C. Socci

Islet isolation assessment in man and large animals

SummaryRecent progress in islet isolation from the pancreas of large mammals including man, accentuated the need for the development of precise and reproducible techniques to assess islet yield. In this report both quantitative and qualitative criteria for islet isolation assessment were discussed, the main topics being the determination of number, volume, purity, morphologic integrity andin vitro andin vivo function tests of the final islet preparations. It has been recommended that dithizone should be used as a specific stain for immediate detection of islet tissue making it possible to estimate both the total number of islets (dividing them into classes of 50 µ diameter range increments) and the purity of the final preparation. Appropriate morphological assessment should include confirmation of islet identification, assessment of the morphological integrity and of the purity of the islet preparation. The use of fluorometric inclusion and exclusion dyes together have been suggested as a viability assay to simultaneously quantitate the proportion of cells that are intact or damaged. Perifusion of islets with glucose provides a dynamic profile of glucose-mediated insulin release and of the ability of the cells to down regulate insulin secretion after the glycemic challenge is interrupted. Although perifusion data provides a useful guide to islet viability the quantity and kinetics of insulin release do not necessarily predict islet performance after implantation. Therefore, the ultimate test of islet viability is their function after transplantation into a diabetic recipient. For this reason,in vivo models of transplantation of an aliquot of the final islet preparation into diabetic nude (athymic) rodents have been suggested. We hope that these general guidelines will be of assistance to standardize the assessment of islet isolations, making it possible to better interpret and compare procedures from different centers.

Islet isolation for allotransplantation: variables associated with successful islet yield and graft function

Aims/hypothesisEfficient islet isolation is an important prerequisite for successful clinical islet transplantation. Although progressively improved, islet yield and quality are, however, unpredictable and variable and require standardisation.MethodsSince 1989 we have processed 437 pancreases using the automated method. The donor characteristics, pancreas procurement, and digestion and purification procedures including a wide enzyme characterisation of these pancreases were analysed and correlated with islet yield and transplant outcome.ResultsBy univariate analysis, islet yield was significantly associated with donor age (r=0.16; p=0.0009), BMI (r=0.19; p=0.0004), good pancreas condition (p=0.0031) and weight (r=0.15; p=0.0056), total collagenase activity (r=0.22; p=0.0001), adjusted collagenase activity/mg (r=0.18; p=0.0002), collagenase activity/solution volume (r=0.18; p=0.0002) and neutral protease activity/solution volume (r=0.14; p=0.0029). A statistically significant contribution to the variability of islet yield in a multivariate analysis performed on donor variables was found for donor BMI (p=0.0008). In a multivariate analysis performed on pancreas variables a contribution was found for pancreas weight (p=0.0064), and for a multivariate analysis performed on digestion variables we found a contribution for digestion time (p=0.0048) and total collagenase activity (p=0.0001). Twenty-four patients with type 1 diabetes received single islet preparations from single donors. In these patients, multivariate analyses showed that the reduction in insulin requirement was significantly associated with morphological aspects of islets (p=0.0010) and that 1-month C-peptide values were associated with islet purity (p=0.0071).Conclusions/interpretationThese data provide baseline donor, digestion and purification selection criteria for islet isolation using the automated method and indicate that the morphological aspect may be a clinically relevant measure of islets on which the decision for transplant can be based.

Islet Transplantation Is Associated with Improvement of Renal Function among Uremic Patients with Type I Diabetes Mellitus and Kidney Transplants

