Pancreas and kidney transplantation: long-term endocrine function

Impact of early corticosteroid withdrawal on simultaneous pancreas-kidney transplant long-term outcomes: Single center experience and comparison to the International Pancreas Transplant Registry

BACKGROUND

There remains a paucity of modern data comparing early steroid withdrawal (ESW) versus chronic corticosteroid (CCS) immunosuppression in simultaneous pancreas kidney (SPK) transplant recipients with long-term follow-up. Therefore, the purpose of this study is to assess the effectiveness and tolerability of ESW compared to CCS post-SPK.

METHODS

This was a retrospective single-center matched comparison with the International Pancreas Transplant Registry (IPTR). Patients from University of Illinois Hospital (UIH) represented the ESW group and were compared to those matched CCS patients from the IPTR. Included patients were adult recipients of a primary SPK transplant between 2003 and 2018 within the US receiving rabbit anti-thymocyte globulin induction. Patients were excluded if they had early technical failures, missing IPTR data, graft thrombosis, re-transplant, or positive crossmatch SPK.

RESULTS

A total of 156 patients were matched and included in the analysis. Patients were predominantly African American (46.15%) males (64.1%) with Type 1 diabetes etiology (92.31%). Overall pancreas allograft survival (hazard ratio [HR] = .89, 95% confidence interval [CI] .34-2.30, p = .81) and kidney allograft survival (HR = .80, 95%CI .32-2.03, p = .64) were similar between the two groups. Immunologic pancreas allograft loss was statistically similar at 1-year (ESW 1.3% vs. CCS 0%, p = .16), 5-year (ESW 1.3% vs. CCS 7.7%, p = .16), and 10-year (ESW 11.0% vs. CCS 7.7%, p = .99). The 1-year (ESW 2.6% vs. CCS 0%, p > .05), 5-year (ESW 8.3% vs. CCS 7.0%, p > .05), and 10-year (ESW 22.7% vs. CCS 9.9%, p = .2575) immunologic kidney allograft loss were also statistically similar. There was no difference in 10-year overall patient survival (ESW 76.2% vs. CCS 65.6%, p = .63).

CONCLUSIONS

No differences were found between allograft or patient survival post-SPK when comparing an ESW or CCS protocol. Future assessment is needed to determine differences in metabolic outcomes.

Diabetic Neuropathy Is Independently Associated With Worse Graft Outcomes and Incident Cardiovascular Disease After Pancreas Transplantation: A Retrospective Cohort Study in Type 1 Diabetes

BACKGROUND

Information about the impact of diabetic neuropathy (DN) on outcomes after pancreas transplantation (PT) is scarce. We assessed the independent relationship between DN markers with both graft survival and incident cardiovascular disease (CVD) after transplantation.

METHODS

A cohort study in individuals with type 1 diabetes and end-stage kidney disease who underwent PT between 1999 and 2015 was conducted. DN was assessed with vibration perception thresholds (VPTs) and orthostatic hypotension (pre-PT and 6 mo, 2-3, 5-6, and 8-10 y after transplantation). Pretransplantation and posttransplantation DN markers were related with graft failure/dysfunction and incident CVD during follow-up.

RESULTS

We included 187 participants (70% men, age 39.9 ± 7.1 y, diabetes duration 27.1 y), with a median follow-up of 11.3 y. Abnormal VPTs (≥25 V) were observed in 53%. After transplantation, VPTs improved (22.4 ± 8.4 pretransplant versus 16.1 ± 6.1 V at 8-10 y post-PT; P < 0.001); additionally, the prevalence of abnormal VPTs decreased (53% pretransplant versus 24.4% at 8-10 y; P < 0.001). After adjusting for age, sex, diabetes duration, blood pressure, body mass index, and previous CVD, pretransplant VPTs ≥25 V were independently associated with pancreas graft failure/dysfunction (hazard ratio [HR], 2.01 [1.01-4.00]) and incident CVD (HR, 2.57 [1.17-5.64]). Furthermore, persistent abnormal VPTs after 6 mo posttransplantation were associated with the worst outcomes (HR, 2.80 [1.25-6.23] and HR, 3.19 [1.14-8.96], for graft failure/dysfunction and incident CVD, respectively).

