Duct stem cells of the exocrine glands: their potentiality and activation

초록

During development, the gland cells originate from the ductal cells, indicating the existence of stem/progenitor cells in duct cell lining in embryonic gland. Although it still remains in question, many researchers showed tissue regeneration mimicking embryonic development of glandular tissues. The regenerating glandular tissue was heterogeneous in composition. Some areas were composed by tubules and ductules in surrounding loose connective tissue while others were denser with differentiating acini derived from tubules or ductules. Small tubular structures formed by elongated epithelial cells with irregular lumen in the neogenic tissue were ascribed as tubules, while similar structures, displaying larger lumen lined by low epithelial cells, were considered as ductules. Differentiating acini showed direct connections with the epithelial lining of the tubules or ductules. This may indicate sequential processes of neogenic renewal of pancreatic tissue with formation of tubules evolving into ductules and differentiating acini. We reported that a rich population of nestin-positive cells showed high replicability during culture, and the nestin-positive duct cells were preferentially distributed at the periphery of the explants where cell proliferation takes place actively, suggesting that those nestin cells could be considered as multipotential nestin-positive duct stem (NPDS) cells.