The potential effects of islet transplantation on the renal function of 36 patients with type I diabetes mellitus and kidney transplants were studied with 4 yr of follow-up monitoring. Kidney-islet recipients were divided into two groups, i.e., patients with successful islet transplants (SI-K group) (n = 24, fasting C-peptide levels of >0.5 ng/ml for >1 yr) and patients with unsuccessful islet transplants (UI-K group) (n = 12, fasting C-peptide levels of <0.5 ng/ml). Kidney graft survival rates and function, urinary albumin excretion rates, and sodium handling were compared. Na(+)/K(+)-ATPase activity in protocol kidney biopsies and in red blood cells was cross-sectionally analyzed. The SI-K group demonstrated better kidney graft survival rates (100, 83, and 83% at 1, 4, and 7 yr, respectively) than did the UI-K group (83, 72, and 51% at 1, 4, and 7 yr, respectively; P = 0.02). The SI-K group demonstrated reductions in exogenous insulin requirements and higher C-peptide levels, compared with the UI-K group, whereas GFR values were similar. Microalbuminuria (urinary albumin index) increased significantly in the UI-K group only (UI-K, from 92.0 +/- 64.9 to 183.8 +/- 83.8, P = 0.05; SI-K, from 108.5 +/- 53.6 to 85.0 +/- 39.0, NS). In the SI-K group, but not in the UI-K group, natriuresis decreased at 2 and 4 yr (P < 0.01). The SI-K group demonstrated greater Na(+)/K(+)-ATPase immunoreactivity in renal tubular cells (P = 0.05) and higher activity in red blood cells (P = 0.03), compared with the UI-K group. The Na(+)/K(+)-ATPase activity in red blood cells was positively correlated with circulating C-peptide levels but not with glycated hemoglobin levels. Successful islet transplantation was associated with improvements in kidney graft survival rates and function among uremic patients with type I diabetes mellitus and kidney grafts.

Expansion of Th17 cells and functional defects in T regulatory cells are key features of the pancreatic lymph nodes in patients with type 1 diabetes.

OBJECTIVE Autoimmune diseases, including type 1 diabetes, are thought to have a Th17-cell bias and/or a T-regulatory cell (Treg) defect. Understanding whether this is a hallmark of patients with type 1 diabetes is a crucial question that is still unsolved, largely due to the difficulties of accessing tissues targeted by the disease. RESEARCH DESIGN AND METHODS We phenotypically and functionally characterized Th17 cells and Tregs residing in the pancreatic-draining lymph nodes (PLNs) of 19 patients with type 1 diabetes and 63 nondiabetic donors and those circulating in the peripheral blood of 14 type 1 diabetic patients and 11 healthy subjects. RESULTS We found upregulation of Th17 immunity and functional defects in CD4+CD25bright Tregs in the PLNs of type 1 diabetic subjects but not in their peripheral blood. In addition, the proinsulin-specific Treg-mediated control was altered in the PLNs of diabetic patients. The dysfunctional Tregs isolated from diabetic subjects did not contain contaminant effector T cells and were all epigenetically imprinted to be suppressive, as defined by analysis of the Treg-specific demethylated region within the forkhead box P3 (FOXP3) locus. CONCLUSIONS These data provide evidence for an unbalanced immune status in the PLNs of type 1 diabetic subjects, and treatments restoring the immune homeostasis in the target organ of these patients represent a potential therapeutic strategy.

Fresh human islet transplantation to replace pancreatic endocrine function in type 1 diabetic patients. Report of six cases.

The aim of this study was to evaluate the feasibility of islet allografts in patients with type 1 diabetes melititus. Six patients received human islets from either one or two donors via the portal vein, after (n=4) or simultaneously with (n=2) a kidney graft. The patients with functioning kidney grafts (nos. 1–4) were already on triple immunosuppressive therapy (cyclosporine A, azathioprine, prednisone). Prednisone was increased to 60 mg/day for 15 days after the islet transplant in patient 1. Patient 2–4 and the patients who underwent a simultaneous kidney-islets graft (nos. 5, 6) also received antilymphocyte globulin. Intravenous insulin was given for the first 15 days to maintain blood glucose concentrations within the normal range. Patient 1 rejected the islets within 15 days of islet transplantation. In patient 2, a 25% reduction in insulin requirement was observed and 12 months after transplantation post-prandial serum C-peptide was 1.5 ng/ml. In patient 3, the insulin requirement decreased from 40 to 8 units/day with a post-prandial serum C-peptide of 4.1 ng/ml 12 months after islet transplantation. In patient 4 the post-prandial secretion of C-peptide increased to 6.4 ng/ml. Six months after the islet infusion, insulin therapy was discontinued and HbA1c, 24-h metabolic profile and oral glucose tolerance test remained within the normal range. He had remained off insulin for 5 months until recently, when foot gangrene paralleled a worsening of post-prandial glycaemic control. Twelve months after transplantation he is receiving 8 units insulin/day. Patients 5 and 6 received a simultaneous kidney and islet graft and 6 months after transplantation their post-prandial C-peptide secretion peaks were 2.5 and 1.9 ng/ml respectively. Their daily insulin requirement was not significantly modified. In conclusion, these results show that an adequate number of human islets injected intraportally in type 1 diabetic patients can replace the pancreatic endocrine function and can lead to insulin independence.

