Acinar Cell Culture Establishment and Quantification

Acinar cultures were established according to previous publications (Kurup and Bhonde, 2002 (link); Means et al., 2005 (link); Ardito et al., 2012 (link)). Briefly, dorsal pancreata were minced in Hank's buffered saline solution and digested sequentially in 0.02% trypsin (5 min, 37°C) and 1 mg/ml collagenase P (Roche Applied Science, Mannheim, Germany; 15 min, 37°C), following filtration to eliminate undigested material, and repeated washing to eliminate debris and dead cells, acinar cell clusters were embedded in rat tail collagen gels (Corning, Corning, NY), and cultured in Waymouth's medium (Life Technologies, Carlsbad, CA) supplemented with 1% fetal bovine serum, 0.4 mg/ml soybean trypsin inhibitor, and 1 µg/ml dexamethasone. Cultures were fixed and imaged after 5 days. To quantify cyst size, we randomly selected >10 fields per mouse, imaged, and quantified the maximal diameter of each transformed cyst using ImageJ.