Identification of human cord blood-derived hepatic stem cells, and establishment of cell therapy for lethal liver disease

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In this grant in aid for scientific research, we carried out a research project on development of cell therapy using human umbilical cord blood. In the project, we planned that identification of hepatic stem cells from cord blood through in vitro and in vivo assay, and establishment of therapeutic animal models for lethal liver disease using cord blood cell after the treatment of differentiation into functional hepatocytes. The outcome of the research was as follows.At first, we purified the cells derived from cord blood using fluorescence-activated cell sorter. The positive and negative fractions of cell surface markers (i.e., CD45, CD34, c-met, lineage markers, and so on) were sorted, and were cultured in our original medium supplemented with FGF-1, FGF-2, HGF, SCF and LIF. In this culture condition, total cord blood cells were able to produce albumin and metabolite ammonia. The in vitro assay revealed that the purified CD45-positive cells and lineage markers-negative cells derived f … More rom cord blood can express albumin mRNA. Further examination showed that purified CD34-positive cells were able to express albumin mRNA in our original culture condition.Next, we performed a transplantation assay using purified cord blood cells. Cord blood cells were transplanted into liver-injured recipient mice, and their liver and the sera were analyzed. After the cell transplantation, the liver of recipient mice transplanted with CD34-positive cells contained human albumin-producing cells, indicating that cord blood CD34-positive cells engrafted in the liver and gave rise to hepatocytes. Furthermore, in the case of chronically liver-injured recipient mice, transplanted total cord blood cells were able to express marker-genes of functionally mature hepatocytes. These results showed that cord blood cells contain the hepatic progenitor cells, which can give rise to functionally mature hepatocytes.In conclusion, our data implied that human umbilical cord blood could be a source of hepatic progenitor 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. Less