Islet transplantation in the future: Use of a bioartificial pancreas

Tight glycemic control effectively delays the onset and slows the progression of diabetic complications in patients with insulin-dependent diabetes mellitus. Successful pancreas transplantation corrects abnormal glucose metabolism but subjects patients to morbidity and mortality associated with chronic immunosuppression. Immune exclusion devices containing pancreatic islets (bioartificial pancreas devices) are designed to provide glycemic control through islet transplantation without immunosuppression. The immune exclussion is achieved by separating allogeneic or xenogeneic islets from the host by semipermeable membranes that allow only small molecules, such as glucose, insulin, and nutrients, to pass through. Immune lymphocytes and immunoglobulins are excluded by the membrane and are unable to cause destruction of the islets. This report provides a brief review of three types of bioartificial pancreas devices used for the treatment of diabetes, i.e., perfusion-based vascular devices, diffusion-based chambers and microcapsules, and describes recent progress in each area.     

Laparoscopic and robotic donor pancreatectomy for living donor pancreas and pancreas–kidney transplantation

Pancreas transplantation is a widely accepted procedure that can efficiently restore euglycemia and prevent progression of complications. In most instances, the limiting factor for deceased donor organ transplantation is the availability and quality of the available organs. Living donor pancreas transplant was introduced at the University of Minnesota in 1979. Because of the potential risks for the donor and the technical challenges in the recipient operation, this procedure has not become very popular since then. In 1999, in the attempt to decrease the morbidity associated with open distal pancreatectomy, the first laparoscopic donor distal pancreatectomy with hand-assisted technique was performed at the same institution. In 2000, the FDA approved the robotic surgical system Da Vinci for general use. Since then, the system has been extensively used at our institution to perform living donor nephrectomy. The only case reported worldwide of robotic distal pancreatectomy and nephrectomy for living donor pancreas–kidney transplantation was successfully performed by our team in 2006 at the University of Illinois at Chicago and proved as a promising technique. The application of minimally invasive techniques has allowed an increased acceptance of the procedure among potential donors and may, therefore, increase the number of donors for this life-saving transplant. The initial results are encouraging and clearly prove feasibility.     

Islet transplantation in IDDM patients

Summary This single-centre study investigated parameters that positively correlated with the success rate after islet allotransplantation in insulin-dependent diabetic (IDDM) patients. Twenty-one intrahepatic, fresh islet transplantations were performed in 20 IDDM patients (one patient had two transplants), after or simultaneous with kidney transplantation. The correlation between number and purity of transplanted islets and final outcome was investigated. One patient died of a cardiac arrest several hours after islet transplantation; this patient was not included in the follow-up analysis. Three patients (15 %) experienced acute, irreversible, early failure of islet function, which was considered as a ’presumed rejection'. Nine patients (45 %) achieved either complete insulin-independence (seven cases) or a reduction (> 50 %) of exogenous insulin requirement (two cases), with sustained serum C-peptide secretion (0.89 ± 0.04 nmol/l; duration: 21 ± 7 months, range 2–58 months). Liver biopsy, performed 3 years after transplantation in one successful case, showed normal islets within the hepatic parenchyma. Eight cases (40 %) did not show any metabolic effect of islet transplantation, with low serum C-peptide levels (’presumed function exhaustion'). Metabolic investigations performed in successful cases showed an early phase of insulin release after arginine, mild and reversible postprandial hyperglycaemia and normal HbA_1c levels. Success of islet transplantation positively correlates with the number (p < 0.05) of the transplanted islets. Islet transplantation is a safe procedure, with 45 % success rate, in terms of insulin-independence or relevant reduction of exogenous insulin requirement, although success can be transient. [Diabetologia (1997) 40: 225–231] Received: 20 June 1996 and in final revised form: 28 October 1996     

Establishment of a prolonged pancreas preservation model for islet isolation research in mice

