In vitro pre-vascularized model of the human skin based on collagen hydrogel reinforced by fibrin-coated nanofibrous membrane.

Introducing pre-vascularization in functional full-thickness skin equivalents is critical to improve inosculation upon implantation. This study introduces a mechanically reinforced, bi-layered human skin model comprised of epidermis and pre-vascularized dermis. By combining a collagen type I hydrogel with an electrospun PCL/PLCL nanofibrous membrane coated with fibrin provisional matrix, we developed a composite scaffold that prevents the cell-induced hydrogel contraction and replicates the mechanical heterogeneity of native skin. The model utilizes a simultaneous tri-culture of human endothelial cells, adipose tissue-derived stromal cells, and keratinocytes. A custom 3D-printed, adjustable insert for cultivation at an air-liquid interface facilitates stratification of the dermal and epidermal layers. Our results demonstrate that adipose tissue-derived stromal cells effectively function as pericyte-like stabilizers, driving the formation of dermal capillary-like networks in 3D. This reinforced, pre-vascularized model provides a tool for improving tissue substitutes in vitro and in vivo, and a biomimetic platform for studying dermal-epidermal crosstalk and microvascular formation.