Liver 'organ on a chip'

Highlights: • Ex vivo hepatic culture systems vary in complexity, from 2D to perfusion. • Cells can be sourced from humans (cell lines, stem cells, or primary) for species fidelity. • Including non-parenchymal cells is important to hepatocyte functionality. • Perfusion culture systems best mimic the complex physiology of the liver. • Scaling is important to reproduce paracrine signaling of the liver. The liver plays critical roles in both homeostasis and pathology. It is the major site of drug metabolism in the body and, as such, a common target for drug-induced toxicity and is susceptible to a wide range of diseases. In contrast to other solid organs, the liver possesses the unique ability to regenerate. The physiological importance and plasticity of this organ make it a crucial system of study to better understand human physiology, disease, and response to exogenous compounds. These aspects have impelled many to develop liver tissue systems for study in isolation outside the body. Herein, we discuss these biologically engineered organoids and microphysiological systems.