Transplantation of liver organoids in the omentum and kidney.

Liver organoids were reconstructed by mouse-immortalized hepatocytes and nonparenchymal cells (sinusoidal endothelial cells and hepatic stellate cells) in a radial-flow bioreactor (RFB). A biodegradable apatite-fiber scaffold (AFS) was used as a scaffold packed in the RFB, which enables three-dimensional cell cultures. The organoids cocultured in the RFB showed a liver-like structure with high-density layers of hepatocytes and the formation of vessel-like structures. A liver organoid consisting of three cocultured cells was transplanted under the kidney capsule (kidney group) or into the omentum (omentum group) using BALB/c nude mice. Transplanted liver organoids survived in the kidney or omentum. The expression of mRNAs of albumin, connexin 26 and 32, hepatocyte nuclear factor 4α, and glucose-6-phosphatase was increased in both groups at 8 weeks after transplantation in comparison to the pretransplant status. Tyrosine aminotransferase appeared only in the omentum group. The results suggested that the functions of liver organoids differed depending on the transplanted site in the recipient animals.