Long-Term In Vitro Expansion of Salivary Gland Stem Cells Driven by Wnt Signals

• Published in: Stem cell reports Vol. 6; no. 1; pp. 150 - 162
• Main Authors: Maimets, Martti, Rocchi, Cecilia, Bron, Reinier, Pringle, Sarah, Kuipers, Jeroen, Giepmans, Ben N.G., Vries, Robert G.J., Clevers, Hans, de Haan, Gerald, van Os, Ronald, Coppes, Robert P.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 12.01.2016; Elsevier
• Subjects: Animals; Antigens, Neoplasm - metabolism; beta Catenin - metabolism; Cell Adhesion Molecules - metabolism; Cell Culture Techniques; Cell Proliferation; Cell Self Renewal; Cells, Cultured; Epithelial Cell Adhesion Molecule; Female; Mice, Inbred C57BL; Mice, Inbred NOD; Mice, Knockout; Mice, SCID; Mice, Transgenic; Microscopy, Confocal; Microscopy, Electron, Transmission; Radiation Injuries, Experimental - therapy; Salivary Glands - cytology; Salivary Glands - metabolism; Salivary Glands - radiation effects; Spheroids, Cellular - cytology; Spheroids, Cellular - metabolism; Stem Cell Transplantation - methods; Stem Cells - cytology; Stem Cells - metabolism; Stem Cells - ultrastructure; Time Factors; Wnt Signaling Pathway
• ISSN: 2213-6711; 2213-6711
• DOI: 10.1016/j.stemcr.2015.11.009

Adult stem cells are the ultimate source for replenishment of salivary gland (SG) tissue. Self-renewal ability of stem cells is dependent on extrinsic niche signals that have not been unraveled for the SG. The ductal compartment in SG has been identified as the location harboring stem cells. Here, we report that rare SG ductal EpCAM+ cells express nuclear β-catenin, indicating active Wnt signaling. In cell culture experiments, EpCAMhigh cells respond potently to Wnt signals stimulating self-renewal and long-term expansion of SG organoids, containing all differentiated SG cell types. Conversely, Wnt inhibition ablated long-term organoid cultures. Finally, transplantation of cells pre-treated with Wnt agonists into submandibular glands of irradiated mice successfully and robustly restored saliva secretion and increased the number of functional acini in vivo. Collectively, these results identify Wnt signaling as a key driver of adult SG stem cells, allowing extensive in vitro expansion and enabling restoration of SG function upon transplantation. [Display omitted] •EpCAMhigh cells generate salivary gland organoids in the presence of Wnt proteins•Wnt signaling is required for the maintenance of salivary gland stem cells in vitro•Wnt agonists promote long-term salivary gland stem cell expansion in culture•Expanded salivary gland stem cells regenerate damaged salivary glands in vivo Coppes and colleagues show that activation of Wnt signaling in EpCAMhigh cells purified from salivary gland (SG) tissue leads to the formation of organoids/miniglands, containing all SG lineages. Furthermore, Wnt proteins are required for self-renewal and robustly promote the long-term expansion of SG stem cells, which are efficiently able to regenerate radiation-damaged SG.