Self-organization of human hepatic organoid by recapitulating organogenesis in vitro.

Abstract Background Careful orchestration among endodermal epithelial, endothelial, and mesenchymal cells initiate liver organogenesis prior to vascular function. Nonparenchymal endothelial or mesenchymal cells not only form passive conduits, but also establish an organogenic stimulus. Herein, we have evaluated the potential roles of primitive endothelial and mesenchymal cells toward hepatic organization in vitro. Methods To track the cellular movements and localization, we retrovirally transduced enhanced green fluorescence protein and kusabira orange into human fetal liver cells (GFP-hFLCs) and human umbilical vein endothelial cells (KO-HUVECs), respectively. GFP-hFLCs were cocultivated with KO-HUVECs and human mesenchymal stem cells (hMSCs) under conventional two-dimensional (2D) conditions. Results Even under 2D culture, fetal liver, endothelial, and mesenchymal cells self-organized into a macroscopically visible three-dimensional (3D) organoid. Time-lapse confocal imaging showed dynamic cellular organizations of GFP-hFLCs and KO-HUVECs. Endothelial cells organized into patterned clusters wrapping fetal liver cells, forming vessel-like lumens inside. Mesenchymal cells supported the generated organoid from outside. Conclusion Generation of whole organ architecture remains a great challenge so far. Our preliminary results showed that recapitulation of primitive cellular interactions during organogenesis elicit the intrinsic self-organizing capacity to form hepatic organoids. Future studies to define precise conditions mimicking organogenesis may ultimately lead to the generation of a functional liver for transplantation and for other applications such as drug development.