Simplified Method to Isolate Highly Pure Canine Pancreatic Islets

Objectives: The canine model has been used extensively to improve the human pancreatic islet isolation technique. At the functional level, dog islets show high similarity to human islets and thus can be a helpful tool for islet research. We describe and compare 2 manual isolation methods, M1 (initial) and M2 (modified), and analyze the variables associated with the outcomes, including islet yield, purity, and glucose-stimulated insulin secretion (GSIS). Methods: Male mongrel dogs were used in the study. M2 (n = 7) included higher collagenase concentration, shorter digestion time, faster shaking speed, colder purification temperature, and higher differential density gradient than M1 (n = 7). Results: Islet yield was similar between methods (3111.0 +/- 309.1 and 3155.8 +/- 644.5 islets/g, M1 and M2, respectively; P = 0.951). Pancreas weight and purity together were directly associated with the yield (adjusted R-2 = 0.61; P = 0.002). Purity was considerably improved with M2 (96.7% +/- 1.2% vs 75.0% +/- 6.3%; P = 0.006). M2 improved GSIS (P = 0.021). Independently, digestion time was inversely associated with GSIS. Conclusions: We describe an isolation method (M2) to obtain a highly pure yield of dog islets with adequate beta-cell glucose responsiveness. The isolation variables associated with the outcomes in our canine model confirm previous reports in other species, including humans.