Culturing keratinocytes and fibroblasts in a three-dimensional mesh results in epidermal differentiation and formation of a basal lamina-anchoring zone

The purpose of this study was to characterize an in vitro co-culture model in which fibroblasts grown in a three-dimensional nylon mesh were recombined with human keratinocytes. The cultures were kept for 3 and 5 weeks and then processed for electron microscopy. Keratinocytes showed reconstruction of an epidermis consisting of a basal layer with hemidesmosomes, a stratified epithelium with tonofilaments and desmosomes, a granular layer with keratinosomes and keratohyaline granules, and a transitional stratum corneum. Anchoring filaments, lamina densa, anchoring fibrils, bundles of elastin-associated microfibrils (diameters 10 nm) and fine collagen fibrils were formed. Collagen fibrils near the epidermis were much thinner than those in the lower levels. The present study shows that the dermal model containing metabolically active fibroblasts in their natural environment will support epidermal morphogenesis and differentiation including the formation of a basal lamina and anchoring zone.