Establishment and long-term expansion of adult hepatobiliary organoids co-cultured with liver endothelial cells

The liver has a unique ability to regenerate in response to injury or disease with hepatocytes and biliary epithelial cells (BECs) driving the regenerative response. Liver progenitor cells (LPCs) also play role in regeneration with the ability to differentiate into either hepatocytes or BECs. However, during chronic liver disease, the regenerative capacity of the liver is impaired. The use of LPCs is a promising therapeutic strategy for patients with chronic liver diseases. LPCs can be expanded <i>in vitro</i> as self-renewing organoids, however, most approaches to LPC organoids do not include critical cells from the LPC niche in 3D organoid cultures. In this study, we highlight the role of liver endothelial cells (LiECs), as a part of LPC niche, in supporting the hepatobiliary organoids in long-term culture even in the absence of defined growth supplements, such as Wnt agonists. Furthermore, LiECs alter the gene expression profile of hepatobiliary organoids involved in inflammation, migration, extracellular matrix organization, and receptor signaling pathway through paracrine manner. Our findings expand the role of LiECs for regulating stemness of LPCs and elucidate a role for niche cells in a LPC organoid co-culture model with a reduction in growth supplements.