3D bioprinting of a cell-laden thermogel: an effective tool to assess drug-induced hepatotoxic response

Recent advances in bioprinting techniques have led to the investigation of novel hydrogel formulations to overcome the extensive in vitro culture required by the seeding of prefabricated 3D scaffolds. In this framework, the combination of different materials arises as a promising route to develop hydrogel matrices with cytocompatible gelation mechanisms and tailored chemo-mechanical behavior[1]. Thus, tunable properties can be achieved through the integration of multiple solidification/gelling mechanisms and multi-step cross-linking systems[2–4]. Here, a thermoresponsive Pluronic/alginate semi-synthetic hydrogel is used to bioprint 3D hepatic constructs, with the aim to investigate liver-specific metabolic activity of the 3D constructs compared to traditional 2D cultures[5]. A novel method for bioprinting hepatic cells is presented, via a robust and reproducible manufacturing process, characterized by high-shape fidelity, mild depositing conditions and easily manageable gelation mechanism. Furthermore, the dissolution of the sacrificial Pluronic templating agent significantly ameliorates the diffusive properties of the printed hydrogel. The findings herein demonstrate high viability and liver-specific metabolic activity, as assessed by synthesis of urea, albumin, and expression levels of the detoxifying CYP1A2 enzyme of cells embedded in the 3D hydrogel system. A markedly increased sensitivity to a well-known hepatotoxic drug (i.e. acetaminophen) is observed for cells in 3D constructs compared to 2D cultures. Therefore, the developed 3D model may represent an innovative in vitro platform, alternative to in vivo tests, for investigating drug-induced hepatotoxicity.