Minimal focal steatosis of liver after islet transplantation in humans: a long-term study

Several reports have been published on islet transplantation in humans, but few data are available on the effect of islet infusion on the hepatic structure. Our aim was to evaluate in a longitudinal study the impact on the liver of intrahepatic islet transplantation. Clinical outcome and liver imaging were evaluated in 31 cases of islet-kidney transplantation (follow-up 38 +/- 4 months, range 12-96 months). Patients were divided into three groups: full function (FF, 9 cases: established insulin independence); partial function (PF, 16 cases: transient insulin independence, prolonged C-peptide secretion): no function (NF, 6 cases: exhaustion of C-peptide secretion within the first year). Upper abdomen sonogram was regularly performed during the whole follow-up period. Percutaneous liver biopsy was performed in case of echographic abnormalities. Multiple small areas of focal hyperechogenicity were observed in nine cases after 6-12 months. These findings were observed only in FF (two) and in PF (seven) patients. Fasting C-peptide levels at the time of echography were higher in negative than in positive patients (2.42 +/- 0.16 vs. 1.51 +/- 0.10 ng/ml, p = 0,0001). Liver biopsies showed focal macrovesicular steatosis, surrounded by normal liver parenchyma. Normal liver function was maintained. In conclusion, our results indicate that islet transplantation can lead to structural changes of the liver parenchyma (focal steatosis). It is more often observed in patients with partial function. Sonogram can be considered a specific method to reveal liver changes after islet transplantation.     

Metabolic effects of restoring partial beta-cell function after islet allotransplantation in type 1 diabetic patients

Successful intraportal islet transplantation normalizes glucose metabolism in diabetic humans. To date, full function is not routinely achieved after islet transplantation in humans, with most grafts being characterized by only partial function. Moreover, the duration of full function is variable and cannot be sufficiently predicted with available methods. In contrast, most grafts retain partial function for a long time. We hypothesized that partial function can restore normal protein and lipid metabolism in diabetic individuals. We studied 45 diabetic patients after islet transplantation. Labeled glucose and leucine were infused to assess whole-body glucose and protein turnover in 1) 6 type 1 diabetic patients with full function after intraportal islet transplantation (FF group; C-peptide > 0.6 nmol/l; daily insulin dosage 0.03 +/- 0.02 U x kg(-1) body wt x day(-1); fasting plasma glucose < 7.7 mmol/l; HbA1c < or = 6.5%), 2) 17 patients with partial function (PF group; C-peptide > 0.16 nmol/l; insulin dosage < 0.4 U x kg(-1) body wt x day(-1)), 3) 9 patients with no function (NF group; C-peptide < 0.16 nmol/l; insulin dosage > 0.4 U x kg(-1) body wt x day(-1)), and 4) 6 patients with chronic uveitis as control subjects (CU group). Hepatic albumin synthesis was assessed in an additional five PF and five healthy volunteers by means of a primed-continuous infusion of [3,3,3-2H3]leucine. The insulin requirement was 97% lower than pretransplant levels for the FF group and 57% lower than pretransplant levels for the PF group. In the basal state, the PF group had a plasma glucose concentration slightly higher than that of the FF (P = 0.249) and CU groups (P = 0.08), but was improved with respect to the NF group (P < 0.01). Plasma leucine (101.1 +/- 5.9 micromol/l) and branched-chain amino acids (337.6 +/- 16.6 micromol/l) were similar in the PF, FF, and CU groups, and significantly lower than in the NF group (P < 0.01). During insulin infusion, the metabolic clearance rate of glucose was defective in the NF group versus in the other groups (P < 0.01). Both the basal and insulin-stimulated proteolytic and proteosynthetic rates were comparable in the PF, FF, and CU groups, but significantly higher in the NF group (P = 0.05). In addition, the PF group had a normal hepatic albumin synthesis. Plasma free fatty acid concentrations in the PF and FF groups were similar to those of the CU group, but the NF group showed a reduced insulin-dependent suppression during the clamp. We concluded that the restoration of approximately 60% of endogenous insulin secretion is capable of normalizing the alterations of protein and lipid metabolism in type 1 diabetic kidney recipients, notwithstanding chronic immunosuppressive therapy. The results of the present study indicate that "success" of islet transplantation may be best defined by a number of metabolic criteria, not just glucose concentration/metabolism alone.     

