Study on hepatic differentiation of mesenchymal stem cells derived from human umbilical cord blood, and cell therapy for liver disease by use of mesenchymal stem cells.

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In this grant in aid for scientific research, we carried out a research project on therapeutic-model development of cell transplantation for liver disease by use of mesenchymal stem cells derived from human umbilical cord blood (CB-MSC).At first, we established a stable cell line of CB-MSC under our original culture condition supplement with fibroblast growth factor-2 (FGF-2), and succeeded to culture these cells in long term. The cell surface markers of our CB-MSC were confirmed to be similar to those of previous reports.Next, we tried to differentiate CB-MSC cell line into mature hepatocytes. In order to induce maturation, FGF-2 was removed from media, and the medium was supplemented with EHS gel. After the maturation step, CB-MSC was induced to express hepatic markers, such as glutamine synthetase and tyrosine amino-transferase (TAT). Additionally, we constructed retroviral vector expressing hepatic nuclear factor-4 (HNF-4), then, CB-MSC was infected with the retrovirus. HNF-4 expressing CB-MSC also expressed the transcripts of TAT.Finally, we tested cell transplantation of CB-MSC into chronically liver-injured mice. We employed immunodeficient (SCID) mice damaged chronically by a urokinase-type plasminogen activator transgene under a control of albumin promotor/enhancer (ALB-uPA/SCID mice). These mice were kindly provided from the Yoshizato Project, Cooperative Link of Unique Science and Technology for Economy Revitalization. The transplanted cord blood cells engrafted in the liver of ALB-uPA/SCID mice more efficiently than previously reported mouse-models. The engrafted CB cells exhibited the similar phenotype of functional hepatocytes.Our results suggested that human cord blood can supply the transplantable hepatic cells for liver disease. The outcome of the research project will be a basis of liver regenerative medicine, and we think the purpose of this grant in aid for scientific research was accomplished.