Hepatocytes are the primary cell type of the liver and function to provide the majority of the detoxification in the body. It is widely accepted that hepatocytes lose their function rapidly when cultured on a planar 2D surface. There is a desire within drug discovery and academic research to create a liver model that maintains higher levels of functionality for a longer period of time, ideally for many weeks.This would enable chronic exposure experiments to be carried out with some confidence that the results would bear similarities to results from primary cells and humans. The liver model is also an area where co-culturing of different cell types has proven to be of the most use. In addition to the parenchymal hepatocytes, researchers have been adding the non-parenchymal stellate and kupffer cells which clearly aid in supporting culture longevity and hepatocyte function.