2011 update on pancreas transplantation: comprehensive trend analysis of 25,000 cases followed up over the course of twenty-four years at the International Pancreas Transplant Registry (IPTR)

Donor risk factors, retrieval technique, preservation and ischemia/reperfusion injury in pancreas transplantation

PURPOSE OF REVIEW

Pancreas transplantation is still hampered by a high incidence of early graft loss, and organ quality concerns result in high nonrecovery/discard rates. Demographic donor characteristics, surgical retrieval strategy, preservation fluid and ischemia time are crucial factors in the process of organ selection and are discussed in this review.

RECENT FINDINGS

The donor shortage is driving an increasing utilization of nonideal organs which would previously have been identified as unsuitable. Recent literature suggests that organs from extended criteria donors - older (>45 years), BMI >30  kg/m(2), and donation after cardiac death (DCD) - can achieve the same graft and patient survival as those from standard criteria donors, with the proviso that the accumulation of risk factors and long ischemic times should be avoided. Visual assessment of the pancreas is advisable before declining/accepting a pancreas. University of Wisconsin represents the gold standard solution; however, histidine-tryptophan-ketoglutarate and Celsior result in equal outcomes if cold ischemia time (CIT) is less than 12  h. Currently in pancreas transplantation, there is no proven effective ischemia/reperfusion injury prophylaxis than trying to keep CIT as short as possible.

SUMMARY

Demographic risk factors, inspection of the pancreas by an experienced surgeon and predicted CIT are crucial factors in deciding whether to accept a pancreas for transplantation. However, there is a need for an improved evidence base to determine where to set the 'cut-off' for unsuitable pancreatic grafts.

Trends in immunosuppression after pancreas transplantation: what is in the pipeline?

PURPOSE OF REVIEW

To provide an overview of currently available immunosuppressive strategies and novel therapeutic developments in pancreas transplantation.

RECENT FINDINGS

From 1966 through 2012 more than 30 000 pancreas transplantations have been performed around the world with excellent patient and graft survival. However, drug-related side effects and toxicities remain to negatively affect long-term outcomes. At present, more than 90% of pancreas transplant recipients receive induction therapy with depleting or nondepleting antibodies. The most widely used maintenance protocols are based on tacrolimus and mycophenolate mofetil with early or delayed corticosteroid withdrawal. In case of documented side effects related to this standard protocol, several regimens are actively pursued to switch to mammalian target of rapamycin inhibitors as well as to attempt initial calcineurin inhibitor avoidance and immunosuppression minimization. In addition, the recent documented negative impact of donor-specific antibodies on pancreas transplantation outcome has resulted in new treatment protocols for antibody-mediated rejection including intravenous immunoglobulins, anti-CD20 antibodies and protease inhibitors.

SUMMARY

Implementation of novel therapeutic strategies and combination protocols to reduce or avoid drug toxicities and immune-related complications that are evaluated in prospective and randomized trials is requested to improve outcomes after pancreas transplantation.

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.

Pancreas graft thrombosis: causes, prevention, diagnosis, and intervention

PURPOSE OF REVIEW

Pancreas graft thrombosis remains one of the most common reasons for pancreas transplant loss. Patients with a history of thrombotic events should be identified and evaluated for thrombophilia to identify transplant candidates at highest risk.

RECENT FINDINGS

Early after transplant, vascular thrombosis is multifactorial, but beyond 2 weeks, inflammation or acute rejection predominate as the cause of thrombosis. Most pancreas transplant centers utilize some form of anticoagulation following transplantation. Aspirin is highly recommended. Unfractionated or low-molecular-weight heparin is often administered, but some centers use heparin selectively and typically at low dose to avoid postoperative bleeding. Warfarin is less frequently given and its use should probably be limited to patients with thrombophilia.

SUMMARY

Thrombectomy, either surgical or percutaneous, may salvage the pancreas graft if performed early after the occurrence of thrombosis.

What would surgeons like from materials scientists?