CONCLUSIONS

In individuals with type 1 diabetes and end-stage kidney disease, PT was associated with an improvement of VPTs. This simple and widely available DN study was independently associated with pancreas graft function and CVD posttransplantation.

Effect of donor pancreas extraction time on pancreas transplantation-a Swiss tertiary center experience

We aimed to assess the effect of donor pancreas extraction time (ET) on postoperative complications and graft function after pancreas transplantation (PT). We analyzed all consecutive donor pancreas procurements for the simultaneous pancreas and kidney transplantation (SPK) and the associated PT in a Swiss transplant center over a 20-year period. Pancreas ET was defined as the time from cold flush to static storage of the pancreas on ice. The primary endpoint was the effect of extraction time on surgical complications. Secondary endpoints comprised the effect of ET on graft function (insulin-free survival) and graft pancreatitis. Of 115 procured pancreas grafts the median donor pancreas ET was 65 min (IQR: 48-78 min). In multivariable analysis, ET did not negatively affect major complications (OR 1.41 [95% CI: .59-3.36]; p = .438) and insulin-free survival (HR 1.42 [95% CI: .55-3.63]; p = .459). The median CIT was 522 (441-608) min. CIT was associated with major complications (OR 2.51 [95% CI: 1.11-5.68]; p = .027), but without impact on insulin-free survival (HR 1.94 [95% CI: .84-4.48]; p = .119). Patients with and without graft pancreatitis had no statistically significant differences in ET and CIT (p = .164 and p = .47, respectively). In multivariable analysis, Amylase levels > 270 U/L on postoperative day 1 were significantly associated with major complications (OR 3.61 [95% CI: 1.06-12.32]; p = .040). Our results suggest that although no effect of ET on complications and graft function after PT was found, shorter CIT and less graft pancreatitis can have a positive impact on surgical complications. Results could possibly be influenced by the exceptional quality of the pancreas donors, with short travel distances and preservation times in Switzerland.

Weight gain following pancreas transplantation in type 1 diabetes is associated with a worse glycemic profile: A retrospective cohort study

AIMS

Evaluate the weight trajectories after pancreas transplantation (PT) and their relationships with pancreas graft outcomes in type 1 diabetes (T1D).

METHODS

Retrospective cohort study. T1D individuals who underwent PT were recruited (T1D-PT; n = 194) and divided into three groups according to transplantation date: 1999-2004 (n = 57), 2005-2009 (n = 79), 2010-2015 (n = 58). For weight comparisons, a random sample of T1D without renal impairment was also recruited during 2015 (n = 61; T1D-control).

RESULTS

The median follow-up for the T1D-PT group was 11.1 years. Despite significant weight loss at 6 months (65.7 ± 12.4 vs. 64.1 ± 11.4 Kg; p < 0.001), a stepped increase was seen thereafter (60 months: 68.0 ± 14.0 Kg; p < 0.001). Participants from the 2010-2015 period showed higher weight gain (p < 0.001), outweighing that observed in the T1D-control (60 months: +4.69 ± 8.49 vs. -0.97 ± 4.59 Kg; p = 0.003). Weight gain between 6 and 36 months was directly associated with fasting glucose and HbA1c at 36 months, and with HbA1c at 60 months (p < 0.05). However, in Cox-regression models adjusted for age, sex, and several recipient and PT-related variables, the third tertile of weight gain between 6 and 36 months showed a non-significant increase in the graft failure/dysfunction (HR 2.33 [0.75-7.27]).

CONCLUSIONS

Weight gain post-PT was associated with glucose-related biochemical markers of graft dysfunction, which needs confirmation in further studies.

Beneficial Effect of Successful Simultaneous Pancreas-Kidney Transplantation on Plasma Profile of Metalloproteinases in Type 1 Diabetes Mellitus Patients

