Persistence of functional hepatocyte-like cells in immune-compromised mice

Background: Human embryonic stem cells (hESCs) can be efficiently differentiated to hepatocyte-like cells (HLCs) in vitro and demonstrate many of the functions and gene expression found in the adult liver. Aims: In this study, we assess the therapeutic value of HLCs in long-term cell-based therapies in vivo. Methods: hESC-derived HLCs were injected into the spleen of acutely injured NODscidIL-2Rγnull mice and analysed at various time points post-transplantation up to 3 months. Results: Large clusters of human cells engrafted in the spleen after 3 days and had expanded considerably by 31 days. At these time points, we identified human cells expressing parenchymal hepatocyte markers, exhibiting biliary duct-like structures and expressing myofibroblast markers. Three months after transplantation, we could detect human HLCs that were positive for albumin and CK18 by immunostaining and human DNA by fluorescent in situ hybridisation. Moreover, we could detect secretion of human serum albumin by enzyme-linked immunoabsorbant assay. Conclusions: We observed the persistence, engraftment and function of HLCs in vivo up to 3 months post-translation; however, all murine recipients developed large splenic and liver tumours that contained endodermal and mesodermal cell types. Although our studies demonstrate that hESC-derived HLCs have the potential to play an important role in cell-based therapies, current methodologies and transplantation strategies require substantial refinement before they can be deployed safely.