Abstract
To apply cell transplantation for treatment of diabetes mellitus, a sufficient number of β-cell sources are required. In the present study, we examined whether an epithelial cell line obtained from normal adult rat liver, namely hepatic stem-like (HSL) cells, which can be converted to both hepatocytes and billiary epithelial cells, could be a potential β-cell source. The growth speed of HSL cells was rapid and these cells were easily expanded in vitro. Bipotential hepatic stem cells, HSL cells, also expressed PGP9.5, which is expressed in neurons, β-cells, and progenitor cells of the pancreatic endocrine cells as well. Sodium butyrate induced morphological changes in HSL cells and converted them into flattened cells with large cytoplasm. When HSL cells were incubated with a combination of 5 mM sodium butyrate and 1 nM betacellulin, most of the cells were converted into morphologically neuron-like cells. RT-PCR analysis revealed that a series of transcriptional factors involved in differentiation of pancreatic endocrine cells was induced by the treatment with sodium butyrate and betacellulin. mRNAs for insulin, pancreatic polypeptide, and somatostatin were also observed. Immunoreactive pancreatic polypeptide, somatostatin, and insulin were detected in sodium butyrate and betacellulin-treated HSL cells. In conclusion, HSL cells obtained from adult normal liver also have the potential to differentiate into pancreatic endocrine cells in vitro. HSL cells may be one of the potential β-cell sources for cell transplant therapy for insulin-dependent diabetes.