Background & Aims: Acinar cells constitute 90% of the pancreas epithelium, are polarized, and secrete digestive enzymes. These cells play a crucial role in pancreatitis and pancreatic cancer. However, there are limited models to study normal acinar cell differentiation in vitro. The aim of this work was to generate and characterize purified populations of pancreatic acinar cells from embryonic stem (ES) cells. Methods: Reporter ES cells (Ela-pur) were generated that stably expressed both β-galactosidase and puromycin resistance genes under the control of the elastase I promoter. Directed differentiation was achieved by incubation with conditioned media of cultured fetal pancreatic rudiments and adenoviral-mediated co-expression of p48/Ptf1a and Mist1, 2 basic helix-loop-helix transcription factors crucial for normal pancreatic acinar development and differentiation. Results: Selected cells expressed multiple markers of acinar cells, including digestive enzymes and proteins of the secretory pathway, indicating activation of a coordinated differentiation program. The genes coding for digestive enzymes were not regulated as a single module, thus recapitulating what occurs during in vivo pancreatic development. The generated cells displayed transient agonist-induced Ca2+ mobilization and showed a typical response to physiologic concentrations of secretagogues, including enzyme synthesis and secretion. Importantly, these effects did not imply the acquisition of a mixed acinar-ductal phenotype. Conclusions: These studies allow the generation of almost pure acinar-like cells from ES cells, providing a normal cell-based model for the study of the acinar differentiation program in vitro.

This study was supported by Spanish Ministry of Education and Science Grants (SAF2001-0432 and GEN2001-4748-C05 to A.S.; GEN2001-4748-C01 and SAF2004-01137 to F.X.R. and SAF2006-4973 to M.A.V.), Instituto de Salud Carlos III grants (02/3053 and PI05/2738 to A.S.; and Red HERACLES to M.A.V.), Catalan Government grants (SGR2005 to M.A.V.), and by a National Institutes of Health grant (DK55489 to S.F.K.). A.S. was supported by the Instituto de Salud Carlos III; M.R., F.D. and M. M. were recipients of a Graduate Fellowship from the Ministry of Education and Science, Instituto de Salud Carlos III, and the Catalan Government, respectively.