CUTANEOUS CELL AND EXTRACELLULAR-MATRIX RESPONSES TO ULTRAVIOLET-B IRRADIATION

The present study examined fibroblasts and keratinocytes in monolayers and cultured within dermal and skin substitutes and their use in asse ssing the effect of UVB irradiation on cutaneous cells and extracellul ar matrix organization. Dermal substitutes (DS) were produced by incor porating normal fibroblasts into a collagen lattice and skin substitut es (SS) were obtained by seeding normal keratinocytes onto the DS. Ker atinocyte monolayers, fibroblast monolayers, DS, and SS were exposed o nce a day to a UVB source(10 mJ/cm(2)). The irradiation protocol was s topped when the keratinocytes of the non-irradiated cultures (control groups) had reached confluence. Microscopic observations revealed that UVB radiation decreased both fibroblast and keratinocyte growth and e nhanced their differentiation resulting in (1) less fibroblasts in the DS and SS, and (2) incomplete coverage of the DS by keratinocytes. Mi croscopic observations and histological analyses revealed major morpho logical changes. Both cell types became bigger and presented wide nucl ei and vacuoles in the cytoplasm. No organized deep epidermal layer wa s observed in irradiated compared to non-irradiated SS. Irradiated DS and SS extracellular matrices showed an irregular aggregating collagen fiber organization with serious discrepancies suggesting large defect s in the structural properties of the extracellular matrix. The presen t study demonstrated that exposure to a UVB source led to profound mor phological and functional disturbances in both cutaneous cells and in the extracellular matrices of the DS and SS. The present technology wo uld be of great interest for step-by-step studies of UVR effects on cu taneous cell morphology and functional properties, and could be an alt ernative to using animals for pharmacological and toxicological evalua tions. (C) 1996 Wiley-Liss, Inc.