Surgery involves the repair, resection, replacement, or improvement of body parts and functions and in numerous ways, surgery should be considered human engineering. There are many areas in which surgical materials could be improved, but surgeons are generally unaware of materials available for use, while materials scientists do not know what surgeons require. This article will review some of the areas where surgeons and materials scientists have interacted in the past and will discuss some of the most pressing problems which remain to be solved. These include better implant materials for hernia repair, breast reconstruction, the treatment of diabetes, vascular stenting and reconstruction, and electrical pacing devices. The combination of tissue engineering and nanomaterials has great potential for application to nearly every aspect of surgery. Tissue engineering will allow cells or artificial organs to be grown for specific uses while nanotechnology will help to ensure maximal biocompatibility. Biosensors will be combined with improved electrodes and pacing devices to control impaired neurological functions.

Trauma after transplant: hold the antibiotics please

OBJECTIVE

Despite the increase in transplantation and the prevalence of trauma as a major disease entity, few data exist about transplant patients who suffer trauma. We conducted a study to determine whether transplant patients (TP) have worse outcomes, particularly of infections, than do their non-transplant (NTP) counterparts after trauma.

METHODS

We performed a retrospective review of trauma patients from 2006 to 2010. All patients who had undergone organ transplantation were included and compared through 1:3 propensity matching with their NTP counterparts. Data for the groups were compared to determine differences in outcomes.

RESULTS

The review included 17 TP (13 kidney, 2 liver, 1 kidney/liver, and 1 kidney/pancreas) as compared with 51 NTP. The patients were matched for injury severity score (ISS), age, and gender, with most suffering blunt trauma (82.4% [14/17] TP vs. 90% [46/51] NTP, p = 0.5). The groups had similar initial Glasgow Coma Scale (GCS) scores (13.2 ± 4.5 TP vs. 13.9 ± 2.5 NTP, p=0.6), serum lactate concentrations (2.0 ± 1.8 mmol/L TP vs. 2.3 ± 1.5 mmol/L NTP, p=0.39), and base deficits (-1.5 ± 4.0 TP vs. 0.6 ± 3.0 NTP, p=0.21). Comorbidities were more common in the TP than in the NTP group. The groups had similar lengths of stay (days on ventilator: 0.1 ± 0.3 TP vs. 0.4 ± 1.6 NTP, p=0.9; days in ICU: 0.2 ± 0.6 TP vs. 2.4 ± 5.9 NTP, p=0.16; days in hospital: 5.2 ± 6.8 TP vs. 7.5 ± 10.2 NTP, p=0.86), and two deaths occurred in each of the two groups (p=0.26). Overall complications were similar (52.94% [9/17] TP vs. 62.75% [32/51] NTP, p=0.57), and there were only two infections, both in the NTP group (p=1.0). Antibiotics were given to 59% of the TP vs. 39% of the NTP, with an average duration of 8.4 days for the TP vs. 3.9 days for the NTP.

CONCLUSION

When matched equally for degree of injury, the TP and NTP had similar outcomes. There also appeared to be no differences in infectious complications in the two groups, yet more of the TP had exposure to more days of antibiotics. Similar protocols of antimicrobial therapy should apply to both TP and NTP to avoid the overuse of antimicrobial agents and ensure maintenance of the susceptibility patterns of pathogens.

Pancreas transplantation: a single-institution experience in Japan

Purpose

We herein report our experience with pancreas transplantation in 26 patients at a single institution in Japan between August 2001 and December 2011.

Methods

We reviewed the medical records of 26 pancreas transplantations performed in our institute.

Results

The early complications (within 2 weeks) included one graft venous thrombosis, one arterial thrombosis, and two reoperations for bleeding. Of the 26 pancreas transplant recipients, five lost pancreas graft function. Of 24 simultaneous pancreas–kidney recipients, three lost kidney graft function due to noncompliance. The patient, pancreas, and kidney survival rates were 100, 96 and 93 % at 1 year; 100, 80 and 93 % at 5 years; and 100, 67 and 68 % at 10 years, respectively. Of all these complications, venous thrombosis after pancreas transplantation was the most critical.

