Islet transplantation has become available across the globe since a novel protocol was reported. However, because donors are in short supply, only a minority of patients benefit from this procedure. Pancreatic progenitor cells are a promising resource for regeneration of new islets, but whether progenitor cells reside in ductal epithelium is not clear.

Mouse pancreas was examined by immunohistochemistry with cell surface markers specific for ductal cells. We developed an isolation method for ductal cells by flow cytometric cell sorting using a newly identified specific marker for ductal cells. By using an in vitro colony assay, we characterized their proliferative and multipotent capacity.

CD133 is expressed specifically in ductal epithelium. Flow cytometric analysis revealed that purified ductal cells are highly enriched in the CD133⁺CD34⁻CD45⁻Ter119⁻ fraction. An analysis of clonal epithelial colonies formed by individual cells revealed that progenitor cells with multilineage differentiation capacity are present in neonatal ductal epithelium. Moreover, these progenitor cells express c-Met. In adult mice, progenitor cells that show a high proliferative capacity but appear committed to a ductal lineage are co-purified with CD133⁺CD34⁻CD45⁻Ter119⁻ cells.

We established a system for isolating and culturing mouse pancreatic ductal cells that relies on flow cytometric cell sorting. Clonal analysis revealed that a population of progenitor cells is present among CD133⁺ ductal cells. Isolation of these cells will facilitate future studies into the roles of pancreatic progenitor cells in regeneration and carcinogenesis.