524 Tissue-engineered human skin age spot model with individualized hyperpigmentation lesion through high-resolution patterned 3D bioprinting and its use for the evaluation of cosmetic ingredients

Solar lentigines (SLs) are a major social and cosmetic concern to many individuals. To date, simple 2D monolayer cell cultures exposed UV or classical reconstructed pigmented epidermis without dermal compartment used explore the cellular molecular mechanisms involved in SL disorders. However, none of these conventional approaches recapitulates complexity SLs. Here, we developed first 3D full-thickness vitro model age spot including functional individualized hyperpigmentary zone (HPZ) surrounded by defined perilesional (PLZ) using unique high-resolution patterned bioprinting approach. The HPZ was printed predefined micropattern spotting, on equivalent, keratinocyte pre-induced melanocytes with IL1a KGF. Concomitantly, PLZ co-deposited non-induced cells. Macroscopic observations bioprinted constructs showed onset well-defined zone, which IL1a/KGF cells were spotted. Warthin Starry histological staining significant increase melanin deposition basal epidermal layer compared surrounding PLZ. Within HPZ, expression melan-A unchanged PLZ, suggesting that hyperpigmentation result an activation melanogenesis rather than hyperproliferation melanocytes. Analysis type VII collagen punctiform within revealing disorganized basement membrane, as observed vivo. Niacinamide treatment prevents lesion demonstrating responsiveness our ingredients targeting spots. This may be relevant tool further better understand underlying SLs disorders effectively identify novel pigmentation modulators based more scientific bases.