Methods and compositions are described for the treatment of type I
insulin-dependent
diabetes mellitus and other conditions using newly identified stem cells that are capable of differentiation into a variety of pancreatic
islet cells, including
insulin-producing beta cells, as well as hepatocytes. Nestin has been identified as a
molecular marker for pancreatic stem cells, while
cytokeratin-19 serves as a marker for a distinct class of
islet ductal cells. Methods are described whereby nestin-positive stem cells can be isolated from
pancreatic islets and cultured to obtain further stem cells or pseudo-
islet like structures. Methods for
ex vivo differentiation of the pancreatic stem cells are disclosed. Methods are described whereby pancreatic stem cells can be isolated, expanded, and transplanted into a patient in need thereof, either allogeneically, isogeneically or xenogenically, to provide replacement for lost or damaged
insulin-secreting cells or other cells.