Enhancing cell survival in 3D printing of organoids using innovative bioinks loaded with pre-cellularized porous microscaffolds

Extrusion bioprinting is a relevant 3D technology to create biological systems in regenerative medicine, pharmaceutical development and cancer research. Bioink is the necessary component to incorporate the cells that will be printed by extrusion bioprinting. However, bioinks and extrusion printing can generate shear stresses mechanically unfavorable for cell survival. We thus developed a bioink, based on methacrylated collagen and hyaluronic acid, in combination with porous poly(D,L-lactic-co-glycolic acid) solid microscaffolds to protect cells against mechanical stress during extrusion printing. We found that porosities of the microscaffolds allowed human chondosarcoma cells to colonize the structure. Moreover, metabolic activity of these chondrosarcoma cells, fibroblast cells, and dental pulp stem cells (DPSCs) incorporated within bioink (before printing) increased 4-fold in presence of a polylysine- or collagen-coated microscaffolds compared with those cultured without microscaffolds. Their survival increased by 10% either by hand deposition or by bioprinting extrusion (bioprinter BioBot®Basic) compared to cells in bioink without microscaffolds. In addition to the mechanoshield properties provided by microscaffolds, they allow the migration of DPSCs stem cells towards HCS-2/8 cancer cells after 7 days of co-culture in an organoid created by bioprinting extrusion while without microscaffolds the cells aggregated and remained static.