{beta}-Cell function following human islet transplantation for type 1 diabetes

Islet transplantation can provide metabolic stability for patients with type 1 diabetes; however, more than one donor pancreas is usually required to achieve insulin independence. To evaluate possible mechanistic defects underlying impaired graft function, we studied five subjects at 3 months and four subjects at 12 months following intraportal islet transplantation who had received comparable islet equivalents per kilogram (12,601 +/- 1,732 vs. 14,384 +/- 2,379, respectively). C-peptide responses, as measures of beta-cell function, were significantly impaired in both transplant groups when compared with healthy control subjects (P < 0.05) after intravenous glucose (0.3 g/kg), an orally consumed meal (600 kcal), and intravenous arginine (5 g), with the greatest impairment to intravenous glucose and a greater impairment seen in the 12-month compared with the 3-month transplant group. A glucose-potentiated arginine test, performed only in insulin-independent transplant subjects (n = 5), demonstrated significant impairments in the glucose-potentiation slope (P < 0.05) and the maximal response to arginine (AR(max); P < 0.05), a measure of beta-cell secretory capacity. Because AR(max) provides an estimate of the functional beta-cell mass, these results suggest that a low engrafted beta-cell mass may account for the functional defects observed after islet transplantation.     

The use of exenatide in islet transplant recipients with chronic allograft dysfunction: safety, efficacy, and metabolic effects

BACKGROUND: A current limitation of islet transplantation is reduced long-term graft function. The glucagon-like peptide-1 receptor agonist, exenatide (Byetta, Amylin Pharmaceuticals, CA) has properties that could improve existing islet function, prevent further loss of islet mass and possibly even stimulate islet regeneration. METHODS: This prospective study evaluated the safety, efficacy, and metabolic effects of exenatide in subjects with type 1 diabetes mellitus and islet allograft dysfunction requiring exogenous insulin. RESULTS: Sixteen subjects commenced exenatide, 12 continue (follow-up 214+/-57 days; range 108-287), four (25%) discontinued medication because of side effects. At 6 months, exogenous insulin was significantly reduced with stable glycemic control (0.15+/-0.02 vs. 0.11+/-0.025 U/kg per day; P<0.0001); three subjects discontinued insulin from 4, 5, and 9 U/day, respectively, two sustained insulin independence with A1c reduction below graft dysfunction criteria. Postprandial capillary blood glucose was significantly decreased (129.4+/-3.8 vs. 118.7+/-4.6 mg/dL; P<0.001), C-peptide and C-peptide-to-glucose ratio increased significantly by 5th and 6th months of treatment (ratio, 1.09+/-0.15 vs. 1.52+/-0.18; P<0.05). Weight loss more than 3 kg occurred in 8 of 12 (67%) subjects. Stimulation testing demonstrated improved glucose disposal and C-peptide secretion (glucose area under the curve 52,332+/-3,219 vs. 42,072+/-1,965; P=0.002 mg x min x dL, mixed meal stimulation index 0.50+/-0.06 vs. 0.66+/-0.09; P=0.03 pmol x mL), with marked suppression of glucagon secretion and progressive increase in amylin secretion. Side effects were more frequent and severe compared with published reports in type 2 diabetes, tolerated doses were lower. CONCLUSIONS: Exenatide was tolerated in this patient population after appropriate dose titration and there appeared to be gradual but sustained positive effects on glycemic control and islet graft function.     

