Regulatorische CD4+CD25+ T-Zellen (Tregs) stellen eine kleine Zellpopulation dar (1-5% der peripheren Blutzellen), die hauptsächlich für die Regulierung von Immunreaktionen verantwortlich ist. In der vorliegenden Arbeit wurden diese Zellen gemeinsam mit Stammzellen syngen und allogen kotransplantiert, um ihren Effekt auf das Anwachsen der Spenderzellen und die Rekonstitution der Hämatopoese nach Ganzkörperbestrahlung zu untersuchen. Es wurden humanisierte dreifach transgene Empfängermäuse (C57Bl/6-TTG) verwendet (human CD4+, murin CD4-, human HLA-DR+), wodurch sowohl bei syngener als auch bei allogener Transplantation eine Unterscheidung zwischen Spender- und Empfängerzellen möglich ist. Zunächst wurden CD4+CD25+ T-Zellen durch Separation aus Milzzellen bzw. Buffy Coats gewonnen und in vitro mittels Durchflusszytometrie und ELISpot charakterisiert. Anschließend fanden syngene und allogene Transplantationen mit einer Laufzeit von 61 Tagen statt. Überleben und Gewicht wurden täglich ermittelt und außerdem wurden wöchentlich Blutbilder erstellt und durchflusszytometrische Chimärismusanalysen (murines und humanes CD4, CD8, MHC (H2Db, H2Kd)) durchgeführt. Durch die magnetische Separation konnte die FoxP3-Expression der murinen Zellen (Transplantat) von 1,6% in der Ausgangspopulation auf 68,5% in der CD4+CD25+ Population gesteigert werden. In den ELISpot-Assays zeigten diese separierten Zellen, wie für Tregs typisch, keine Produktion von Interleukin-2. Nach syngener Transplantation (Spender: wildtyp C57Bl/6) von 2x106 Knochenmarkzellen und 1x106 CD4+CD25+ T-Zellen überlebten 100% der Tiere, wie zu erwarten war. Dabei setzte bei Tregs-kotransplantierten Tieren die Blutbildung nach bestrahlungsbedingter Leukozytopenie aufgrund bisher nicht bekannter Mechanismen früher wieder ein und der Donor-Zell-Chimärismus war an Tag 19 nach Transplantation signifikant höher als in der Kontrollgruppe. Dies zeigt, dass regulatorische T-Zellen im syngenen Transplantationsmodell einen positiven Effekt auf die Akzeptanz bzw. das Anwachsen des Transplantats haben. Dieses Modell entspricht klinisch einer autologen Transplantation. Nach einer knochenmarkzerstörenden Therapie werden dem Patienten eigene Stammzellen reinfundiert, um die Blutbildung und das Immunsystem wieder in Gang zu bringen. Der Zusatz von regulatorischen T-Zellen zum autologen Stammzelltransplantat könnte das Anwachsen der Zellen beschleunigen und die gefährliche Phase der Immunsuppression, in der es häufig zu Sekundärinfektionen kommt, verkürzen. Die Transplantation der gleichen Zahl von allogenen Spenderzellen (wildtyp Balb/c) führte überraschend zum Tod aller dreifach transgenen Empfängertiere. Der Vergleich zu Experimenten mit wildtyp C57Bl/6-Empfängertieren zeigte, dass dreifach transgene Mäuse sehr viel höhere Zellzahlen im Transplantat zum Überleben benötigen (Daten nicht gezeigt). Das Ausbleiben der Blutbildung nach der Bestrahlung führte zu vermindertem Allgemeinbefinden, gestörter Futter- und Wassseraufnahme und Exsikkose bis zum Tod bzw. aus Tierschutzgründen zur Euthanasie. Durch Erhöhung der Zellzahl im Transplantat auf 1x107 Knochenmark + 5x106 Milzzellen überlebten 25% der Mäuse, bei 3x107 Knochenmark + 5x106 Milzzellen waren es 50%. Anders als im syngenen Modell führte die Kotransplantation 1,5x106 allogener CD4+CD25+ T-Zellen zu 3x107 Knochenmark + 5x106 Milzzellen zum Versterben der Tiere. Dies verdeutlicht, dass regulatorische T-Zellen in diesem allogenen Transplantationsmodell das Anwachsen des Transplantats behindern (Transplantatversagen). Hier gilt es zu klären, ob dieser Effekt spezifisch für die gewählten Mausstämme ist und welche Mechanismen für das Transplantatversagen verantwortlich sind. In einem dreifach transgenen Mausmodell konnte ein positiver Effekt von regulatorischen T-Zellen auf die Rekonstitution der Hämatopoese bei syngener Kotransplantation nachgewiesen werden. Im allogenen Transplantationsmodell hingegen führte die Kotransplantation CD4+CD25+ T-Zellen zum Versterben der Empfänger. Der beschriebene und schon publizierte positive Effekt spenderspezifischer Tregs zur Behandlung von Graft versus Host Disease nach allogener Stammzelltransplantation widerspricht diesen Ergebnissen nicht, da es bei diesen Patienten schon zum Engraftment von hämatopoetischen Stammzellen gekommen ist. Dies hat weitreichende Konsequenzen für die therapeutische Anwendung regulatorischer T-Zellen bei hämatologischen Erkrankungen in der Human- und Veterinärmedizin. / Regulatory CD4+CD25+ T cells (Tregs) represent a small cell population (1-5% of peripheral blood cells) mainly responsible for the regulation of the immune system. In the present work, these cells were cotransplanted with syngeneic and allogeneic stem cells in order to analyze the effect of Tregs on the reconstitution of hematopoiesis after total body irradiation. Humanized triple transgenic hosts (C57Bl/6-TTG) (human CD4+, murine CD4-, human HLA-DR+) were applied allowing differentiation of donor and host cells in syngeneic and allogeneic transplantation settings. Murine and human CD4+CD25+ T cells were magnetically separated out of splenocytes or buffy-coats and characterized in vitro by means of flow cytometry and ELISpot. Afterwards syngeneic and allogeneic transplantation experiments were performed for a period of 61 days. Survival and weight were assessed daily and once a week blood parameters and chimerism analyses (murine and human CD4, CD8, MHC (H2Db/ H2Kd)) were carried out. FoxP3 expression increased from 1,6% in the initial murine cell fraction to 68,5% in the separated CD4+CD25+ T cells. ELISpot assays showed the typical lack of interleukin 2 production of Tregs. After syngeneic transplantation (donor: wildtype C57Bl/6) of 2x106 bone marrow cells and 1x106 CD4+CD25+ T cells, 100% of mice survived what was to be expected. Cotransplanted animals showed earlier reconstitution of hematopoiesis after leukocytopenia and significant higher donor-cell-chimerism on day 19 after transplantation. The mechanisms for this positive effect of Tregs in syngeneic transplantation on the engraftment have to be investigated. This model clinically correspond an autologous transplantation where patients are treated with their own stem cells after a myeloablative treatment (chemotherapy or irradiation). The addition of regulatory T cells to the transplant could accelerate the engraftment and shorten the risky period of immunosuppression. Injection of the same numbers of allogeneic cells (donor: wildtype Balb/c) did not preserve hosts from mortality. Compared to experiments with wildtype recipients, results showed that triple transgenic mice need much higher cell numbers in the transplant for survival (data not shown). The failure of hematopoiesis after irradiation led to reduced general condition, disordered ingestion and exsikkosis leading to death respectively to euthanasia for reasons of protection of animals. By scaling up the cell number in the inoculum to 1x107 bone marrow cells + 5x106 splenocytes 25% of mice survived, with 3x107 bone marrow cells + 5x106 splenocytes survival was 50%. In contrast to syngeneic experiments, cotransplantation of 1,5x106 allogeneic CD4+CD25+ T cells and 3x107 bone marrow cells + 5x106 splenocytes did not prevent animals from mortality. In this allogeneic transplantation model Tregs restrain engraftment (graft failure). It has to be clarified if this effect is specific for the utilized mouse strains and which mechanisms are responsible for the graft failure. In the syngeneic triple transgenic mouse model cotransplantation of CD4+CD25+ T cells showed a positive effect on reconstitution of hematopoiesis after irradiation. In the allogeneic setting however cotransplantation of allogeneic regulatory T cells avoided the engraftment of transplanted cells. The described and published effect of donor-specific Tregs for treatment of graft versus host disease after allogeneic transplantation does not contradict the presented results because treated patients already possessed engrafted hematopoietic stem cells. The results have wide consequences for the therapeutic appliance of regulatory T cells in hematological diseases in human and veterinary medicine.

Currently, the transplantation of islets of Langerhans is a viable means to maintain control of blood sugar levels and reduce the risk of hypoglycemia in defined populations with brittle type I diabetes mellitus or those requiring pancreatectomy. However, the process of islet isolation is highly variable and not all isolations result in islet numbers or quality suitable for transplantation. This thesis aimed to improve transplantation success through optimization and standardization of the isolation process and to identify pretransplant variables associated with early islet engraftment. A previously disregarded enzyme activity, tryptic-like activity (TLA), has been identified to influence pancreas digestion efficiency and islet isolation success in both the preclinical and clinical situations. For human pancreases, islet isolation success rates improved from 0% in the lowest TLA group to over 50% in the highest TLA groups without affecting islet quality. These findings should help standardize evaluation of enzymes for clinical islet isolation. A closed, automated, pump-made gradient system was compared to the open, manual method for islet separation. No differences were observed in expected gradient volumes, islet yields or total purities between the two methods. The pump-made gradient system successfully removed manual influences on density gradient production while fulfilling regulatory requirements for closed system processing. Islet quantification was evaluated with computer-assisted digital imaging analysis (DIA) and a semi-closed assessment system. By using the DIA system method, which measures islet purity and pellet volume instead of manual counting methods, variation in islet counts and purity reduced by almost half. By using a transplant outcome measurement of C-peptide adjusted by blood glucose and creatinine, we identified four pretransplant factors that affect early transplant outcome. Of the four factors, one was related to the organ transport time, one to function of the islets, and two to the transplanted tissue volume. When these four factors were put into a predictive model, it accounted for about 40% of the transplant outcome. The work contained in this thesis identifies and optimizes a number of critical elements related to islet isolation and transplantation protocols.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Thesis (Ph.D. in Immunology) -- University of Colorado at Denver and Health Sciences Center, 2006. / Typescript. Includes bibliographical references (leaves 151-168). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2001. / Härtill 6 uppsatser.