Establishing a prolonged pancreas preservation model in a small animal is important for islet isolation research. Use of a rat pancreas model has been reported, but no published reports have used a mouse pancreas for prolonged cold preservation prior to islet isolation. For the model, a mouse is preferred over a rat because of its small size, well-known immune characterization and variety of gene-modulated models. In the present study, we established a prolonged pancreas preservation model in a mouse for islet isolation research. The collagenase solution was injected successfully after 24 and 48 h cold preservations in University of Wisconsin solution, and islets could be isolated from both groups of preserved pancreata. The islet yields from the control, 24 h preserved, and 48 h preserved pancreata were 183.9 ± 13.9, 128.5 ± 15.5, and 24.6 ± 12.9 per pancreas, respectively. The propidium iodide–positive area assay was significantly increased in both preserved groups, and insulin secretion levels in response to 20.0 mM glucose and stimulation indices were significantly decreased in the 48 h preserved group. Inflammation-related genes mRNA levels were significantly upregulated in the 24 h preserved group, as previously shown in the human model. Thus, this model might be useful for prehuman islet isolation screening research, reserving research using human pancreata for the most promising approaches.     

Establishment of a prolonged pancreas preservation model for islet isolation research in mice

Establishing a prolonged pancreas preservation model in a small animal is important for islet isolation research. Use of a rat pancreas model has been reported, but no published reports have used a mouse pancreas for prolonged cold preservation prior to islet isolation. For the model, a mouse is preferred over a rat because of its small size, well-known immune characterization, and variety of gene-modulated models. In the present study, we established a prolonged pancreas preservation model in a mouse for islet isolation research. The collagenase solution was injected successfully after 24 and 48 h cold preservations in University of Wisconsin solution, and islets could be isolated from both groups of preserved pancreata. The islet yields from the control, 24 h preserved, and 48 h preserved pancreata were 183.9 ± 13.9, 128.5 ± 15.5, and 24.6 ± 12.9 per pancreas, respectively. The propidium iodide-positive area assay was significantly increased in both preserved groups, and insulin secretion levels in response to 20.0 mM glucose and stimulation indices were significantly decreased in the 48 h preserved group. Inflammation-related genes mRNA levels were significantly upregulated in the 24 h preserved group, as previously shown in the human model. Thus, this model might be useful for prehuman islet isolation screening research, reserving research using human pancreata for the most promising approaches.     

Islet transplantation at the Diabetes Research Institute Japan

Since the Edmonton Protocol was announced, more than 600 patients with type 1 diabetes at more than 50 institutions have received islet transplantation to treat their disease. We recently established a new islet isolation protocol, called the Kyoto Islet Isolation Method, based on the Ricordi method. It includes an in-situ cooling system for pancreas procurement, pancreatic ductal protection, a modified two-layer (M-Kyoto /perfluorochemical [PFC]) method of pancreas preservation, and a new islet purification solution (Iodixanol-based solution). Using this islet isolation method, we isolated islets from 19 human pancreata of non-heart-beating donors and transplanted 16 preparations into seven patients with type 1 diabetes between April 7, 2004 and November 18, 2005. The percentage of those meeting the release criteria of the Edmonton Protocol was more than 80%. We also performed living-donor transplantation of islets for unstable diabetes on January 19, 2005. Establishment of this method enables us to make diabetic patients insulin-independent, using islets not only from two or three pancreata of non-heart-beating donors but also using islets from half a pancreas from a living donor.     

