A novel method for quantitative monitoring of transplanted islets of langerhans by positive contrast magnetic resonance imaging.

The Automatic Quantitative Ultrashort Echo Time imaging (AQUTE) protocol for serial MRI allows quantitative in vivo monitoring of iron labeled pancreatic islets of Langerhans transplanted into the liver, quantifying graft implantation and persistence in a rodent model. Rats (n = 14), transplanted with iron oxide loaded cells (0-4000 islet equivalents, IEQ), were imaged using a 3D radial ultrashort echo time difference technique (dUTE) on a Siemens MAGNETOM 3T clinical scanner up to 5 months postsurgery. In vivo 3D dUTE images gave positive contrast from labeled cells, suppressing liver signal and small vessels, allowing automatic quantification. Position of labeled islet clusters was consistent over time and quantification of hyperintense pixels correlated with the number of injected IEQs (R² = 0.898, p < 0.0001), and showed persistence over time (5 months posttransplantation). Automatic quantification was superior to standard imaging and manual counting methods, due to the uniform suppressed background and high contrast, resulting in significant timesavings, reproducibility and ease of quantification. Three-dimensional coverage of the whole liver in the absence of cardiac/respiratory artifact provided further improvement over conventional imaging. This imaging protocol reliably quantifies transplanted islet mass and has high translational potential to clinical studies of transplanted pancreatic islets.

Assessment of 18F-FDG-leukocyte imaging to monitor rejection after pancreatic islet transplantation.

AIM: We sought to investigate the feasibility of 18F-FDG-leukocyte imaging to detect islet rejection. METHODS: Two thousand Sprague-Dawley (SD, syngeneic group) or Lewis (allogeneic group) islet equivalents were intraportally injected into SD rat recipients. Four and 7 days after transplantation, 10(8) 18F-FDG-labeled splenocytes were injected into the jugular vein. Splenocytes were harvested from naïve or sensitized (12 days after intraportal transplantation of 2000 Lewis IEQ) SD rats. Positron emission tomography (PET) imaging was started 5 minutes after splenocyte infusion and performed hourly for 4 hours. RESULTS: One hour after splenocyte injection, FDG was mainly detected in the heart and lungs. It was then further distributed to other organs, and from the second hour, the highest tracer concentration was located in the abdomen. Liver FDG uptake was similar between syngeneic, allogeneic, and sensitized allogeneic groups at 4 and 7 days after islet transplantation. DISCUSSION: No islet rejection was detected by 18F-FDG-leukocyte imaging. The amount of transplanted tissue was only few millilitres and the additional related inflammation in case of rejection is small and difficult to detect. The liver showed a relatively high spontaneous tracer uptake; the related background prevented detection of a potential increase in tracer uptake in cases of islet rejection.

A comparison of cold storage solutions for pancreas preservation prior to islet isolation.

BACKGROUND: Several solutions are used to preserve the pancreas prior to islet isolation. This study sought to assess whether the type of solution had an impact on the isolation outcome. METHODS: We reviewed data from 125 islet isolation procedures performed from January 2002 to January 2005. Pancreata were preserved in University of Wisconsin (UW) (n = 101), Celsior (CS) (n = 19), or IGL-1 (n = 5) solutions. Islet isolation results and transplantation rates were compared between groups. RESULTS: UW, CS, and IGL-1 groups were similar according to donor's age, weight, and body mass index. Weight of undigested pancreas was 20 +/- 13.1, 21.4 +/- 15.7, and 17.4 +/- 8.7 g for UW, CS, and IGL-1, respectively (P > .2). Final total number of IEQ was 267,000 +/- 132,000, 277,000 +/- 155,000, and 311,000 +/- 163,000, respectively (P > .4). Success rate (defined as >250,000 IEQ) was 55.5%, 52.9%, and 60% for UW, Celsior, and IGL-1 (P > .9); the transplantation rate was 42.2% for UW, 36.8% for Celsior, and 80% for IGL-1 preservation (P > .2). CONCLUSIONS: In this preliminary study, UW, Celsior, and IGL-1 solutions demonstrated similar islet isolation results. The new IGL-1 solution appears promising.

[Evaluation of the management of COPD exacerbations: an audit in French emergency services]. / Prise en charge des exacerbations de BPCO : audit de pratique aux urgences.

