A simple method of canine pancreatic islet isolation and intrahepatic transplantation

Abstract

Clinical pancreatic islet transplantation has been impeded by the inability to isolate an adequate mass of functional tissue that will ameliorate diabetes. A simplified method of canine islet isolation was developed that allowed for either intrasplenic or intrahepatic transplantation. Following total pancreatectomy, parenchymal digestion was accomplished by intraductal collagenase perfusion and stationary incubation. The digested tissue was dispersed by filtration through a steel mesh (400 μm), washed, and separated on a discontinuous dextran density gradient. Enhanced islet tissue (2–4 ml) was recovered from the uppermost interface of the gradient and autotransplanted. The islet isolation procedure was tested in two series of dogs undergoing either intrasplenic or intrahepatic engraftment. Immediate and sustained normoglycemia (plasma glucose <200 mg%) was obtained in 5 of 8 dogs (63%) in the intrasplenic group and 6 of 8 dogs (75%) in the intrahepatic group. The mean fasting plasma glucose concentration 2 weeks after transplantation was 102.8 ± 6.4 mg% in the intrasplenic group and 103.3 ± 8.4 mg% in the intraportal group. The mean IVGTT K-values 2 weeks after transplantation were −1.41 ± 0.35% and −1.21 ± 0.13%, respectively. On the basis of insulin content, the islet yield was 33.0 ± 3.7% of the total pancreas in the intrasplenic group and 33.0 ± 3.1% in the intrahepatic group. Islet mass was enhanced 10.2 ± 1.5 and 20.0 ± 6.2 fold, respectively, on the basis of insulin/amylase ratios. The success rate in this canine model compared favorably with previously published results from other laboratories. This procedure, including surgery, was routinely performed within 4 hr, allowed for transplantation the same day without the requirement of overnight incubation, and utilized an inexpensive dextran density gradient, furthering efforts toward human clinical trials.