Keratinocyte Capability for Smooth Sheet Formation on a Step Pattern Substrate

The proper architecture of the epidermis is crucial for the barrier function of the skin against the external environment. In interfollicular regions, the epidermis preserves a flat outer surface despite the undulating topography of the underlying basement membrane. However, the mechanisms by which the epidermis adapts its architecture to the basal topography remain unclear. In this study, using a substrate with micropatterned steps of a few cell heights, we demonstrate for the first time that keratinocytes on the topographically patterned substrate autonomously form a cell sheet with a smooth upper surface. Keratinocytes accumulate at higher densities near the rising edge of a step, resulting in a cell sheet with a logarithmic slope on its upper surface. Furthermore, we find that both adherens junction-mediated intercellular adhesion and cell proliferation are essential for the formation of the smooth keratinocyte sheet. These findings suggest the robustness of keratinocyte population morphogenesis against variations in basal topography, providing new insights into skin tissue engineering.