Dynamic flow enables long‐term maintenance of 3‐D vascularized human skin models

Approaches to develop three-dimensional (3-D) vascularized human skin equivalents (vHSEs) that can mimic native skin are currently gaining momentum. Yet, the reproducible fabrication of vHSEs with superior barrier properties, sustained vasculature and high durability remains a challenge. Here, we aim to improve the stability of scaffold-free vHSEs by utilizing a dynamic flow culture system. We established that in static vHSEs, the uncontrolled interplay between matrix metalloproteinases (MMPs) and their inhibitors (TIMPs), and unconstrained angiogenesis lead to dermal instability. To obviate, we explored the effect of dynamic flow environment on vHSEs durability, using a custom-built 3-D printed bioreactor. Dynamic flow culture restored tissue homeostasis by balancing the expression of MMPs and their inhibitors, and via modulation of angiogenesis. This consecutively improved the skin barrier properties, facilitated the fabrication of thicker tissues, and enhanced wound closure. Moreover, we show that vHSEs in flow culture promoted vascular openings as perfusable sites. Altogether, this study highlights the importance of a dynamic milieu in the regulation of cellular signaling for the cultivation of vascularized tissue constructs.