In vitro transdifferentiation of adult hematopoietic stem cells: an alternative source of engraftable hepatocytes.

BACKGROUND/AIMS: We attempted to establish an ex vivo model for transdifferentiation of hematopoietic stem cells (HSCs) into functional hepatocytes for transplantation into healthy liver.
METHODS: We mimicked the liver regenerating microenvironment in culture by incorporating extracellular matrix components and sera obtained from mice with liver damaged by a hepatotoxic chemical. The differentiated hepatic cells were characterized in terms of liver-specific gene and protein expression. Cellular changes were determined by examining ultrastructure, and the functional activity was confirmed by cytochrome p450 enzyme assay. The engraftability of these hepatic cells in healthy liver tissue was checked by immunohistochemical analysis.
RESULTS: A specific sub-population of bone marrow-derived cells transdifferentiated into hepatic cells, confirmed by the expression of genes and proteins. The differentiated cells were found functionally active and ultrastructurally similar to primary hepatocytes in terms of the formation of microvilli and other cellular organelles. In healthy liver, these cells engrafted into hepatocyte plates and maintained the expression of albumin and cytokeratin-18.
CONCLUSIONS: Hepatic culture system differentiated HSCs into functional hepatocytes, which were engraftable in healthy liver. This finding offers an alternative strategy for treating many liver ailments using autologous bone marrow cells, hence avoiding immuno-suppressive drugs.