Intrahepatic islet transplantation in type 1 diabetic patients does not restore hypoglycemic hormonal counterregulation or symptom recognition after insulin independence

Islet allotransplantation can provide prolonged insulin independence in selected individuals with type 1 diabetes. Whether islet transplantation also restores hypoglycemic counterregulation is unclear. To determine if hypoglycemic counterregulation is restored by islet transplantation, we studied hormone responses and hypoglycemic symptom recognition in seven insulin-independent islet transplant recipients using a 3-h stepped hypoglycemic clamp, and compared their responses to those of nontransplanted type 1 diabetic subjects and nondiabetic control subjects. Glucagon responses of islet transplant recipients to hypoglycemia were significantly less than that observed in control subjects (incremental glucagon [mean +/- SE]: -12 +/- 12 vs. 64 +/- 22 pg/ml, respectively; P < 0.05), and not significantly different from that of nontransplanted type 1 diabetic subjects (-17 +/- 10 pg/ml). Epinephrine responses and symptom recognition were also not restored by islet transplantation (incremental epinephrine [mean +/- SE]: 195 +/- 128 [islet transplant recipients] vs. 238 +/- 73 [type 1 diabetic subjects] vs. 633 +/- 139 pg/ml [nondiabetic control subjects], P < 0.05 vs. control; peak symptom scores: 3.3 +/- 0.9 [islet transplant recipients] vs. 3.1 +/- 1.1 [type 1 diabetic subjects] vs. 6.7 +/- 0.8 [nondiabetic control subjects]). Thus the results indicate that despite providing prolonged insulin independence and near-normal glycemic control in these patients with long-standing type 1 diabetes, hypoglycemic hormonal counterregulation and symptom recognition were not restored by intrahepatic islet transplantation.     

Results of our first nine intraportal islet allografts in type 1, insulin-dependent diabetic patients

With the first demonstration of insulin independence following intraportal islet transplantation into a patient with type 1 diabetes, a new era of clinical islet transplantation will begin. This report provides our initial experience of clinical islet transplantation with a total of nine consecutive portal vein islet transplants in seven diabetic recipients. The first three transplants were done in nonrenal failure diabetics (NRFI) using 6319 +/- 2173 islets/kg body weight with islets processed from single pancreas and cultured for 7 days at 24 degrees C. Prednisone, azathioprine, and cyclosporine were initiated prior to transplant. While all three recipients demonstrated C-peptide function posttransplant, all three rejected their grafts at 2 weeks. Five days of OKT3 treatment failed to recover more than 10% of their rejecting islet grafts. The studies were then shifted to established kidney transplant recipients (EKI) maintaining their basal immunosuppression while adding 7 days of Minnesota antilymphoblast globulin (MALG) to the recipient using islets from single donor pancreas that had been cultured for 7 days at 24 degrees C. There were an average of 6161 +/- 911 islets transplanted intraportally into three EKI recipients. All three had C-peptide response from the transplant, but none achieved insulin independence. While the first patient rejected his graft at 2 weeks, two recipients demonstrated long-term islet function up to 10 months posttransplant. Sustacal challenge testing demonstrated C-peptide responsiveness, but in a delayed pattern suggesting insufficient islet mass had been transplanted. The next three kidney transplant recipients received islets from more than one donor pancreas averaging 13,916 +/- 556 islets/kg body weight. The first of these was the first to achieve insulin independence from 10 to day 25 posttransplant when she appeared to have a rejection episode. The second and third recipients were retransplanted with islets from multiple donors having achieved partial islet function from single pancreas donor. The first patient on triple immunosuppression is demonstrating long-term partial function at 184 days but is not insulin independent. The third patient on prednisone and azathioprine received one half his islets after 7-day culture and the other half after 7-day culture combined with cryopreservation. He is continuing to demonstrate insulin independence for 154 days post-transplant with a glycated hemoglobin value of 5.6%. Sustacal challenge data demonstrate a total stimulated C-peptide response of 155 rhomol/ml at 4 months post-transplant compared with 148 +/- 12 rhomol/ml for normal controls (NC) and 425 rhomol/ml for nondiabetic, established kidney transplant recipients on triple immunosuppression.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ex vivo and systemic transfer of adenovirus-mediated CTLA4Ig gene combined with a short course of FK506 therapy prolongs islet graft survival