INTRODUCTION: Acute exacerbations of chronic obstructive pulmonary disease (COPD) patients are major events in the history of this chronic respiratory disease. Their management in French emergency services is unknown, although national guidelines exist. METHODS: This is a descriptive audit study, over a 10 weeks period (12/01-22/03/2009), of the management of COPD exacerbations in the RESUVal (Réseau des Urgences de la Vallée du Rhône, France) network emergency departments. RESULTS: The enrollement of 16 emergency units allowed the analysis of 221 exacerbations of COPD. Measurement of respiratory rate and description of the sputum were mentioned in only 99 (45%) medical records. The rest of the initial assessment was generally satisfactory. Regarding the therapeutic management, 215 (97%) patients received oxygen, beta-2-agonist aerosols were administrated for 209 (95%) patients and anticholinergic aerosols were used for 176 (80%) patients. A systemic corticosteroid and antibiotics were respectively prescribed for 116 (52%) and 123 (56%) patients. Non-invasive ventilation (NIV) was used in only 59% of patients presenting a pH<7.35. CONCLUSIONS: These findings demonstrate that management of exacerbations of COPD could be improved through systematic patients' respiratory rate and sputum characteristics recording or NIV utilization reinforcement.

Combined pancreatic islets-lung transplantation in cystic fibrosis-related diabetes: case reports.

UNLABELLED: We report two cases of percutaneous portal embolization of pancreatic islets performed after double lung transplantation in cystic fibrosis (CF) patients using the pancreas of the same donor. CASE 1: A 19-year-old man with CF had insulin-dependent diabetes, which was poorly controlled despite an external insulin pump (96 IU/d): HbA(1c) = 9.8% and 1 to 3 hypoglycemic events per day. On October 29, 2007, he received a double lung graft because of chronic respiratory failure. For days after lung transplantation, 149,000 cultured IEQ (Islet EQuivalent) were injected by percutaneous intraportal infusion under local anesthesia. Immunosuppression consisted of steroids, cyclosporine, and azathioprine. Two years later, the forced expiratory volume (FEV) was 83%; C peptide level reached 1.4 µg/L, and the diabetes was satisfactorily controlled with an HbA(1c) of 7.5% and a decrease in insulin requirements to 30 U/d in the absence of hypoglycemic events. CASE 2: On July 10, 2006, a 32-year-old man with CF-related diabetes received a double lung graft because of chronic respiratory failure. Under multiple insulin injections, the HbA(1c) was 9.6% with numerous hypoglycemic events. On March 11, 2008, he again received a double lung graft because of persistent humoral rejection. Despite severe bleeding during the postoperative course, 234,000 IEQ were injected via the portal vein one week after lung transplantation. Immunosuppression consisted of steroids, tacrolimus, and mycophenolate mofetil. Eighteen months after the combined graft, the FEV was 52%; the plasma C-peptide reached 0.79 µg/L, the HbA(1c), 6% and the insulin requirements decreased to 55 U/d in the absence of hypoglycemic events. CONCLUSION: Combined lung-islet transplantation for patients with CF-related diabetes improved pulmonary and metabolic function.

Glucose inhibits angiogenesis of isolated human pancreatic islets.

Owing to strong interactions between pancreatic islets and the surrounding capillary network, we hypothesized that high glucose concentrations might affect key angiogenesis factors from isolated human islets, thus contributing to beta-cell failure in diabetes. Human islets from eight distinct donors were studied following 96 h in culture in the presence of normal (5.5 mmol/l) or high (16.7 mmol/l) glucose concentrations. Similar studies were performed with HUVECs. Human angiogenesis-related genes and corresponding proteins were studied by real-time quantitative PCR (RT-qPCR) and protein arrays respectively. Angiogenesis and proliferation assays were also performed with HUVECs under the same culture conditions. RT-qPCR and proteome analysis of human islets incubated with 16.7 mM/l glucose revealed a significant decrease in pro-angiogenic factors including vascular endothelial growth factor (VEGF) mRNA by 20% and VEGF protein levels by 42% as well as additional proteins such as fibroblast growth factor-4 by 41%, MMP9 by 18%, monocyte chemoattractant protein-1 by 21%, and prolactin by 25%. In contrast, we observed a 17% increase in thrombospondin-1 (TSP-1, listed as THBS1 in the HUGO database) and a 37% increase in angiotensinogen gene expression levels, but neither angiotensin-converting enzyme nor angiotensin II type 1 receptor gene expression was affected. The amounts of anti-angiogenic proteins such as TSP-1 and serpin B5/maspin were also increased by 70 and 98% respectively as well as endostatin by 63%. Angiogenesis assays of HUVECS in the presence of high glucose concentrations revealed a 30% decrease in tree-like tubular network formation. These data suggest that glucose reduces key factors of islet angiogenesis, which might exacerbate beta-cell failure.

