Pancreas transplantation: a review

Allo- and auto-percutaneous intra-portal pancreatic islet transplantation (PIPIT) for diabetes cure and prevention: the role of imaging and interventional radiology

Although the life expectancy of patients with type 1 diabetes mellitus (T1DM) has improved since the introduction of insulin therapy, the acute life-threatening and long-term complications from diabetes mellitus are significant causes of both mortality and morbidity. Percutaneous intra-portal pancreatic islet transplantation (PIPIT) is a minimally invasive, repeatable procedure which allows a β-cell replacement therapy through a liver islet engraftment, leading to insulin release and glycaemic control restoration in patients with diabetes. Allo-PIPIT, in which isolated and purified islets from cadaveric donor are used, does not require major surgery, and is potentially less expensive for the recipient. In case of long-term T1DM, islet-after-kidney (IAK) transplantation can simultaneously cure diabetes and chronic renal failure, while islet-transplant-alone (ITA) is performed in brittle, short-term T1DM, based on the infusion of an adequate islet mass and on a steroid-free immunosuppressive regimen according to the Edmonton protocol. Results of the Collaborative Islet Transplant Registry (CITR) demonstrate that allo-PIPIT reduces episodes of hypoglycemia and diabetic complications, and improves quality of life of diabetic patients. Auto-PIPIT, in which the own patient's islets are used, has been investigated as a preventive treatment for pancreatogenic diabetes in patients who undergo extensive pancreatectomy for malignant and non-malignant disease. This Review outlines the role of imaging and interventional radiology in allo- and auto-PIPIT.

A Comparative Analysis of the Safety, Efficacy, and Cost of Islet Versus Pancreas Transplantation in Nonuremic Patients With Type 1 Diabetes

Few current studies compare the outcomes of islet transplantation alone (ITA) and pancreas transplantation alone (PTA) for type 1 diabetes (T1D). We examined these two beta cell replacement therapies in nonuremic patients with T1D with respect to safety, graft function and cost. Sequential patients received PTA (n = 15) or ITA (n = 10) at our institution. Assessments of graft function included duration of insulin independence; glycemic control, as measured by hemoglobin A1c; and elimination of severe hypoglycemia. Cost analysis included all normalized costs associated with transplantation and inpatient management. ITA patients received one (n = 6) or two (n = 4) islet transplants. Mean duration of insulin independence in this group was 35 mo; 90% were independent at 1 year, and 70% were independent at 3 years. Mean duration of insulin independence in PTA was 55 mo; 93% were insulin independent at 1 year, and 64% were independent at 3 years. Glycemic control was comparable in all patients with functioning grafts, as were overall costs ($138 872 for ITA, $134 748 for PTA). We conclude that with advances in islet isolation and posttransplant management, ITA can produce outcomes similar to PTA and represents a clinically viable option to achieve long-term insulin independence in selected patients with T1D.

Islet transplantation in type 1 diabetic patients using calcineurin inhibitor-free immunosuppressive protocols based on T-cell adhesion or costimulation blockade

BACKGROUND

The applicability of islet transplantation as treatment for type 1 diabetes is limited by long-term graft dysfunction, immunosuppressive drug toxicity, need for multiple donors, and increased risk of allosensitization. We describe two immunosuppressive regimens based on the costimulation blocker belatacept (BELA) or the antileukocyte functional antigen-1 antibody efalizumab (EFA), which permit long-term islet allograft survival and address some of these concerns.

METHODS

Ten patients with type 1 diabetes with hypoglycemic unawareness received intraportal allogeneic islet transplants. Immunosuppression consisted of antithymocyte globulin induction and maintenance with sirolimus or mycophenolate and BELA (n=5) or EFA (n=5).

RESULTS

All five BELA-treated patients achieved independence after single transplants; one resumed partial insulin use 305 days after transplant but is now independent after a second transplant. All five patients treated with EFA achieved independence after one (3/5) or two (2/5) islet transplants and remained independent while on EFA (392-804 days). After EFA was discontinued because of withdrawal of the drug from the market, two patients resumed intermittent insulin use; the others remain independent. No patient in either group developed significant side effects related to the study drugs, and none have been sensitized to alloantigens. All have stable renal function.

CONCLUSIONS

These two novel immunosuppressive regimens are effective, well tolerated, and the first calcineurin inhibitor/steroid-sparing islet protocols resulting in long-term insulin independence. Although EFA is no longer available for clinical use, these early results demonstrate that a regimen using BELA may be an effective alternative to improve graft function and longevity while minimizing renal and β-cell toxicity.

