Liver Regeneration Supported by Muse Cells.

Cellular compensation from extrahepatic resources is expected to improve the prognosis of liver diseases. Currently, liver dysfunction is treated by a variety of modalities including drugs, cytokines, vascular interventions, energy devices, surgery, and liver transplantation; however, in recent years there have been few significant advancements in treatment efficacy. A next-generation therapeutic strategy for liver disease, cellular compensatory therapy (i.e., cell therapy), is now being considered for clinical practice. Liver dysfunction is attributed to a lack of sufficient functional cells. However, processes involved in recovery of liver function are not fully elucidated, which has complicated the interpretation of treatment effects at the cellular level. Our genotyping study of living donor liver transplantation revealed that a variety of graft liver tissues contained the donor genotype, indicating that extrahepatic cells had differentiated into liver component cells during liver regeneration. Multilineage-differentiating stress-enduring (Muse) cells appear to be a strong candidate for extrahepatic resources that can contribute to liver regeneration. Muse cells are defined as stage-specific embryonic antigen 3-expressing cells that contribute to tissue regeneration and have the potential to differentiate into three germ layers. The significant advantage of Muse cells over other "pluripotent cells" is that Muse cells are present in bone marrow/blood as well as a variety of connective tissues, which provides safety and ethical advantages for clinical applications. Here, we review current therapeutic topics in liver diseases and discuss the potential for cell therapy using Muse cells based on our recent studies of Muse cell administration in a mouse model of physical partial hepatectomy.