FREE INTRAPERITONEAL ISLET AUTOGRAFTS IN PANCREATECTOMIZED DOGS - IMPACT OF ISLET PURITY AND POSTTRANSPLANTATION EXOGENOUS INSULIN

Background. We compared the ability of impure, dispersed pancreatic is let tissue (DPIT) and purified islets to engraft in the peritoneal cav ity of dogs. We also tested whether posttransplantation insulin therap y affects islet engraftment. Methods. Thirty-two dogs underwent total pancreatectomy. DPIT was autotransplanted intraperitoneally in nine do gs. Purified islets were autotransplanted intraperitoneally in 13 dogs and intraportally in seven dogs. Dogs received comparable islet mass. One half of the recipients of intraperitoneal grafts received 12 days of posttransplantation exogenous insulin. Three dogs did not undergo transplantation. Intravenous glucose tolerance tests were done at 60 a nd 180 days. Results. The long-term graft functional survival rate of intraperitoneal DPIT grafts was significantly better than the rate of intraperitoneal purified islets (p < 0.01) and was as good as the rate of intraportal purified islets. Purified islets transplanted intraper itoneally failed early compared with other groups, with only 46% funct ioning at 3 weeks (p = 0.05); exogenous insulin reduced this early fai lure rate (p = 0.05). At 6 months 67% of intraperitoneal DPIT and 86% of intraportal purified grafts were functioning. Glucose disposal did not differ between groups. Conclusions. The peritoneal cavity is a saf e, practical site for islet transplantation, particularly for high-vol ume DPIT grafts. DPIT may provide a larger, more viable beta-cell mass than purified islets, or the acinar-ductal tissue may have a positive effect on engraftment. Exogenous insulin may promote engraftment of t ransplanted islets with a marginal beta-cell mass.