Islet transplantation in type 1 diabetics using an immunosuppressive protocol based on the anti-LFA-1 antibody efalizumab

The applicability of islet transplantation as treatment for type 1 diabetes is limited by renal and islet toxicities of currently available immunosuppressants. We describe a novel immunosuppressive regimen using the antileukocyte functional antigen-1 antibody efalizumab which permits long-term islet allograft survival while reducing the need for corticosteroids and calcineurin inhibitors (CNI). Eight patients with type 1 diabetes and hypoglycemic unawareness received intraportal allogeneic islet transplants. Immunosuppression consisted of antithymocyte globulin induction followed by maintenance with efalizumab and sirolimus or mycophenolate. When efalizumab was withdrawn from the market in mid 2009, all patients were transitioned to regimens consisting of mycophenolate and sirolimus or mycophenolate and tacrolimus. All patients achieved insulin independence and four out of eight patients became independent after single-islet transplants. Insulin independent patients had no further hypoglycemic events, hemoglobin A1c levels decreased and renal function remained stable. Efalizumab was well tolerated and no serious adverse events were encountered. Although long-term follow-up is limited by discontinuation of efalizumab and transition to conventional imunnosuppression (including CNI in four cases), these results demonstrate that insulin independence after islet transplantation can be achieved with a CNI and steroid-free regimen. Such an approach may minimize renal and islet toxicity and thus further improve long-term islet allograft survival.

Treatment of diabetes with encapsulated islets

Cell encapsulation has been proposed for the treatment of a wide variety of diseases since it allows for transplantation of cells in the absence of undesired immunosuppression. The technology has been proposed to be a solution for the treatment of diabetes since it potentially allows a mandatory minute-to-minute regulation of glucose levels without side-effects. Encapsulation is based on the principle that transplanted tissue is protected for the host immune system by a semipermeable capsule. Many different concepts of capsules have been tested. During the past two decades three major approaches of encapsulation have been studied. These include (i) intravascular macrocapsules, which are anastomosed to the vascular system as AV shunt, (ii) extravascular macrocapsules, which are mostly diffusion chambers transplanted at different sites and (iii) extravascular microcapsules transplanted in the peritoneal cavity. The advantages and pitfalls of the three approaches are discussed and compared in view of applicability in clinical islet transplantation.

Surgical complications of simultaneous pancreas-kidney transplantation: a 16-year-experience at one center

Fifty-one simultaneous pancreas-kidney transplants (SPKT) were performed between 1988 and 2004 in patients of mean age 34 years and 23 years duration of diabetes treatment. All kidney and pancreas recipients were on maintenance hemodialysis therapy prior to SPKT. The pancreas with duodenal segment and the kidneys were harvested from cadaveric heart-beating donors. Cold ischemia time in UW solution varied from 4 to 14 hours (mean, 9 hours 35 minutes). Twenty patients had the duodenal segment sutured to the urinary bladder, and the remaining 31 grafts were drained to an isolated ileal loop. Quadruple immunosuppression was administered as well as an anticoagulant and antibiotic prophylaxis. Forty-nine patients (49/51, 96%) regained insulin independence in the immediate postoperative period; 44 (86%) displayed immediate graft function. The remaining patients experienced postoperative ATN, the longest duration was 18 days. Of 51 patients, 38 (14.5%) are alive (follow-up, 6 to 180 months), 26 (68.5%) have good pancreatic function, and 34 (89%), good kidney function. Nineteen (50%) patients regard their quality of life as improved compared to their pretransplant status, which is mainly attributed to being dialysis and insulin free. Of 19 patients, 14 (74%) reported measuring glycemia regularly due to fear of losing the pancreas graft. Of 19 persons, seven (37%) returned to work after transplantation. Four (8.3%) lost their kidney graft secondary to vascular complications (n = 2) or rejection (n = 2). Four pancreas grafts with bladder drainage required conversion to enteric drainage owing to persistent urinary infections or urinary fistulae. Fifteen (29%) patients lost their pancreatic grafts within 1 year of transplantation due to the following: vascular complications (n = 12), septic complications (n = 1), or rejection (n = 2). Thirteen patients died within 1 year after transplantation, 5 of septic complications, 5 of neuroinfection, 1 of pulmonary embolism, and 2 of myocardial infarction. In conclusion, SPKT is a successful treatment for diabetic nephropathy, burdened by the possibility of serious complications.

