Aims/hypothesis
Pancreatic islet transplantation (PIT) offers a physiological treatment for type 1 diabetes, but the failure of islet engraftment hinders its application. The female hormone ...17β-oestradiol (E2) favours islet survival and stimulates angiogenesis, raising the possibility that E2 may enhance islet engraftment following PIT.
Methods
To explore this hypothesis, we used an insulin-deficient model with xenotransplantation of a marginal dose of human islets in nude mice rendered diabetic with streptozotocin. This was followed by 4 weeks of treatment with vehicle, E2, the non-feminising oestrogen 17α-oestradiol (17α-E2), the oestrogen receptor (ER) α agonist propyl-pyrazole-triol (PPT), the ERβ agonist diarylpropionitrile (DPN) or the G protein-coupled oestrogen receptor (GPER) agonist G1.
Results
Treatment with E2, 17α-E2, PPT, DPN or G1 acutely improved blood glucose and eventually promoted islet engraftment, thus reversing diabetes. The effects of E2 were retained in the presence of immunosuppression and persisted after discontinuation of E2 treatment. E2 produced an acute decrease in graft hypoxic damage and suppressed beta cell apoptosis. E2 also acutely suppressed hyperglucagonaemia without altering insulin secretion, leading to normalisation of blood glucose.
Conclusions/interpretation
During PIT, E2 synergistic actions contribute to enhancing human islet-graft survival, revascularisation and functional mass. This study identifies E2 as a short-term treatment to improve PIT.
Islet transplantation is a promising therapy for T1DM. Key factors influencing islet yield have been identified with conflicting results. In this study, we analyzed 276 isolations to identify ...variables for islet yield and, additionally, islet size and size distribution. Pearson correlation analyses demonstrated that BMI had a positive correlation with pancreas size, actual islet count (AIC), and islet equivalent (IEQ)/g (all p ≤0.009), while CIT had a negative correlation with AIC and IEQ/g (all p ≤0.003). In mixed linear regression, BMI also had a positive correlation with islet size but only for shorter digestion times (≤15 min); there was no association between BMI and islet size for longer digestion times (>15 min). CIT was not associated with islet size. Donor age, sex, and preservation solutions were shown to have no correlation with islet yields or size distribution. Pancreas size had a positive correlation with AIC and a negative association with IEQ/g; it also had positive association with islet size but only for females, not males. Overdigestion was positively associated with islet counts; however, there was also a greater proportion of smaller islets when digestion rate was >74% (p = 0.005). Of the three collagenases analyzed, Sigma V had the lowest digestion rate (mean = 65%), approximately 5% or 10% lower than Roche Liberase HI (p = 0.04) and Serva NB1 (p = 0.0003), respectively; however, the Sigma V group showed better islet size preservation. Yet, the enzymes resulted in similar IEQ/g digested tissue. Of the isolated islets, 70.2% were smaller than 150 μm and contributed only 20.4% to the total IEQ, while 7.4% of the islets were larger than 250 μm but contributed 42.4% to the total IEQ. In summary, BMI, pancreas size, and CIT are useful variables for predicting islet yield, but selection of enzyme and balancing digestion time and rate are also important.
Islet transplantation is a promising treatment for diabetes but longterm success is limited by progressive graft loss. Aggregates of the beta cell peptide islet amyloid polypeptide (IAPP) promote ...beta cell apoptosis and rapid amyloid formation occurs in transplanted islets. Porcine islets are an attractive alternative islet source as they demonstrate long-term graft survival. We compared the capacity of transplanted human and porcine islets to form amyloid as an explanation for differences in graft survival. Human islets were transplanted into streptozotocin-diabetic immune-deficient mice. Amyloid deposition was detectable at 4 weeks posttransplantation and was associated with islet graft failure. More extensive amyloid deposition was observed after 8 weeks. By contrast, no amyloid was detected in transplanted neonatal or adult porcine islets that had maintained normoglycemia for up to 195 days. To determine whether differences in IAPP sequence between humans and pigs could explain differences in amyloid formation and transplant viability, we sequenced porcine IAPP. Porcine IAPP differs from the human sequence at 10 positions and includes substitutions predicted to reduce its amyloidogenicity. Synthetic porcine IAPP was considerably less amyloidogenic than human IAPP as determined by transmission electron microscopy, circular dichroism, and thioflavin T binding. Viability assays indicated that porcine IAPP is significantly less toxic to INS-1 beta cells than human IAPP. Our findings demonstrate that species differences in IAPP sequence can explain the lack of amyloid formation and improved survival of transplanted porcine islets. These data highlight the potential of porcine islet transplantation as a therapeutic approach for human diabetes.
