Pancreatic Stem Cells

This chapter reviews evidence for the existence and identity of pancreatic progenitor and stem cells, and describes the criteria for experimental demonstration of such cells. The most rigorous definition of a stem cell states that it is a cell that, upon proliferation, produces some progeny that have the same developmental potential, as well as other progeny that have a more restricted developmental potential. In Type I diabetes, the insulin-producing β-cells that reside in the pancreatic islets of Langerhans are destroyed by autoimmune attack, and it is thought that self-renewing stem cells could provide an unlimited source of β-cells for transplantation. Such therapeutic efforts require the prospective isolation of stem cells with the potential to produce β-cells and the development of methods to direct their expansion and differentiation. From a developmental biology perspective, the role of stem cells in the pancreas is a fascinating problem. Much of the field is focused on the identification of β-cell progenitors and the characterization of their molecular requirements, but it is not known what role such cells play during pancreas maintenance and regeneration, or whether the adult pancreas contains a population of true stem cells.