Early morbidity after pancreas transplantation

This study aims to evaluate and compare the early outcome of both pancreas-alone transplantation (PTA) and simultaneous kidney-pancreas transplantation (SPKT) focusing on the complications affecting the first month after the procedures. The records of all patients who underwent PTA or SPKT were reviewed. We considered the length of ICU stay, the need for postoperative ventilatory support, hemodynamic and metabolic data (arterial pH, serum glucose, need for exogenous insulin), infectious diseases incidence, microbiological colonization rate and any kind of postoperative complication arising during the first month after the transplantation. PTA recipients underwent a quicker surgery (P < 0.01) with shorter ICU stay (P < 0.05) and a lower need for postoperative mechanical ventilation (P < 0.05). They also had a higher hemodynamic stability (P < 0.05) with less cardiological complications (P < 0.05) in the intra- and postoperative phases; bacterial colonisation was also less frequent in PTA recipients (P < 0.05). On the contrary, no significant difference was noted with regard to postoperative nausea/vomiting, sudden myocardial death, ICU re-admissions, graft function, rate of rejection, grafts explantation and re-transplantation. PTA could be considered as preemptive for severe diabetic complications in patients with long-lasting severe type I diabetes. However, establishing the correct timing of PTA is of paramount importance in order not to expose the patients early to risks arising from a major surgery and heavy immunosuppressive treatments.

Macrovascular disease after simultaneous pancreas and kidney transplantation

The objective of this study was to evaluate the outcome of simultaneous pancreas and kidney transplantation (SPK) with focus on cardiovascular mortality and morbidity in relation to graft function. From January 1985 through 1999, 87 SPK were performed in the unit. Sixty recipients were males, median age at diabetes onset 13 yr (1-40) and age at transplantation 39 yr (29-54). No case was lost to follow-up. Morbidity and mortality during median 8 yr of follow-up (range 1-15 yr) were recorded. Major macrovascular disease (MVD) was defined as myocardial infarction or sudden death (AMI), stroke or peripheral gangrene requiring amputation of leg, foot or fingers. At the evaluation, 26 of 87 patients (30%) had died, 19 after loss of the pancreas graft and 20 after loss of the kidney. MVD was the dominant cause of death. Non-lethal MVD had previously been recorded in 62%. Of the 61 patients alive, 22 had lost their pancreas graft and 12 the concomitant kidney. MVD had occurred in 32%. Whereas 89% of the concomitant kidneys functioned when the pancreas graft did so, only 37% of the kidneys functioned if the pancreas had been lost, p < 0.0001. The mortality rate was significantly higher among patients who lost both grafts (16/26) than in those who lost only the pancreas graft (3/15), p = 0.01. Progressive MVD is a major clinical problem for SPK transplant patients, particularly if the kidney fails.

Percutaneous transhepatic pancreatic islet cell transplantation in type 1 diabetes mellitus: radiologic aspects

PURPOSE

To report our experience with percutaneous transhepatic pancreatic islet cell transplantation in patients with type 1 diabetes mellitus.

MATERIALS AND METHODS

Between March 1999 and May 2002, 34 patients underwent 68 islet cell transplantation procedures. Patients with C-peptide-negative type 1 diabetes were selected on the basis of poor metabolic control (hypoglycemia or lability) despite compliance with optimal medical therapy. Islet cells were isolated from brain-dead donors. Access to the portal vein was gained from a right percutaneous transhepatic approach, and islet cells were infused with intermittent pressure monitoring. Twenty patients underwent two transplantations, seven patients underwent three transplantations, and seven patients underwent one transplantation. Complications during and after the procedure and postprocedural diabetic status were monitored.

RESULTS

Successful portal vein cannulation and islet cell infusion were achieved in all cases. Fluoroscopy was used as the primary guidance modality in 58 of 68 (85%) procedures, and ultrasonography was used in 10 of 68 (15%). Total recorded fluoroscopy time varied from 0.6 to 103 minutes, with a median of 6.9 minutes. Potentially serious complications occurred in six of 68 (9%) procedures. Two patients developed portal venous thrombosis, and with subsequent anticoagulation therapy, one of the two developed an expanding hepatic hematoma that required surgery. Clinically important hemorrhage occurred in four patients, three of whom required blood transfusions. Of 26 patients who received completed transplants, all became insulin independent, and 81% (21 of 26) remained insulin free at 1 year.