Conclusions

As the largest series of pancreas transplantations in a single institution in Japan, our series yielded better results than the worldwide data recorded by the International Pancreas Transplant Registry. Routine postoperative anticoagulation therapy is not necessary for the prevention of graft thrombosis if sufficient fluid infusion is strictly controlled and the graft blood flow is frequently monitored. When graft thrombosis occurs, both early detection and appropriate intervention are extremely important if the pancreas graft is to survive.

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.

Islet transplantation in type 1 diabetes: ongoing challenges, refined procedures, and long-term outcome

Remarkable progress has been made in islet transplantation over a span of 40 years. Once just an experimental curiosity in mice, this therapy has moved forward, and can now provide robust therapy for highly selected patients with type 1 diabetes (T1D), refractory to stabilization by other means. This progress could not have occurred without extensive dynamic international collaboration. Currently, 1,085 patients have undergone islet transplantation at 40 international sites since the Edmonton Protocol was reported in 2000 (752 allografts, 333 autografts), according to the Collaborative Islet Transplant Registry. The long-term results of islet transplantation in selected centers now match registry data of pancreas-alone transplantation, with 6 sites reporting five-year insulin independence rates ≥50%. Islet transplantation has been criticized for the use of multiple donor pancreas organs, but progress has also occurred in single-donor success, with 10 sites reporting increased single-donor engraftment. The next wave of innovative clinical trial interventions will address instant blood-mediated inflammatory reaction (IBMIR), apoptosis, and inflammation, and will translate into further marked improvements in single-donor success. Effective control of auto- and alloimmunity is the key to long-term islet function, and high-resolution cellular and antibody-based assays will add considerable precision to this process. Advances in immunosuppression, with new antibody-based targeting of costimulatory blockade and other T-B cellular signaling, will have further profound impact on the safety record of immunotherapy. Clinical trials will move forward shortly to test out new human stem cell derived islets, and in parallel trials will move forward, testing pig islets for compatibility in patients. Induction of immunological tolerance to self-islet antigens and to allografts is a difficult challenge, but potentially within our grasp.

Diabetes treatment in 2025: can scientific advances keep pace with prevalence?

Despite the known benefits of a healthy lifestyle, many individuals find it hard to maintain such a lifestyle in our modern world, which facilitates sedentary behavior and overeating. As a consequence, the prevalence of type 2 diabetes mellitus is predicted to increase dramatically over the coming years. Will developments in treatments be able to counteract the resulting impact on morbidity and mortality? The various lines of research can be grouped into three main categories: technological, biological, and pharmacological. Technological solutions are focused on the delivery of insulin and glucagon via an artificial pancreas, and components of the system are already in use, suggesting this option may well be available within the next 10 years. Of the biological solutions, pancreas transplants seem unlikely to be used widely, and islet cell transplants have also been hampered by a lack of appropriate donor tissue and graft survival after transplant. However, significant progress has been made in these areas, and additional research suggests manipulating other cell types to replace beta cells may be a viable option in the longer term. The last category, pharmacological research, appears the most promising for significantly reducing the burden of type 2 diabetes mellitus. In recent years, research has concentrated on reducing blood glucose, and the increasing pace of research has been reflected in a growing number of antidiabetic agents. In the past few years, studies of the complementary approach of protecting cells from the damaging effects of high blood glucose have also been reported, as has research into the control of energy intake and energy expenditure. Evidence from studies of dietary restriction and bariatric surgery suggests it may be possible to reset metabolism to effectively cure diabetes, and research into pharmacological agents that could selectively restore energy balance is currently the most exciting prospect for future treatments for people with type 2 diabetes mellitus.

Imaging of miscellaneous pancreatic pathology (trauma, transplant, infections, and deposition)

In this article's coverage of miscellaneous pancreatic topics, a brief review of pancreatic trauma; pancreatic transplantation; rare infections, such as tuberculosis; deposition disorders, including fatty replacement and hemochromatosis; cystic fibrosis; and others are discussed with pertinent case examples.

T cell autoreactivity in the transplant milieu

Autoreactive T cell responses in autoimmune disease are directed to tissue antigens but differ from allospecific T cells in several important respects, reflecting the circumstances of their selection, activation and expansion in vivo. Both genetic and acquired traits conspire to generate autoreactive effector cells that are refractory to normal control mechanisms, resulting in persistent and deleterious immunity to tissue antigens. When these same tissue antigens are reintroduced into an autoimmune setting, such as with pancreas or islet transplantation into a type 1 diabetic individual, the potential for recurrent activation of the underlying effector memory response presents a therapeutic challenge.