Kidney transplantation in morbidly obese patients can be technically demanding. Furthermore, morbidly obese patients experience a high rate of wound infections and related complications, which mostly ...result from the longer length and extent of the incision. These complications can be avoided through minimally invasive surgery; however, conventional laparoscopic instruments are unsuitable for the safe performance of a kidney transplant in morbidly obese patients. Herein, we report the first minimally invasive, total robotic kidney transplant in a morbidly obese patient. A left, deceased donor kidney was transplanted into a 29‐year‐old woman with a body mass index (BMI) of 41 kg/m2 who had been on hemodialysis for 5 years. The operation was performed intraabdominally using the DaVinci Robotic Surgical System with 4 trocars and a 7 cm midline incision. The operative time was 223 min, and the blood loss was less than 50 cc. The kidney had immediate graft function. No perioperative complications were observed, and the patient was discharged on postoperative day 5 with normal kidney function. Minimally invasive access and robotic technology facilitated the safe performance of a successful kidney transplant in a morbidly obese patient.
Robotic assisted, minimally invasive kidney transplantation may avoid wound‐related complications in morbidly obese kidney transplant recipients.
This prospective phase 1/2 trial investigated the safety and reproducibility of allogeneic islet transplantation (Tx) in type I diabetic (T1DM) patients and tested a strategy to achieve ...insulin‐independence with lower islet mass. Ten C‐peptide negative T1DM subjects with hypoglycemic unawareness received 1–3 intraportal allogeneic islet Tx and were followed for 15 months. Four subjects (Group 1) received the Edmonton immunosuppression regimen (daclizumab, sirolimus, tacrolimus). Six subjects (Group 2) received the University of Illinois protocol (etanercept, exenatide and the Edmonton regimen). All subjects became insulin‐ independent. Group 1 received a mean total number of islets (EIN) of 1460 080 ± 418 330 in 2 (n = 2) or 3 (n = 2) Tx, whereas Group 2 became insulin‐ independent after 1 Tx (537 495 ± 190 968 EIN, p = 0.028). All Group 1 subjects remained insulin free through the follow‐up. Two Group 2 subjects resumed insulin: one after immunosuppression reduction during an infectious complication, the other with exenatide intolerance. HbA1c reached normal range in both groups (6.5 ± 0.6 at baseline to 5.6 ± 0.5 after 2–3 Tx in Group 1 vs. 7.8 ± 1.1 to 5.8 ± 0.3 after 1 Tx in Group 2). HYPO scores markedly decreased in both groups. Combined treatment of etanercept and exenatide improves islet graft function and facilitates achievement of insulin‐independence with less islets.
Combined TNF‐alpha blockade and exenatide facilitates achieving insulin‐independence after allogeneic islet transplantation in brittle type I diabetic patients, but fails to show a measurable islet trophic effect and increase of functional islet mass over time.
The authors report results on a new robotic kidney transplantation technique for obese patients that has comparable patient outcomes compared to an open procedure.
