A Bioengineered Skin Organoid Platform for Modeling Human Skin Physiology and Cytotoxicity.

Three-dimensional in vitro skin models are developed for studying skin physiology and drug toxicology. Most currently existing models are constructed through self-aggregation or layer-by-layer assembly of fibroblasts and keratinocytes only disregarding other important skin cell types. In this study, we used organoid fabrication technology to enable self-organization of multiple skin cell types into complex, tissue-like structures. The human skin organoids (SO) model was generated through aggregation of six primary human skin cell types-keratinocytes, melanocytes, dermal papilla cells, endothelial cells, fibroblasts, and adipocytes-under non-adhesive, gravity-driven culture conditions. The SOs exhibited spontaneous morphogenesis and developed compartmentalized structures resembling the native skin, including a stratified epidermis and a dermal-hypodermal core. The SOs maintained their skin-like organization for at least 21 days in culture and demonstrated key functional properties, including epidermal barrier integrity), active retinol metabolism, and responsiveness to chemical toxicity and ultraviolet radiation. In addition, SOs supported melanogenesis and vasculogenesis. In conclusion, we developed a self-organizing, multi cell type skin organoid system that recapitulates essential features of human skin architecture and function in vitro. Its complexity, scalability, and physiological relevance makes it a valuable platform for studies in skin physiology, toxicology, regenerative medicine, and disease modeling, including fibrotic skin disorders and skin cancer.