Source: Dissertation Abstracts International, Volume: 70-07, Section: B, page: 4063. Adviser: David R. Lairson. Includes bibliographical references.

Thesis (Ph.D. in Nursing) -- University of Colorado Denver, 2008. / Typescript. Includes bibliographical references (leaves 192-203). Free to UCD Anschutz Medical Campus. Online version available via ProQuest Digital Dissertations;

Introdução: O diabetes melito pós-transplante (DMPT) é uma complicação comum em transplantados renais e está associada a desfechos desfavoráveis. Tanto a adiponectina como a quimiocina ligante 5 (CCL5) têm relação com o metabolismo da glicose, o que permite supor que polimorfismos nesses genes possam levar ao desenvolvimento de DMPT. Objetivo: Verificar a associação dos polimorfismos do gene da adiponectina e da CCL5 com DMPT em transplantados renais caucasianos. Métodos: Trata-se de um estudo caso-controle aninhado a uma coorte de transplantados renais do Hospital de Clínicas de Porto Alegre (HCPA). Duzentos e setenta transplantados renais caucasianos (83 com DMPT e 187 sem DMPT), com pelo menos um ano de transplante, foram incluídos no estudo. Pacientes com diabetes melito pré-transplante e com múltiplos transplantes de órgãos foram excluídos. O diagnóstico de DMPT foi realizado através dos critérios da Associação Americana de Diabetes. Dados sócio-demográficos e clínicos foram coletados. A genotipagem dos polimorfismos 276G/T (rs1501299) do gene da adiponectina e dos polimorfismos rs2280789 e rs3817665 do gene da CCL5 foi realizada pela técnica de discriminação alélica por PCR (polymerase chain reaction) em tempo real. O estudo foi aprovado pelo Comitê de Ética em Pesquisa do HCPA e todos os pacientes assinaram o Termo de Consentimento Livre e Esclarecido. Resultados: O genótipo TT do polimorfismo 276G/T do gene da adiponectina foi mais frequente nos pacientes com DMPT do que naqueles sem diabetes, em comparação aos genótipos GG/GT (modelo recessivo; p=0,031). O genótipo TT foi identificado como fator de risco independente para o DMPT em transplantados renais caucasianos, no modelo ajustado para as variáveis: idade no momento do transplante, índice de massa corporal pré-transplante e uso de tacrolimus (TT vs. GG/GT, HR=1,88 IC95% 1,03-3,45, p=0,041). Não houve diferença na distribuição dos genótipos e alelos dos polimorfismos rs2280789 e rs3817655 do gene da CCL5 entre os pacientes com e sem DMPT. Conclusões: O polimorfismo 276G/T do gene da adiponectina está associado ao DMPT em transplantados renais caucasianos. / Background: New onset diabetes after transplantation (NODAT) is an increasingly recognized complication of kidney transplantation that is associated with poor outcomes. Both adiponectin and chemokine ligand 5 (CCL5) are related to glucose metabolism, allowing hypothesize that genetic variation in their genes can lead to development of NODAT. Objective: To investigate the association between adiponectin and CCL5 genes polymorphisms with NODAT in Caucasian kidney transplant recipients. Methods: This nested case-control study was undertaken within a cohort of kidney transplant recipients from Hospital de Clínicas de Porto Alegre, Southern Brazil. Two hundred seventy Caucasian kidney transplant recipients (83 with NODAT and 187 without NODAT) with at least one year of transplantation were included in this study. Patients with pretransplant diabetes mellitus and multi-organ transplantation were excluded. NODAT diagnosis was determined by American Diabetes Association criteria. Demographic and clinical data were collected. Subjects were genotyped for 276G/T adiponectin gene polymorphism and rs2280789 and rs3817655 CCL5 gene polymorphisms by real-time PCR (polymerase chain reaction). This study was approved by the Ethics Committee of Hospital de Clínicas de Porto Alegre and all subjects received adequate information about this study and gave informed consent. Results: The TT genotype of 276G/T adiponectin gene polymorphism was significantly more frequent in NODAT than non-NODAT patients, compared to GG/GT genotypes (recessive model; p=0.031). TT genotype was identified as an independent risk factor for NODAT in Caucasian kidney transplant recipients, after adjusting for age at transplantation, pretransplant BMI and tacrolimus usage (TT vs. GG/GT, HR=1.88 95%CI 1.03-3.45, p=0.041). There were no differences in genotype and allele distributions of rs2280789 and rs3817655 CCL5 gene polymorphisms between NODAT and non-NODAT groups. Conclusions: The 276G/T adiponectin gene polymorphism is associated with NODAT in Caucasian kidney transplant recipients.