In vitro basal lamina formation may require non-epidermal cell living substrate.

In an adult human epidermal cell culture system in which three different types of dermo-epidermal junctions could be observed, the in vitro synthesis of basement membrane and type IV collagen was studied with electron microscopy and indirect immunofluorescence via an antiserum to type IV collagen. Essentially, keratinocytes juxtaposed to non-living substrate did not produce either type IV collagen or an ultrastructural basement membrane, whereas both products were found at dermo-epidermal junctions composed of living keratinocytes juxtaposed to living dermis. This suggests that the microenvironment of the keratinocyte may influence the synthesis of junctional components.