Fig. 2. Sacrificial extrusion-assisted bioprinting:

(A) Step-by-step display of a chip bioprinting: (i) the device is prepared with a bottom lid, (ii) imprinting a matrix material, (iii) bioprinting of the matrix material and (iv) liquefying the infusion bioink. (B) Agarose channels within GelMA hydrogel: (i) printed agarose template fibers, (ii) perfused fluorescent dye in the channel. (C) Pluronic F-127 channels within GelMA hydrogel: (i) bifurcated microchannels in the GelMA hydrogel, (ii) HUVECs CD31 (green) and nuclei (blue) staining. (D) Vascularized gelatin-based tissues, (left) HUVEC-lined vascular channel supporting a fibroblast-laden gelatin within a 3D perfusion chip (right) and long-term perfusion of HUVEC-lined (red) network supporting HNDF-laden (green) gelatin at day 45 (Scale bar: 100 μm). (E) Carbohydrate-glass lattice as the sacrificial element: patterned channels support positive pressure and pulsatile flow of human blood with inter-vessel junctions supporting branched fluid flow (left). Spiral flow patterns (right, 0.4 s; Scale bars: 1 mm for left and 2 mm for right). Reprinted with permission from references Datta et al. [37], Bertassoni et al. [33], Zhang et al. [44], Kolesky et al. [6] and Miller et al. [50].