A Multiple-Cell Microenvironment in a 3-Dimensional System Enhances Direct Cellular Reprogramming Into Hepatic Organoids.

OBJECTIVES: The difficulty in proliferation and availability and the rapid loss functions of primary human hepatocytes highlight the need to develop an alternative, preferably renewable source of human induced hepatocytes in regenerative medicine. Liver organoids generated on a multiple-cell microenvironment in a 3-dimensional (3D) system can provide a highly efficient solution to this issue.

METHODS: Human hepatocytes were induced from fibroblasts by the lentiviral expression of FOXA3, HNF1A, and HNF4A. Together with these induced hepatocytes, human umbilical vein endothelial cells and mesenchymal stem cells in a 3D system were used to produce liver organoids. Liver-related gene and protein expression of liver organoids and induced hepatocytes were tested using a 2-dimensional (2D) system.

RESULTS: Liver organoids notably increased the expression of hepatic transcription factors, marker genes, transporter genes, and liver metabolism enzyme genes, while it decreased the specific gene expression of fibroblasts. Liver organoids expressed comparable liver-specific proteins, such as ALB, AAT, and HNF4A in the 3D system.

CONCLUSION: Direct reprogramming in multiple-cell microenvironments in 3D systems is more controllable and efficient than cell reprogramming in 2D systems. Liver organoids have the potential for use in disease modeling, pharmaceutical applications, and cellular transplantation.