It is not fully elucidated whether the restoring of normal glucose metabolism after successful simultaneous pancreas-kidney transplantation (SPK) improves vascular wall morphology and function in type 1 diabetic (T1D) patients. Therefore, we compared arterial stiffness, assessed by pulse wave velocity (PWV), carotid intima-media thickness (IMT), and biomarkers of arterial wall calcification in T1D patients after SPK or kidney transplantation alone (KTA). In 39 SPK and 39 KTA adult patients of similar age, PWV, IMT, circulating matrix metalloproteinases (MMPs) and calcification biomarkers were assessed at median 83 months post transplantation. Additionally, carotid plaques were visualized and semi-qualitatively classified. Although PWV and IMT values were similar, the occurrence of atherosclerotic plaques (51.3 vs. 70.3%, p < 0.01) and calcified lesions (35.9 vs. 64.9%, p < 0.05) was lower in SPK patients. There were significantly lower concentrations of MMP-1, MMP-2, MMP-3, and osteocalcin in SPK subjects. Among the analyzed biomarkers, only logMMP-1, logMMP-2, and logMMP-3 concentrations were associated with log HbA_1c. Multivariate stepwise backward regression analysis revealed that MMP-1 and MMP-3 variability were explained only by log HbA_1c. Normal glucose metabolism achieved by SPK is followed by the favorable profile of circulating matrix metalloproteinases, which may reflect the vasoprotective effect of pancreas transplantation.

Lack of Improvement in Insulin Sensitivity After Pancreas Transplantation in Recipients With a High Level of Calcineurin Inhibitors

OBJECTIVES

This study aimed to assess posttransplant changes in insulin sensitivity and β-cell function of pancreas transplant recipients according to the type of diabetes mellitus (DM) and the pretransplant insulin sensitivity measured by the Matsuda Index (MI).

METHODS

We analyzed 60 patients who underwent pancreas transplantation and oral glucose tolerance test pretransplant and at 1 month posttransplant.

RESULTS

At 1 month posttransplant, insulin sensitivity did not show significant improvement; particularly, the MI was significantly lower after transplant in recipients with type 1 DM (T1DM) and those with pretransplant MI of 5 or greater. β-cell function was significantly improved after transplant in all recipients regardless of the type of DM and pretransplant MI values. Glucose control was significantly improved in recipients with T1DM and in all recipients regardless of the pretransplant MI values. Additional oral glucose tolerance test at 1 year posttransplant revealed that insulin sensitivity remained unimproved and β-cell function was higher compared with pretransplant. Glucose control had partially reverted to pretransplant levels in recipients with T1DM and those with pretransplant MI of 5 or greater.

CONCLUSIONS

Unlike β-cell function and glucose control, insulin sensitivity did not significantly improve until posttransplant 1 year after pancreas transplantation regardless of the type of DM or the degree of pretransplant insulin sensitivity.

Cutting-edge biotechnological advancement in islet delivery using pancreatic and cellular approaches

There are approximately 1 billion prediabetic people worldwide, and the global cost for diabetes mellitus (DM) is estimated to be $825 billion. In regard to Type 1 DM, transplanting a whole pancreas or its islets has gained the attention of researchers in the last few decades. Recent studies showed that islet transplantation (ILT) containing insulin-producing β cells is the most notable advancement cure for Type 1 DM. However, this procedure has been hindered by shortage and lack of sufficient islet donors and the need for long-term immunosuppression of any potential graft rejection. The strategy of encapsulation may avoid the rejection of stem-cell-derived allogeneic islets or xenogeneic islets. This review article describes various biotechnology features in encapsulation-of-islet-cell therapy for humans, including the use of bile acids.

Short and long-term metabolic outcomes in patients with type 1 and type 2 diabetes receiving a simultaneous pancreas kidney allograft

BACKGROUND

In contrast to insulin-dependent type 1 diabetes mellitus (T1DM), the indication for Simultaneous pancreas-kidney transplantation (SPK) in patients with type 2 diabetes mellitus (T2DM) is still ambiguous and wisely Eurotransplant (ET) only granted transplant-permission in a selected group of patients. However, with regard to improvement of metabolic conditions SPK might still be a considerable treatment option for lean insulin dependent type 2 diabetics suffering from renal disease.

METHODS

Medical data (2001-2013) from all consecutive T1DM and T2DM patients who received a SPK or kidney transplant alone (KTA) at the University Hospital of Leipzig were analyzed. Donor, recipients and long-term endocrine, metabolic and graft outcomes were investigated for T1DM and T2DM-SPK recipients (transplanted upon a special request allocation by ET) and T2DM patients who received a KTA during the same period.

