Postdoc Max Planck Institute of Molecular Cell Biology and Genetics and Technische Universität München Dresden, Sachsen, Germany
Abstract: Modelling liver disease has been hampered by the lack of culture systems that represent disease progression in vitro. The current tissue-derived organoid models fail to reproduce the remarkable complexity of the tissue, both at the cellular composition as well as at the tissue architecture level. Here, we describe a next-generation organoid model composed of adult hepatocytes, cholangiocytes and liver mesenchymal cells that reconstruct the architecture of the periportal region of the liver lobule and, when manipulated, model aspects of cholestatic liver injury and biliary fibrosis in vitro. We first generate reproducible hepatocyte organoids (HepOrg) with a physiological and functional bile canaliculi network that retain morphological features of in vivo physiology and cholestatic response. Then, by combining these improved HepOrg models with cholangiocytes and portal fibroblasts, we generate periportal assembloids that recapitulate the architecture and cellular interactions of the liver periportal region. Periportal assembloids are functional as they consistently drain bile from the bile canaliculi into the lumen of bile ducts. Strikingly, the manipulation of the relative number of portal mesenchymal cells is sufficient to induce a fibrotic-like state in the assembloids, independently of an immune compartment. By generating chimeric assembloids from Mdr2-/- mutant and wild-type cells, we demonstrate the utility of our system to investigate cell-autonomous mechanisms in cholestatic injury and biliary fibrosis. Taken together, we demonstrate that periportal liver assembloids represent the first 3D in vitro system suitable to study the mechanisms underlying bile canaliculi formation, bile drainage and the contributions of the different cell types to cholestatic liver disease and biliary fibrosis, in an all-in-one model. This proof-of-concept study opens an avenue for more complex liver tissue-derived organoid models, which better recapitulate liver complexity, as well as physiological and pathological liver features in vitro.