Risks and benefits of transplantation in the cure of type 1 diabetes: whole pancreas versus islet transplantation. A single center study

BACKGROUND: Pancreas and islet transplantation are the only available options to replace beta-cell function in patients with type 1 diabetes. Great variability in terms of rate of success for both approaches is reported in the literature and it is difficult to compare the respective risks and benefits. OBJECTIVES: The aim of this study was to analyze risks and benefits of pancreas transplantation alone (PTA) and islet transplantation alone (ITA) by making use of the long-term experience of a single center where both transplantations are performed. We focused on the risks and benefits of both procedures, with the objective of better defining indications and providing evidence to support the decision-making process. The outcomes of 33 PTA and 33 ITA were analyzed, and pancreas and islet function (i.e., insulin independence), perioperative events, and long-term adverse events were recorded. RESULTS: We observed a higher rate of insulin independence in PTA (75%) versus ITA (59%), with the longer insulin independence among PTA patients receiving tacrolimus. The occurrence of adverse events was higher for PTA patients in terms of hospitalization length and frequency, re-intervention for surgical and immunological acute complications, CMV reactivation, and other infections. CONCLUSIONS: In conclusion, these results support the practice of listing patients for PTA when the metabolic control and the progression of chronic complications require a rapid normalization of glucose levels, with the exception of patients with cardiovascular disease, because of the high surgical risks. ITA is indicated when replacement of beta-cell mass is needed in patients with a high surgical risk.     

Clinical islet isolation outcomes with a highly purified neutral protease for pancreas dissociation

Background: Pancreas dissociation is a critical initial component of the islet isolation procedure and introduces high variability based on factors including the enzyme type, specificity and potency. Product refinement and alterations to the application strategies have improved isolation outcomes over time; however, islet utilization from donor organs remains low. In this study we evaluate a low endotoxin-high activity grade neutral protease in clinical islet isolation.

Materials and Methods: The use of a non-collagenolytic enzyme, either thermolysin or high active neutral protease, was randomized in clinical islet isolations to evaluate efficacy. Additionally a retrospective comparison to neutral protease NB was conducted.

Results:The thermolysin group had lower trapped islet population and increased purity and post-culture islet mass in comparison to high active grade neutral protease. Comparison of neutral protease NB GMP grade to high active neutral protease displayed no measurable difference in islet mass or viability and transplantation outcomes at 1 mo post-transplant were favorable for both groups.

Conclusions: High activity neutral protease can generate clinical grade islets and may prove beneficial to islet function and viability based on a reduced endotoxin load but dosing of neutral protease requires ongoing optimization.     

Living donor pancreas transplantation in Japan

Background/purpose

Living-donor pancreas transplants (LDPs) were introduced at Chiba-East National Hospital in 2004, and 12 LDPs have been performed at this institution to date. Based on the outcome of these 12 LDPs, the efficacy and safety of LDPs are herein discussed.

Methods

Twelve diabetic patients underwent LDPs; ten had simultaneous pancreas and kidney transplants from living donors, one had pancreas transplant after a kidney transplant from a living donor, and one had a pancreas transplant alone from a living donor. The donors were parents or brothers and the ABO blood types were incompatible in three LDPs. The procedures for the donor and recipient operations were performed according to the technique established by the University of Minnesota. Bladder drainage was used in 11 recipients and enteric drainage was used in one patient. Tacrolimus, basiliximab, mycophenolate mofetil, and prednisone were used for induction and immunosuppressive treatment. A splenectomy, double-filtered plasmapheresis, and plasma exchange were added in the ABO-incompatible LDPs.

Results

No complications were observed in the donors during hospitalization. The 1-year survivals of the patients, kidney grafts, and pancreas grafts were 100, 100, and 100%, respectively. The 3-year survivals were 91.7, 90, and 91.7%, respectively. Three patients developed leakage of pancreatic juice and one patient required a surgical procedure. Cytomegalovirus antigenemia was detected in five patients (42%).

Conclusions

Based on the excellent outcome of the LDPs at this institution, LDPs is therefore expected to become a promising option for the treatment of patients with severe diabetes.     