RESULTS

Eighty nine T1DM and 12 T2DM patients received a SPK and 26 T2DM patients received a KTA. Patient survival at 1 and 5 years was 89.9 and 88.8% for the T1DM group, 91.7 and 83.3% for the T2DM group, and 92.3 and 69.2% for the T2DM KTA group, respectively (p < 0.01). Actuarial pancreas graft survival for SPK recipients at 1 and 5 years was 83.1 and 78.7% for the T1DM group and 91.7 and 83.3% for the T2DM group, respectively (p = 0.71). Kidney allograft survival at 5 years was 79.8% for T1DM, 83.3% for T2DM, and 65.4% for T2DM KTA (p < 0.01). Delayed graft function (DGF) rate was significantly higher in type 2 diabetics received a KTA. Surgical, immunological and infectious complications showed similar results for T1DM and T2DM recipients after SPK transplant and KTA, respectively. With regard to the lipid profile, the mean high-density lipoprotein (HDL)- cholesterol levels were significantly higher in T1DM recipients compared to T2DM patients before transplantation (p = 0.02) and remained significantly during follow up period.

CONCLUSION

Our data demonstrate that with regard to metabolic function a selected group of patients with T2DM benefit from SPK transplantation. Consensus guidelines and further studies for SPK transplant indications in T2DM patients are still warranted.

Long-term Metabolic Outcomes of Functioning Pancreas Transplants in Type 2 Diabetic Recipients

BACKGROUND

Limited data are available regarding the long-term metabolic outcomes of functioning pancreas transplants in patients with type 2 diabetes mellitus (T2DM).

METHODS

To compare the long-term effects of pancreas transplantation in terms of insulin resistance and β cell function, comparison of metabolic variables was performed between type 1 diabetes mellitus (T1DM) and T2DM patients from 1-month posttransplant to 5 years using generalized, linear-mixed models for repeated measures.

RESULTS

Among 217 consecutive patients who underwent pancreas transplantation at our center between August 2004 and January 2015, 193 patients (151 T1DM and 42 T2DM) were included in this study. Throughout the follow-up period, postoperative hemoglobin A1c did not differ significantly between T1DM and T2DM patients, and the levels were constantly below 6% (42 mmol/mol) until 5 years posttransplant, whereas C-peptide was significantly higher in T2DM (P = 0.014). There was no difference in fasting insulin, homeostasis model assessment (HOMA) of insulin resistance, HOMA β cell, or the insulinogenic index between the groups. Furthermore, fasting insulin and HOMA-insulin resistance steadily decreased in both groups during the follow-up period.

CONCLUSIONS

There was no significant difference in the insulin resistance or β-cell function after pancreas transplantation between T1DM and T2DM patients. We demonstrated that pancreas transplantation is capable of sustaining favorable endocrine functions for more than 5 years in T2DM recipients.

Influence of SPK with Enteric Drainage on the Pancreatic Exocrine Function in Diabetic Patients with Uremia

OBJECTIVE

This study aimed to determine the use of fecal elastase in evaluating the effect of simultaneous pancreas-kidney transplantation with enteric drainage on the pancreatic exocrine function of diabetic patients with uremia.

METHODS

A total of 19 patients with simultaneous pancreas-kidney transplantation (SPK) with enteric drainage, 31 diabetic patients with uremia (chronic renal failure (CRF)), 22 diabetic patients with uremia who underwent renal transplantation (RT), and 20 normal individuals (CON) were included in the study. Pancreatic exocrine insufficiency was determined using fecal elastase. Results. The fecal pancreatic elastase level in SPK patients with enteric drainage was 479 μg/g, which was significantly higher than 229 μg/g in CRF patients and 197 μg/g in RT patients. Using 200 μg/g as the established threshold, a reduced fecal pancreatic elastase level was found in 14/31 of CRF patients, 12/22 of RT patients, 1/19 of SPK patients with enteric drainage, and 1/20 of CON patients. The correlation analysis revealed a significant association between fecal elastase and glycosylated hemoglobin.

CONCLUSIONS

The present study indicated that SPK with enteric drainage improves pancreatic endocrine and exocrine functions. Fecal elastase may be a clinically relevant means to determine the therapeutic effects.

The Effect of Corticosteroid Withdrawal on Glucose Metabolism and Anti-GAD Antibodies in Simultaneous Pancreas-Kidney Transplant Patients

CONTEXT

Corticosteroid withdrawal may reduce insulin resistance; however, it could also influence pancreatic autoantibody profile in simultaneous pancreas-kidney (SPK) transplant patients.

