Human precision-cut liver slices (hPCLS) are a widely used experimental model for studying human liver physiology and evaluating the safety of new drugs. These ultra-thin sections of liver tissue preserve the organ’s three-dimensional architecture and the complexity of its cellular composition, allowing researchers to investigate liver function under conditions that closely resemble human physiology. However, they have a major limitation: in the laboratory, they remain viable for only about 48 hours, making it difficult to study biological processes and drug effects over extended periods.

The study, published in Advanced Science, was conducted by an international team of researchers from several European research centers, including Humanitas Research Hospital and Humanitas University. The study was led by Salvatore Piscuoglio, senior and corresponding author, Associate Professor at Humanitas University and Head of the Precision Medicine Laboratory at Humanitas Research Hospital, together with Charlotte K. Y. Ng, Associate Professor at Humanitas University and Head of the Computational Biology Laboratory at Humanitas Research Hospital. The research also benefited from the contribution of the Pathology Unit at Humanitas Research Hospital, with the participation of Luigi Maria Terracciano, Scientific Director of Humanitas Research Hospital and Rector of Humanitas University.

Extending liver tissue viability in the laboratory

To overcome this limitation, the researchers developed an optimized ex vivo culture system, named hPCLS-EV (Extended Viability). The approach combines three key elements: reduced tissue slice thickness, increased oxygen availability, and culture at an air-liquid interface, which enables more efficient oxygenation than conventional methods. Under these conditions, liver slices preserve their structural organization for a longer period. Hepatocytes, the cells responsible for most of the liver’s metabolic functions, maintain their integrity, while stromal cells and resident immune cell populations, essential components of the liver microenvironment, are also preserved.

A liver that continues to function

In addition to preserving tissue architecture, the new culture system maintains key liver functions over time, extending the experimental observation window compared with conventional models. Analyses showed sustained albumin secretion, preserved glutathione levels, a key molecule involved in protection against oxidative stress, and maintained activity of cytochrome P450 enzymes, essential for the metabolism of drugs. Gene expression profiling further confirmed the preservation of tissue integrity. Although a reduction in the activity of some metabolic pathways was observed by day three, gene expression subsequently stabilized, with no evidence of marked tissue damage or fibrotic remodeling through day five of culture.

Overall, these findings indicate that the system preserves the biological characteristics required to investigate liver processes that require longer observation periods than those achievable with conventional hPCLS models.

A reliable platform for drug toxicity testing

To assess its performance, the researchers used hPCLS-EV to model drug-induced liver injury (DILI), one of the leading causes of drug development failure and post-marketing drug withdrawal. Two compounds with distinct mechanisms of hepatotoxicity were tested: acetaminophen (paracetamol) and troglitazone. The system successfully reproduced drug-specific patterns of liver injury. In acetaminophen-treated slices, researchers observed an early depletion of glutathione reserves, one of the hallmark early events of overdose toxicity. In contrast, troglitazone induced a slower, progressive increase in oxidative stress, consistent with its different mechanism of hepatotoxicity.

A more stable platform for preclinical research

The availability of a system capable of preserving tissue architecture, cellular composition, and key liver functions for several days represents an important advance for preclinical research. By extending tissue viability, the platform enables researchers to monitor the progression of liver injury and treatment responses over time, strengthening its potential as a tool for toxicology studies, investigations into disease mechanisms, and ultimately precision medicine applications based on patient-derived tissue samples.