CONCLUSION

The percutaneous transhepatic approach for the implantation of islet cells into the portal vein is a safe procedure, and together with use of current cell separation techniques and an immunosuppressive regimen, offers a marked advance in the treatment of type 1 diabetes mellitus.

Successful PTA and stenting for acute iliac arterial injury following pancreas transplantation

Iliac artery injuries may occur during solid organ transplantation. We describe an approach to an iliac artery clamp injury after pancreatic allotransplantation. The patient is a 48-year-old diabetic male who underwent successful cadaveric pancreatico-duodenal transplantation complicated by a left common iliac artery clamp injury. The injury resulted in both graft and lower leg ischemia. The injury was recognized promptly and diagnosed by magnetic resonance angiogram (MRA). The lesion was successfully treated with percutaneous transluminal angioplasty and stenting with resolution of both graft and leg ischemia. We propose this technique as a minimally invasive approach to an iliac injury that can be used to treat vascular injuries during solid organ transplantation.

Intrathymic islet transplantation in the canine: I. Histological and functional evidence of autologous intrathymic islet engraftment and survival in pancreatectomized recipients

BACKGROUND

Although an attractive alternative to daily insulin therapy, allogeneic pancreatic islet transplantation has yielded suboptimal results in clinical trials, in contrast to islet allotransplantation in animal models, which have demonstrated consistent success. The successful transplantation of isolated islets to the thymus, with a single concomitant dose of antilymphocyte serum, has been demonstrated in rodents, and more significantly, such intrathymic islet allografts have been shown to induce recipient tolerance toward subsequent extrathymic donor strain islet allografts. Intrathymic islet autotransplantation has been pursued, as a prelude to studies of allogeneic IT islet transplantation and tolerance induction, in canine, porcine, and non-human primate models, to assess the large animal thymus as a site capable of supporting a viable islet graft. However, little functional or histological evidence has established definitive survival of islets transplanted within the thymus of a phylogenetically advanced species, which may be requisite to tolerance induction. This study describes the successful intrathymic autotransplantation of isolated islets using a canine model.

METHODS

Purpose-bred juvenile dogs, aged 4-6 months, underwent partial (n=4), or total pancreatectomy (n=11), and transplantation of autologous islets. The pancreas (or pancreatic limb) was distended with collagenase solution, and digested using a modification of the semiautomated system of Ricordi. Islets were purified by discontinuous gradient centrifugation, using Euroficoll (ficoll in Euro-Collin's kidney preservation solution). Partially pancreatectomized canines underwent IT transplantation of purified autologous islets (8000+/-4000 IEs), and were killed 8 weeks posttransplant. Totally pancreatectomized canines underwent transplantation of autologous islets to the liver (via portal vein embolization, n=5, IPO group) or the thymus (via direct IT injection, n=6, IT group), and were serially evaluated for a period of 8 weeks posttransplant to assess fasting blood glucose (FBG), serum insulin (SI) levels, and i.v. glucose tolerance (IVGTTs). K values (defined as the %-decrease/minute of the log(e) of blood glucose values) were calculated from IVGTT results.

RESULTS

After autotransplantation in this cohort of animals, five of five IPO, and three of six IT islet recipients, remained normoglycemic (mean FBG< or =250 mg%) immediately posttransplant, and all recipients exhibited significantly elevated SI levels compared to apancreatic controls (n=10, followed 72 hr postpancreatectomy). Normal k values (=-1.1) were observed in two of five IPO, and in one of six IT recipients, 8 weeks after transplantation, and thymic tissue insulin content was increased compared to non-islet-bearing thymi (93.7+/-48.6 ng/g tissue vs. 0.7+/-0.4 ng/g tissue). At 8 weeks posttransplantation thymi from both partially and totally pancreatectomized animals were resected and processed for histological examination. Microscopic analysis of islet-bearing thymi revealed positive staining for islet-specific hormones (insulin and glucagon) within all IT recipients., Identification of islets within thymi of hyperglycemic IT recipients was problematic as islet beta cells were highly degranulated as a result of the recipients glycemic state.