Adenovirus-mediated CTLA4Ig gene transfer has been reported to enhance graft survival in several rodent transplantation models. In this study, we investigated the efficacy of ex vivo and systemic transfer of the CTLA4Ig gene by adenoviral vectors in pancreatic islet allo-transplantation. Islet grafts from BN rats were transplanted to chemically induced diabetic LEW rats. First, ex vivo CTLA4Ig gene transfer into isolated islets was performed prior to transplantation. Survival of transduced grafts under the kidney capsule was slightly prolonged (8.6+/-1.3 days) compared with survival of untransduced grafts (6.7+/-1.2 days); when combined with a short course of FK506, graft survival was further extended (32.6+/-10.7 days vs. 13.7+/-1.0 days with FK506 alone). Secondly, systemic gene transfer was accomplished by intravenous administration immediately after the transplantation procedure. In these animals, islet grafts under the kidney capsule survived longer (15.2+/-3.3 days) than in controls (6.7+/-1.2 days), and when FK506 was administered perioperatively, all the islet grafts survived for more than 100 days. In systemically transduced recipients, the survival of islet grafts transplanted into the liver was not significantly different from that of the grafts placed under the kidney capsule. In order to examine organ-specific immunogenicity, heterotopic BN cardiac grafts were transplanted to LEW rats intra-abdominally, with the virus transferred systemically as in the islet model. In contrast to the islet grafts, all the cardiac grafts were accepted for longer than 100 days, even without FK506 therapy. Finally, the LEW recipients with long-surviving islet or cardiac grafts were re-transplanted with islet grafts from the same donor strain (BN) on day 100. The second islet grafts survived longer than 100 days in half of the cardiac recipients, but consistently failed in the islet recipients. We conclude that in this transplant model, CTLA4Ig gene transfer and FK506 treatment synergistically improved islet graft survival, systemic transfer of the gene was more effective than ex vivo transfer to the islets, and donor-specific tolerance could not be achieved for islet transplantation but was achieved for cardiac transplantation.     

Prevalence of hepatic steatosis after islet transplantation and its relation to graft function

Islet allotransplantation can provide insulin independence in selected individuals with type 1 diabetes. The long-term effects of these transplants on the liver are unknown. Recently, two cases of periportal steatosis after islet transplantation have been described. In this study, we performed ultrasound and magnetic resonance imaging (MRI) in 30 C-peptide-positive islet transplant recipients to detect steatosis and to explore the association of the radiological findings with clinical and metabolic factors. Steatosis was observed on MRI in six (20%) subjects. Histological findings of hepatic steatosis concurred with the imaging findings. Steatosis completely resolved in one subject whose graft failed. More subjects with steatosis required supplementary exogenous insulin than not (67 vs. 21%; P < 0.05). The clinical features of subjects with and without steatosis were otherwise similar, although C-peptide levels were higher in insulin-independent subjects with steatosis (0.98 +/- 0.12 vs. 0.70 +/- 0.18 nmol/l; P = 0.05), despite similar blood glucose levels. Serum triglycerides and the use of exogenous insulin were associated with increased odds of steatosis in a logistic regression model (chi(2) [degrees freedom] = 13.6 [2]); P = 0.001). MRI-detected steatosis is a common finding; the steatosis appears to be due to a paracrine action of insulin secreted from intrahepatic islets. Hepatic steatosis may be associated with insulin resistance or graft dysfunction.     

