Calcineurin inhibitors such as cyclosporine A and FK506 have been used for transplant therapy and treatment of autoimmune diseases. However, the inhibition of calcineurin outside the immune system has a number of side effects, including hyperglycemia. In the search for safer drugs, we developed a cell-permeable inhibitor of NFAT (nuclear factor of activated T cells) using the polyarginine peptide delivery system. This peptide provided immunosuppression for fully mismatched islet allografts in mice. In addition, it did not affect insulin secretion, whereas FK506 caused a dose-dependent decrease in insulin secretion. Cell-permeable peptides can thus provide a new strategy for drug development and may eventually be useful clinically.

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In comparison with UW organ preservation, exposure of pancreata to the TLM result in greater islet yields and extended preservation times.

Islet allotransplantation can achieve insulin independence in patients with type I diabetes. Recent reports show that the two-layer method (TLM), which employs oxygenated perfluorochemical (PFC) and UW solution, is superior to simple cold storage in UW for pancreas preservation in islet transplantation. However, UW solution has several disadvantages, including the inhibition of Liberase activity. In this study, we investigated the features of a new solution, designated M-Kyoto solution. M-Kyoto solution contains trehalose and ulinastatin as distinct components. Trehalose has a cytoprotective effect against stress, and ulinastatin inhibits trypsin. In porcine islet isolation, islet yield was significantly higher in the M-Kyoto/PFC group compared with the UW/PFC group. There was no significant difference in ATP content in the pancreas between the two groups, suggesting that different islet yields are not due to their differences as energy sources. Compared with UW solution, M-Kyoto solution significantly inhibited trypsin activity in the digestion step; moreover, M-Kyoto solution inhibited collagenase digestion less than UW solution. In conclusion, the advantages of M-Kyoto solution are trypsin inhibition and less collagenase inhibition. Based on these data, we now use M-Kyoto solution for clinical islet transplantation from nonheart-beating donor pancreata.

The Collaborative Islet Transplant Registry (CITR) collects data on clinical islet isolations and transplants. This retrospective report analyzed 1017 islet isolation procedures performed for 537 recipients of allogeneic clinical islet transplantation in 1999–2010. This study describes changes in donor and islet isolation variables by era and factors associated with quantity and quality of final islet products. Donor body weight and BMI increased significantly over the period (p < 0.001). Islet yield measures have improved with time including islet equivalent (IEQ)/particle ratio and IEQs infused. The average dose of islets infused significantly increased in the era of 2007–2010 when compared to 1999–2002 (445.4 ± 156.8 vs. 421.3 ± 155.4 ×103 IEQ; p < 0.05). Islet purity and total number of β cells significantly improved over the study period (p < 0.01 and <0.05, respectively). Otherwise, the quality of clinical islets has remained consistently very high through this period, and differs substantially from nonclinical islets. In multivariate analysis of all recipient, donor and islet factors, and medical management factors, the only islet product characteristic that correlated with clinical outcomes was total IEQs infused. This analysis shows improvements in both quantity and some quality criteria of clinical islets produced over 1999–2010, and these parallel improvements in clinical outcomes over the same period.

Although application of the Edmonton protocol has markedly improved outcomes for pancreatic islet transplantation, the insulin independence rate after islet transplantation from one donor pancreas has proven to remain low. During the isolation process and subsequent clinical transplantation, islets are subjected to severe adverse conditions that impair survival and ultimately contribute to graft failure. Pancreas preservation with the two-layer method (TLM) has proven to improve transplant results by protecting isolated islets against apoptosis through the mitochondrial pathway. However, pancreas storage with TLM cannot protect against activation of c-Jun NH 2 -terminal kinase (JNK) in isolated islets. This study investigated whether delivery of a JNK inhibitory peptide (JNKI) via the protein transduction system can prevent apoptosis of islet cells immediately after isolation. For efficient delivery of the (JNKI into isolated islets, we synthesized JNKI as a C-terminal fusion peptide with the 11-arginine protein transduction domain (11R-JNKI). 11R efficiently delivered the JNKI into isolated islets and 11R-JNKI prevented islet apoptosis immediately after isolation and improved islet graft function. These findings suggest that peptide drugs could be useful for the prevention of the impairment of islet † These authors contributed equally to this study. cells and lead to improvement in the outcomes for pancreatic islet transplantation.

We evaluated islet transplantation from non-heart beating donors (NHBDs) with our Kyoto Islet Isolation Method. All patients had positive C-peptide after transplantation. The average HbA 1C levels of the five recipients significantly improved from 7.8 ± 0.4% at transplant to 5.2 ± 0.2% currently (p < 0.01). Three patients with no or a single autoantibody became insulin independent while the other two patients with double autoantibodies reduced their insulin requirement but did not become insulin independent. C-peptide in patients who became insulin-independent gradually increased after each transplantation whereas C-peptide in patients who did not become insulin-independent from 3 months after the first transplantation to the next transplantation dramatically decreased. The b -score of the three patients who became insulin independent was the best of eight. In conclusion, our method makes it feasible to use NHBDs for islet transplant into type 1 diabetic patients efficiently.Abbreviations: CIT, cold ischemic time; NHBD, nonheart beating donor; PFC, perfluorochemical; WIT, warm ischemic time