Alternatives to animal testing to assess MASH drugs and hepatotoxicity

The Food and Drug Administration (FDA) Modernization Act 2.0 "allows for alternatives to animal testing for purposes of drug and biological product applications." This provides an opportunity to develop and improve alternatives to animal studies to assess drugs in the liver. Two-dimensional cultures of liver cells fail to maintain their differentiated state and fail to reproduce liver disease phenotypes. Therefore, several platforms using human liver cells are being developed either to (1) assess hepatotoxicity of drugs or (2) create "diseases in a dish" to assess the effectiveness of drugs in treating liver diseases, primarily focused on treating MASH. The technological approaches include precision cut liver slices, human liver spheroids, human liver organoids, bioprinted human liver tissues, and microphysiological systems. This review evaluates each of these technologies and their role in providing alternatives to testing in animals.