Controlled microvasculature for organ-on-a-chip applications produced by high-definition laser patterning.

Organs-on-Chips (OoCs) are 3D models aiming to faithfully replicatespecific functions of human organs or tissues. While promising as an alternative to traditional 2D cell culture and animal models in drug development, controlled realization of complex microvasculature within OoC remains a significant challenge. Here, we demonstrate how femtosecond laser patterning allows to produce hollow microvascular-like channels inside a collagen-based matrix directly within a microfluidic chip. The hydrogel preparation protocol was optimized to maintain structural stability, facilitating successful endothelialization of produced channels. The resulting microvascular structures exhibit notable physiological relevance, as evidenced by the expression of key endothelial markers (ZO-1, and VE-cadherin) and the successful reproduction of the barrier function. Furthermore, tumor necrosis factor-alpha (TNF-α) exposure induces a concentration-dependent increase in vascular permeability and expression of intercellular adhesion molecule-1 (ICAM-1). The proposed method holds the potential to control and faithfully reproduce the vascularization process in OoC platforms, in both physiological and inflammatory conditions.