Metabolic effects of successful intraportal islet transplantation in insulin-dependent diabetes mellitus

The intraportal injection of human pancreatic islets has been indicated as a possible alternative to the pancreas transplant in insulin-dependent diabetic patients. Aim of the present work was to study the effect of intraportal injection of purified human islets on: (a) the basal hepatic glucose production; (b) the whole body glucose homeostasis and insulin action; and (c) the regulation of insulin secretion in insulin-dependent diabetes mellitus patients bearing a kidney transplant. 15 recipients of purified islets from cadaver donors (intraportal injection) were studied by means of the infusion of labeled glucose to quantify the hepatic glucose production. Islet transplanted patients were subdivided in two groups based on graft function and underwent: (a) a 120-min euglycemic insulin infusion (1 mU/kg/min) to assess insulin action; (b) a 120-min glucose infusion (+75 mg/di) to study the pattern of insulin secretion. Seven patients with chronic uveitis on the same immunosuppressive therapy as grafted patients, twelve healthy volunteers, and seven insulin-dependent diabetic patients with combined pancreas and kidney transplantation were also studied as control groups. Islet transplanted patients have: (a) a higher basal hepatic glucose production (HGP: 5.1 +/- 1.4 mg/kg/ min; P < 0.05 with respect to all other groups) if without graft function, and a normal HGP (2.4 +/- 0.2 mg/kg/min) with a functioning graft; (b) a defective tissue glucose disposal (3.9 +/- 0.5 mg/kg/min in patients without islet function and 5.3 +/- 0.4 mg/kg/min in patients with islet function) with respect to normals (P < 0.01 for both comparisons); (c) a blunted first phase insulin peak and a similar second phase secretion with respect to controls. In conclusion, in spite of the persistence of an abnormal pattern of insulin secretion, successful intraportal islet graft normalizes the basal HGP and improves total tissue glucose disposal in insulin-dependent diabetes mellitus.

Kidney Function after Islet Transplant Alone in Type 1 Diabetes: Impact of Immunosuppressive Therapy on Progression of Diabetic Nephropathy

OBJECTIVE—Islet transplantation alone is an alternative for the replacement of pancreatic endocrine function in patients with type 1 diabetes. The aim of our study was to assess the impact of the Edmonton immunosuppressive protocol (tacrolimus-sirolimus association) on kidney function. RESEARCH DESIGN AND METHODS—Nineteen patients with type 1 diabetes and metabolic instability received islet transplantation alone and immunosuppressive therapy according to the Edmonton protocol. Serum creatinine (sCr), creatinine clearance (CrCl), and 24-h urinary protein excretion (UPE) were assessed at baseline and during a follow-up of 339 patient-months. RESULTS— After islet transplantation we observed 1) sCr within the normal range in all but two patients in whom sCr increased immediately after islet transplantation, and despite withdrawal of immunosuppression, patients progressed to end-stage renal disease (ESRD); 2) CrCl remained within the normal range for those patients who had normal baseline values and decreased, progressing to ESRD in two patients with a decreased baseline CrCl; and 3) 24-h UPE worsened (>300 mg/24 h) in four patients. In the two patients who progressed to ESRD, the worsening of 24-h UPE occurred immediately after islet transplantation. In one patient 24-h UPE worsening occurred at 18 months, and, after withdrawal of immunosuppression, it returned to the normal range. In another patient 24-h UPE increased at 24 months and remained stable while immunosuppression was continued. CONCLUSIONS—In type 1 diabetic patients receiving islet transplantation alone, the association of tacrolimus and sirolimus should be used only in patients with normal kidney function. Alternative options for immunosuppressive treatment should be considered for patients with even a mild decrease of kidney function.

