Bioprinted human liver tissue model for evaluating Microcystin-LR-induced hepatotoxicity.

Microcystin-LR (MC-LR), a potent cyanobacterial hepatotoxin, poses increasing risks to environmental and human health, yet its toxicological effects in physiologically relevant human liver systems remain insufficiently understood. To address this gap, we developed a three-dimensional (3D) bioprinted human liver tissue model incorporating hepatocytes and hepatic stellate cells within a GelMA hydrogel. The printed constructs exhibited high structural fidelity, >85% cell viability, and progressive functional maturation over seven days, as demonstrated by increased ALB secretion, transporter activity, and antioxidant enzyme expression. Using this platform, we systematically evaluated MC-LR (0-200 nM) exposure for up to 14 days. MC-LR induced significant concentration- and time-dependent hepatotoxicity, including reduced ALB and CYP3A4 expression, impaired xenobiotic metabolism, and pronounced lipid accumulation. Notably, fibrogenic responses were strongly activated, with α-smooth muscle actin, collagen type I, and transforming growth factor-β1 increasing by eightfold, fourfold, and twofold, respectively, demonstrating that MC-LR disrupts lipid homeostasis and triggers hepatic stellate cell activation even at environmentally relevant concentrations. Furthermore, obeticholic acid, a selective FXR agonist, effectively alleviated lipid accumulation and suppressed fibrotic marker expression, revealing a potential therapeutic strategy. Overall, this study establishes a robust human-relevant 3D liver model that recapitulates key structural and functional features of the liver, enabling high-fidelity assessment of environmental toxin-induced hepatotoxicity. The platform provides mechanistic insights into MC-LR action and serves as a promising tool for environmental risk assessment and therapeutic evaluation.