Human assembloids recapitulate periportal liver tissue in vitro

Abstract The development of complex multicellular human in vitro systems holds great promise for modelling disease and progressing drug discovery and tissue engineering¹. In the liver, despite the identification of key signalling pathways involved in hepatic regeneration²,³, in vitro expansion of human hepatocytes directly from fresh patient tissue has not yet been achieved, limiting the possibility of modelling liver composite structures in vitro. Here, we first developed human hepatocyte organoids (h-HepOrgs) from 28 different patients. Patient-derived hepatocyte organoids sustain long-term expansion of hepatocytes in vitro and maintain patient-specific gene expression, and bile canaliculi features and function of the in vivo tissue. After transplantation, expanded human hepatocyte organoids rescue the phenotype of a mouse model of liver disease. By combining human hepatocyte organoids with portal mesenchyme and our previously published cholangiocyte organoids⁴⁻⁶, we generated patient-specific periportal liver assembloids that retain the histological arrangement, gene expression and cell interactions of the periportal liver tissue, with cholangiocytes and mesenchyme embedded in the hepatocyte parenchyma. We leveraged this platform to model aspects of biliary fibrosis. Our human periportal liver assembloid system represents a novel in vitro platform to investigate human liver pathophysiology, accelerate drug development, enable early diagnosis and progress personalized medicine.