All-Cellulose Hydrogel-Based Bioinks for the Versatile 3D Bioprinting of Different Cell Lines

The development of bioink formulations with suitable properties is fundamental for the progress of 3D bioprinting. The potential of cellulose, the most abundant biopolymer, in this realm has often been underestimated, relegating it essentially to a reinforcement additive of bioinks. In this work, cell-laden bioink formulations, composed exclusively of cellulose, viz., "all-cellulose bioinks", were developed by combining carboxymethyl cellulose (CMC) and nanofibrillated cellulose (NFC) in different mass proportions (90/10, 80/20, and 70/30%). The incorporation of NFC increases the printability of the inks (from Pr = 0.7 to 0.9) while maintaining their shear-thinning behavior, and increasing contents of NFC also decrease the degradation rate of the hydrogels after 7 days. The bioprinting of the cell-laden formulations, with HaCaT (keratinocyte) and ATDC5 (chondrogenic) cells, resulted in high (>80%) cell viabilities for up to 7 days, corroborating the versatility of the bioinks and their potential to originate distinct 3D living structures for biomedical applications.