC proliferation) but still without major epidermal damage. Epidermal destruction of high dose samples was nearly complete at 72 h with significant loss of dermal matrix also evident. However viable basal cells remained in some areas, with signs of proliferation and epidermal regeneration. MMP-1 activity in the culture media was also evaluated by ELISA. A 50% increase in activity was observed in irradiated samples at 24 h. By 48 h, mid dose samples showed a 100% increase in activity, while high dose samples showed a 150% increase. At 72 h, mid dose sample MMP-1 activity was comparable to controls, while high dose sample activity remained elevated by 125%. Similar experiments were conducted with excised human skin. The response was similar to EFT. The earliest response was increased sunburn cell formation, with tissue thinning at 40 J/cm2 and extensive damage at 61 J/cm2. Basal cell proliferation and epidermal regeneration was also observed in the excised human skin by 72 h in high dose samples. These results show that the EFT human skin equivalent behaves similarly to excised human skin in terms of solar UV induced damage and wound healing. The model may thus prove useful for additional applications in dermal/epidermal wound healing phenomena.
Basement membrane, Collagenase (MMP) release, Cytokine release, Dermal phenomena, EFT-200 cultures, EpiDerm-FT, EpidermFT, IL-8, Immunohistochemistry, Keratinocyte/fibroblast (KC/FB) interactions, MMP, Matrix metalloproteinase 1(MMP-1), Necrosis regeneration, Solar UV irradiation, Sunburn cell formation, Wound healing
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