The study investigates the potential of expanding and differentiating human adult duct tissue into islet cells for transplantation. The researchers cultured digested pancreatic tissue, normally discarded after islet isolation, under conditions that allowed the expansion of ductal cells as a monolayer. This monolayer was then overlaid with Matrigel, a thin layer of extracellular matrix, which induced the formation of three-dimensional ductal cysts. From these cysts, 50 to 150 μm diameter islet-like clusters of pancreatic endocrine cells budded. Over a 3-4 week culture period, the insulin content per flask increased 10- to 15-fold, while the DNA content increased up to 7-fold. The cultivated human islet buds were immunofluorescence positive for cytokeratin 19 (a marker of duct cells) and hormone-positive for islet cells. Insulin secretion studies showed a 2.3-fold increase in insulin secretion in response to glucose stimulation. This study demonstrates that human duct tissue can be expanded in vitro and differentiated into glucose-responsive islet tissue, providing a potential new source of pancreatic islet cells for transplantation.The study investigates the potential of expanding and differentiating human adult duct tissue into islet cells for transplantation. The researchers cultured digested pancreatic tissue, normally discarded after islet isolation, under conditions that allowed the expansion of ductal cells as a monolayer. This monolayer was then overlaid with Matrigel, a thin layer of extracellular matrix, which induced the formation of three-dimensional ductal cysts. From these cysts, 50 to 150 μm diameter islet-like clusters of pancreatic endocrine cells budded. Over a 3-4 week culture period, the insulin content per flask increased 10- to 15-fold, while the DNA content increased up to 7-fold. The cultivated human islet buds were immunofluorescence positive for cytokeratin 19 (a marker of duct cells) and hormone-positive for islet cells. Insulin secretion studies showed a 2.3-fold increase in insulin secretion in response to glucose stimulation. This study demonstrates that human duct tissue can be expanded in vitro and differentiated into glucose-responsive islet tissue, providing a potential new source of pancreatic islet cells for transplantation.