OBJECTIVE

To evaluate the effect of corticosteroid withdrawal on glucose metabolism and anti-glutamic acid decarboxylase (GAD) antibody titers in SPK patients with type 1 diabetes after 12 months of follow-up.

DESIGN

In this retrospective study, fasting glucose and glycated hemoglobin (A1c) were compared before and after 3, 6, and 12 months of corticosteroid withdrawal in 80 SPK patients. In addition, weight, anti-GAD, and C-peptide levels were compared before and after withdrawal. Finally, fasting and postglucose, insulin, and C-peptide levels were compared before and after withdrawal in 25 patients undergoing oral glucose tolerance test (OGTT).

RESULTS

Fasting glucose levels did not change during corticosteroid discontinuation. After 12 months, A1c slightly increased from 4.6% (0.4%) to 4.8% (0.6%) (P < .01) and C-peptide decreased from 2.8 (1.1) ng/mL to 2.4 (1.3) ng/mL (P <. 01). In patients submitted to OGTT, glucose, insulin, and C-peptide levels did not change. There was no alteration in the proportion of anti-GAD positive tests (41% vs 45%). Anti-GAD titers remained stable or decreased in 70% of positive patients.

CONCLUSION

Corticosteroid withdrawal has no significant effect on glucose metabolism and on anti-GAD profile among SPK patients.

Simultaneous pancreas-kidney transplantation: The role in the treatment of type 1 diabetes and end-stage renal disease

Type 1 diabetes mellitus (DM) is one of the most common and debilitating diseases to affect the world. Many patients are afflicted by microvascular and macrovascular complications, and succumb to end-stage renal disease (ESRD). Although dialysis and insulin therapy provides better glycemic control, it nonetheless significantly decreases a patient's quality of life. Moreover, they cannot reverse ESRD or alleviate complications. Simultaneous pancreas-kidney (SPK) transplantation has revolutionized the way we manage type 1 DM; it provides a physiological means of achieving normoglycemia while rendering patients free of dialysis. Understanding this procedure is important because it is becoming a more common management strategy for patients with type 1 DM. In this review, we will begin with a brief summary of type 1 DM, followed by a comprehensive description of SPK procedure, including the history and technique. We will then present the outcomes of transplantation.

Transplantation of Encapsulated Pancreatic Islets as a Treatment for Patients with Type 1 Diabetes Mellitus

Encapsulation of pancreatic islets has been proposed and investigated for over three decades to improve islet transplantation outcomes and to eliminate the side effects of immunosuppressive medications. Of the numerous encapsulation systems developed in the past, microencapsulation have been studied most extensively so far. A wide variety of materials has been tested for microencapsulation in various animal models (including nonhuman primates or NHPs) and some materials were shown to induce immunoprotection to islet grafts without the need for chronic immunosuppression. Despite the initial success of microcapsules in NHP models, the combined use of islet transplantation (allograft) and microencapsulation has not yet been successful in clinical trials. This review consists of three sections: introduction to islet transplantation, transplantation of encapsulated pancreatic islets as a treatment for patients with type 1 diabetes mellitus (T1DM), and present challenges and future perspectives.

Long-term outcome after pancreas transplantation

PURPOSE OF REVIEW

Pancreas transplantation provides the only proven method to restore long-term normoglycemia in patients with insulin-dependent diabetes mellitus. Although many studies describe the very important risk factors for short-term survival of a pancreas transplant, there is not a lot of information available about factors that distinguish short-term from long-term graft function.

RECENT FINDINGS

The analysis of 18,159 pancreas transplants from the International Pancreas Transplant Registry, performed from 25 July 1978 to 31 December 2005, showed an improvement not only in short-term but also in long-term graft function. Most recent 5-year, 10-year and 20-year graft function for transplants with the appropriate follow-up time showed 80, 68 and 45%, respectively, for simultaneous pancreas/kidney transplants; 62, 46 and 16%, respectively, for pancreas after kidney; and 59, 39 and 12%, respectively, for pancreas transplants alone. Important factors influencing long-term function were factors that described the quality of the deceased donor. Pancreas transplants in younger or African-American recipients showed a higher risk of graft failure. Anti-T-cell induction therapy had a significant impact on long-term survival in solitary transplants.

SUMMARY

With a careful donor selection, not only short-term but also long-term pancreas graft function and, therefore, good metabolic control can be achieved for the diabetic patient.

