Microfabrication of basal lamina analogs with complex topographic features

A microfabrication approach was used to produce novel analogs of the basal lamina with complex topographic features. A test pattern of ridges and channels with length scales (40 μm to 310 μm) similar to invaginations in native basal lamina was laser machined into a polyimide master chip. Negative replicates of the chip were used as templates to produce thin (~21 μm) collagen or gelatin membranes that recapitulated the complex topographic features of the master chip. To demonstrate their utility, membranes were incorporated into dermal analogs and their surfaces seeded with cultured human epidermal keratinocytes to form skin equivalents. The keratinocytes formed a differentiated and stratified epidermis that conformed to the features of the microfabricated membrane. Interestingly, the topography of the membrane influenced the differentiation of the keratinocytes as stratification was enhanced in the deeper channels. Membrane topography also controlled the gross surface features of the skin equivalent; infolds of the epidermis increased with channel depth. These microfabricated basal lamina analogs will help to elucidate the influence of topography on epithelial cell proliferation and differentiation and should have applications in the tissue engineering of skin equivalents as well as other basal lamina containing tissues