Curing diabetes with transplantation?

Type 1 diabetes affects >1 million people in the United States, where it accounts for up to 10% of all diabetes cases. Glycemic control via the use of exogenous insulin injections in diabetic patients is incomplete, resulting in multiple long-term complications such as retinopathy, neuropathy, vasculopathy, and nephropathy. The goal of beta-cell replacement by whole-pancreas or islet transplantation is to achieve long-term insulin independence, and the proposed benefits are improved quality of life, prevention of recurrent diabetic nephropathy, stabilization or improvement in secondary complications, and improved mortality. No other regimen of insulin delivery can achieve this level of physiologic regulation.

Progress in abdominal organ transplantation

The excellent results of vascularized organ transplantation have resulted in an increasing number of end-stage organ failure patients seeking such treatment. The results of organ transplantation depend on a number of factors – the quality of the donor (and an organ), living vs. deceased donation, magnitude of ischemic injury (and its prevention), and recipient-dependent factors. Ischemia/reperfusion injury in organ transplantation is a multifactorial process, which may lead to delayed graft function. In addition, surgical and preservation techniques, type of immunosuppressive regimens, complications after transplantation and post-transplant management may also have a significant impact on short- and long-term results of transplantation. In this paper we describe advances in transplantation in recent years, with particular emphasis on kidney, liver, intestines, whole pancreas and pancreatic islets.

Portal venous versus systemic venous drainage of pancreas grafts: impact on long-term results

Portal venous (PV) and systemic venous (SV) drainage methods are used in pancreas transplantation. The impact of the reconstruction technique on long-term outcome remains unclear. We compared the efficacy and side effects of both methods in 192 recipients who received synchronous pancreas kidney transplants between November 1995 and November 2007. SV and PV drainage were used in 147 and 45 cases, respectively. Pancreas function was determined by hemoglobin A1c levels and annual oral glucose tolerance test. Serum creatinine assessed kidney function. Serum lipid (low-density lipoprotein, high-density lipoprotein and cholesterol) levels and body mass index were measured annually. Patient and graft survival were calculated by log-rank analysis. Pancreas survival for SV versus PV patients was similar after 5 years (81.8% vs. 75.5%) and 10 years (65.1% vs. 60%; p = NS). Similarly, no difference was detected between the groups regarding kidney survival after 5 years (92.9% vs. 84.4%) and 10 years (81.6% vs. 75.5%; p = NS). Patient survival did not differ at 5 years (94.3% vs. 88.8%) and 10 years (85.1% vs. 84.4%; p = NS). Pancreas and kidney function and the lipid profiles were similar in both groups. SV and PV drainage of pancreas grafts offer similar long-term graft survival and function and choice of method should remain the preference of the surgeon.

Results of pancreas transplantation alone with special attention to native kidney function and proteinuria in type 1 diabetes patients

We report on our single-center experience with pancreas transplantation alone (PTA) in 71 patients with type 1 diabetes, and a 4-year follow-up. Portal insulin delivery was used in 73.2% of cases and enteric drainage of exocrine secretion in 100%. Immunosuppression consisted of basiliximab (76%), or thymoglobulin (24%), followed by mycophenolate mofetil, tacrolimus, and low-dose steroids. Actuarial patient and pancreas survival at 4 years were 98.4% and 76.7%, respectively. Relaparatomy was needed in 18.3% of patients. Restored endogenous insulin secretion resulted in sustained normalization of fasting plasma glucose levels and HbA1c concentration in all technically successful transplantations. Protenuria (24-hour) improved significantly after PTA. Renal function declined only in recipients with pretransplant glomerular filtration rate (GFR) greater than 90 ml/min, possibly as a result of correction of hyperfiltration following normalization of glucose metabolism. Further improvements were recorded in several cardiovascular risk factors, retinopathy, and neuropathy. We conclude that PTA was an effective and reasonably safe procedure in this single-center experience.

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.