Pancreas transplantation for treatment of diabetes mellitus

Surgical complications after pancreatic transplantation: A computed tomography imaging pictorial review

Pancreatic transplantation is considered by the American Diabetes Association and the European Association for the Study of Diabetes an acceptable surgical procedure in patients with type 1 diabetes also undergoing kidney transplantation in pre-final or end-stage renal disease if no contraindications are present. Pancreatic transplantation, however, is a complex surgical procedure and may lead to a range of postoperative complications that can significantly impact graft function and patient outcomes. Postoperative computed tomography (CT) is often adopted to evaluate perfusion of the transplanted pancreas, identify complications and as a guide for interventional radiology procedures. CT assessment after pancreatic transplantation should start with the evaluation of the arterial Y-graft, the venous anastomosis and the duodenojejunostomy. With regard to complications, CT allows for the identification of vascular complications, such as thrombosis or stenosis of blood vessels supplying the graft, the detection of pancreatic fluid collections, including pseudocysts, abscesses, or leaks, the assessment of bowel complications (anastomotic leaks, ileus or obstruction), and the identification of bleeding. The aim of this pictorial review is to illustrate CT findings of surgical-related complications after pancreatic transplantation. The knowledge of surgical techniques is of key importance to understand postoperative anatomic changes and imaging evaluation. Therefore, we first provide a short summary of the main techniques of pancreatic transplantation. Then, we provide a practical imaging approach to pancreatic transplantation and its complications providing tips and tricks for the prompt imaging diagnosis on CT.

Challenges Associated with Pancreas and Kidney Retransplantation-A Retrospective Analysis

Simultaneous pancreas and kidney transplantation (SPK) is an accepted treatment for diabetic patients with renal failure, and is associated with increased survival and quality of life for recipients. There are only a few publications on the outcomes of simultaneous pancreas–kidney retransplantation (Re-SPK) after previous SPK and the loss of function of both grafts. A total of 55 patients with type 1 diabetes mellitus underwent pancreas retransplantation at our center between January 1994 and March 2021. Twenty-four of these patients underwent Re-SPK after a previous SPK. All 24 operations were technically feasible. Patient survival rate after 3 months, 1 year, and 5 years was 79.2%, 75%, and 66.7%, respectively. The causes of death were septic arterial hemorrhage (n = 3), septic multiorgan failure (n = 2), and was unknown in one patient. Pancreas and kidney graft function after 3 months, 1 year, and 5 years were 70.8% and 66.7%, 66.7% and 62.5%, and 45.8% and 54.2%, respectively. Relaparotomy was performed in 13 out of 24 (54.2%) patients. The results of our study show that Re-SPK, after previously performed SPK, is a technical and immunological challenge, associated with a significantly increased mortality and complication rate; therefore, the indication for Re-SPK should be very strict. Careful preoperative diagnosis is indispensable.

Exocrine drainage in pancreas transplantation: Complications and management

The aim of this minireview is to compare various pancreas transplantation exocrine drainage techniques i.e., bladder vs enteric. Both techniques have different difficulties and complications. Numerous comparisons have been made in the literature between exocrine drainage techniques throughout the history of pancreas transplantation, detailing complications and their impact on graft and patient survival. Specific emphasis has been made on the early postoperative management of these complications and the related surgical infections and their consequences. In light of the results, a number of bladder-drained pancreas grafts required conversion to enteric drainage. As a result of technical improvements, outcomes of the varied enteric exocrine drainage techniques (duodenojejunostomy, duodenoduodenostomy or gastric drainage) have also been discussed i.e., assessing specific risks vs benefits. Pancreatic exocrine secretions can be drained to the urinary or intestinal tracts. Until the late 1990s the bladder drainage technique was used in the majority of transplant centers due to ease of monitoring urine amylase and lipase levels for evaluation of possible rejection. Moreover, bladder drainage was associated at that time with fewer surgical complications, which in contrast to enteric drainage, could be managed with conservative therapies. Nowadays, the most commonly used technique for proper driving of exocrine pancreatic secretions is enteric drainage due to the high rate of urological and metabolic complications associated with bladder drainage. Of note, 10% to 40% of bladder-drained pancreata eventually required enteric conversion at no detriment to overall graft survival. Various surgical techniques were originally described using the small bowel for enteric anastomosis with Roux-en-Y loop or a direct side-to-side anastomosis. Despite the improvements in surgery, enteric drainage complication rates ranging from 2%-20% have been reported. Treatment depends on the presence of any associated complications and the condition of the patient. Intra-abdominal infection represents a potentially very serious problem. Up to 30% of deep wound infections are associated with an anastomotic leak. They can lead not only to high rates of graft loss, but also to substantial mortality. New modifications of established techniques are being developed, such as gastric or duodenal exocrine drainage. Duodenoduodenostomy is an interesting option, in which the pancreas is placed behind the right colon and is oriented cephalad. The main concern of this technique is the challenge of repairing the native duodenum when allograft pancreatectomy is necessary. Identification and prevention of technical failure remains the main objective for pancreas transplantation surgeons. In conclusion, despite numerous techniques to minimize exocrine pancreatic drainage complications e.g., leakage and infection, no universal technique has been standardized. A prospective study/registry analysis may resolve this.

Autoimmune Diabetes Recurrence After Pancreas Transplantation: Diagnosis, Management, and Literature Review

Background

Pancreas transplantation can be a viable treatment option for patients with type 1 diabetes mellitus (T1DM), especially for those who are candidates for kidney transplantation. T1DM may rarely recur after pancreas transplantation, causing the loss of pancreatic graft. The aim of this study was to describe the prevalence of T1DM recurrence after pancreas transplantation in our series.

Material/Methods

Eighty-one patients transplanted from 2002 to 2015 were included. Autoantibody testing (GADA and IA-2) was performed before pancreas transplantation and during the follow-up.

Results

The series includes 48 males and 33 females, mean age 37.4±5.7 years and mean duration of diabetes 25.5±6.5 years. Patients received simultaneous pancreas kidney (SPK) transplantation. After SPK transplantation, 56 patients retained pancreatic graft, 8 patients died, and 17 patients lost their pancreatic graft. T1DM recurrence occurred in 2 of the 81 transplanted patients, yielding a prevalence of 2.5%, with an average time of appearance of 3.3 years after transplant. Pancreatic enzymes were normal in the 2 patients, ruling out pancreatic rejection. T1DM recurrence was confirmed histologically, showing selective lymphoid infiltration of the pancreatic islets.

Conclusions

T1DM recurrence after pancreas transplantation is infrequent; however, it is one of the causes of pancreatic graft loss that should always be ruled out. Negative autoimmunity prior to transplantation does not ensure that T1DM does not recur.