TLR4 Mediates Early Graft Failure After Intraportal Islet Transplantation

We have previously shown that islet emboli in the portal vein block blood flow and induce local inflammatory reaction, resulting in functional loss of islet grafts following intraportal transplantation. This study was designed to test whether Toll‐like receptor (TLR) activation mediates early islet graft failure. Syngeneic islet grafts were transplanted into chemically induced diabetic mice, and TLR deficient mice were used as donors and/or recipients of islet grafts. Islet viability, proinflammatory cytokines, high‐mobility group box‐1 (HMGB1) and NF‐κB activation were analyzed by bioluminesce imaging (BLI), quantitative RT‐PCR (qRT‐PCR) and histology. Early islet graft failure was observed in mice with intraportal islet engrafts with increased proinflammatory cytokines, HMGB1 expression, NF‐κB activation, caspase‐3 and TUNEL positive cells. Deficiency of TLR4 in donor, but not in recipient, inhibited NF‐κB activation, reduced proinflammatory cytokines and improved viability of islet grafts. Blockade of HMGB1 with anti‐HMGB1 monoclonal antibody (mAb, 2g7) inhibited inflammatory reactions, as evidenced by reduced TNFα and IL‐1ß production, and improved islet viability. We conclude that TLR4 activation mediates early graft failure following intraportal islet transplantation. Inhibition of TLR4 activation represents a novel strategy to attenuate early graft failure following intraportal islet transplantation.     

Five-year follow-up after clinical islet transplantation

Islet transplantation can restore endogenous beta-cell function to subjects with type 1 diabetes. Sixty-five patients received an islet transplant in Edmonton as of 1 November 2004. Their mean age was 42.9 +/- 1.2 years, their mean duration of diabetes was 27.1 +/- 1.3 years, and 57% were women. The main indication was problematic hypoglycemia. Forty-four patients completed the islet transplant as defined by insulin independence, and three further patients received >16,000 islet equivalents (IE)/kg but remained on insulin and are deemed complete. Those who became insulin independent received a total of 799,912 +/- 30,220 IE (11,910 +/- 469 IE/kg). Five subjects became insulin independent after one transplant. Fifty-two patients had two transplants, and 11 subjects had three transplants. In the completed patients, 5-year follow-up reveals that the majority ( approximately 80%) have C-peptide present post-islet transplant, but only a minority ( approximately 10%) maintain insulin independence. The median duration of insulin independence was 15 months (interquartile range 6.2-25.5). The HbA(1c) (A1C) level was well controlled in those off insulin (6.4% [6.1-6.7]) and in those back on insulin but C-peptide positive (6.7% [5.9-7.5]) and higher in those who lost all graft function (9.0% [6.7-9.3]) (P < 0.05). Those who resumed insulin therapy did not appear more insulin resistant compared with those off insulin and required half their pretransplant daily dose of insulin but had a lower increment of C-peptide to a standard meal challenge (0.44 +/- 0.06 vs. 0.76 +/- 0.06 nmol/l, P < 0.001). The Hypoglycemic score and lability index both improved significantly posttransplant. In the 128 procedures performed, bleeding occurred in 15 and branch portal vein thrombosis in 5 subjects. Complications of immunosuppressive therapy included mouth ulcers, diarrhea, anemia, and ovarian cysts. Of the 47 completed patients, 4 required retinal laser photocoagulation or vitrectomy and 5 patients with microalbuminuria developed macroproteinuria. The need for multiple antihypertensive medications increased from 6% pretransplant to 42% posttransplant, while the use of statin therapy increased from 23 to 83% posttransplant. There was no change in the neurothesiometer scores pre- versus posttransplant. In conclusion, islet transplantation can relieve glucose instability and problems with hypoglycemia. C-peptide secretion was maintained in the majority of subjects for up to 5 years, although most reverted to using some insulin. The results, though promising, still point to the need for further progress in the availability of transplantable islets, improving islet engraftment, preserving islet function, and reducing toxic immunosuppression.     