Islet separation and islet cell culture in vitro from human embryo pancreas

INTRODUCTlONDiabetesmellitusisthemostc0mmondiseaseanditsdeathrateranksthe8thintheworld.Upt0n0w,itsincidencehasatendencytoincrease[11.Sincedisorderofsugarmetabolismmightresultinmicrovasculardegenerati0nandinjuryofimportanthumanorgans,itwillendangerhumanhealthseri0usly-Inl969,Younszaifirstreportedthemethodthatcoulddecreasediabetessymptomsbyislettissuetransplantation.In1981,ourcountrybegantotreatdiabetestype1bytransplantingculturedislettissues.Inourstudy,wedigestedthepiecesofpancreaswithcol…     

Islet cell transplantation for the treatment of type 1 diabetes in the USA

Islet cell transplantation (ICTx) is one of the most effective treatments for type 1 diabetes and is less invasive compared to whole organ transplantation. The US has been the leader in the research and clinical applications of ICTx for the last 40 years. ICTx requires complex procedures, including pancreas procurement and preservation; pancreas digestion; islet purification; and transplantation. Even with the dramatic progresses in each of the procedures listed above, there are still challenges to make ICTx the standard therapy. These challenges are: (1) obtaining enough islets from a single donor and (2) preventing graft loss due to allogenic rejection and recurrence of autoimmune islet destruction. A new preservation strategy for pancreata and pancreatic ducts using ET-Kyoto solution as well as a new islet purification method using iodixanol has substantially improved islet yields. Continuous research to improve the efficacy of islet isolation will solve the issue of obtaining enough islets from a single donor. Immunological tolerance is an ideal solution for the issue of rejection and autoimmune recurrence and a regulatory T cell strategy seems promising. Moreover, the SUITO index is a simple and powerful tool to assess engrafted islet mass and is, therefore, useful for evaluating the efficacy of new immunosuppressant strategies. Once ICTx becomes a standard treatment, the donor shortage will become the next challenge. Marginal or living donor islet transplantations could help alleviate this issue; however, bio-artificial islet transplantation with animal islets could be the ultimate solution.     

Clinical islet transplantation in Japan

Introduction

The results of clinical islet transplantation in Japan are, here in, reported and discussed its efficacy and problems.

Methods

Since the first islet transplantation was performed in 2004, 65 islet isolations and 34 islet transplantations to 18 type 1 diabetic patients have been performed in Japan.

Results

Following islet transplantation, patients experienced decreased insulin requirements and lower hemoglobin A1C levels, and positive serum C-peptide levels. All patients achieved stabilized blood glucose levels and the disappearance of hypoglycemic unawareness. Although three patients achieved insulin independency for a limited period, persistent islet graft function was difficult to maintain. Overall islet graft survival was 86.5% at 6 months, 78.7% at 1 year, and 62.9% at 2 years after the first islet transplantation. In our institution, we carried out 23 islet isolations and six islet transplantations to four patients. Although insulin independency was not achieved, all patients showed a disappearance of hypoglycemic unawareness.

Conclusions

Using data from the Japanese Trial of Islet Transplantation, the effectiveness of islet transplantation was shown even when using the pancreata from non-heart-beating donors. Although there are a number of problems to be solved and further improvement is needed, we can state that the introduction of clinical islet transplantation offers hope for type 1 diabetic patients.     

Outcomes in partial liver transplantation: deceased donor split-liver vs. live donor liver transplantation

BackgroundOrgan shortage has resulted in greater emphasis on partial liver transplantation (PLT) as an alternative to whole-organ liver transplantation.MethodsThis study was conducted to assess outcomes in PLT and to compare outcomes of deceased donor split-liver transplantation (DD-SLT) and live donor liver transplantation (LDLT) in adults transplanted in the USA using data reported to the United Network for Organ Sharing in the era of Model for End-stage Liver Disease (MELD) scores.ResultsBetween 2002 and 2009, 2272 PLTs were performed in the USA; these represented 5.3% of all liver transplants carried out in the country and included 557 (24.5%) DD-SLT and 1715 LDLT (75.5%) procedures. The most significant differences between the DD-SLT and LDLT groups related to mean MELD scores, which were lower in LDLT recipients (14.5 vs. 20.9; P < 0.001), mean recipient age, which was lower in the LDLT group (50.7 years vs. 52.8 years; P < 0.001), and mean donor age, which was lower in the DD-SLT group (23.0 years vs. 37.3 years; P < 0.001). Allograft survival was comparable between the two groups (P= 0.438), but patient survival after LDLT was better (P= 0.04). In Cox regression analysis, LDLT was associated with better allograft (hazards ratio [HR]= 0.7, 95% confidence interval [CI] 0.630–0.791; P < 0.0001) and patient (HR = 0.6, 95% CI 0.558–0.644; P < 0.0001) survival than DD-SLT.ConclusionsPartial liver transplantation represents a potentially underutilized resource in the USA. Despite the differences in donor and recipient characteristics, LDLT is associated with better allograft and patient survival than DD-SLT. A different allocation system for DD-SLT allografts that takes into consideration cold ischaemia time and recipient MELD score should be considered.     