Simultaneous Pancreas and Kidney Transplantation is Associated With Inferior Long-Term Outcomes in African Americans

OBJECTIVES

Simultaneous pancreas and kidney transplant (SPK) is the most effective treatment for patients with type 1 diabetes mellitus and renal failure. However, the effect of ethnicity on SPK outcomes is not well understood.

METHODS

We studied the influence of recipient ethnicity on SPK using the United Network for Organ Sharing database. A retrospective review of 20,196 SPK patients from 1989 to 2014 was performed. The recipients were divided into 4 groups: 15,833 whites (78.40%), 2708 African Americans (AA) (14.39%), 1456 Hispanics (7.21%), and 199 Asians (0.99%).

RESULTS

Hispanics and Asians experienced the best overall graft and patient outcomes. Both groups demonstrated significantly superior graft and patient survival rates compared with whites at 1, 3, 5, 10, and 15 years (all P < 0.0001). African Americans experienced significantly superior 1- and 3-year patient survival compared with whites (both P < 0.0001). African Americans also experienced significantly superior 1-year kidney and pancreas graft survival compared with whites (P < 0.0001). However, AA experienced significantly inferior patient and allograft outcomes for all other time points compared with whites.

CONCLUSIONS

Based on United Network for Organ Sharing data from 1989 to 2014, AA have worse long-term patient and graft survival rates compared with whites, Hispanics, and Asians undergoing SPK.

Pancreas transplantation: Advantages of a retroperitoneal graft position

INTRODUCTION

In the 50 years since the first pancreas transplant performed at the University of Minnesota, the surgical techniques employed have undergone many modifications. Techniques such as retroperitoneal graft placement have further improved the ability to reproduce the physiology of the «native» pancreas. We herein present our experience of a modified technique for pancreatic transplant, with the organ placed into a fully retroperitoneal position with systemic venous and enteric drainage of the graft by duodeno-duodenostomy.

METHODS

All pancreas transplantations performed between May 2016 and January 2017 were prospectively entered into our transplant database and retrospectively analyzed.

RESULTS

A total of 10 transplants were performed using the retroperitoneal technique (6 men: median age of 41 years [IQR 36-54]). Median cold ischemia times was 10,30h [IQR 5,30-12,10]. The preservation solution used was Celsior (n=7), IGL-1 (n=2), and UW (n=1). No complications related to the new surgical technique were identified. In one patient, transplantectomy at 12h was performed due to graft thrombosis, probably related to ischemic conditions from a donor with prolonged cardio-respiratory arrest. Another procedure was aborted without completing the graft implant due to an intraoperative immediate arterial thrombosis in a patient with severe iliac atheromatosis. No primary pancreas non-function occurred in the remaining 8patients. The median hospital stay was 13,50 days [IQR 10-27].

CONCLUSIONS

Retroperitoneal graft placement appears feasible with easy access for dissection the vascular site; comfortable technical vascular reconstruction; and a decreased risk of intestinal obstruction by separation of the small bowel from the pancreas graft.

Outcomes From Pancreatic Transplantation in Donation After Cardiac Death: A Systematic Review and Meta-Analysis

BACKGROUND

Pancreas transplantation remains the gold standard for treatment for type I diabetes providing an insulin-independent, normoglycemic state. Increasingly, donation after cardiac death (DCD) donors are used in view of the organ donor shortage. We aimed to systematically review recipient outcomes from DCD donors and where possible compared these with donor after brain death (DBD) donors.

METHODS

We searched the databases MEDLINE via PubMed, EMBASE, and The Cochrane Library from inception to March 2015, for studies reporting the outcome of DCD pancreas transplants. We appraised studies using the Newcastle-Ottawa scale and meta-analyzed using a random effects model.

RESULTS

We identified 18 studies, 4 retrospective and 6 prospective cohort studies and 8 case reports. Our bias assessment revealed that although studies were well conducted, some studies had potential confounding factors and absence of comparator groups. Eight of the 18 studies included a DBD comparison group comprising 23 609 transplant recipients. Importantly, there was no significant difference in allograft survival up to 10 years (hazard ratio, 0.98; 95% confidence interval [95% CI], 0.74-1.31; P = 0.92), or patient survival (hazard ratio, 1.31; 95% CI, 0.62-2.78; P = 0.47) between DCD and DBD pancreas transplants. We estimated that the odds of graft thrombosis was 1.67 times higher in DCD organs (95% CI, 1.04-2.67; P = 0.006). However, subgroup analysis found thrombosis was not higher in recipients whose DCD donors were given antemortem heparin (P = 0.62).

CONCLUSIONS

Using current DCD criteria, pancreas transplantation is a viable alternative to DBD transplantation, and antemortem interventions including heparinization may be beneficial. This potential benefit of DCD pancreas donation warrants further study.

Pancreatic Transplantation: Evaluation and Management

More than 2 million people in the United States have type 1 diabetes mellitus. Pancreatic transplantation has emerged as the single most effective means of achieving normal glucose homeostasis in this patient population. Newer immunosuppressive agents and surgical techniques continue to evolve, resulting in improved long-term graft and patient survival. Herein, an understanding of the evaluation, technical aspects, and perioperative management of pancreas transplantation is outlined.

Biomarkers in pancreas transplant

PURPOSE OF REVIEW

The review analyzes the current biomarkers used in monitoring pancreas transplant, from the simple and time-tested, to more sophisticated, including markers of allo- and autoimmunity, that are likely to play a larger role in future studies.

RECENT FINDINGS

Evaluation of alloimmunity includes serum levels of donor-specific antibody, and, ultimately, pancreas transplant biopsies with C4d staining. Our center has focused on markers of autoimmunity, including assessment of autoantibodies and autoreactive T cells. We have found that conversion of autoantibodies (including GAD65, IA-2, and ZnT8), or the development of a new positive autoantibody, particularly ZnT8, are associated with type 1 diabetes (T1D) recurrence in the pancreas transplant. Autoreactive T cells have also been identified in the peripheral blood, pancreas transplant and peripancreas transplant-lymph nodes, that have the potential to mediate human β/islet cell destruction in vivo.

SUMMARY

The monitoring of pancreas transplant biomarkers, particularly those associated with autoimmunity, has led to new insights into the pathogenesis of T1D. Progress in the elucidation of mechanisms of autoimmunity may lead to novel therapeutic approaches to both T1D recurrence of the pancreas transplant and perhaps also new onset T1D.

