The postoperative course and quantitative aspects of rat islet and segmental pancreas isografts

Duct-ligated segmental pancreas transplants with systemic venous drainage were compared to intrahepatic islet grafts for beta-cell mass (proportional to tissue insulin content) and function in diabetic Lewis rats. Rats were serially killed to measure insulin in the segmental pancreas grafts and in the liver of the islet recipients. Segmental pancreas weight was maximum and insulin concentration and content lowest (P less than 0.05) on Day 3 when acute inflammation was present. At 21 days, there was no inflammation, and graft weight had decreased, but not to Day 0 level because of normal growth; insulin concentration was similar on Days 21 and 0. At 3 months, moderate fibrosis of the graft was present, but both total insulin and insulin concentration had increased (P less than 0.05). In the recipients of islet grafts, total insulin in the liver on Day 1 was only 43% of that contained in the original islet preparation, but by 3 months the insulin content in the liver had increased to that transplanted. IVGTT K values were similar in normal rats (-3.5 +/- 0.7%) and in recipients of segmental pancreas (-4.5 +/- 1.6%) and islet (-4.0 +/- 1.5%) grafts at 3 months post transplant. Acute segmental graft pancreatitis resolved, followed by an increase in beta-cell mass. Islet cell damage during transplantation is either reversible or residual viable islets proliferate, and provide metabolic control equivalent to segmental pancreas transplants, even though the final beta-cell mass is less.