Expression of Notch signalling markers in bone marrow cells that differentiate into a liver cell lineage in a rat transplant model.

Notch signalling pathway plays an important role in cell differentiation. To investigate the implications of Notch signalling in the differentiation of rat bone marrow (BM) cells into a liver cell lineage, we used cultured BM cells to examine the mRNA expression of Musashi-1, which positively regulates Notch signalling, and made a transplant model to examine the protein expression of Notch signalling markers. For the in vivo experiment, BM cells were collected from transgenic rats expressing green fluorescence protein (GFP) and transplanted into the spleens of recipient rats, in which liver damage had been induced with carbon tetrachloride. The expression of Notch receptor 1 (Notch-1), Jagged-1 and Musashi-1, in the transplanted GFP-positive BM cells was investigated by immunohistochemistry. The expression of the liver-specific proteins, alpha-fetoprotein and cytokeratin19 was also investigated. Musashi-1 mRNA became detectable in the BM cells on culture day 7 in vitro. After transplantation, GFP-positive BM cells were observed in the portal areas of the recipient's livers. Notch-1, Jagged-1, Musashi-1, alpha-fetoprotein and cytokeratin19 were all expressed in the transplanted BM cells. These results suggest that the Notch signalling pathway plays a role in the differentiation of BM cells into a liver cell lineage.