In vitromodels for liver organogenesis and synthetic tissues including assembloid formation and multiple modes of collective migration

Chronic liver disease has reached epidemic proportions, affecting over 800 million people globally. The current treatment, orthotopic liver transplantation, has several limitations. Promising solutions have emerged in the field of liver regenerative medicine, with liver organogenesis holding significant potential. Early liver organogenesis, occurring between E8.5 and 11.5, involves the formation of epithelial-mesenchymal interactions leading to morphogenesis, hepatic cord formation, and collective migration. However, there is a lack of methods for in vitro modeling of this process. In this study, we present a detailed series of methods enabling the modeling of various stages and aspects of liver organogenesis. In one method series, we utilize assembloid technology with hepatic and mesenchymal spheroids, which replicate early structures found in liver organogenesis, model early morphogenesis, and demonstrate interstitial cell migration as seen in vivo. These innovative assembloid systems help identify factors influencing assembloid formation and migration. Hepatic spheroid cultivation systems were also employed to model collective migration and branching morphogenesis. Fibroblast-conditioned media play a significant role in initiating dose-dependent branching migration. Future work will involve high temporal and spatial resolution imaging of hepatic and mesenchymal interactions to determine the cascade of cellular and molecular events involved in tissue formation, morphogenesis, and migration.