Nestin-positive pancreatic stem (NPPS) cells upon neogenic motivation and isolation of NPP-rich ductal epithelia from neogenic tissue following partia

초록

Recently nestin is generally used as a specific marker of stem cells or progenitor cells for various functional tissues or organs including pancreas. We hypothesized that nestin-positive pancreatic progenitor cells could arise from ductal cells in response to neogenic stimulation. Following subtotal Px in rat, we identified a population of nestin expressing cells in the neogenic tissue, particularly in the neogenic ductules or tubules, but not in the differentiating acini, indicating that nestin is expressed in undifferentiated cells and fades as differentiate. We demonstrated that nestin cells in the neogenic pancreatic tissue differ from the cells in the mesenchyme surrounding ductules or tubules. We isolated the neogenic ductules or tubules from the pancreatic remnant 3 days after Px, and maintained them in culture for 2-3 days. Duct epithelial cells grew radically from the mass of ductules, forming explants of duct epithelia while some cells of mesenchymal features grew around those explants but to a lesser extent. Nestin was expressed by many of those duct cell explants but not by the mesenchymal cells immunoreactive for vimentin. Immunoreaction for cytokeratin-20, a specific marker for ductal cells, was also present in the ductal explants, but simultaneous expression of both nestin and cytokeratin was not encountered indicating again, that nestin-positive cells are still undifferentiated. Differentiation of endocrine cells including insulin and glucagon secreting cells was consistently identified in a sub-population of the duct cell explants. While most of these cells expressed neither nestin nor cytokeratin-20, a few intermediate cells expressing simultaneously insulin or glucagon and nestin were found indicating that nestin-positive cells are indeed progenitor endocrine cells. Based on these results, we suggest that adult pancreatic stem cells expressing nestin can differentiate into endocrine cells and thus present great potential in beta cell replaceme