Evolution of pancreas transplantation: long-term results and perspectives from a high-volume center

OBJECTIVE

To describe the evolution of pancreas transplantation from 1979 to 2011. The aim was to examine factors influencing long-term patient and graft survival, surgical methods, and risk factors influencing organ performance after transplantation.

BACKGROUND

Pancreas transplantation has become the therapy of choice for patients suffering insulin-dependent diabetes and end stage renal failure.

METHODS

Retrospective analysis of 509 consecutive pancreas transplants (442 simultaneous pancreas and kidney [SPK], 20 pancreas transplanted alone [PTA], and 47 pancreas transplanted after kidney [PAK]), performed at the University Hospital Innsbruck. The data were statistically analyzed using the Kaplan-Meier method and log-rank test.

RESULTS

After overcoming initial immunological and technical problems between 1979 and 1988 (5-year pancreas graft survival rate, 29.7%), pancreas transplantation evolved during the second decade (1989-1996; 5-year pancreas graft survival rate, 42.2%). Technical changes, optimized immunosuppression, careful pretransplant evaluation, and improved graft monitoring have become standard in the last decade and result in excellent 5-year patient (94.3%), kidney (89.4%), and pancreas (81.5%) graft survival. Five-year graft survival was superior in SPK (68.8%) compared with PAK (62.5%) and PTA (16.4%). SPK retransplantation can be carried out safely with 5-year patient (87.5%) and pancreas graft (75.0%) survival. Overall 5-year patient survival after loss of the first pancreas graft is significantly better in patients who underwent retransplantation (89.4% vs. 67.9%, P = 0.001). Long-term pancreas graft survival is independent of donor body mass index, sex, and cause of death, anastomosis time and the number of human leukocyte antigen (HLA) mismatches, recipient age, body mass index, sex, current panel reactive antibodies, and waiting time. Significant risk factors for reduced graft survival are cold ischemia time and donor age.

CONCLUSIONS

During the last 32 years, many problems in pancreas transplantation have been overcome and it may currently represent the therapeutic gold standard for some patients with diabetes and end stage renal failure.

Pancreatic islet transplantation

Pancreatic islet transplantation is a minimally invasive treatment that has the potential to prevent diabetes after total pancreatectomy for benign disease (islet autotransplantation) and to reverse diabetes in those with type 1 diabetes (islet allotransplantation). In both scenarios, the treatment involves extracting sufficient numbers of pancreatic islets from the resected or donor pancreas and infusing these through the portal vein into the patient's liver. The results for both forms of this treatment have been encouraging over recent years, with up to 85% of adult patients remaining insulin independent for at least 1 year after transplantation. However, there are a number of challenges that need to be overcome before these treatments can be used routinely in children. The aim of this review is to outline the rationale, methodology, and current results of islet allotransplantation, and to discuss the potential new developments that could enable this important treatment to be widely applicable to children. Although islet autotransplantation is not discussed in detail, the overall rationale and methods are similar. However, as the procedure involves the transplantation of the patient's own islets, and the indication for the procedure is not for autoimmune disease, there are none of the difficult immune challenges of allotransplantation.

[Small intestine, pancreas and islet cell transplantation]

The past decade has seen substantial improvements in patient and graft survival after intestinal transplantation. This improvement has been achieved by advances in donor and recipient selection, patient management, immunosuppression and surgical techniques. Intestinal transplantation is therefore considered a therapeutic option in the treatment of short bowel syndrome. Mile stones include the development of the calcineurin inhibitor Tacrolimus for immunosuppression as well as induction therapy using immune modulating substances like interleukin-2 receptor antagonists and antilymphocyte preparations. In addition to improvements in immunosuppression, antimicrobial prophylaxis and diagnosis of rejection, advances in surgical techniques have been crucial to achieving increased graft survival. Pancreas transplantation, generally with simultaneous kidney transplantation, is now available as a treatment option for patients with labile diabetes mellitus (usually type 1). Allogeneic islet transplantation was developed in the 1990s as a minimally invasive alternative to pancreas transplantation. Pancreatic islets are isolated enzymatically from the donor pancreas, in most cases infused into the portal vein and thus engrafted into the liver. Currently, technical and medical problems as well as high costs prevent the application of islet transplantation as a therapeutic option for a larger number of patients with diabetes mellitus.