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The purpose of the present study was to test the influence of donor age on islet isolation yield in swines. Large White pigs of 10 months (group 1, n = 10) and 2-3 years (group 2, n = 5) were used. A modification of the automated method for human islet isolation was used for pig islet separation. After ductal injection of a collagenase solution (Seromed, type C-1000) the islets were separated through a continuous digestion process. In group 1 it was possible to obtain an average of 636,100 islets (volume = 476.1 mm3, insulin content = 101.4 Units). In group 2 the average total islet number was 799,800 representing a volume of 1190.6 mm3 (Insulin content 210 Units). Total islet number was not significantly different in the two groups, however when islet volume and total insulin content were considered, older animals allowed a significantly higher yield (P less than 0.01 for volume and P less than 0.05 for insulin content). These findings indicate that it is possible to separate large number of pig islets from both young (10 months) and older (2-3 years) animals and that selection of donor pigs will improve islet isolation yield. These results may be of assistance in the definition of requirements for more effective islet isolation in swines.

Background. Cytomegalovirus (CMV) infection in the immunosuppressed transplant recipient is a cause of significant morbidity. With ganciclovir prophylaxis, the overall incidence of CMV after simultaneous kidney-whole pancreas transplantation remains as high as 40%, while CMV infection has never been reported following pancreatic islet transplantation (PIT) alone (i.e., without kidney transplantation). We designed the following study to objectively quantify the rate of transmission of CMV after clinical PIT. Methods. The 26 pancreatic islet grafts used at our institution since 1/2001 and the corresponding 11 PIT recipients were studied. The CMV serology of all organ donors was tested using a latex agglutination assay for anti-CMV antibody (CMV Scan™, Becton Dickinson®, Cockeysville, MD), a test capable of detecting one CMV-infected cell per 50,000 cells. Following PIT, recipients were closely monitored for clinical symptoms consistent with CMV infection. All patients were tested monthly for the presence of CMV antigenemia using immunofluorescent monoclonal antibodies for the CMV pp65 antigen (Light Diagnostics™, Chemicon®, Temecula, CA). All patients received valganciclovir 450 mg PO BID for 3 months following each PIT. Immunosuppression consisted of daclizumab, sirolimus, and tacrolimus. Results. Eight of the PIT recipients (72%) were CMV seronegative prior to PIT (R−). Eighteen of the 26 pancreatic islet grafts (69%) were from CMV+ donors (D+), and the remaining eight (31%) were from CMV− donors (D−). A single R− recipient received only D− pancreatic islets, while the remaining seven received at least one D+ pancreatic islets graft. In all there were 6 D+R+, 3 D−R+, 12 D+R−, and 5 D−R− PITs. No patient developed symptoms consistent with CMV infection at any time following PIT. Monthly routine blood testing of all recipients has revealed no detectable CMV antigenemia in any patient. Conclusion. In our series neither CMV transmission nor CMV infection was seen after PIT. The risk of CMV transmission is lower after PIT than the risk after simultaneous kidney--pancreas transplantation.

The purpose of this study was to determine the effect of pancreatic islets on the survival of clusters of rat hepatocytes transplanted across a major histocompatibility barrier into an ectopic site. Aggregates of hepatocytes and pancreatic islets were obtained from Wistar-Furth rats by an automated method of collagenase digestion. Approximately 8000 Wistar-Furth hepatocyte clusters (100 to 300 micron diameter) were transplanted beneath the renal capsule of Lewis rats with or without the addition of 800 pancreatic islets. Recipients received subcutaneous injections of cyclosporine A (CsA): 30 mg/kg on days 0, 1, and 2, 10 mg/kg on days 3 to 7, and 10 mg/kg every other day for days 8 to 28. In the absence of CsA recipient treatment, all the allografts were rejected within 7 days. The combined hepatocyte-islet allografts in recipients treated with CsA showed maintenance of morphologic integrity of both hepatocytes and islet cells 1, 2, and 4 weeks after transplantation, whereas in the absence of pancreatic islets, the hepatocellular aggregates degenerated despite CsA treatment, leaving only a thin rim of hepatocytes immediately adjacent to the renal parenchyma. It can be concluded that in immunosuppressed recipients hepatocyte-islet renal subcapsular allografts survived despite the presence of an intact liver, which indicates a possible role of trophic factors released locally from the islets.

