A Novel Approach to Pattern Dermal Papilla Spheroids in Dermal–Epidermal Composites Using Non-Adherent Microwell Arrays

Bioengineered dermal–epidermal composites (DECs) have demonstrated promise initiating skin regeneration and hair follicle neogenesis after injury. DECs in our work comprise a collagen matrix embedded with human dermal papilla cells (HDPCs) overlaid with human keratinocytes. HDPCs, as three-dimensional spheroids, enhance hair follicle formation, working in tandem with keratinocytes. Herein, 3D printed stamped PDMS microwell arrays were used as a strategy for spatially patterning dermal papilla spheroids in the dermal components of the DEC. DECs were transferred to cell culture media for 5 days followed by air–liquid interface culture for 2 days. Spheroid diameter, cell viability, and qPCR gene expression analyses were conducted. DECs were surgically grafted on immunocompromised mice, and healing was followed for 10 weeks. HDPCs cultured in the microwell arrays formed patterned viable spheroids and successfully transferred to the collagen dermal matrix. RNA analysis using qPCR showed upregulation of key HDPC markers (VCAN and BMP6) in DC microwell patterned HDPC spheroids compared to monolayers. This work represents a novel 3D printing strategy optimizing designing patterned HDPC spheroids in the extracellular matrix to regenerate functional human skin instead of scar tissue after injury.