Human islet transplantation: lessons from 13 autologous and 13 allogeneic transplantations

BACKGROUND: A series of 13 islet autotransplantations and 13 islet allotransplantations performed between 1992 and 1999 at the University Hospital of Geneva are presented. Factors affecting the outcome are analyzed. METHODS: Islet autotransplantation has been performed in seven patients with chronic pancreatitis and in six patients with benign tumors undergoing extensive pancreatectomy. Islet allografts were performed in C-peptide-negative patients simultaneously or after a kidney or lung transplantation. Each recipient received islets from one to four donors. Panel-reactive antibodies were monitored by microlymphocytotoxicity test. RESULTS: Eleven of 13 patients who underwent autotransplantation maintained insulin independence for 6 months to 5 years. Two years after autologous islet transplantation, five of nine patients were insulin independent with an glycosylated hemoglobin of 5.9%. Three late islet failures occurred in patients with chronic pancreatitis. Islet yield was significantly lower in patients with chronic pancreatitis than in patients with benign tumors (2044 equivalent islet number/gram resected pancreas versus 5184 equivalent islet number/gram; P=0.037). In islet allotransplantation, no early graft loss was found. All 13 patients who underwent allotransplantation had basal C-peptide levels above 0.3 nmol/L for 3 months to 5 years. Mean glycosylated hemoglobin decreased from 9.1% before transplantation to 5.5% at month 3. Insulin independence was achieved in two type I diabetic patients. In four of six patients with graft failure, the graft had induced panel-reactive antibodies. CONCLUSIONS: In islet autotransplantation, the reduced number of islets that can be isolated from fibrotic pancreata may be the major limiting factor. In islet allotransplantation, early graft function can now be consistently achieved. Islet allografts seem to be highly immunogenic, and chronic islet failure cannot be prevented consistently by conventional immunosuppression.     

Improved metabolic control and quality of life in seven patients with type 1 diabetes following islet after kidney transplantation

BACKGROUND: The beneficial effects of glycemic control on both survival and function of transplanted kidneys in patients with type 1 diabetes mellitus (T1DM) and end-stage renal disease (ESRD) have been recognized. METHODS: Herein, we present the clinical outcome of a single-center pilot trial of islet after kidney (IAK) transplantation in seven patients with T1DM. The immunosuppression protocol for the kidney graft was converted to sirolimus+tacrolimus regimen 6 months before islet transplantation to exclude negative effects on kidney graft function. Primary endpoint was achievement of insulin independence after transplantation. Clinical outcome, metabolic control, severe hypoglycemia, kidney function, Quality of Life (QOL) psychometric measures, and adverse events were monitored. RESULTS: Seven patients showed graft function with improved metabolic control (A1c, fasting glycemia, and metabolic tests) after IAK (14,779+/-3,800 IEQ/kg). One-year insulin independence was 30% with persistent graft function in 86% (C-peptide-positive). A1c reduction was 1.95+/-0.31% from baseline (P<0.0001). No episodes of severe hypoglycemia were observed, even after resuming insulin. The direct consequence of these benefits was a significant improvement in diabetes QOL. Adverse events included procedure-related pleural effusion (n=2), cholecystitis (n=1), and additional immunosuppression-related, all resolved without sequelae. Kidney function (by estimated glomerular filtration rate) remained stable during follow-up in six of seven patients. CONCLUSIONS: Islet transplantation represents a feasible therapeutic option for patients with T1DM bearing a stable kidney allograft. Insulin independence at 1 year is lower than what reported in islet transplant alone. Nevertheless, clear benefits in terms of optimal metabolic control and absence of severe hypoglycemia are invariably present.     