Lessons From Pancreas Transplantation in Type 1 Diabetes: Recurrence of Islet Autoimmunity

Type 1 diabetes recurrence (T1DR) affecting pancreas transplants was first reported in recipients of living-related pancreas grafts from twins or HLA identical siblings; given HLA identity, recipients received no or minimal immunosuppression. This observation provided critical evidence that type 1 diabetes (T1D) is an autoimmune disease. However, T1DR is traditionally considered very rare in immunosuppressed recipients of pancreas grafts from organ donors, representing the majority of recipients, and immunological graft failures are ascribed to chronic rejection. We have been performing simultaneous pancreas-kidney (SPK) transplants for over 25 years and find that 6-8 % of our recipients develop T1DR, with symptoms usually becoming manifest on extended follow-up. T1DR is typically characterized by (1) variable degree of insulitis and loss of insulin staining, on pancreas transplant biopsy (with most often absent), minimal to moderate and rarely severe pancreas, and/or kidney transplant rejection; (2) the conversion of T1D-associated autoantibodies (to the autoantigens GAD65, IA-2, and ZnT8), preceding hyperglycemia by a variable length of time; and (3) the presence of autoreactive T cells in the peripheral blood, pancreas transplant, and/or peripancreatic transplant lymph nodes. There is no therapeutic regimen that so far has controlled the progression of islet autoimmunity, even when additional immunosuppression was added to the ongoing chronic regimens; we hope that further studies and, in particular, in-depth analysis of pancreas transplant biopsies with recurrent diabetes will help identify more effective therapeutic approaches.

Is simultaneous pancreas kidney transplant the most cost-effective strategy for type 1 diabetes patients with renal failure?

Introduction:

Simultaneous pancreas kidney transplant (SPK) has shown beneficial outcomes in type 1 diabetes patients with renal failure (IDDM-RF). The objective of this study was to assess its cost-effectiveness compared with other treatment strategies for IDDM-RF.

Methods:

A decision analytic model was developed for IDDM-RF treatment with four possible strategies: deceased donor kidney transplant (DDKT), living donor kidney transplant (LDKT), SPK and dialysis. A cost-utility analysis from the healthcare provider perspective was conducted based on a five-year model. Local data were used whenever possible except for SPK survival variables, wherein data from United Network for Organ Sharing and Scientific Registry of Transplant Recipients were used. Sensitivity analyses were performed to evaluate the impact of uncertainties around key variables.

Results:

In the baseline analysis, LDKT was the most cost-effective strategy with the lowest cost per quality-adjusted life year gained, i.e. SGD77,068, followed by SPK (SGD82,991), DDKT (SGD92,432) and dialysis (SGD181,192). The DDKT was extended dominated by dialysis and LDKT strategies. Incremental cost-effectiveness ratios with dialysis as a reference for LDKT and SPK strategies were SGD43,094 and SGD56,201, respectively. Both strategies are considered highly cost-effective under World Health Organization (WHO) guidelines. In the sensitivity analysis, a 6% increase in both SPK kidney graft survival and patient survival would make SPK the most cost-effective strategy.

Conclusions:

Both LDKT and SPK are highly cost-effective strategies in the treatment of IDDM-RF. SPK is potentially the most cost-effective strategy if a 6% increase in both SPK kidney graft survival and patient survival is achieved.

Component analysis of hospital cost of pancreas-kidney transplant and correlations with different variables in a Brazilian hospital

INTRODUCTION

Simultaneous pancreas-kidney transplantation is associated with a high rate of complications when it is compared with transplantation of other organs; these increased complications can result in increased financial costs of the procedure. The objective of this study was to determine operating costs and financial results of simultaneous pancreas-kidney transplantation and its different variables in a Brazilian hospital.

PATIENTS AND METHODS

Between January 2008 and December 2011, the monthly costs of 105 patients were calculated. These patients were divided into 2 groups; the first consecutive 53 patients were labeled group I and the second set of 52 patients were labeled group II. The cost evaluation was made in US dollars.

RESULTS

A total of 89 patients corresponded to the public health system and 16 patients to the supplementary health system. The percentage of hospital discharge was 92.4%. There was an increase in operating room costs in group II compared with group I with no statistically significant difference ($18,749.33 for group I and $17,608.26 for group II). The outcome of the operation was positive; it was greater for group II than for group I ($16,303.22 vs $3494.53).

CONCLUSIONS

Simultaneous pancreas-kidney transplantation is a financially feasible procedure in Brazil, with the public health system being the main payment source.

Hydrogen-rich saline protects against ischemia/reperfusion injury in grafts after pancreas transplantations by reducing oxidative stress in rats

Purpose. This study aimed to investigate the therapeutic potential of hydrogen-rich saline on pancreatic ischemia/reperfusion (I/R) injury in rats. Methods. Eighty heterotopic pancreas transplantations (HPT) were performed in syngenic rats. The receptors were randomized blindly into the following three groups: the HPT group and two groups that underwent transplantation and administration of hydrogen-rich saline (HS, >0.6 mM, 6 mL/kg) or normal saline (NS, 6 mL/kg) via the tail vein at the beginning of reperfusion (HPT + HS group, HPT + NS group). Samples from the pancreas and blood were taken at 12 hours after reperfusion. The protective effects of hydrogen-rich saline against I/R injury were evaluated by determining the changes in histopathology and measuring serological parameters, oxidative stress-associated molecules, and proinflammatory cytokines. Results. Administration of hydrogen-rich saline produced notable protection against pancreatic I/R injury in rats. Histopathological improvements and recovery of impaired pancreatic function were observed. In addition, TNF-α, IL-1β, and IL-6 were reduced markedly in the HPT + HS group. Additionally, there were noticeable inhibitory effects on the pancreatic malondialdehyde level and considerable recruitment of SOD and GPx, which are antioxidants. Conclusion. Hydrogen-rich saline treatment significantly attenuated the severity of pancreatic I/R injury in rats, possibly by reducing oxidative stress and inflammation.

Three types of simultaneous pancreas and kidney transplantation

PURPOSE

The purposes of this study were to study and compare clinical and functional outcomes after simultaneous deceased donor pancreas and kidney transplantation (SPK DD), simultaneous deceased donor pancreas and living donor kidney transplantation (SPK DL), and simultaneous living donor pancreas and kidney transplantation (SPK LL).

METHODS

From January 1, 1996 to September 1, 2005, 8918 primary, simultaneous pancreas and kidney transplantation (SPK) procedures were reported to the International Pancreas Transplant Registry. Of these, 8764 (98.3%) were SPK DD, 115 (1.3%) were SPK DL, and 39 (0.4%) were SPK LL. We compared these 3 groups with regard to several endpoints including patient and pancreas and kidney graft survival rates.

RESULTS

The 1-year and 3-year patient survival rates for SPK DD were 95% and 90%, 97% and 95% for SPK DL, and 100% and 100% for SPK LL recipients, respectively (P ≥ .07). The 1-year and 3-year pancreas graft survival rates for SPK DD were 84% and 77%, 83% and 71% for SPK DL, and 90% and 84% for SPK LL recipients, respectively (P ≥ .16). The 1-year and 3-year kidney graft survival rates for SPK DD were 92% and 84%, 94% and 86% for SPK DL, and 100% and 89% for SPK LL recipients, respectively (P ≥ .37).

