Two key requirements to develop a functional bioink for high fidelity extrusion bioprinting are that the formulation presents a shear thinning behaviour that reduces the viscosity significantly during the extrusion process, helping preserve the cell viability, and that the formulation presents thixotropic behaviour with fast recovery that favors the formation of a stable filament after the ink is extruded through the nozzle. The curves of viscosity vs. shear rate for GelMA-CBP formulations indicated that all the inks possessed shear thinning behavior at 37 ºC (Figures ).