Intra-Ductal Glutamine Administration Reduces Oxidative Injury During Human Pancreatic Islet Isolation

Oxidative stress during islet isolation induces a cascade of events injuring islets and hampering islet engraftment. This study evaluated islet isolation and transplantation outcomes after intra-ductal glutamine administration. Human pancreata deemed unsuitable for pancreas or islet transplantation were treated with either a 5 mM solution of l-glutamine (n = 6) or collagenase enzyme alone (n = 6) through the main pancreatic duct. Islet yield, viability, in vitro function; markers of oxidative stress [malondialdehyde (MDA) and Glutathione (GSH)] and apoptosis were assessed. Islet yields were significantly increased in the glutamine group compared to controls (318, 559 +/- 25, 800 vs. 165, 582 +/- 39, 944 mean +/- SEM, p < 0.01). The amount of apoptotic cells per islet was smaller in the glutamine group than the control. The percentage of nude mice rendered normoglycemic with glutamine-treated islets was higher than the controls (83% n = 10/12 vs. 26% n = 6/23; p < 0.01), and the time to reach normoglycemia was decreased in the glutamine group (1.83 +/- 0.4 vs. 7.3 +/- 3 days; p < 0.01). Glutamine administration increased GSH levels (7.6 +/- 1.7 nmol/mg protein vs. 4.03 +/- 0.5 in control, p < 0.05) and reduced lipid-peroxidation (MDA 2.45 +/- 0.7 nmol/mg of protein vs. 6.54 +/- 1.7 in control; p < 0.05). We conclude that intra-ductal administration of glutamine reduces oxidative injury and apoptosis and improves islet yield and islet graft function after transplantation.     

The postoperative course and quantitative aspects of rat islet and segmental pancreas isografts

Duct-ligated segmental pancreas transplants with systemic venous drainage were compared to intrahepatic islet grafts for beta-cell mass (proportional to tissue insulin content) and function in diabetic Lewis rats. Rats were serially killed to measure insulin in the segmental pancreas grafts and in the liver of the islet recipients. Segmental pancreas weight was maximum and insulin concentration and content lowest (P less than 0.05) on Day 3 when acute inflammation was present. At 21 days, there was no inflammation, and graft weight had decreased, but not to Day 0 level because of normal growth; insulin concentration was similar on Days 21 and 0. At 3 months, moderate fibrosis of the graft was present, but both total insulin and insulin concentration had increased (P less than 0.05). In the recipients of islet grafts, total insulin in the liver on Day 1 was only 43% of that contained in the original islet preparation, but by 3 months the insulin content in the liver had increased to that transplanted. IVGTT K values were similar in normal rats (-3.5 +/- 0.7%) and in recipients of segmental pancreas (-4.5 +/- 1.6%) and islet (-4.0 +/- 1.5%) grafts at 3 months post transplant. Acute segmental graft pancreatitis resolved, followed by an increase in beta-cell mass. Islet cell damage during transplantation is either reversible or residual viable islets proliferate, and provide metabolic control equivalent to segmental pancreas transplants, even though the final beta-cell mass is less.     

Clinical use of donation after circulatory death pancreas for islet transplantation

Due to a shortage of donation after brain death (DBD) organs, donation after circulatory death (DCD) is increasingly performed. In the field of islet transplantation, there is uncertainty regarding the suitability of DCD pancreas in terms of islet yield and function after islet isolation. The aim of this study was to investigate the potential use of DCD pancreas for islet transplantation. Islet isolation procedures from 126 category 3 DCD and 258 DBD pancreas were performed in a 9-year period. Islet yield after isolation was significantly lower for DCD compared to DBD pancreas (395 515 islet equivalents [IEQ] and 480 017 IEQ, respectively; p = .003). The decrease in IEQ during 2 days of culture was not different between the two groups. Warm ischemia time was not related to DCD islet yield. In vitro insulin secretion after a glucose challenge was similar between DCD and DBD islets. After islet transplantation, DCD islet graft recipients had similar graft function (AUC C-peptide) during mixed meal tolerance tests and Igls score compared to DBD graft recipients. In conclusion, DCD islets can be considered for clinical islet transplantation.     