Introduction Une des limites majeures à la transplantation d’îlots est liée à la perte rapide et précoce des îlots immédiatement après transplantation. De nombreuses études suggèrent que cette perte ...serait liée au contact direct des îlots pancréatiques avec le sang à l’origine d’une réaction inflammatoire. Le but était ici de développer un modèle d’étude de ces réactions et de déterminer les mécanismes cellulaires à l’origine de cette destruction précoce des îlots. Matériels et méthodes Différents modèles ont été développer afin de d’identifier cette réaction inflammatoire in vitro : un modèle syngénique constitué d’îlots pancréatiques et de macrophages de rat lewis, un modèle allogénique constitué d’îlots pancréatiques et de macrophages de rat Wistar, un modèle xénogénique constitué d’îlots pancréatiques de rat lewis et de macrophages de souris balb/c. Les réactions inflammatoires sont étudiées à l’aide de la chambre de Boyden. Les préparations d’îlots pancréatiques présentent une pureté variant de 90 % à 50 %. Enfin, la voie des chémokines est inhibée par l’utilisation d’un antagoniste spécifique du CCL-5, le PSC-RANTES à la concentration de 10 pg/ml. Résultats Nous avons pu observé que quelque soit le modèle utilisé, la migration macrophagique est comparable (1,41 ± 0,12 pour le modèles syngénique, 1,52 ± 0,18 pour le modèle allogénique, 1,35 ± 0,03 pour le modèle xénogénique pour une préparation d’îlots de 90 %, n = 6). De plus, et la migration macrophagique est significativement augmentée pour des pureté inférieure : pour une pureté de 50 %, l’indice de migration est de 1,92 ± 0,19 pour le modèle syngénique (n = 6 ; p < 0,001). L’addition de PSC-RANTES entraîne une inhibition complète de la migration macrophagique dans toutes les conditions testées : 0,67 ± 0,18 pour le modèle syngénique (n = 6 ; p < 0,01). Discussion Ces résultats suggèrent que la chambre de Boyden permet de modéliser in vitro les réactions inflammatoires précoces. La voie des chémokines semble jouer un rôle primordial dans ces réactions. Conclusion Cibler la voie des chémokines semble donc être une approche prometteuse pour limiter cette perte précoce d’îlots après transplantation.
To increase living donation for kidney transplantation, we investigated desensitization of recipients with positive crossmatch against a potential living donor.
Between June 2001 and March 2007, 57 ...consecutive sensitized candidates for kidney transplantation, with crossmatch positive potential living donors, were treated with various desensitization protocols. All patients received plasmapheresis every other day with intravenous immune globulin 100 mg/kg starting 1 week before the scheduled transplant. Postoperatively, the recipients continued to receive every other day plasmapheresis with intravenous immune globulin for the initial week. Immunosuppression therapy consisted of induction with thymoglobulin and a combination of tacrolimus, mycophenolate, and corticosteroids.
Six patients failed to convert with pretransplant immunomodulation and were not transplanted; 51 underwent live donor kidney transplant. Mean follow-up was 23 months and 36 patients have more than 1-year follow-up. One-year patient and graft survivals were 95% and 93%, respectively. There were 25 episodes of biopsy-proven or clinically presumed rejection in 22 patients in the first year. Of the 17 biopsy-proven episodes, 12 were antibody-mediated rejection and five were acute cellular rejection. Of the patients with antibody-mediated rejection (biopsy proven or empiric), two patients (12%) lost their graft by 1 year. The median modification of diet in renal disease at 6 and 12 months was 55 mL/min (range 9-104 mL/min) and 48 mL/min (range 8-99), respectively.
Despite increased rejection rates, graft and patient survivals indicate that desensitization of positive crossmatch patients is a reasonable alternative for a sensitized patient who could potentially wait 10 or more years for a suitable cadaveric kidney.
Aims/hypothesis In obesity, beta cells activate compensatory mechanisms to adapt to the higher insulin demand. Interleukin-1 receptor antagonist (IL-1Ra) prevents obesity-induced hyperglycaemia and ...is a potent target for the treatment of diabetes, but the mechanisms of its secretion and regulation in obesity are unknown. In the present study, we hypothesise the regulation of IL-1Ra secretion by purinergic P2X₇ receptors in islets. Methods Production and regulation of P2X₇ were studied in pancreatic sections from lean and obese diabetic patients, non-diabetic controls and in isolated islets. IL-1Ra, IL-1β and insulin secretion, glucose tolerance and beta cell mass were studied in P2x7 (also known as P2Rx7)-knockout mice. Results P2X₇ levels were elevated in beta cells of obese patients, but downregulated in patients with type 2 diabetes mellitus. Elevated glucose and non-esterified fatty acids rapidly activated P2X₇ and IL-1Ra secretion in human islets, and this was inhibited by P2X₇ blockade. In line with our results in vitro, P2x7-knockout mice had a lower capacity to secrete IL-1Ra. They exhibited severe and rapid hyperglycaemia, glucose intolerance and impaired beta cell function in response to a high-fat/high-sucrose diet, were unable to compensate by increasing their beta cell mass in response to the diet and showed increased beta cell apoptosis. Conclusions/interpretation Our study shows a tight correlation of P2X₇ activation, IL-1Ra secretion and regulation of beta cell mass and function. The increase in P2X₇ production is one mechanism that may explain how beta cells compensate by adapting to the higher insulin demand. Disturbances within that system may result in the progression of diabetes.
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