Proteomics Reveals Novel Oxidative and Glycolytic Mechanisms in Type 1 Diabetic Patients' Skin Which Are Normalized by Kidney-Pancreas Transplantation

Background In type 1 diabetes (T1D) vascular complications such as accelerated atherosclerosis and diffused macro-/microangiopathy are linked to chronic hyperglycemia with a mechanism that is not yet well understood. End-stage renal disease (ESRD) worsens most diabetic complications, particularly, the risk of morbidity and mortality from cardiovascular disease is increased several fold. Methods and Findings We evaluated protein regulation and expression in skin biopsies obtained from T1D patients with and without ESRD, to identify pathways of persistent cellular changes linked to diabetic vascular disease. We therefore examined pathways that may be normalized by restoration of normoglycemia with kidney-pancreas (KP) transplantation. Using proteomic and ultrastructural approaches, multiple alterations in the expression of proteins involved in oxidative stress (catalase, superoxide dismutase 1, Hsp27, Hsp60, ATP synthase δ chain, and flavin reductase), aerobic and anaerobic glycolysis (ACBP, pyruvate kinase muscle isozyme, and phosphoglycerate kinase 1), and intracellular signaling (stratifin-14-3-3, S100-calcyclin, cathepsin, and PPI rotamase) as well as endothelial vascular abnormalities were identified in T1D and T1D+ESRD patients. These abnormalities were reversed after KP transplant. Increased plasma levels of malondialdehyde were observed in T1D and T1D+ESRD patients, confirming increased oxidative stress which was normalized after KP transplant. Conclusions Our data suggests persistent cellular changes of anti-oxidative machinery and of aerobic/anaerobic glycolysis are present in T1D and T1D+ESRD patients, and these abnormalities may play a key role in the pathogenesis of hyperglycemia-related vascular complications. Restoration of normoglycemia and removal of uremia with KP transplant can correct these abnormalities. Some of these identified pathways may become potential therapeutic targets for a new generation of drugs.

Risks and benefits of transplantation in the cure of type 1 diabetes: whole pancreas versus islet transplantation. A single center study.

BACKGROUND Pancreas and islet transplantation are the only available options to replace beta-cell function in patients with type 1 diabetes. Great variability in terms of rate of success for both approaches is reported in the literature and it is difficult to compare the respective risks and benefits. OBJECTIVES The aim of this study was to analyze risks and benefits of pancreas transplantation alone (PTA) and islet transplantation alone (ITA) by making use of the long-term experience of a single center where both transplantations are performed. We focused on the risks and benefits of both procedures, with the objective of better defining indications and providing evidence to support the decision-making process. The outcomes of 33 PTA and 33 ITA were analyzed, and pancreas and islet function (i.e., insulin independence), perioperative events, and long-term adverse events were recorded. RESULTS We observed a higher rate of insulin independence in PTA (75%) versus ITA (59%), with the longer insulin independence among PTA patients receiving tacrolimus. The occurrence of adverse events was higher for PTA patients in terms of hospitalization length and frequency, re-intervention for surgical and immunological acute complications, CMV reactivation, and other infections. CONCLUSIONS In conclusion, these results support the practice of listing patients for PTA when the metabolic control and the progression of chronic complications require a rapid normalization of glucose levels, with the exception of patients with cardiovascular disease, because of the high surgical risks. ITA is indicated when replacement of beta-cell mass is needed in patients with a high surgical risk.

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.