Inkjet-bioprinted 3D Microstructured Human Skin Equivalent

Tissue-engineered human skin equivalents which can represent the original human skin with a physiological relevance are in high-demand to replace the conventional animal testing in the cosmetics field and also to promote regeneration of large-area skin defects. In human skin, there are papillary microarchitectures in the dermo-epidermal junction, which serve both structural and functional roles as for they provide a strengthened mechanical anchoring and an active interaction between the dermis and the epidermis. However, conventional skin equivalents have been made simply by stacking dermis and epidermis layers in a planar manner, lacking the detailed microstructures of the native human skin. Here, we present a bioprinted human skin model with 3D microstructured dermis. The piezo-type inkjet printer enables the fabrication of cell patterns with a dermal fibroblast-laden collagen ink with high accuracy. As fibroblasts are widely known as they rearrange and reorganize the surrounding extracellular matrices by adhering and anchoring within them, we use this phenomena to form papillary microstructures in the dermal layer. By changing local density of dermal fibroblasts or by applying various shapes of cell patterns using inkjet cell printing, we are able to induce controlled 3D microstructures from printed fibroblasts as intended. Epidermal keratinocytes were then inkjet-printed onto the 3D microstructured dermis to form a densely packed monolayer. We believe that the inkjet-bioprinted 3D microstructured human skin equivalents will provide an enhanced physiological connection between in vitro and in vivo.2