The extrahepatic diversion of essential splanchnic hepatotrophic factors may cause the liver atrophy and insufficiency that follows portacaval shunting. To investigate this, control dogs with end-to-side portacaval shunts (control-PCS, n = 6) were compared with dogs shunted 1 month after intraportal pancreatic islet autotransplantation (islet-Tx-PCS, n = 5). From the distal pancreas of each experimental dog, 1.95 +/- 0.49 X 10(5) islets were isolated by collagenase digestion and retransplanted within 3 hours. Assays of hepatocellular function (caffeine clearance) and hepatic blood flow (indocyanine green), conventional biochemical liver function tests, and glucose, insulin, and glucagon responses to intravenous glucose challenge were measured monthly and when dogs were killed. Four of six control-PCS dogs were killed 32 +/- 9 days after shunting because of more than 20% body weight loss; one control-PCS dog lost only 7% of body weight by day 56 and stabilized. No significant loss of body weight occurred in islet-Tx-PCS dogs (n = 5). Liver function test abnormalities seen in control-PCS dogs were absent in islet-Tx-PCS dogs. Both control-PCS and islet-Tx-PCS indocyanine green half-life measurements were significantly (p less than 0.05) prolonged at all times, indicating equally reduced hepatic blood flow after shunting for both groups. In contrast, islet-Tx-PCS caffeine half-life periods were significantly (p less than 0.05) shorter than in control-PCS dogs and were similar to those in normal dogs, indicating a protective effect of the transplanted islets on hepatocellular function. We conclude that intraportal pancreatic islet autotransplants prevent, by the local release of hepatotrophic factors within the liver, the metabolic abnormalities and loss of hepatic function after PCS.

The loss of parenchyma after pancreatectomy causes an extreme disruption of glucose homeostasis known as “pancreatogenic diabetes” which is characterized by disabling episodes of hyperglycemia or hypoglycemia, increased morbidity and mortality, and target organ damage. The number of subjects undergoing pancreatic surgery is increasing, owing to early diagnosis of premalignant lesions and to the referral of patients affected by surgical pancreatic diseases to high-volume institutions. Therefore, a growing number of pancreatectomized patients with long life expectancy is exposed to the risk of pancreatogenic diabetes, with a significant impact on quality and duration of life. Islet autotransplantation (IAT) could offer a valuable option to avoid “pancreatogenic diabetes.” In fact, the most successful islet transplants have been performed in no autoimmune diabetes patients, in an autologous setting, in conjunction with total or near total pancreatectomy for the treatment of pancreatic or hepatobiliary conditions. Here we discuss the feasibility, efficiency, and safety of IAT for the prevention of surgical diabetes after extensive or total pancreatic resection for pancreas disease other than chronic pancreatitis.

Curing type 1 diabetes means replacing the lost insulin secretion with a perpetual, autonomous, and self-regulating source of insulin delivery able to correct all the metabolic abnormalities and prevent the long-term chronic complications of the disease. In Milan, substantial experience in islet transplantation and beta-cell replacement has been gained and maintained during the last three decades, thereby achieving a leading position in the production of human islets for transplantation and its establishment as one of the most experienced centers in the world with more than 370 islet infusions performed and high-level scientific production. During this long period the field of islet transplantation has evolved significantly from the breakthrough of the first cases in early 1990s, since significant advances in islet isolation and engraftment, together with improved immunosuppressive strategies, have been reported. A major effort is now being focused on a special multidisciplinary and integrated project aiming at bringing islet transplantation and beta-cell replacement to the level of a successful clinical routine procedure.