CONCLUSIONS

These results indicate that autologous islets, transplanted to the canine thymus, engraft, function, and survive for up to 8 weeks after islet autotransplantation to the canine thymus and establish the feasibility of intrathymic islet transplantation in a phylogenetically advanced animal model. The ability of islets to survive within the thymic environment for a period of at least 8 weeks after transplantation suggests that the successful induction of specific unresponsiveness secondary to intrathymic transplantation will not be impaired or limited by the inability of a viable islet mass to survive within the thymus for a sufficient period.

Neurologic complications of transplantation

BACKGROUND

Organ transplantation is one of the most dynamic fields in medicine and has evolved into a life-saving option for thousands of patients with previously fatal conditions. The posttransplantation clinical course is frequently associated with neurologic complications that are usually related to pretransplant morbidity, the surgical procedure of transplantation, immunosuppression, and opportunistic infection.

REVIEW SUMMARY

Neurologic complications of organ transplantation may be divided into complications common to all types of allografts and complications that are specific for a particular type of organ transplantation. The most common complications include seizures, opportunistic central nervous system (CNS) infection, metabolic encephalopathy, stroke, intracranial hemorrhage, and drug-related adverse events. Opportunistic CNS infection may have a subtle presentation and should not be overlooked, as the consequences of delayed treatment may be grave. Neurotoxicity of immunosuppressive agents is also a frequent cause of neurologic complications and may occur in the setting of normal serum drug levels. The clinical course of transplant patients is frequently complex, requiring close cooperation between the transplant team and specialty consultants. Prolonged survival of transplant patients will shift the focus of neurologic complications from acute, perioperative to chronic complications of immunosuppression.

CONCLUSIONS

Neurologic complications of organ transplantation are commonly related to opportunistic infection or neurotoxicity of immunosuppressive agents, requiring careful titration of immunosuppression. Timely diagnosis of CNS infection or other causes of neurologic dysfunction may significantly improve recovery and outcome in these patients.

The solution to hyperglucagonemia after pancreas transplantation in inbred rats

BACKGROUND

We studied the possible role of the diseased host pancreas and site of venous graft drainage in the development of hyperglucagonemia after pancreas transplantation, to identify the crucial steps of the technique capable of eliminating hyperglucagonemia and its possible diabetogenic effect.

METHODS

Therefore, we compared 4 groups of inbred rats: (1) heterotopic pancreas transplantation with either systemic (n = 9); or (2) portal (n = 5) venous drainage after prior induction of diabetes with streptozotocin; (3) orthotopic pancreaticoduodenal transplantation with portal venous drainage after prior pancreaticoduodenectomy (n = 7), and (4) sham-operation (Sham; n = 10). The postoperative period was 6 months.

RESULTS

Only heterotopic transplantation with systemic venous drainage and loss of glucagon's first pass hepatic extraction, resulted in arterial hyperglucagonemia, whereas the arterial plasma insulin level was only slightly higher in comparison with the other groups. After either type of heterotopic transplantation the glucagon content of host pancreata remained unchanged, whereas the insulin content was approximately 5% of that in the pancreas of Sham rats. The insulin and glucagon contents of all grafts were similar to those of the control pancreas in Sham rats, and the insulin release was sufficient to normalize fasting plasma glucose and lipids after either type of transplantation.

CONCLUSION

To remove the diseased host pancreas appears unnecessary, as the hyperglucagonemia and the concomitant slight hyperinsulinemia, capable of preventing glucagon's diabetogenic effects, are due to loss of the first pass hepatic extraction by systemic venous drainage alone. This disadvantage can be eliminated by portal venous graft drainage.

Clinical outcomes and insulin secretion after islet transplantation with the Edmonton protocol

