Bioink design for organ-scale projection-based 3D bioprinting

Projection-based three-dimensional bioprinting offers an approach for manufacturing biomimetic tissues with complex spatial structures and bioactivity, presenting potential for creating implantable organs or organoids to test drug response. Nevertheless, the extended printing times required for organ-scale manufacturing represents a challenge. Here we provide step-by-step instructions to manufacture organ-scale structures using bioinks while preserving high bioactivity. This approach incorporates Ficoll 400 to mitigate the heterogeneity of bioink with respect to refractive index and density, while 4-(2-aminoethyl)benzenesulfonyl fluoride and oil-sealing ensure the stability of the bioink components, thereby allowing extended printing times. This procedure also enables high-cell-viability printing via the calibration of the pH value of the bioink. This Protocol is appropriate for users with basic laboratory skills and fundamental knowledge in biotechnology to manufacture organ-scale structures for utilization in a wide variety of experimental designs. The approach is generalizable, as demonstrated by the successful printing of corpora cavernosa structures with a cell density of 10 million per milliliter, measuring 10 mm × 10 mm × 10 mm. After 7 d of culture, the cell viability was measured at 82.5%, highlighting the potential applicability in tissue engineering. All bioink preparation and printing steps are expected to take 5 h, while the development of printed structures requires 7 d of continuous culture.