Development of 3D Biofabricated Cell Laden Hydrogel Vessels and a Low‐Cost Desktop Printed Perfusion Chamber for In Vitro Vessel Maturation

: The vascular system represents the key supply chain for nutrients and oxygen inside the human body. Engineered solutions to produce sophisticated alternatives for autologous or artificial vascular implants to sustainably replace diseased vascular tissue still remain a key challenge in tissue engineering. In this paper, cell-laden 3D bioplotted hydrogel vessel-like constructs made from alginate di-aldehyde (ADA) and gelatin (GEL) are presented. The aim is to increase the mechanical stability of fibroblast-laden ADA-GEL vessels, tailoring them for maturation under dynamic cell culture conditions. BaCl2 is investigated as a crosslinker for the oxidized alginate-gelatin system. Normal human dermal fibroblast (NHDF)-laden vessel constructs are optimized successfully in terms of higher stiffness by increasing ADA concentration and using BaCl2 , with no toxic effects observed on NHDF. Contrarily, BaCl2 crosslinking of ADA-GEL accelerates cell attachment, viability, and growth from 7d to 24h compared to CaCl2 . Moreover, alignment of cells in the longitudinal direction of the hydrogel vessels when extruding the cell-laden hydrogel crosslinked with Ba2+ is observed. It is possible to tune the stiffness of ADA-GEL by utilizing Ba2+ as crosslinker. In addition, a customized, low-cost 3D printed polycarbonate (PC) perfusion chamber for perfusion of vessel-like constructs is introduced.