Islet transplantation offers the prospect of good glycemic control without major surgical risks. After our initial report of successful islet transplantation, we now provide further data on 12 type 1 diabetic patients with brittle diabetes or problems with hypoglycemia previous to 1 November 2000. Details of metabolic control, acute complications associated with islet transplantation, and long-term complications related to immunosuppression therapy and diabetes were noted. Insulin secretion, both acute and over 30 min, was determined after intravenous glucose tolerance tests (IVGTTs). The median follow-up was 10.2 months (CI 6.5-17.4), and the longest was 20 months. Glucose control was stable, with pretransplant fasting and meal tolerance-stimulated glucose levels of 12.5+/-1.9 and 20.0+/-2.7 mmol/l, respectively, but decreased significantly, with posttransplant levels of 6.3+/-0.3 and 7.5+/-0.6 mmol/l, respectively (P < 0.006). All patients have sustained insulin production, as evidenced by the most current baseline C-peptide levels 0.66+/-0.06 nmol/l, increasing to 1.29+/-0.25 nmol/l 90 min after the meal-tolerance test. The mean HbA1c level decreased from 8.3+/-0.5% to the current level of 5.8+/-0.1% (P < 0.001). Presently, four patients have normal glucose tolerance, five have impaired glucose tolerance, and three have post-islet transplant diabetes (two of whom need oral hypoglycemic agents and low-dose insulin (<10 U/day). Three patients had a temporary increase in their liver-function tests. One patient had a thrombosis of a peripheral branch of the right portal vein, and two of the early patients had bleeding from the hepatic needle puncture site; but these technical problems were resolved. Two patients had transient vitreous hemorrhages. The two patients with elevated creatinine levels pretransplant had a significant increase in serum creatinine in the long term, although the mean serum creatinine of the group was unchanged. The cholesterol increased in five patients, and lipid-lowering therapy was required for three patients. No patient has developed cytomegalovirus infection or disease, posttransplant lymphoproliferative disorder, malignancies, or serious infection to date. None of the patients have been sensitized to donor antigen. In 11 of the 12 patients, insulin independence was achieved after 9,000 islet equivalents (IEs) per kilogram were transplanted. The acute insulin response and the insulin area under the curve (AUC) after IVGTT were consistently maintained over time. The insulin AUC from the IVGTT correlated to the number of islets transplanted, but more closely correlated when the cold ischemia time was taken into consideration (r = 0.83, P < 0.001). Islet transplantation has successfully corrected labile type 1 diabetes and problems with hypoglycemia, and our results show persistent insulin secretion. After a minimum of 9,000 IEs per kilogram are provided, insulin independence is usually attained. An elevation of creatinine appears to be a contraindication to this immunosuppressive regimen. For the subjects who had labile type 1 diabetes that was difficult to control, the risk-to-benefit ratio is in favor of islet transplantation.

Durability of sodium sulfate-treated polylysine-alginate microcapsules

Chelated hollow microcapsules are unstable under in vitro conditions because of their hygroscopic nature. Nongel inducing cations, such as Na+, stabilize the outer membrane of the alginate-polylysine-alginate microcapsules leading to more stable beads. We made different batches of empty capsules with a mean +/- SEM diameter of 607+/-11 microns, and found that within 1 week of incubating these capsules in normal saline at 37 degrees C, they increased to 718+/-10 microns (p < 0.05, n = 5). In initial experiments, we made different batches of capsules and divided them into two groups. One group was left untreated (control) whereas the other was treated with 6 mM Na2SO4 for 30 min, before incubation in saline at 37 degrees C. Control capsules increased in weight and size, before beginning to melt in less than 1 week. In contrast, treated capsules rapidly lost weight and remained intact during 1 month of follow-up. In perifusion experiments, we found no deleterious effect of sodium sulfate treatment on the function of islets enclosed in the capsules.

Metabolic consequences of orthotopic pancreaticoduodenal transplantation with preservation of near normal physiology

BACKGROUND

Several case reports suggested the use of pancreaticoduodenal allotransplantation alone or in combination with multivisceral transplants to treat exocrine and endocrine deficiency after pancreatectomy for chronic pancreatitis, upper abdominal malignancies, and cystic fibrosis. Our objective was to establish the metabolic consequences of this technique.

METHODS

Inbred rats, which either underwent pancreaticoduodenectomy before receiving an orthotopic duodenopancreas transplant (Tx, n= 18) or laparotomy (sham, n=18), were subjected 3 months postoperatively to oral and "isoglycemic" i.v. glucose tolerance tests with arterial blood sampling (n=12) or oral glucose tolerance test with additional portal blood sampling (n=6). Fecal fat and chymotrypsin were evaluated in the 11th postoperative week as indicators of pancreatic exocrine function in eight animals of each group.

RESULTS

The incremental arterial plasma glucose integrated over a 90-min period was similar after oral and i.v. glucose in the respective groups, but was significantly lower in Tx versus sham rats after oral glucose. Incremental portal glucose was also lower after oral glucose, while hepatic glucose extraction remained unchanged. The incremental response of arterial glucose-dependent insulinotropic peptide, and of arterial and portal insulin, was comparable in Tx and sham rats; also in both groups the arterial response was significantly greater with oral versus i.v. glucose, and the incretin effect for insulin was intact after transplantation. Fecal fat and chymotrypsin levels did not differ between the two groups.