First successful case of simultaneous liver and kidney transplantation for patients with chronic liver and renal failure in Japan

Establishment of a preferential liver allocation rule for simultaneous liver and kidney transplantation (SLK) and revisions of laws regarding organ transplants from deceased donors have paved the way for SLK in Japan. Very few cases of SLK have been attempted in Japan, and no such recipients have survived for longer than 40 days. The present report describes a case of a 50‐year‐old woman who had undergone living donor liver transplantation at the age of 38 years for management of post‐partum liver failure. After the first transplant surgery, she developed hepatic vein stenosis and severe hypersplenism requiring splenectomy. She was then initiated on hemodialysis (HD) due to the deterioration of renal function after insertion of a hepatic vein stent. She was listed as a candidate for SLK in 2011 because she required frequent plasma exchange for hepatic coma. When her Model for End‐stage Liver Disease score reached 46, the new liver was donated 46 days after registration. The reduced trisegment liver and the kidney grafts were simultaneously transplanted under veno‐venous bypass and intraoperative HD. The hepatic artery was reconstructed prior to portal reconstruction in order to shorten anhepatic time. Although she developed subcapsular bleeding caused by hepatic contusion on the next day, subsequent hemostasis was obtained by transcatheter embolization. Thereafter, her recovery was uneventful, except for mild rejection and renal tubular acidosis of the kidney graft. This case highlights the need to establish Japanese criteria for SLK.     

An analysis of the role of collagenase and protease in the enzymatic dissociation of the rat pancreas for islet isolation

Summary Crude Clostridium histolyticum collagenase is widely used for the enzymatic degradation of pancreatic extracellular matrix in order to isolate the islets of Langerhans. The variable enzymatic composition of crude collagenases is a critical issue which contributes to the poor reproducibility of islet isolation procedures. In this study, the separate contributions of collagenase and protease to the islet isolation process were analysed by testing various combinations of purified collagenase and purified protease in rat pancreas dissociations under conditions which eliminated all other proteolytic activity. Under these conditions, complete tissue dissociation by purified collagenase required 99±10 min, whereas increasing amounts of protease progressively reduced this time to a minimum of 36±1 min. Histochemical analysis of the dissociation process showed that protease enhanced the degradation of all four major components of the extracellular matrix: collagen was degraded more completely, while proteoglycans, glycoproteins and elastin were degraded at a higher rate. Pancreas dissociation under the present, strictly controlled conditions resulted in a high yield of viable islets: 4.2–5.0 l islet tissue volume (3,300–3,800 islets) were isolated per g pancreas in the presence of a high or low protease concentration, respectively. Prolonged dissociation in the presence of protease resulted in a dramatic decrease in islet yield which correlated with the observation that the enzyme accelerated islet disintegration. It is concluded that the collagenase-induced dissociation of the extracellular matrix is facilitated by protease. Our study shows that high yields of viable islets can be obtained under controlled enzymatic conditions, provided that the exposure of islets to protease is limited.     