CONCLUSIONS

Patient survival rates and graft survival rates for pancreas and kidney were similar among the 3 groups evaluated in this study.

Imaging in pancreatic transplants

Pancreatic transplantation, performed alone or in conjunction with kidney transplantation, is an effective treatment for advanced type I diabetes mellitus and select patients with type II diabetes mellitus. Following advancements in surgical technique, postoperative management, and immunosuppression, pancreatic transplantation has significantly improved the length and quality of life for patients suffering from pancreatic dysfunction. While computed tomography (CT) and magnetic resonance imaging (MRI) have more limited utility, ultrasound is the preferred initial imaging modality to evaluate the transplanted pancreas; gray-scale assesses the parenchyma and fluid collections, while Doppler interrogation assesses vascular flow and viability. Ultrasound is also useful to guide percutaneous interventions for the transplanted pancreas. With knowledge of the surgical anatomy and common complications, the abdominal radiologist plays a central role in the perioperative and postoperative evaluation of the transplanted pancreas.

Financial cost of the admissions for simultaneous pancreas-kidney transplant in a Brazilian hospital

PURPOSE

To perform a cost analysis of simultaneous pancreas-kidney transplantation (SPKT) in a Brazilian hospital.

METHODS

Between January 2008 and December 2011, 105 consecutive SPKTs at the Hospital of Kidney and Hypertension in Sao Paulo were evaluated. We evaluated the patient demographics, payment source (public health system or supplementary system), and the impact of each hospital cost component. The evaluated costs were corrected to December 2011 values and converted to US dollars.

RESULTS

Of the 105 SPKT patients, 61.9% were men, and 38.1% were women. Eight patients died, and 97 were discharged (92.4%). Eighty-nine procedures were funded by the public health system. The cost for the patients who were discharged was $18.352.27; the cost for the deceased patients was $18.449.96 (p = 0.79). The FOR for SPKT during this period was positive at $5,620.65. The costs were distributed as follows: supplies, 36%; administrative costs, 20%; physician fees, 15%; intensive care unit, 10%; surgical center, 10%; ward, 9%.

CONCLUSION

Mortality did not affect costs, and supplies were the largest cost component.

Current status of clinical islet transplantation

Islet transplantation (IT) is today a well-established treatment modality for selected patients with type 1 diabetes mellitus (T1DM). After the success of the University of Alberta group with a modified approach to the immune protection of islets, the international experience grew along with the numbers of transplants in highly specialized centers. Yet, long-term analysis of those initial results from the Edmonton group indicated that insulin-independence was not durable and most patients return to modest amounts of insulin around the fifth year, without recurrent hypoglycemia events. Many phenomena have been identified as limiting factor for the islet engraftment and survival, and today all efforts are aimed to improve the quality of islets and their engrafting process, as well as more optimized immunosuppression to facilitate tolerance and ultimately, better long term survival. This brief overview presents recent progress in IT. A concise historical perspective is provided, along with the latest efforts to improve islet engraftment, immune protection and ultimately, prolonged graft survival. It is apparent that as the community continues to work together further optimizing IT, it is hopeful a cure for T1DM will soon be achievable.

Immunoisolated transplantation of purified langerhans islet cells in testis cortex of male rats for treatment of streptozotocin induced diabetes mellitus

The objective of this study is to induce experimental diabetes mellitus by streptozotocin in normal adult Wistar rats via comparison of changes in body weight, consumption of food, volume of water, urine and levels of glucose, insulin and C-peptide in serum, between normal and diabetic rats. Intra-venous injection of 60 mg/kg dose of streptozotocin in 250-300 g (75-90 days) adult Wistar rats makes pancreas swell and causes degeneration in Langerhans islet β-cells and induces experimental diabetes mellitus in 2-4 days. For a microscopic study of degeneration of Langerhans islet β-cells of diabetic rats, biopsy from pancreas tissue of diabetic and normal rats, staining and comparison between them, were done. In this process, after collagenase digestion of pancreas, islets were isolated, dissociated and identified by dithizone method and then with enzymatic procedure by DNase and trypsin, the islet cells changed into single cells and β-cells were identified by immune fluorescence method and then assayed by flow-cytometer. Donor tissue in each step of work was prepared from 38 adult male Wistar rats weighted 250-300 g (75-90 days). Transplantation was performed in rats after 2-4 weeks of diabetes induction. In this study, the levels of insulin, C-peptide and glucose in diabetic rats reached to normal range as compared to un-diabetic rats in 20 days after transplantation of islet cells. Transplantation was performed under the cortex of testis as immunoisolated place for islet cells transplantation.

Design of a bioartificial pancreas

Islet transplantation has been shown to be a viable treatment option for patients afflicted with type 1 diabetes. However, the lack of availablity of human pancreases and the need to use risky immunosuppressive drugs to prevent transplant rejection remain two major obstacles to the routine use of islet transplantation in diabetic patients. Successful development of a bioartificial pancreas using the approach of microencapsulation with perm-selective coating of islets in hydrogels for graft immunoisolation holds tremendous promise for diabetic patients because it has great potential to overcome these two barriers. In this review article, we will discuss the need for a bioartificial pancreas, provide a detailed description of the microencapsulation process, and review the status of the technology in clinical development. We will also critically review the various factors that will need to be taken into consideration in order to achieve the ultimate goal of routine clinical application.

Human islet cell isolation: the initial step in an islet transplanting program in Shiraz, Southern Iran

OBJECTIVES

Type 1 diabetes mellitus is an emerging epidemic worldwide and results from autoimmune destruction of insulin-producing β cells. Islet transplanting is a potential treatment for type 1 diabetes mellitus.

MATERIALS AND METHODS

The Shiraz Organ Transplant Center is a leading center for organ transplants, especially pancreatic transplants, in Iran. For this reason, we want to establish an islet transplanting program. Here, we briefly describe our experience with islet isolation on 6 pancreata from deceased donors. We discussed the necessary equipment required for this procedure, as well as the professionals needed and a specially planned facility.

RESULTS

Islet yield was ≤ 100 000 (islet equivalent), viability 40% to 45%, and the purity was 30% to 45%. We do not have a refrigerated COBE processor for purification; therefore, the yield was low. Our experience shows that we should improve things, so as to acquire more islets for developing clinical grade cell therapy.

CONCLUSIONS

Overall, isolation costs are high, and accessing a safer, more economic, and persistent source of material and reagents will improve this technique.