CONCLUSIONS

1) In the Tx rat lower incremental plasma glucose after oral glucose intake likely results from decreased intestinal glucose uptake; 2) preservation of a normal entero-insular axis of insulin together with the absence of intestinal malabsorption of lipids suggest that orthotopic transplantation of a duodeno-pancreas preserved endocrine and exocrine pancreatic function and therefore qualifies as treatment modality for the above named indications.

Storage and microencapsulation of islets for transplantation

Microencapsulation is an effective means of immunoisolation for pancreatic islet transplants. However, the process of isolating, purifying, encapsulating, and transplanting islets in a single day is labor intensive and difficult for routine use. There is an apparent need for reliable methods of islet storage, and cryopreservation has emerged as an attractive system of islet banking. While studies have shown that cryopreserved islets are viable when tested unencapsulated after thawing, it is not clear if the combination of freezing and encapsulation would affect islet function. The purpose of the present study was to determine the in vitro function of cryopreserved islets following thawing and microencapsulation. Islets were isolated from the pancreata of Sprague-Dawley rats and cryopreserved under liquid nitrogen for either 1 week or 1 month, following an overnight culture at 37 degrees C. Upon thawing, the islets were tested either unencapsulated or after encapsulation in polylysine-alginate membrane. In all experiments islets were preperifused for 1 h at 37 degrees C with a modified Krebs-Ringer bicarbonate buffer containing 3.3 mM (60 mg/dl) glucose and maintained at pH 7.4 by continuous gassing with 95% air/5% CO2. Following basal effluent sample collection on ice, the glucose concentration was raised to 16.7 mM (300 mg/dl). It was found that, within 10 min of high glucose stimulation, an average of twofold increase in insulin secretion (p < 0.01) was obtained in islets within or without microcapsules. We conclude that islets cryopreserved for 1 month prior to thawing and microencapsulation retained functional viability as determined in in vitro experiments.

Surgical complications after pancreas transplantation with portal-enteric drainage

BACKGROUND

Despite recent advances, surgical complications remain an important source of morbidity after pancreas transplantation (PTX). Several previous studies have delineated the surgical complications after PTX with systemic-bladder (S-B) drainage, but data are limited regarding the incidence and outcomes of surgical complications after PTX with portal-enteric (P-E) drainage.

STUDY DESIGN

We retrospectively studied surgical complications after 83 vascularized PTXs with P-E drainage in 79 patients (65 simultaneous kidney-PTXs [SKPT] and 18 solitary PTXs [SPT], 8 pancreas alone and 10 pancreas after kidney transplantation). Twelve (15%) were retransplants. A surgical complication was defined as the need for repeat laparotomy within the first 3 months after PTX.

RESULTS

A total of 53 surgical complications requiring repeat laparotomy occurred in 31 patients (37%). The incidence of surgical complications in SKPT and SPT was 38% and 33%, respectively. The most common indications for repeat laparotomy were: vascular thrombosis in 13% (SKPT 14% and SPT 11%), intraabdominal infection in 10% (SKPT 12% and SPT 0%), intraabdominal bleeding in 8% (SKPT 8% and SPT 11%), and duodenal allograft leak in 4% (SKPT 3% and SPT 6%). Patient survival rates at 1 and 3 years with versus without surgical complications were 84% and 80% versus 94% and 86%, respectively (p = NS). Pancreas graft survival rates at 1 and 3 years with versus without surgical complications were 48% and 44% versus 89% and 76%, respectively (p < 0.0001). The incidence of surgical complications was 45% in the first 42 P-E transplantations performed between 1990 and 1995, compared with 29% in the next 41 transplantations performed during 1996 and 1997 (p = NS). The mean number of repeat laparotomies per patient decreased from 1.2 in the former group to 0.5 in the latter group (p = NS). The incidence rates of vascular thrombosis, intraabdominal infection, and duodenal leak in the former and latter groups were 17% versus 10%, 12% versus 7%, and 2% versus 5%, respectively.

CONCLUSIONS

Surgical complications after PTX are common, and their incidence and outcomes with P-E drainage are similar to those with S-B drainage. The complication rate does not vary according to the type of transplant (SKPT versus SPT). Increasing experience with P-E drainage results in a decreased incidence of surgical complications.