Induction of mouse pancreatic ductal differentiation, an in vitro assay.

Despite recent technical advances for studying lineage tracing and gene functions, our knowledge of pancreatic duct progenitor cells and mechanisms involved in their differentiation remains a huge void in our understanding of pancreatic development. A deeper insight into ductal differentiation is needed because ductal cells may harbor pancreatic stem/progenitor cells that could give rise to new islets. Also, since the most common pancreatic tumors form structures expressing ductal cell-specific markers, studies of ductal development may provide better markers for pancreatic tumor classification. One major longstanding problem in the study of pancreatic ductal differentiation has been the lack of an effective in vitro model. We thus wished to develop an in vitro system for the study of pancreatic duct development. In doing so, we have developed a specific culture condition to promote ductal differentiation of E11.5 pancreatic rudiments. Normally, pancreatic explants cultured in vitro develop to form endocrine, acinar, as well as ductal cells. Here, we report that addition of a combination of EGF, fibroblast growth factor-10, and platelet-derived growth factor-AA to the explant cultures promotes ductal differentiation, while preventing endocrine and acinar differentiation. This culture system for differentiation and enrichment of pancreatic ductal cells may allow identification of gene(s) involved in ductal development.