TY - JOUR A1 - Ulrichs, Karin A1 - Müller-Buchholtz, W. T1 - MHC class II antigen expression on the various cells of normal and activated isolated pancreatic islets N2 - It is the aim of this study to characterize and quantify the cells within isolated rat islets that express MHC class 11 antigens. A set of five monoelonal antibodies and two polyclonal antisera of defined specificlty were used in combination with a newly devised procedure for three·dimensional immunofluorescence evaluation of intact islets. It is shown that in addition to passen· ger cells, such as Iymphocytes, macro· phages, and dendrlticlike cells, vascular endothelial and endocrine cells are also capable of expressing class 11 antigens. This expression Is strongly influenced by in vitro culture. pregnancy, streptozotocin- induced diabetes, transplantation trauma, and alloantigenic stimuli. The pos· sible role of the above cells in antigen presentation related to islet transplantation is discussed. KW - pancreas Islets KW - beta cells KW - islet transplantation KW - la antigens Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-44722 ER - TY - THES A1 - Gehlen, Martin Ludwig T1 - Kontrollierte Expansion von Insulin produzierenden Beta-Zellen des endokrinen Pankreas durch das Protein p8 T1 - Controlled expansion of insulin producing beta-cells of the endocrine pancreas by the p8 protein N2 - p8 ist ein vor einigen Jahren erstmals im Zusammenhang mit Pankreatitis beschriebenes 80 Aminosäuren langes Protein, das im exokrinen Pankreas mit vermehrtem Zellwachstum assoziiert ist. Wir konnten p8 auch in beta-Zellen des endokrinen Pankreas nachweisen. Um Informationen über die subzelluläre Lokalisation zu erhalten, wurde ein Plasmid, das für ein Fusionsprotein aus p8 und GFP (grün fluoreszierendes Protein) kodiert, kloniert und in verschiedene Ziellinien transfiziert. Die Ergebnisse dieser Versuche sprechen dafür, dass p8 ein nukleäres Protein ist. Durch ein Deletionskonstrukt des Fusionsproteins wurde ein nukleäres Lokalisationssignal (NLS) am C-terminalen Ende des Proteins identifiziert. Um weitere Informationen über Funktion und Wirkungsweise von p8 zu erhalten, wurden induzierbar stabile INS-1-Zellen (beta-Zelllinie) etabliert. Stimulation dieser Zellen mit IPTG führte zu einer 5fachen Überexpression von p8. Die Zellzahl der p8-überexprimierenden Zellen und die der nicht-p8-überexprimierenden Zellen wurde zeitabhängig verglichen. Je nach Versuchsaufbau wurden nach 96 Stunden Zellwachstum unter p8-Überexpression 31% bis 37% mehr Zellen als in dem Vergleichskollektiv ohne p8-Überexpression ermittelt. Von Seufert et al. wurden in den Zellmedien der p8 überexprimierenden stabilen INS-1-Zellen kumulativ erhöhte Insulin-Spiegel gemessen. Dieses spricht dafür, dass Überexpression von p8 in beta-Zellen Proliferation ausloest, nicht aber zu einem Differenzierungsverlust führt. Unsere Untersuchungen nähren die Hoffnung, dass in Zukunft mit Hilfe von p8 Spender-beta-Zellen in vitro vermehrt und im Rahmen einer Zelltherapie einem Diabetiker transplantiert werden könnten. N2 - p8 is a novel 80 amino acid protein which is strongly expressed in acute pancreatitis. There is an association with cellular growth in the exocrine pancreas. We were able to show existance of p8 in beta-cells of the endocrine pancreas. To gain information about the subcellular distribution we cloned a plasmid containing the DNA of a fusion protein of GFP (green fluorescence protein) and p8. This plasmid was transfected in several cell lines, giving evidence that p8 is a nuclear protein. Establishing deletion constructs of the fusion protein it was possible to show the existance of an c-terminal NLS (nuclear localization signal). We established an induceable double stable transfected beta-cell line (INS-1). IPTG induces a fivefold p8 overexpression. Cell counts were performed. After 96h of cellular growth we determined a 37% increase of cells grown under the influence of p8 overexpression compared to cells grown without p8 overexpression. Furthermore, we found significantly elevated insulin levels in the culture medium. In conclusion it was shown that p8 is a nuclear protein with c-terminal NLS. p8 induces beta-cell proliferation without leading to a lack of beta-cell differentiation. KW - Protein p8 KW - Inseltransplantation KW - beta-Zellproliferation KW - p8 protein KW - islet transplantation KW - beta-cell proliferation Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-12027 ER - TY - JOUR A1 - Chen, Chunguang A1 - Rawat, Divya A1 - Samikannu, Balaji A1 - Bender, Markus A1 - Preissner, Klaus T. A1 - Linn, Thomas T1 - Platelet glycoprotein VI‐dependent thrombus stabilization is essential for the intraportal engraftment of pancreatic islets JF - American Journal of Transplantation N2 - Platelet activation and thrombus formation have been implicated to be detrimental for intraportal pancreatic islet transplants. The platelet‐specific collagen receptor glycoprotein VI (GPVI) plays a key role in thrombosis through cellular activation and the subsequent release of secondary mediators. In aggregometry and in a microfluidic dynamic assay system modeling flow in the portal vein, pancreatic islets promoted platelet aggregation and triggered thrombus formation, respectively. While platelet GPVI deficiency did not affect the initiation of these events, it was found to destabilize platelet aggregates and thrombi in this process. Interestingly, while no major difference was detected in early thrombus formation after intraportal islet transplantation, genetic GPVI deficiency or acute anti‐GPVI treatment led to an inferior graft survival and function in both syngeneic mouse islet transplantation and xenogeneic human islet transplantation models. These results demonstrate that platelet GPVI signaling is indispensable in stable thrombus formation induced by pancreatic islets. GPVI deficiency resulted in thrombus destabilization and inferior islet engraftment indicating that thrombus formation is necessary for a successful intraportal islet transplantation in which platelets are active modulators. KW - basic (laboratory) research / science KW - coagulation and hemostasis KW - graft survival KW - islet transplantation KW - molecular biology Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224471 VL - 21 SP - 2079 EP - 2089 ER -