The heterogeneity of dermal mesenchymal cells reproduced in skin equivalents regulates barrier function and elasticity

The heterogeneity of dermal mesenchymal cells, including perivascular mesenchymal cells and papillary and reticular fibroblasts, plays critical roles in skin homeostasis. Herein, we present human skin equivalents (HSEs), in which pericytes, papillary fibroblasts, and reticular fibroblasts are spatially organized through autonomous three-cell interactions among epidermal keratinocytes, dermal fibroblasts, and vascular endothelial cells. The replication of dermal mesenchymal cell heterogeneity enhances skin functions, including epithelialization, epidermal barrier formation, and dermal elasticity, enablingin vitroevaluation of drug efficacy using methodologies that are identical to those used in human clinical studies. Furthermore, ascorbic acid-induced epidermal turnover and synthesis of well-aligned extracellular matrix via perivascular niche cells play crucial roles in improving skin barrier function and elasticity. Therefore, HSEs with heterogeneous dermal mesenchymal cells may improve our understanding of the mechanisms underlying skin homeostasis through cell-to-cell communication and serve as a model to animal experiments for developing precision medicine.