(692e) Bioprinting of Large-Scale Hydrogels with Build-in Vascular Channels

Creating three dimensional (3D) vascular networks within tissue-engineered scaffolds is one of the major challenges in tissue engineering and regenerative medicine. Although there are some successful examples of vascularized channels, there is still a demand for robust fabrication of high-resolution 3D channel structures within thick (human-scale) scaffolds. 3D bioprinting enables fabrication of 3D scaffolds from multi-materials (bioinks) including hydrogels and cells with spatial resolution. In this work, we used extrusion-based bioprinting to fabricate thick scaffolds with highly tunable channels. Unlike freeform printing approaches, where a hydrogel is printed within another hydrogel or viscous medium, we developed a novel sequential printing approach. In our approach, a sacrificial ink formulation is printed sequentially with a photocurable “matrix” bioink formulation. Sacrificial bioink is printed at the interface of the matrix bioink. UV curing is followed by printing of additional matrix bioink, and final curing. The sacrificial hydrogel is then removed to achieve perfusable, high resolution, freeform channels. This approach allows us to fabricate human-scale scaffolds with tunable channels. In this study, matrix bioinks are formulated from photocurable hyaluronic acid-based or alginate-based hydrogels, with or without human mesenchymal stem cells (hMSC). Sacrificial hydrogel ink is formulated from Pluronic F-127. Human umbilical vein endothelial cells (HUVEC) are seeded within the channel surfaces. Within 7 days, uniform confluent endothelial layers are formed with the help of perfusion leading to a non-leaky layer within the channels. Meanwhile, the matrix embedded hMSCs show high viability during the whole culturing process. Our novel approach shows great potential to rapidly fabricate large scale vascularized scaffolds that can be used as in vitro models or tissue engineered implants.