Simple evaluation of engraftment by secretory unit of islet transplant objects for living donor and cadaveric donor fresh or cultured islet transplantation

BACKGROUND: Evaluation of engraftment is important to assess the success of islet transplantation. Recently we developed secretory unit of islet transplant objects (SUITO) index for simple evaluation of engraftment. Assuming that normal subjects aged <40 years have 100% pancreatic beta-cell function, SUITO index was calculated by the formula: 1500 x fasting C-peptide immunoreactivity [ng/dL]/(fasting blood glucose [mg/dL] - 63). In this study, we compared the efficacy of islet transplantation from cadaveric and living donors using the SUITO index. METHODS: We performed eight islet transplantations with non-heart-beating donors (NHBDs) into five patients. Two patients received fresh islets once, one patient received fresh islets twice, one patient received cultured islets once, and one patient received cultured islets twice plus fresh islets once. In addition, one patient received fresh islets from a living donor. We calculated the SUITO index from postoperative days 3 to 30 for each case. RESULTS: Mean SUITO index after one fresh islet transplant was 11.7 +/- 1.0, after two fresh islet transplants was 28.5 +/- 3.4, after one cultured islet transplant was 2.1 +/- 0.4, after two cultured islet transplant was 12.1 +/- 1.9, and after two cultured islet transplant plus one fresh islet transplant was 26.7 +/- 1.7. The mean SUITO index after single living donor islet transplant was 40.7 +/- 2.6, which was significantly higher compared with all other groups. Insulin independence was obtained when the SUITO index was >26, which might reflect that 26% beta-cell mass was required for insulin independence. CONCLUSION: SUITO index is useful to evaluate islet engraftment and to predict the possibility of insulin independence.     

Islet cell transplantation: the future?

BACKGROUND: Islet of Langerhans' cell transplantation is a promising strategy for the treatment of type-1 diabetes mellitus. Results of this procedure have yet to match those of whole organ pancreas transplantation, but are rapidly improving, as witnessed by increasing rates of insulin independence and graft function (i.e., C-peptide production) after islet transplantation. DISCUSSION: Identification of obstacles to the success of islet transplantation, such as primary nonfunction, immunosuppression-related metabolic workload, or recurrence of autoimmunity, will allow the development of new strategies tailored to overcome them. In particular, novel immunosuppressive protocols, with or without the aim of inducing tolerance, and immunoisolation devices are reaching the stage of clinical applicability. Finally, several strategies, such as utilization of porcine xenogeneic islets or genetically engineered beta-cell lines, or in vitro expansion of cultured beta-cells could theoretically expand indefinitely the pool of islet tissue for transplantation.     

Effect of donor age on function of isolated human islets

This study intended to evaluate the impact of donor age on the function of isolated islets. Analysis of human islets from cadaveric donors (age 16-70 years) was performed using glucose-stimulated insulin release (GSIR) (n = 93), islet ATP content (n = 27), diabetic nude mouse bioassay (n = 72), and the insulin secretory function after single-donor clinical islet allotransplantation (n = 7). The GSIR index was significantly higher in younger donors (age < or =40 years) than in older donors and negatively correlated with the donor age (r = -0.535). Islet ATP was higher in younger donors (115.7 +/- 17.7 vs. 75.7 +/- 6.6 pmol/microg DNA). The diabetes reversal rate of mice with 2,000 IE was significantly higher in younger donors (96 vs. 68%). C-peptide increment to glucose during intravenous glucose tolerance test at days 90-120 after clinical transplantation showed negative correlation with donor age (r = -0.872) and positive correlation with the islet mass (r = 0.832). On the other hand, acute insulin response to arginine only showed correlation with the islet mass and not with donor age. These results show that insulin secretory response to glucose deteriorates with increasing age and that it may be related to changes in ATP generation in beta-cells.