Objective: The hepatic integration of human adipose tissue derived mesenchymal stem cells (hAT-MSC) in vivo with or without prior differentiation to hepatocyte-like cells in vitro was investigated.
Methods and Results: Cells, isolated either from peritoneal or subcutaneous adipose tissue, expressed mesenchymal stem cell surface markers and featured multiple lineage differentiation. Under conditions favoring hepatocyte differentiation, hAT-MSC gained hepatocytic functions in vitro including urea formation, glycogen synthesis, cytochrome P450 enzyme activity, and expression of hepatocyte-specific transcripts of carbamoylphosphate synthetase (CPS), albumin, and cytochrome P450 type 3A4 (CYP3A4). Transgenic expression of GFP emerged upon hepatocyte differentiation when driven by the hepatocyte-specific promoter of the cytosolic phosphoenolpyruvate carboxykinase (PCK1) gene but was constitutive from the ubiquitin gene promoter. Human AT-MSC were transplanted into livers of immunodeficient Pfp/Rag2-/- mice with or without prior hepatocyte differentiation in vitro. Donor-derived human cells engrafted in the mouse host liver predominantly in the periportal region of the liver lobule. They expressed HepPar1 and albumin, typical features of differentiated human hepatocytes, in the otherwise negative mouse liver background. Engraftment was significantly more efficient using hAT-MSC pre-differentiated to hepatocyte-like cells in vitro as compared with undifferentiated cells.
Conclusions: Pre-differentiation of human MSCs from adipose tissue into hepatocyte-like cells in vitro facilitates long term functional hepatic integration in vivo.