Islet-derived multipotential cells/progenitor cells.

The pancreatic beta-cell has a pivotal role in the regulation of glucose homeostasis; its death leads to type I diabetes. Neogenesis of beta-cells, the differentiation of beta-cells from non-beta-cells, could be an important mechanism of islet cell repopulation. To examine the ability of the adult pancreas to generate new beta-cells, we characterized the phenotype of beta precursor cells in embryos and then determined that cells expressing embryonic traits appeared in islets of adult mouse pancreas following deletion of preexisting insulin cells by streptozotocin, a specific beta-cell toxin. These precursor cells generated new beta-cells (NBCs) that repopulated the islets. The number of NBCs increased dramatically after restoration of normoglycemia by insulin therapy. Future studies will seek to identify the source of the NBCs and to examine the mechanisms that lead to their differentiation.