Islet transplantation in type 1 diabetes: hype,hope and reality – a clinician's perspective

The β‐cell replacement by islet transplantation is an attractive approach for normalizing blood glucose without hypoglycaemia in patient with type 1 diabetes mellitus (T1D). A pioneer study by the Edmonton group more than a decade ago showed that alloislet transplantation may result in insulin independence for at least 1 year after transplantation. This breakthrough excited researchers, physicians and patients, who felt that the ultimate goal of cure for T1D was at hand. Longer follow‐up of patients who underwent islet transplantation showed less favourable results, with only approximately 10% of the patients remaining insulin‐free 5 years after transplantation. In the last few years, progress has been made, and the success rate of islet transplantation has steadily increased. Important hurdles, however, related to limited tissue supply and need for life‐long immunosuppressive drugs have yet to be overcome. Herein, we review recent achievements in islet transplantation and the challenges that still need to be addressed before this procedure can become a standard therapy for T1D. Copyright © 2013 John Wiley & Sons, Ltd.     

The IKEM pancreas and islet transplant program as part of healthcare for type 1 diabetes patients: retrospective analysis of outcome from 1983 to 2010

Currently, 25-30 pancreas transplantations per year are carried out in type 1 diabetes (T1D) recipients residing in Czech Republic. Most of the recipients are transplanted together with kidney allografts, but pancreas is also transplanted alone in selected patients with brittle diabetes. Since 2005, the Institute for Clinical and Experimental Medicine (IKEM) islet transplant program was initiated as complementary therapeutic modality. The aim of this paper was to analyze the transplant program at our clinical center, and to examine the survival of recipients, and their pancreas, kidney, and islet grafts. Patient and graft survival rates were evaluated in the following three categories using Kaplan-Meier test: simultaneous pancreas and kidney transplantation (SPKTx), pancreas transplantation alone (PTA), and islet transplantation (ITx). Three hundred and ninety SPKTx, 34 PTA and 44 ITx were carried out between 1983 and 2010. One- and 5-year patient survival rates were 92 % and 81% in SPKTx, respectively. In SPKTx, the 1-year survival rate of pancreas grafts was 78%, and the 5-year rate was 66%. Kidney graft survival rates were 89% and 79%, respectively, after the same follow-up periods. In the PTA category, recipient survivals were 100% after 1 year, and 92% after 3 years. 70% and 65% of pancreatic grafts were working properly at 1 and 3-year follow-ups, respectively. To date, we have carried out 44 islet transplantations in 31 recipients. Islet function (C-peptide ≥ 0.2 ng/ml) was documented in 60% of recipients after 12 months. So far, only 3 patients remained free of exogenous insulin. While SPKTx is a well established treatment for uremic T1D patients, ITx represents an emerging complementary treatment modality. The latter is especially suitable for high-risk recipients, but routine clinical application is still hampered by the limited availability of usable organ transplants and viability of transplanted islets.     

A review of split liver transplantation with full right/left hemi-liver grafts for 2 adult recipients

Liver transplantation has become a routine operation in many transplantation centers worldwide. However, liver graft availability fails to meet patient demands. Split liver transplantation (SPLT), which divides a deceased donor liver into 2 partial liver grafts, is a promising strategy for increasing graft availability for transplantation and ameliorating organ shortage to a certain degree. However, the transplantation community has not yet reached a consensus on SPLT because of the variable results. Specifically, SPLT for 2 adult recipients using full right/left hemi-liver grafts is clinically more challenging in terms of surgical technique and potential postoperative complications. Therefore, this review summarizes the current status of SPLT, focusing on the transplantation of adult recipients. Furthermore, the initiation of the SPLT program, donor allocation, surgical aspects, recipient outcomes, and obstacles to developing this procedure will be thoroughly discussed. This information might help provide an optimal strategy for implementing SPLT for 2 adult recipients among current transplantation societies. Meanwhile, potential obstacles to SPLT might be overcome in the near future with growing knowledge, experience, and refinement of surgical techniques. Ultimately, the widespread diffusion of SPLT may increase graft availability and mitigate organ donation shortages.