Restoring insulin production for type 1 diabetes

Current therapies for the treatment of type 1 diabetes include daily administration of exogenous insulin and, less frequently, whole-pancreas or islet transplantation. Insulin injections often result in inaccurate insulin doses, exposing the patient to hypo- and/or hyperglycemic episodes that lead to long-term complications. Islet transplantation is also limited by lack of high-quality islet donors, early graft failure, and chronic post-transplant immunosuppressive treatment. These barriers could be circumvented by designing a safe and efficient strategy to restore insulin production within the patient's body. Porcine islets have been considered as a possible alternative source of transplantable insulin-producing cells to replace human cadaveric islets. More recently, embryonic or induced pluripotent stem cells have also been examined for their ability to differentiate in vitro into pancreatic endocrine cells. Alternatively, it may be feasible to generate new β-cells by ectopic expression of key transcription factors in endogenous non-β-cells. Finally, engineering surrogate β-cells by in vivo delivery of the insulin gene to specific tissues is also being studied as a possible therapy for type 1 diabetes. In the present review, we discuss these different approaches to restore insulin production.

Treatment of streptozotocin induced diabetes in male rats by immunoisolated transplantation of islet cells

Insulin injection is the main way to combat against insulin-dependent diabetes mellitus effects. Today in some laboratories in the world, the investigators are trying to find some treatments for this disease with insulin-secreting pancreatic islet cells transplantation. Donor tissue in each step of work was prepared from 36 adult male wistar Rats weighted 250-300 grams (75-90 days). Transplantation was done in rats after 2-4 weeks induction of diabetes with 60mg/kg of streptozotocin injection by intravenous method. Encapsulation of pancreatic islet cells allows for transplantation in the absence of immunosuppression. This technique that is called "immunoisolation" is based on the principle that transplanted tissue is protected for the host immune system by an artificial or natural membrane. In this study, the levels of insulin, C-peptide and glucose in diabetic rats have been reached to normal range as compared to un-diabetic rats in 20 days after transplantation of islet cells, so that testis is immunoisolated place for islet cells transplantation. Inside the testis subcutaneously and intrapretoneally implantation of pure islet cells graft, that is a natural immunoisolation method, rapidly and permanently normalized the diabetic state of streptozocin-administered animals.

Transplantation of the pancreas

Pancreas transplantation consistently induces insulin-independence in beta-cell-penic diabetic patients, but at the cost of major surgery and life-long immunosuppression. One year after grafting, patient survival rate now exceeds 95 % across recipient categories, while insulin independence is maintained in some 85 % of simultaneous pancreas and kidney recipients and in nearly 80 % of solitary pancreas transplant recipients. The half-life of the pancreas graft currently averages 16.7 years, being the longest among extrarenal grafts, and substantially matching the one of renal grafts from deceased donors. The difference between expected (100 %) and actual insulin-independence rate is mostly explained by technical failure in the postoperative phase, and rejection in the long-term period. Death with a functioning graft remains a further major issue, especially in uremic patients who have undergone prolonged periods of dialysis. Refinements in graft preservation, surgical techniques, immunosuppression, and prophylactic treatments are expected to further improve the results of pancreas transplantation.

Current concepts in the simultaneous transplantation of kidney and pancreas

Diabetes mellitus (DM) represents an enormous health care concern for the United States and other countries. According to the American Diabetes Association in 2007, there were more than 23 million Americans living with diabetes. This is a 13.5% increase from 2005, likely representing increases in Type II DM (DMII). Diabetes mellitus results when the beta cells of the pancreas are unable to produce sufficient insulin to prevent hyperglycemia. Simultaneous pancreas and kidney transplantation, or SPK, may be indicated for patients that have experienced renal failure as a complication of DM (either type I or type II). Until recently, technical failure represented a significant impediment to the success of pancreas transplantation. At the turn of the century, however, both renal and pancreatic graft survival dramatically improved. Immunologic and nonimmunologic causes of graft failure continue to challenge inpatient and outpatient management. With vigilance in the ICU postoperatively and in the clinic, SPK can provide significant benefit both in patient survival and quality of life.

Initial Australasian experience with portal-enteric drainage in simultaneous pancreas-kidney transplantation

BACKGROUND

Pancreas-kidney transplantation is currently the most effective method to re-establish euglycaemia in insulin-dependent diabetics with associated renal failure. The standard technique employed has been bladder drainage of exocrine secretions coupled with systemic venous drainage ('systemic-bladder' (SB) drainage). The more physiological technique, enteric exocrine with portal venous drainage ('portal-enteric' (PE) drainage), has been utilized sparingly in the past as a result of fears of technical complications. This paper compares the Monash Medical Centre experience with both techniques.

METHODS

A total of 68 simultaneous pancreas-kidney transplantations were performed at Monash Medical Centre from 1991 until 2004. The first 37 received SB drainage. Since March 2001, 27 have received PE drainage. This retrospective study compared the SB group (n= 37) with the PE group (n= 27), with a 2-year follow-up, examining a number of surgical outcomes.

RESULTS

Two-year patient (94.3 versus 96.0%), kidney (89.2 versus 85.2%), pancreas (77.9 versus 71.4%) and event-free (73.0 versus 67.7%) survivals were all similar between the SB and PE groups, respectively. Although surgery took longer in PE subjects (4 h : 47 min ± 0:48 versus 5 h : 16 min ± 1:00; P= 0.045), less intraoperative transfusions were required (1.3 ± 1.43 versus 0.52 ± 0.90; P= 0.024). Length of hospital stay and time to insulin independence were similar. Pancreas graft thrombosis rates were similar (10.8% SB versus 7.4% PE, P= 0.497).

CONCLUSIONS

PE drainage is a safe and viable method for pancreas transplantation, which can be performed with excellent outcomes. An increased rate of complications with PE drainage has not been demonstrated in this series.

Donor pretreatment with tetrahydrobiopterin saves pancreatic isografts from ischemia reperfusion injury in a mouse model

Depletion of the nitric oxide synthase cofactor tetrahydrobiopterin (H4B) during ischemia and reperfusion is associated with severe graft pancreatitis. Since clinically feasible approaches to prevent ischemia reperfusion injury (IRI) by H4B-substitution are missing we investigated its therapeutic potential in a murine pancreas transplantation model using different treatment regimens. Grafts were subjected to 16 h cold ischemia time (CIT) and different treatment regimens: no treatment, 160 μM H4B to perfusion solution, H4B 50 mg/kg prior to reperfusion and H4B 50 mg/kg before recovery of organs. Nontransplanted animals served as controls. Recipient survival and endocrine graft function were assessed. Graft microcirculation was analyzed 2 h after reperfusion by intravital fluorescence microscopy. Parenchymal damage was assessed by histology and nitrotyrosine immunohistochemistry, H4B tissue levels by high pressure liquid chromatography (HPLC). Compared to nontransplanted controls prolonged CIT resulted in significant microcirculatory deterioration. Different efficacy according to route and timing of administration could be observed. Only donor pretreatment with H4B resulted in almost completely abrogated IRI-related damage showing graft microcirculation comparable to nontransplanted controls and restored intragraft H4B levels, resulting in significant reduction of parenchymal damage (p < 0.002) and improved survival and endocrine function (p = 0.0002 each). H4B donor pretreatment abrogates ischemia-induced parenchymal damage and represents a promising strategy to prevent IRI following pancreas transplantation.

