(396g) Systematic Application of 3D Bioprinting in the Fabrication of a Composite Full Thickness Human Skin Model

Considering the increasing aversion to the use of animal models in assessing the safety and efficacy of cosmetic and drug products, the use of tissue models is a promising alternative. While in vitro skin models are conventionally fabricated via manual deposition of cells onto a suitable extracellular matrix, a drawback of such a method is its inability to produce irregular tissue shapes and difficulties in scale up. The use of 3D bioprinting techniques has the potential to overcome these limitations through the efficient and uniform fabrication of skin models at a large scale. This study thus focuses on the development and validation of a novel full-thickness biomimetic skin model via extrusion-based bioprinting. A composite PCL collagen acellular layer was first constructed before a layer of fibroblast encapsulated collagen and a layer of cell culture medium containing keratinocytes were sequentially printed above it. The construct was then airlifted after a few days to allow for stratification and differentiation of keratinocytes. Bioprinted skin constructs were then compared with full thickness skin models produced via manual seeding of cells both qualitatively and quantitatively. Compared to full-thickness skin equivalents produced via manual seeding of cells, skin equivalents fabricated via 3D extrusion bioprinting had comparable qualitative and quantitative features when evaluated via cell viability assays, H&E staining and biomarker analysis. Permeability tests also provide evidence of good barrier function of skin models produced via 3D extrusion bioprinting. Our studies thus demonstrate the capability of dynamic extrusion PCL scaffold based printing in producing reconstructed human bi-layered skin equivalents with better epidermal morphogenesis, differentiation and physiological barrier functions. While promising, more studies are needed to optimize this 3D bioprinting methodology in order to improve recovery time and biomimeticity of human skin fabricated.