Insulin secretion from human beta cells is heterogeneous and dependent on cell-to-cell contacts.

AIMS/HYPOTHESIS: We assessed the heterogeneity of insulin secretion from human isolated beta cells and its regulation by cell-to-cell contacts. METHODS: Insulin secretion from single and paired cells was assessed by a reverse haemolytic plaque assay. The percentage of plaque-forming cells, the mean plaque area and the total plaque development were evaluated after 1 h of stimulation with different secretagogues. RESULTS: Not all beta cells were surrounded by a haemolytic plaque under all conditions tested. A small fraction of the beta cell population (20%) secreted more than 90% and 70% of total insulin at 2.2 and 22.2 mmol/l glucose, respectively. Plaque-forming cells, mean plaque area and total plaque development were increased at 12.2 and 22.2 compared with 2.2 mmol/l glucose. Insulin secretion of single beta cells was similar at 12.2 and 22.2 mmol/l glucose. Insulin secretion of beta cell pairs was increased compared with that of single beta cells and was higher at 22.2 than at 12.2 mmol/l glucose. Insulin secretion of beta cells in contact with alpha cells was also increased compared with single beta cells, but was similar at 22.2 compared with 12.2 mmol/l glucose. Delta and other non-beta cells did not increase insulin secretion of contacting beta cells compared with that of single beta cells. Differences in insulin secretion between 22.2 and 12.2 mmol/l glucose were observed in murine but not in human islets. CONCLUSIONS/INTERPRETATION: Human beta cells are highly heterogeneous in terms of insulin secretion so that a small fraction of beta cells contributes to the majority of insulin secreted. Homologous and heterologous intercellular contacts have a significant impact on insulin secretion and this could be related to the particular architecture of human islets.

Sequential kidney/islet transplantation: efficacy and safety assessment of a steroid-free immunosuppression protocol.

The aim of this study was to assess the efficiency and safety of the Edmonton immunosuppression protocol in recipients of islet-after-kidney (IAK) grafts. Fifteen islet infusions were administered to 8 patients with type 1 diabetes and a functioning kidney graft. Immunosuppression was switched on the day of transplantation to a regimen associating sirolimus-tacrolimus-daclizumab. Insulin-independence was achieved in all patients for at least 3 months, with an actual rate of 71% at 1 year after transplantation (5 of 7 patients). After 24-month mean follow-up, five have ongoing insulin independence, 11-34 months after transplantation, with normal HbA1c, fructosamine and mean amplitude of glycemic excursions (MAGE) values. Results of arginine-stimulation tests improved over time, mostly after the second islet infusion. Severe adverse events included bleeding after percutaneous portal access (n=2), severe pneumonia attributed to sirolimus toxicity (n=1), kidney graft loss after immunosuppression discontinuation (n=1), reversible humoral kidney rejection (n=1) and fever of unknown origin (n=1). These data indicate that the Edmonton approach can be successfully applied to the IAK setting. This procedure is associated with significant side effects and only patients with stable function of the kidney graft should be considered. The net harm versus benefit has not yet been established and will require further studies with larger numbers of enrolled subjects.

Detection of insulin mRNA in the peripheral blood after human islet transplantion predicts deterioration of metabolic control.

Recent updates of the Edmonton trial have shown that insulin independence is progressively lost in approximately 90% of islet transplant recipients over the first 5 years. Early prediction of islet graft injury could prompt the implementation of strategies attempting to salvage the transplanted islets. We hypothesize that islet damage is associated with the release and detection of insulin mRNA in the circulating blood. Whole blood samples were prospectively taken from 19 patients with type 1 diabetes receiving 31 islet transplants, immediately prior to transplantation and at regular time-points thereafter. After RNA extraction, levels of insulin mRNA were determined by quantitative reverse tran-scriptase-polymerase chain reaction. All patients exhibited a primary peak of insulin mRNA immediately after transplantation, without correlation of duration and amplitude with graft size or outcome. Twenty-five subsequent peaks were observed during the follow-up of 17 transplantations. Fourteen secondary peaks (56%) were closely followed by events related to islet graft function. Duration and amplitude of peaks were higher when they heralded occurrence of an adverse event. Peaks of insulin mRNA can be detected and are often associated with alterations of islet graft function. These data suggest that insulin mRNA detection in the peripheral blood is a promising method for the prediction of islet graft damage.