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      Induction of Angiogenesis in Omentum with Vascular Endothelial Growth Factor: Influence on the Viability of Encapsulated Rat Pancreatic Islets during Transplantation

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          Abstract

          Transplantation of pancreatic islets is proposed as a treatment for type 1 diabetes, but insufficient blood supply can cause the loss of viable grafted islets. In the present study, we investigated the influence of vascular endothelial growth factor (VEGF) on the angiogenesis of omentum during encapsulated islet allotransplantation and consequently on islet survival. Fifty rat islets, cultured for 24 h, were encapsulated in the presence or absence of human VEGF and implanted in the peritoneal cavity of rats (n = 6). After 7, 14 and 28 days of implantation, encapsulation devices with surrounding omentum were removed. Histological analysis of this tissue was performed. Cellular adhesion at the membrane surface was characterized by a phagocytosis test. The morphological aspect of the islets was analyzed and their functionality was evaluated by measuring insulin secretion. At each step of the study, there was a two-fold increase in the number of vessels in the presence of VEGF. In addition, VEGF increased the vessel diameter and the surface area of the angiogenic pedicle. Moreover, the presence of VEGF significantly decreased the distance between the devices and vessels (16.2 ± 5.6 vs. 51.6 ± 10.1 µm, p < 0.001). Membrane surface analysis showed a decrease in macrophage adhesion in the presence of VEGF. Furthermore, islet structure and functionality was preserved in the presence of VEGF. Stimulation of angiogenesis of omentum induced by VEGF is associated with preservation of islet viability. Local delivery of VEGF proved to be a relevant approach to ameliorate the outcome of islet transplantation.

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          Most cited references 5

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          Vascular permeability factor: a tumor-derived polypeptide that induces endothelial cell and monocyte procoagulant activity, and promotes monocyte migration

           J Brett,  F Wang,  M Clauss (1990)
          Systemic infusion of low concentrations of tumor necrosis factor/cachectin (TNF) into mice that bear TNF-sensitive tumors leads to activation of coagulation, fibrin formation, and occlusive thrombosis exclusively within the tumor vascular bed. To identify mechanisms underlying the localization of this vascular procoagulant response, a tumor-derived polypeptide has been purified to homogeneity from supernatants of murine methylcholanthrene A-induced fibrosarcomas that induces endothelial tissue factor synthesis and expression (half- maximal response at approximately 300 pM), and augments the procoagulant response to TNF in a synergistic fashion. This tumor- derived polypeptide was identified as the murine homologue of vascular permeability factor (VPF) based on similar mobility on SDS-PAGE, an homologous NH2-terminal amino acid sequence, and recognition by a monospecific antibody to guinea pig VPF. In addition, VPF was shown to induce monocyte activation, as evidenced by expression of tissue factor. Finally, VPF was shown to induce monocyte chemotaxis across collagen membranes and endothelial cell monolayers. Taken together, these results indicate that VPF can modulate the coagulant properties of endothelium and monocytes, and can promote monocyte migration into the tumor bed. This suggests one mechanism through which tumor-derived mediators can alter properties of the vessel wall.
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            VEGF prevents apoptosis of human microvascular endothelial cells via opposing effects on MAPK/ERK and SAPK/JNK signaling.

            Vascular endothelial growth factor (VEGF), an endothelial cell-specific mitogen, promotes endothelial cell survival and angiogenesis. We recently showed that VEGF can support the growth of human dermal microvascular endothelial cells (HDMEC) and human umbilical vein endothelial cells in serum-free medium. Reasoning that VEGF might be modulating apoptotic signal transduction pathways, we examined mechanisms involved in the anti-apoptotic effect of VEGF on starvation- and ceramide-induced apoptosis in HDMEC. We observed that VEGF ameliorated the time-dependent increase in apoptosis, as demonstrated by morphologic observations, TUNEL assay, and DNA fragmentation. On the other hand, basic fibroblast growth factor only partially prevented apoptosis in serum-starved HDMEC; platelet-derived growth factor-BB was completely ineffective. VEGF activated the phosphorylation of extracellular signal regulated kinase (ERK)1 (p44 mitogen-activated protein kinase; MAPK) and ERK2 (p42 MAPK) in a time- and concentration-dependent manner. Both the VEGF-induced activation and its anti-apoptotic effect were prevented by the specific MAPK/ERK inhibitor PD98059. The presence of VEGF also inhibited the sustained activation of stress-activated protein kinase/c-jun-NH2-kinase (SAPK/JNK) caused by serum starvation and ceramide treatment. Activation of the MAPK pathway together with inhibition of SAPK/JNK activity by VEGF appears to be a key event in determining whether an endothelial cell survives or undergoes programmed cell death. Copyright 1999 Academic Press.
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              Human islet transplantation network for the treatment of Type I diabetes: first data from the Swiss-French GRAGIL consortium (1999-2000)

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                Author and article information

                Journal
                JVR
                J Vasc Res
                10.1159/issn.1018-1172
                Journal of Vascular Research
                S. Karger AG
                1018-1172
                1423-0135
                2003
                August 2003
                26 September 2003
                : 40
                : 4
                : 359-367
                Affiliations
                aCentre européen d’étude du Diabète, Faculté de Médecine, bLaboratoire d’Anatomie Pathologique, Hôpital de Hautepierre, cTransgène S.A., Strasbourg, dCentre de Transfert et de Technologie du Mans, Le Mans, France
                Article
                72700 J Vasc Res 2003;40:359–367
                10.1159/000072700
                12891005
                © 2003 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                Page count
                Figures: 6, Tables: 1, References: 32, Pages: 9
                Categories
                Research Paper

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