Fig. 3.

Strategies for vascularization of multicellular organ-on-a-chip platforms: (A) A schematic for microfluidic-based approach to a vascularized lung-on-a-chip (adapted from Huh et al[100]) (B) A human renal tubule on a chip created through soft lithography showing tubular channels overlying endothelial channels with flanking orthogonal views (top) and perspective views showing perivascular association with the vessel (bottom, adapted from Rayner et al[109]). (C) A 3D human heart model bioprinted in collagen (left) with vessels perfused in red (top right) and highlighted area shown magnified (bottom right, adapted from Lee et al[113]). (D) In vivo vasculature (top) was used to create a photomask for direct laser-writing of channels into a PEG-based hydrogel (bottom, adapted from Heintz et al[114]).