Liver diseases account for two million deaths worldwide each year, and current treatments are limited. 3D bioprinting is a promising technology, that has recently been investigated to tackle this challenge. However, the cells and hydrogels used for bioprinting are not human-derived and do not replicate the natural in vivo environment. The goal of this study was to develop a printable and cytocompatible liver bioink incorporating human donor-derived biomaterials, including liver decellularized extracellular matrix (dECM) and intrahepatic cholangiocyte organoids (ICOs).

The ink was formulated by using a first enzymatic crosslinking step with hydrogen peroxide (H₂O₂), horseradish peroxidase (HRP), and tyramine-modified hyaluronic acid (HAT), followed by a second crosslinking step with Eosin Y (EO Y). The concentrations of materials were altered to optimise the ink's printability evaluated with shape fidelity measurements. The printed scaffolds retained their structural integrity for three days in AdvDMEM/F12 medium. The stiffness of the scaffolds was comparable to healthy liver tissue based on compression tests. The ICOs viability was assessed in the formulated bioink, and the composition of the bioink was adjusted to improve its cytocompatibility. It was found that EO Y and H₂O₂ at concentrations of 0.01% v/v and 0.85 mM, respectively, were cytotoxic to ICOs. Nevertheless, ICO viability was demonstrated over three days in a bioink consisting of HAT and liver dECM.

The novel bioink showed promising results for creating a human donor-derived bioink for 3D bioprinting liver tissue. Further optimisation is required to enhance the printability of the bioink, and additional tests are necessary to evaluate the effect of the bioink's materials on ICOs. This bioink has the potential to be applied for liver disease modeling and drug development.