Search results for "Islets of Langerhans Transplantation"

Long-term graft function of adult rat and human islets encapsulated in novel alginate-based microcapsules after transplantation in immunocompetent di…

2005

We describe the results of the first study to show that adult rat and human islets can be protected against xenogenic rejection in immunocompetent diabetic mice by encapsulating them in a novel alginate-based microcapsule system with no additional permselective membrane. Nonencapsulated islets lost function within 4–8 days after being transplanted into diabetic Balb/c mice, whereas transplanted encapsulated adult rat or human islets resulted in normoglycemia for >7 months. When rat islet grafts were removed 10 and 36 weeks after transplantation, the mice became immediately hyperglycemic, thus demonstrating the efficacy of the encapsulated islets. The explanted capsules showed only a …

Beyond islet trasplantation in diabetes cell terapy:from embryonic stem cells to transdifferentation of adult cells

2013

Exogenous insulin is, at the moment, the therapy of choice of diabetes, but does not allow tight regulation of glucose leading to long-term complications. Recently, pancreatic islet transplantation to reconstitute insulin-producing cells, has emerged as an alternative promising therapeutic approach. Unfortunately, the number of donor islets is too low compared with the high number of patients needing a transplantation leading to a search for renewable sources of high-quality -cells. This review, summarizes more recent promising approaches to the generation of new -cells from embryonic stem cells for transdifferentiation of adult cells, particularly a critical examination of the seminal work…

INFLUENCE OF ISLET TRANSPORTATION ON PANCREATIC ISLET ALLOTRANSPLANTATION IN TYPE 1 DIABETIC PATIENTS WITHIN THE SWISS-FRENCH GRAGIL NETWORK

2004

The influence of islet transportation on pancreatic islet allotransplantation in type 1 diabetic patients was evaluated within the GRAGIL network.From December 2001 to April 2003, 16 human pancreatic islet transplants were performed in 9 type 1 diabetic patients with an established kidney graft (functioning for at least 6 months) in four centers of the GRAGIL network. Islet isolation was performed in a core laboratory in Geneva, and the islet preparations were shipped by ambulance to each center for transplantation. One month after transplantation, the efficiency of the graft was assessed according to islet transportation time (ITT): ITT less than 2 hours (group 1, n=5), and ITT greater tha…

Oxygen profile of microencapsulated islets: effect of immobilised hemoglobin in the alginate matrix

2001

Intraportal transplantation of allogenic pancreatic islets encapsulated in barium alginate beads in diabetic rats.

2003

The survival of microencapsulated islets transplanted into the unmodified peritoneal cavity is limited, even if capsular overgrowth is restricted to a minimum, due to an insufficient oxygen supply to the islets. Therefore, research efforts should focus on finding or creating a transplantation site, which permits a closer contact between the encapsulated islets and the blood. For this reason, the liver could be an interesting candidate. The aim of the present study was to test the hypothesis that the intraportal transplantation of allogenic islets encapsulated in small-sized barium alginate beads is safe and succeeds to induce normoglycemia in diabetic rats. The intraportal transplantation o…

Nonparenchymal cells in chronically hyperinsulinemic liver acini of diabetic rats, with special regard to hepatic stellate cells

1998

Abstract Background/Aims: An increase in proliferative activity and other distinct hepatocellular alterations — resembling preneoplastic foci and progressing to hepatocellular tumors — have been shown to develop in liver acini draining the blood from islets of Langerhans, transplanted through the portal vein into the liver of streptozotocin-diabetic rats. Methods: Altered and unaltered liver acini were investigated for possible changes in hepatic stellate cells 4–76 days after islet transplantation. Results: Corresponding to a significant increase in the hepatocellular volume, the volume density of total non-parenchymal cells was significantly reduced in altered compared to unaltered liver …

EFFECT OF MICROENCAPSULATION ON OXYGEN DISTRIBUTION IN ISLETS ORGANS

1994

In islet transplantation, limitation of oxygen supply may restrict graft function, particularly when encapsulated tissue is used. Therefore, oxygen tensions (PO2) in isolated islet organs (Brockmann bodies) of Osphronemus gorami were measured. In a thermostatically (37 degrees C) controlled measuring chamber, PO2 values were recorded at subsequent microelectrode positions on a radial track toward the center of the organ. In 2 independent groups, we studied the effect of fluid convection (n = 12) and microencapsulation (n = 12). In both groups, sigmoidal PO2 profiles were found, which permit differentiation in an oxygen-depleted zone surrounding the surface, a steep decline inside the tissue…

Multilayer capsules: a promising microencapsulation system for transplantation of pancreatic islets

2001

In 1980, Lim and Sun introduced a microcapsule coated with an alginate/polylysine complex for encapsulation of pancreatic islets. Characteristic to this type of capsule is, that it consists of a plain membrane which is formed during a single procedural step. With such a simple process it is difficult to obtain instantly a membrane optimized with respect to all the properties requested for islet transplantation. To overcome these difficulties, it is recommended to build up the membrane in several consecutive steps, each optimized for a certain property. In this study, we have analysed such a multilayer microcapsule for the encapsulation of pancreatic islets. Therefore, empty and islet contai…

Magnetic separation of encapsulated islet cells labeled with superparamagnetic iron oxide nano particles.

2012

Islet cell transplantation is a promising option for the restoration of normal glucose homeostasis in patients with type 1 diabetes. Because graft volume is a crucial issue in islet transplantations for patients with diabetes, we evaluated a new method for increasing functional tissue yield in xenogeneic grafts of encapsulated islets. Islets were labeled with three different superparamagnetic iron oxide nano particles (SPIONs; dextran-coated SPION, siloxane-coated SPION, and heparin-coated SPION). Magnetic separation was performed to separate encapsulated islets from the empty capsules, and cell viability and function were tested. Islets labeled with 1000 μg Fe/ml dextran-coated SPIONs expe…

Prolactin supplementation to culture medium improves beta-cell survival

2010

OBJECTIVES.: Recent studies demonstrated that prolactin (PRL) has beneficial effects on β cells for islet transplantation. We examined the effect of human recombinant PRL (rhPRL) supplementation to the culture media to determine its potential use in the context of clinical islet transplantation. MATERIALS AND METHODS.: Each human islet isolated from 14 deceased multiorgan donors was cultured in Miami modified media-1 supplemented with or without rhPRL (500 μg/L) for 48 hr. β-Cell survival and proliferation (BrdU and Ki-67) were determined by laser scanning cytometry. The cytoprotective effects of rhPRL against noxious stimuli were assessed by flow cytometry (tetramethylrhodamine ethyl ester…