Direct differentiation of homogeneous human adipose stem cells into functional hepatocytes by mimicking liver embryogenesis.

The potential of adult human adipose tissue stem cells (hASCs) to differentiate into hepatocytes has generated much excitement over the possible use of hASCs in therapeutic applications. An understanding of the molecular mechanisms that underlie the plasticity of hASCs toward hepatocytes will help to make this possibility a reality. Herein, we show that a homogenous population of hASCs characterized by a high level of CD73, CD90, and CD105 express the pluripotent transcription factors OCT4, SOX2, NANOG, and SALL4 under proliferation conditions. A high level of activin A allows for hASCs acquiring the fate of definitive endoderm (DE) cells and expressing the specific transcription factors HEX, FOXA2, SOX17, and GATA4 synchronously. Using a reproducible three-stage method by mimicking liver embryogenesis, hASCs were directed to differentiate into functional hepatocytes. In the first stage, hASCs were induced to become DE cells by 2 days cultured in serum-free medium and 3 days of activin A treatment. Next, the presence of fibroblast growth factor (FGF) 4 and bone morphogenetic protein (BMP) 2 in the medium for 5 days induced efficient hepatic differentiation from DE cells. After 10 days of further maturated by the sequential exposure to hepatocyte growth factor (HGF), oncostatin M (OSM), and dexamethasone (DEX), the hASC-derived hepatocytes expressed mature hepatocytes marker and exhibited functional characterization, including albumin secretion, glycogen storage, urea production, activity of drug transporters, and cytochrome P450 activity. These findings will be useful for the implementation of hASC-derived hepatocytes in therapeutic purposes, metabolic analyses, drug toxicity screening, and studies of hepatocyte function.