3D bioprinting microgels to construct implantable vascular tissue.

Engineered implantable functional thick tissues require hierarchical vasculatures within cell-laden hydrogel that can mechanically withstand the shear stress from perfusion and facilitate angiogenesis for nutrient transfer. Yet current extrusion-based 3D printing strategies are unable to recapitulate hierarchical networks, highlighting the need for bioinks with tunable properties. Here, we introduce an approach whereby crosslinkable microgels enhance mechanical stability and induce spontaneous microvascular networks comprised of human umbilical cord vein endothelial cells (HUVECs) in a soft gelatin methacryoyl (GelMA)-based bioink. Furthermore, we successfully implanted the 3D printed multi-branched tissue, being connected from the rat carotid artery to the jugular vein direct surgical anastomosis. The work represents a significant step toward in the field of large vascularized tissue fabrication and may have implications for the treatment of organ failure in the future.