Use of rat segmental intestine for fetal pancreatic transplantation

It is thought that the small intestine may provide a scaffold for pancreas regeneration. Herein, we investigated whether fetal pancreatic tissue could be transplanted into the segmental intestine in rats. Fetal pancreases from firefly luciferase transgenic Lewis rat embryos (embryonic day 14.5 and 15.5) were transplanted into streptozotocin (STZ)-induced diabetic wild-type Lewis rats. As a scaffold for pancreatic development, rat small intestinal segments were utilized after the removal of mucosa, and fetal pancreases were grafted into the luminal surface through the stoma. We also transplanted fetal pancreases into the omentum. The survival of transplanted fetal pancreases was monitored by luciferase-derived photons and blood glucose levels. Transplanted fetal pancreas-derived photons were stable for 28 days, suggesting that transplanted fetal pancreatic tissues survived and that their intestinal blood supply was maintained.

Surgical techniques for pancreas transplantation

PURPOSE OF REVIEW

Pancreas transplantation reproducibly induces insulin independence in beta-cell penic diabetic patients. The difference between full insulin independence, partial graft function, and graft loss, mostly results from technical failure, graft rejection, and patient death with function graft. The purpose of this review is to examine recent surgical advances and discuss their contribution to improved graft function.

RECENT FINDINGS

Few actual surgical innovations were described in the period reviewed. Duodenoduodenostomy is an interesting option for drainage of digestive secretions, when the pancreas is placed behind the right colon and is oriented cephalad. The main advantage of this technique is easy endoscopic assessment of donor duodenum but, when allograft pancreatectomy is necessary, repair of native duodenum may be troublesome. Selective revascularization of the gastroduodenal artery, at the back-table, possibly improves blood supply to the head of the pancreas graft and duodenal segment. There is no proof that this additional maneuver is always beneficial, although it can be graft saving in case of poor segmental graft perfusion.

SUMMARY

Transplant surgeons should be familiar with all techniques for pancreas transplantation. Long-term graft function is possible only after technically successful pancreas transplantation. There is clearly a need for more objective assessment and standardization of surgical techniques for pancreas transplantation.

Impact of Medicare coverage on disparities in access to simultaneous pancreas and kidney transplantation

In the setting of disparities in access to simultaneous pancreas and kidney transplantation (SPKT), Medicare coverage for this procedure was initiated July 1999. The impact of this change has not yet been studied. A national cohort of 22 190 type 1 diabetic candidates aged 18-55 for kidney transplantation (KT) alone or SPKT was analyzed. Before Medicare coverage, 57% of Caucasian, 36% of African American and 38% of Hispanic type 1 diabetics were registered for SPKT versus KT alone. After Medicare coverage, these proportions increased to 68%, 45% and 43%, respectively. The overall increase in SPKT registration rate was 27% (95% CI 1.16-1.38). As expected, the increase was more substantial in patients with Medicare primary insurance than those with private insurance (Relative Rate 1.18, 95% CI 1.09-1.28). However, racial disparities were unaffected by this policy change (African American vs. Caucasian: 0.97, 95% CI 0.87-1.09; Hispanic vs. Caucasian: 0.94, 95% CI 0.78-1.05). Even after Medicare coverage, African Americans and Hispanics had almost 30% lower SPKT registration rates than their Caucasian counterparts (95% CI 0.66-0.79 and 0.59-0.80, respectively). Medicare coverage for SPKT succeeded in increasing access for patients with Medicare, but did not affect the substantial racial disparities in access to this procedure.

Effects of premedication with tiletamine/zolazepam/medetomidine during general anesthesia using sevoflurane/fentanyl in swine undergoing pancreas transplantation

OBJECTIVE

To assess cardiac and hemodynamic responses and body temperature during long-term general anesthesia using sevoflurane/fentanyl after premedication with a tiletamine/zolazepam/medetomidine combination in swine undergoing experimental pancreas transplantation.

MATERIALS AND METHODS

Twelve Landrace female pigs of means weight 46.4 +/- 5.1 kg were premedicated by intramuscular administration of tiletamine/zolazepam (3.5 mg/kg), medetomidine (0.03 mg/kg), and atropine (0.02 mg/kg), before anesthesia with 0.75 minimum alveolar concentration sevoflurane and continuous intravenous fentanyl infusion (5.7 +/- 0.7 microg/kg/h). Assessment of heart rate, arterial blood pressure, and temperature in pigs undergoing allogenic pancreas transplant surgery were registered at the start of anesthesia (T0), as well as at 60 (T60), 120 (T120), and 180 (T180) minutes after T0, and finally at the end of anesthesia (T anesthesia end), when we switched off the sevoflurane vaporizer. Analysis of variance was used to determine differences between times with P < .05 considered significant. Results are given as mean values +/- standard deviations.

RESULTS

Arterial blood pressure significantly decreased from T120 to the end of anesthesia, while a significantly decreased heart rate was only evident at T60. Body temperature decreased significantly from T60 to the end of anesthesia. These decreases, however, lacked clinical relevance; all parameters were within normal range. No major anesthetic complications were observed in this study.

CONCLUSIONS

The administration of a tiletamine/zolazepam/medetomidine combination as premedication in swine subjected to pancreas transplantation allowed for a safe reduction of sevoflurane/fentanyl requirements during long-term general anesthesia. Despite arterial blood pressure and body temperature evidencing a decrease during anesthetic maintenance, all parameters remained within normal range values.

Pulsatile intravenous insulin therapy: the best practice to reverse diabetes complications?

In the basal state and after oral ingestion of carbohydrate, the normal pancreas secretes insulin into the portal vein in a pulsatile manner. The end organ of the portal vein is the liver, where approximately 80% of pancreatic insulin is extracted during first pass. In Type 1 diabetes, pancreatic insulin secretion is nearly or completely absent whilst in Type 2 diabetes the normal pattern is absent, abnormal, or blunted. Exogenous subcutaneous insulin treatment results in plasma insulin concentrations that are not pulsatile and a fraction of normal portal vein levels. Oral hypoglycemic agents also do not result in normal pulsatile response to a glucose load. Due to hypoglycemia risk, intensive treatment is not recommended after serious complications develop. Consequently, no conventional therapy has proved effective in treating advanced diabetes complications. Beta-cell replacement using whole pancreas or islet transplantation has been utilized to treat certain problems in Type 1 diabetic patients, but still unavailable for all diabetics. Pulsatile intravenous insulin therapy (PIVIT) is an insulin therapy, which mimics the periodicity and amplitude of normal pancreatic function. Numerous studies show PIVIT effective in preventing, reversing, and reducing the severity and progression of diabetes complications, however, the mechanisms involved with the improvement are not clearly understood. Here, we review the cellular basis of normal and abnormal insulin secretion, current treatments available to treat diabetes, the physiologic basis of PIVIT and possible mechanisms of action.

