Large bone defects remain an unsolved clinical challenge because of the lack of effective vascularization in newly formed bone tissue. 3D bioprinting is a fabrication technology with the potential to create vascularized bone grafts with biological activity for repairing bone defects. In this study, vascular endothelial cells laden with thermosensitive bio-ink were bioprinted in situ on the inner surfaces of interconnected tubular channels of bone mesenchymal stem cell-laden 3D-bioprinted scaffolds. Endothelial cells exhibited a more uniform distribution and greater seeding efficiency throughout the channels. In vitro, the in situ bioprinted endothelial cells can form a vascular network through proliferation and migration. The in situ vascularized tissue-engineered bone also resulted in a coupling effect between angiogenesis and osteogenesis. Moreover, RNA sequencing analysis revealed that the expression of genes related to osteogenesis and angiogenesis is upregulated in biological processes. The in vivo 3D-bioprinted in situ vascularized scaffolds exhibited excellent performance in promoting new bone formation in rat calvarial critical-sized defect models. Consequently, in situ vascularized tissue-engineered bones constructed using 3D bioprinting technology have a potential of being used as bone grafts for repairing large bone defects, with a possible clinical application in the future.
Keywords: 3D bioprinted BMSCs-laden GelMA hydrogel scaffold, (GB); 3D bioprinting; 3D dual-extrusion bioprinted BMSCs-laden GelMA hydrogel and RAOECs-laden 3P hydrogel scaffold, (GB-3PR); 3D dual-extrusion bioprinted GelMA hydrogel and RAOECs-laden 3P hydrogel scaffold, (G-3PR); 3D printed GelMA hydrogel scaffold, (G); 4′,6-diamidino-2-phenylindole, (DAPI); Alizarin red S, (ARS); Alkaline phosphatase, (ALP); Dulbecco's modified Eagle's medium, (DMEM); Dulbecco's phosphate-buffered saline, (DPBS); Fourier-transform infrared, (FTIR); In situ vascularization; Large segmental bone defects; PLA-PEG-PLA, (3P); RNA sequencing Analysis; Tissue engineering; analysis of variance, (ANOVA); bone mesenchymal stem cells, (BMSCs); bone mineral density, (BMD); bone volume to tissue volume, (BV/TV); complementary DNA, (cDNA); differentially expressed genes, (DEGs); endothelial cells, (ECs); ethylenediamine tetraacetic acid, (EDTA); extracellular matrix, (ECM); fetal bovine serum, (FBS); gelatin methacryloyl, (GelMA); gene ontology, (GO); glyceraldehyde-3-phosphate dehydrogenase, (GAPDH); green fluorescent protein, (GFP); hematoxylin and eosin, (H&E); lithium phenyl-2,4,6-trimethylbenzoylphosphinate, (LAP); micro-computed tomography, (micro-CT); nuclear magnetic resonance, (NMR); optical density, (OD); paraformaldehyde, (PFA); phosphate-buffered saline, (PBS); polyethylene glycol, (PEG); polylactic acid, (PLA); polyvinylidene fluoride, (PVDF); radioimmunoprecipitation assay, (RIPA); rat aortic endothelial cells, (RAOECs); real-time polymerase chain reaction, (RT-PCR); standard deviation, (SD); tissue-engineered bone, (TEB); tris buffered saline with Tween-20, (TBST).
© 2022 The Authors.