Impact of donor-related variables on islet isolation outcome in dogs

Clinical human islet transplantation programmes are considerably hampered by the variability of islet isolation outcome. The effects of the islet content of the pancreas and other donor-related variables on isolation outcome have not been evaluated systematically so far--either in large animals, or in man. We studied the impact of interindividual differences in age, body weight and pancreatic islet content on the outcome of collagenase isolation of islets from the splenic pancreas of beagle dogs (n = 31). The islet volume of the splenic pancreas amounted to a mean (+/- SEM) 15.7 +/- 0.9 microliters per gramme pancreas, and varied three-fold (from 8.4 to 27.3 microliters). Isolated islet yield was 7.6 +/- 0.7 microliters/g and varied nine-fold (1.8-16.3 microliters). Animals also varied in age eight-fold (8-67 months) and body weight two-fold (8.6-18.3 kg). Differences in body weight and age explained 60% of variance in the fractional islet volume of the pancreas and 50% of the variance in islet yield (p < 0.001). Fractional islet volume of the splenic pancreas also explained 50% of the variance in islet yield (p < 0.001). We conclude that the outcome of islet isolation may be predictable after controlling for the variable islet content of pancreases, and other donor-related variables, and suggest that similar studies should be done in man.