Current status of islet cell transplantation

Despite substantial advances in islet isolation methods and immunosuppressive protocol, pancreatic islet cell transplantation remains an experimental procedure currently limited to the most severe cases of type 1 diabetes mellitus. The objectives of this treatment are to prevent severe hypoglycemic episodes in patients with hypoglycemia unawareness and to achieve a more physiological metabolic control. Insulin independence and long term-graft function with improvement of quality of life have been obtained in several international islet transplant centers. However, experimental trials of islet transplantation clearly highlighted several obstacles that remain to be overcome before the procedure could be proposed to a much larger patient population. This review provides a brief historical perspective of islet transplantation, islet isolation techniques, the transplant procedure, immunosuppressive therapy, and outlines current challenges and future directions in clinical islet transplantation.

Cellular islet autoimmunity associates with clinical outcome of islet cell transplantation

Background

Islet cell transplantation can cure type 1 diabetes (T1D), but only a minority of recipients remains insulin–independent in the following years. We tested the hypothesis that allograft rejection and recurrent autoimmunity contribute to this progressive loss of islet allograft function.

Methodology/Principal Findings

Twenty-one T1D patients received cultured islet cell grafts prepared from multiple donors and transplanted under anti-thymocyte globulin (ATG) induction and tacrolimus plus mycophenolate mofetil (MMF) maintenance immunosuppression. Immunity against auto- and alloantigens was measured before and during one year after transplantation. Cellular auto- and alloreactivity was assessed by lymphocyte stimulation tests against autoantigens and cytotoxic T lymphocyte precursor assays, respectively. Humoral reactivity was measured by auto- and alloantibodies. Clinical outcome parameters - including time until insulin independence, insulin independence at one year, and C-peptide levels over one year- remained blinded until their correlation with immunological parameters. All patients showed significant improvement of metabolic control and 13 out of 21 became insulin-independent. Multivariate analyses showed that presence of cellular autoimmunity before and after transplantation is associated with delayed insulin-independence (p = 0.001 and p = 0.01, respectively) and lower circulating C-peptide levels during the first year after transplantation (p = 0.002 and p = 0.02, respectively). Seven out of eight patients without pre-existent T-cell autoreactivity became insulin-independent, versus none of the four patients reactive to both islet autoantigens GAD and IA-2 before transplantation. Autoantibody levels and cellular alloreactivity had no significant association with outcome.

Conclusions/Significance

In this cohort study, cellular islet-specific autoimmunity associates with clinical outcome of islet cell transplantation under ATG-tacrolimus-MMF immunosuppression. Tailored immunotherapy targeting cellular islet autoreactivity may be required. Monitoring cellular immune reactivity can be useful to identify factors influencing graft survival and to assess efficacy of immunosuppression.

Trial Registration

Clinicaltrials.gov NCT00623610

Pathophysiological role of platelets and platelet system in acute pancreatitis

The most successful approach for restoring normal long-term glucose homeostasis in type I diabetes mellitus is whole-organ pancreas transplantation. Graft pancreatitis is observed in up to 20% of patients and may lead to loss of the transplanted organ. Several pathophysiological events have been implicated in this form of pancreatitis. The most important cause of early graft pancreatitis is ischemia/reperfusion (I/R)-related disturbance of microvascular perfusion with subsequent hypoxic tissue damage. Recently, considerable evidence accumulated that, among a variety of other pathophysiological events, the activation of platelets can contribute to I/R injury in the course of acute pancreatitis experimentally and clinically. This review summarizes the events affecting platelet function and, therefore, pancreatic microcirculation leading to acute pancreatitis. Therapeutic approaches and own results are presented.

Therapy with the hsp60 peptide DiaPep277 in C-peptide positive type 1 diabetes patients

BACKGROUND

Type 1 diabetes results from a T-cell mediated autoimmune destruction of insulin-producing pancreatic beta-cells. The 60-kDa heat-shock protein (hsp60) is one of the known target self-antigens. An immunogenic peptide from hsp60, p277, arrested beta-cell destruction and maintained insulin production in newly diabetic non-obese diabetic (NOD) mice. A randomized, double-blind, phase Ib/II study of peptide treatment was undertaken in recent onset type 1 diabetes patients with remaining insulin production.

METHODS

Forty-eight recent onset type 1 diabetes patients were assigned subcutaneous injections of 0.2, 1.0 or 2.5 mg peptide DiaPep277 (n = 12 per dosage) at entry, and 1, 6 and 12 months, or four placebo injections (n = 12). The primary clinical endpoints were safety and efficacy (glucagon-stimulated C-peptide production at 6 and 12 months); secondary endpoints were HbA1c levels and daily insulin dose adjusted for body weight at 2, 6, 12 and 18 months.

RESULTS

C-peptide levels decreased over time in all groups except the 2.5 mg-treated. The decrease in C-peptide production was less in treated patients versus placebo, mostly in the 2.5 mg group. HbA1c increased significantly in the 1.0 mg group and in the 2.5 mg group at 2 and 18 months, respectively. No differences were seen in daily insulin doses. One patient was withdrawn from the study possibly owing to a treatment-related adverse event.

CONCLUSIONS

Multiple DiaPep277 peptide administration seems safe and may have a beneficial effect on C-peptide levels over time, but this finding is not supported by lower HbA1c levels or daily insulin requirement. Further investigation on a larger scale is warranted.

Selective unresponsiveness to beta cell autoantigens after induction immunosuppression in pancreas transplantation with anti-interleukin-2 receptor antibody versus anti-thymocyte globulin

Pancreas transplantation in type 1 diabetes patients could result in (re)activation of allo- and autoreactive T lymphocytes. Anti-thymocyte globulin (ATG) induction treatment is a successful, but broadly reactive anti-lymphocyte therapy used in pancreas and islet transplantation. A more selective alternative is daclizumab, a monoclonal antibody directed against the interleukin-2 receptor (CD25) on activated lymphocytes. We tested the hypothesis that daclizumab is more selective and has less immunological side effects than ATG. Thirty-nine simultaneous pancreas-kidney transplantation patients with type 1 diabetes were randomized for induction therapy with ATG or daclizumab. Auto- and recall immunity was measured cross-sectionally by lymphocyte stimulation tests with a series of auto- and recall antigens in 35 successfully transplanted patients. T cell autoimmunity to islets was low in both groups, except for a marginal but significantly higher reactivity against glutamic acid decarboxylase (GAD)65 in daclizumab-treated patients. The memory responses to recall antigens were significantly higher in the daclizumab-treated group compared to ATG-treated patients, specifically against purified protein derivative (PPD) (anti-bacterial immunity), Haemophilus influenzae virus matrix protein-1 (anti-viral immunity) and p53 [anti-tumour (auto)immunity]. These data imply that daclizumab is more specifically affecting diabetes-related immune responses than ATG. The autoimmunity is affected effectively after daclizumab induction, while memory responses towards bacterial, viral and tumour antigens are preserved.

