Objectives: The salivary glands originate from the endoderm and consist of the acinar and ductal epithelial cells with exocrine function. In experimental duct ligation, acinar cells disappear due to apoptosis, followed by proliferation of duct epithelium. We have recently demonstrated that progenitor cells induced by salivary gland duct ligation in the rat (SGP-1). These SGP-1 cells can be induced in vitro to differentiate into hepatic or pancreatic phenotypes. In this report, we tried to isolate the tissue stem cells from the adult mice salivary gland by fluorescence-activated cell sorting (FACS) and verify multipotency of the cells. Methods: & Results: we analyzed the tissue stem cells induced by the salivary gland duct ligation in mice using immunohistochemistry and flow cytometry. Based on the analytical data, we sorted the Sca-1+/c-Kit+ fraction from adult mice salivary glands by FACS. The sorted cells were apparently homogeneous and designated as mouse salivary gland progenitors (mSGP). mSGP cells differentiated into hepatic lineage when cultured in matrigel. In spherical culture with glucagon-like peptide-1 (GLP-1), these cells differentiated into pancreatic endocrine lineage. When 20- to 30-mm diameter spheroid bodies of mSGP were transplanted into liver via portal vein, the cells were integrated into hepatic cords and expressed albumin and a1-antitrypsin suggesting differentiation into hepatic-type cells. Moreover, duct like structures formed by mSGP cells were also appeared, of which epithelial cells were positive for cytokeratin 19. Conclusions: FACS based on histological evidence is efficient to isolate adult tissue stem cells. Tissue stem cells of endodermal origin, for example hepatic oval cells, pancreatic epithelial progenitor cells and salivary gland progenitor cells, have similarities in their molecular markers and their tissue location. These evidences suggest the existence of common tissue stem cells of endoderm derived organs.

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