Fig. 6.

(A) (i) Outline of construct design (solid and microchanneled), top and side views demonstrating interconnected microchannel network within the constructs. (ii) Casting of the anatomically shaped humeral head containing microchannels. (iii) Representative 3D reconstructions of vessel formation for each group along with corresponding 3D morphometric reconstructions of vessel diameters within the defects. Reprinted with permission from Ref. [95]. Copyright 2018, Elsevier Ltd. (B) Schematic drawing representing the printing process of the hollow-strut-packed (i.e., BRT-H) scaffolds for vascularized bone regeneration by means of the synergistic effect of the pipeline structure and bioactive ions. Reprinted with permission from Ref. [96]. Copyright 2020, Elsevier Ltd. (C) Schematic illustration. i) In summary, vascularized bone regeneration was fulfilled with the application of this direct cell-laden hydrogel, characterized by in situ pore-forming based on Mg degradation. (ii) The endothelial marker CD31 to visualize vascularized bone regeneration 3 weeks after defects repaired by the cell-laden porous hydrogel. Reprinted with permission from Ref. [85]. Copyright 2020, Elsevier Ltd. (D) Schematic showing the fabrication process of the 3D-bioprinted hierarchically porous hydrogel constructs by using an aqueous two-phase bioink. (i) The aqueous two-phase emulsion bioink containing the pre-gel GelMA/cell and PEO blend. (ii) 3D bioprinting and photocrosslinking. (iii)Minimally invasive injection of the hierarchically porous hydrogel constructs. (iv) Photographs showing the injectability performances using a porcine tissue model. Reprinted with permission from Ref. [84]. Copyright 2020, Wiley online library.