Figure 5.

Various biomaterials such as natural, semisynthetic, or synthetic polymers have been widely used as bioink sources for construction of desired microtissues or organoids in organ-on-chip models using inexpensive desktop 3D bioprinter platforms. A) Schematic diagram of a two-step 3D bioprinting of hydrogel-based hepatic construct in which hiPSC-HPCs were patterned by the first digital mask with lobule structure (Left) followed by the patterning of supporting cells using a second digital mask with vascular structure. Reproduced with permission.^[181] Copyright 2015, Macmillan Publishers Limited. B) Schematic illustration of the tissue manufacturing process of i) printing of fugitive (vascular) ink within a 3D perfusion chip; ii) casting of ECM material over the printed fugitive inks; iii) evacuating fugitive ink; and iv) perfusion via an external pump. Photographs and confocal microscopy image of bioprinted thick vascularized tissue. Reproduced with permission.^[182] Copyright 2016, Macmillan Publishers Limited. C) Monolithic tissue construct containing patterned vascular architectures and living cells by printing carbohydrate-glass lattice serve as the sacrificial element and the formed vascular network with intervessel junction and vascular lumen. Reproduced with permission.^[183] Copyright 2012, Springer Nature. D) Schematic of procedure of fabricating endothelialized myocardium by an Organovo Novogen MMX bioprinter and the coaxial needle where the bioink is delivered from the core and the ionic crosslinking CaCl₂ solution is sheathed on the side by the two-step crosslinking process. Reproduced with permission.^[143] Copyright 2016, Elsevier Ltd. E) Fabrication of vascularized airway-on-a-chip (VA-OC) by 3D cell printing with the bioink that mixture of tracheal mucosa-derived dECM (tmdECM) and Matrigel. Reproduced with permission.^[188] Copyright 2019, IOP Publishing. F) Multimaterials bioinks optionally incorporated cells by d) mixing with polymers and polymer or polymer mixtures (PEGX) with linear (e.g., gelatin), branched (e.g., 4 arm PEG amine), or multifunctional (e.g., gelatin methacrylate) to form the bioink, and subsequence perform postprinting by secondary crosslinking to increase mechanical robustness. Reproduced with permission.^[189] Copyright 2015, John Wiley & Sons, Inc.