Importance of the liver in systemic complications associated with acute pancreatitis: the role of Kupffer cells

Although its exact nature is still unknown, acute pancreatitis progresses with a local production of inflammatory mediators, eventually leading to systemic inflammatory response syndrome. Knowing that almost all pancreatic mediators released from the pancreas to the bloodstream may pass through the liver before their dilution in the systemic circulation, it would be reasonable to assume a determinant role for this organ in the development of the inflammatory response associated with acute pancreatitis. Thus, recent studies have shown the involvement of the liver in the complex network of events triggering the multiorgan dysfunction associated with the disease. Once pancreatic mediators reach the liver, they strongly activate Kupffer cells, the resident macrophages, greatly amplifying the release of cytokines into the bloodstream and thus contributing to the systemic manifestations of acute pancreatitis. Altogether, these results show that the pancreas is not the only source of mediators that trigger the deleterious effects of acute pancreatitis, but that the liver may orchestrate the final outcome of the disease. The purpose of this review is to discuss progress in understanding the function of the liver in the early stages of the development of systemic organ dysfunction secondary to acute pancreatitis.

Lipid peroxidation in ischemia-reperfusion oxidative injury of the graft preserved in Celsior and University of Wisconsin solutions on a pig pancreas transplantation model

BACKGROUND

Graft pancreatitis (GP) is one the main technical problems associated with pancreas transplant (PT). It occurs in 20% of patients representing a risk factor for thrombosis and cause of graft loss. GP is related to oxidative effects from oxygen-derived free radicals (OFR) in ischemia-reperfusion injury. We evaluated lipid peroxidation by the OFR in the PT of pig organs preserved with either Celsior or Wisconsin solutions.

METHODS

In Landrace pigs we performed 24 pancreas allografts, which were preserved 18 or 24 hours: 12 with Celsior solution (CS) and 12 with Wisconsin solution (UW). No immunosuppression was administered. The oxidative effects were determined by quantification of malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA) and of the carbonyl groups of proteins in our pancreatic tissue samples and measured at different times: (A) baseline in the donor, (B) after perfusion of the graft, (C) after the ischemia period, and (D) 30 minutes after ischemia-reperfusion of the graft.

RESULTS

The MDA and 4-HDA values were similar in conditions A, B, and C, but showed an extraordinary increase after ischemia-reperfusion in D, among both the 18- or 24-hour preserved grafts and in the same proportion with CS and UW. The carbonyl groups of the proteins rose in conditions B and C (cold ischemia), but less so in state D (reperfusion).

CONCLUSIONS

The oxidative injury of a pancreatic graft preserved for 18 or 24 hours occurs during reperfusion, with an extraordinary intensity, but similarly with CS and UW, an observation that may help to explain graft pancreatitis.

Evidence for the homeostatic regulation of induced beta cell mass expansion

AIMS/HYPOTHESIS

Diabetes results from an insufficient insulin-secreting beta cell mass. Restoration of beta cell mass through pharmaceutically induced endogenous beta cell mass expansion may revolutionise diabetes therapy. However, it remains to be determined whether the induced beta cell mass expansion is under homeostatic regulation.

METHODS

Beta cell mass expansion rates were derived from three separate studies of continuous stimulation of islet neogenesis, including the partial duct obstruction of euglycaemic Syrian hamsters, administration of a pentadecapeptide with the same amino acid sequence as residues 104-118 of islet neogenesis-associated protein (INGAP(104-118)) to euglycaemic Syrian hamsters, as well as to euglycaemic CD-1 mice. The incidence of islet neogenesis, average beta cell size, and beta cell replication and apoptotic rates were determined.

RESULTS

Partial duct obstruction led to a approximately 2.5-fold increase in endocrine tissue at day 56 (p<0.05). From day 0 to day 7 the average rate of change of islet area was 12.7% per day, and this rate decreased to 5.3% per day from day 7 to day 42, and to 2.8% per day from day 42 to day 56. Administration of INGAP(104-118) to adult hamsters led to a 31% increase in total beta cell mass at day 30 (p=0.031). From day 0 to day 10 the average rate of beta cell mass expansion was 148 mug/day, whereas from day 10 to day 30 it decreased to 45 mug/day. INGAP(104-118) administration to adult CD-1 mice resulted in an approximately twofold increase in beta cell mass after 31 days (p=0.021). However, at day 90, there was no significant difference vs age-matched control mice (p=0.30), even though the neogenic beta cell mass was approximately fourfold greater (p=0.026). Beta cell replication was decreased by 56% (p<0.048), whereas beta cell apoptosis was fourfold greater (p<0.003) in 90-day INGAP(104-118)-treated mice compared with age-matched control mice.

CONCLUSIONS/INTERPRETATION

These data indicate that in the presence of ongoing islet neogenesis, homeostatic regulatory mechanisms intervene to regulate beta cell mass according to the prevailing metabolic requirements.

Pathophysiological role of platelets in acute experimental pancreatitis: influence of endothelin A receptor blockade

The potential pathophysiological role of platelet-endothelium interactions was investigated during ischemia/reperfusion (I/R), and the effect of a selective endothelin(A) receptor antagonist (ET(A)-RA) was evaluated in an acute pancreatitis model. Acute pancreatitis was induced by warm ischemia (60 min) in Wistar rats, and its effects with and without antagonist treatment were investigated. Equivalent sham-operated animals were also studied. Microcirculatory changes were assessed by in vivo microscopy, and serum levels for lipase/amylase and histological specimens were investigated. Capillary constriction to 83.7 +/- 6.7% of sham-operated diameters was observed after 60 min of ischemia. A capillary density of 56.8 +/- 9.3% of the sham-operated group (396.3 +/- 15.8 mm(-1)) was measured after reperfusion. Stagnant leukocytes (329.5 +/- 30.4%) and platelets (337.5 +/- 32.3%) increased in postcapillary venules (P < 0.05). Administration of the ET(A)-RA significantly reduced I/R injury. Capillary diameters were maintained (101.4 +/- 4.5%), and capillary density was improved to 73.3 +/- 7.6% of sham-operated animals (P < 0.05). Stagnant leukocytes (152.3 +/- 10.6%) and platelets (207.1 +/- 19.8%) in sinusoids and postcapillary venules were reduced (P < 0.05). The extent of acute pancreatitis was reduced in the therapy group as indicated by serum lipase/amylase values and histological tissue damage (P < 0.05). Thus, ET(A)-RA therapy was effective in reducing I/R-induced pancreatitis in this experimental model.