As complicações relacionadas ao diabetes mellitus estão intimamente ligadas à hiperglicemia. Os pacientes que evoluem com grande instabilidade metabólica e progressão das complicações microvasculares apesar do tratamento intensivo com insulina são candidatos ao transplante de pâncreas. Neste contexto, o transplante de ilhotas pancreáticas surge como alternativa por ser menos invasivo e menos imunogênico. No entanto, o processo de digestão do pâncreas e isolamento das ilhotas pancreáticas expõe as células endócrinas a diversos estímulos nocivos, que resultam em diminuição da viabilidade das células isoladas e menor chance de sucesso após o transplante. A geração de espécies reativas de oxigênio (ERO) e o consumo das defesas anti-oxidantes durante o processo de digestão do pâncreas pode contribuir para a perda da viabilidade das ilhotas isoladas. O objetivo deste estudo foi avaliar o impacto da suplementação com glutationa etil mono-éster (GEE), um éster de melhor biodisponibilidade da glutationa (um importante anti-oxidante endógeno) nos resultados do isolamento e do transplante de ilhotas pancreáticas em um modelo animal. GEE foi adicionada na concentração de 10 mM na solução de colagenase durante o isolamento das ilhotas de rato. Após o isolamento, foram realizados estudos in vitro para avaliar a presença de ERO com o ensaio carboxi-H2DCFDA e a viabilidade das ilhotas isoladas com os ensaios JC-1 (integridade mitocondrial) e Sytogreen/brometo de etídio (integridade da membrana celular); viabilidade das células beta-pancreáticas por citometria de fluxo para avaliação de necrose e apoptose, TUNEL para a avaliação do índice de apoptose e secreção de insulina estimulada por glicose. Realizamos também estudos in vivo, com o transplante das ilhotas na cápsula renal de camundongos diabéticos, seguimento dos animais por 30 dias após o transplante e recuperação do enxerto para análise histológica. Quatro grupos de animais foram avaliados: 1) Animais transplantados com número suficiente de ilhotas para reverter o diabetes (500) não isoladas com GEE; 2) Animais transplantados com número suficiente de ilhotas (500) isoladas em presença de GEE; 3) Animais transplantados com número insuficiente de ilhotas (150) não isoladas com GEE e 4) Animais transplantados com número insuficiente de ilhotas (150) isoladas em presença de GEE. A suplementação com GEE na concentração de 10 mM durante o isolamento das ilhotas diminuiu a formação de ERO (Controle 57,0 ± 4,3% versus GEE 47,0 ± 3,9%, p = 0,0034) e aumentou a viabilidade das ilhotas, conforme demonstrado pelo ensaio Sytogreen/brometo de etídio (Controle 70,6 ± 3,4% versus GEE 83,6 ± 4,8%, p= 0,0010) e pela diminuição na porcentagem de células TUNEL-positivas (Controle de 39,2 ± 5,0% versus GEE 29,1 ± 1,9%, p= 0,042) no grupo tratado. O estudo de viabilidade por citometria de fluxo também mostrou um número maior de células beta pancreáticas viáveis no grupo tratado (Controle 21,4 ± 3,4% versus GEE 33,7 ± 3,9%, p= 0,0156). A manutenção da integridade funcional das ilhotas teve impacto nos resultados dos transplantes, com menor índice de célula TUNEL-positivas (Controle 23,3 ± 2,6% versus GEE 8,3 ± 0,8%, p < 0,0001) nos enxertos recuperados após as primeiras 24 horas do transplante e maior porcentagem de animais normoglicêmicos (Controle 30% versus GEE 65,2%, p = 0,004) após transplante de um número marginal de 150 ilhotas na cápsula renal após seguimento de 30 dias. Em conclusão, estes dados corroboram que a formação de ERO é uma causa relevante de dano celular durante o isolamento de ilhotas pancreáticas e sugerem que o uso do compostos anti-oxidante GEE pode ser uma estratégia para melhorar os resultados dos transplantes de ilhotas / The vascular complications related to Diabetes Mellitus are closely linked to hyperglycemia. Patients who develop metabolic instability and progression of microvascular complications despite intensive insulin therapy are candidates to pancreas transplantation. Pancreatic islet transplant is an alternative approach since it is less immunogenic and minimally invasive. However, the success of pancreatic islet transplantation still faces many challenges, mainly related to cell damage during the islet isolation process and early post-transplant period. The increase in reactive oxygen species (ROS) generation and the consumption of antioxidant defenses might be factors related to these injuries. The aim of the present study was to evaluate whether supplementation with glutathione-ethyl-ester (GEE), a compound with higher bioavailability than glutathione (an important endogenous antioxidant), could improve islet viability and efficacy in a marginal islet transplantation model in rodents. GEE was added to a final concentration of 10 mM in collagenase solution during islet isolation. After isolation, in vitro studies were conducted to evaluate the presence of ROS using carboxy-H2DCFDA assay and the viability of isolated islets with JC-1 assay (mitochondrial integrity), Sytogreen/ethidium bromide assay (cellular membrane integrity), fractional beta cell viability assay by flow cytometry, TUNEL assay for apoptosis evaluation and glucose-stimulated insulin secretion. We also performed in vivo studies with islet transplantation under the kidney capsule of diabetic mice, 30 days follow-up after transplantation and recovery of the graft for histological analysis. Four experimental groups were evaluated: 1) animals transplanted with 500 islets, a number considered sufficient to promote diabetes reversion, not isolated in presence of GEE; 2) animals transplanted with 500 islets isolated in presence of GEE; 3) animals transplanted with 150 islets, a number considered insufficient to promote diabetes reversion, not isolated in presence of GEE and 4) animals transplanted with 150 islets isolated in presence of GEE. The addition of GEE at 10 mM concentration during islet isolation was able to decrease ROS content in isolated islets (Control 57.0 ± 4.3% versus GEE 47.0 ± 3.9%, p = 0.0034) and increase islet viability, as demonstrated by the Sytogreen/ethidium bromide assay (Control 70.6 ± 3.4% versus GEE 83.6 ± 4.8%, p = 0.0010) as well as by the reduction in TUNEL-positive cells (Control 39.2 ± 5.0% versus GEE 29.1 ± 1.9%, p = 0.042) in the treated group. The fractional beta-cell viability also showed an improvement in the treated group (Control 21.4 ± 3.4% versus GEE 33.7 ± 3.9%, p = 0.0156). The improved cell viability observed in vitro was translated into better outcomes in vivo, since supplementation of GEE during the isolation process resulted in a significantly lower rate of TUNEL-positive cells (Control 23,3 ± 2,6% versus GEE 8,3 ± 0,8%, p < 0,0001) in the islet grafts recovered after 24h of transplantation and in a higher percentage of normoglycemia (Control 30% versus GEE 65,2%, p = 0,004) after 30 days of follow-up in animals transplanted with the marginal islet mass (150 islets). In conclusion, the current data corroborate that ROS production is a relevant cause of cellular damage during islet isolation and suggest that the use of GEE might be a strategy to improve islet transplantation outcomes

Acredita-se que a diminuição progressiva da massa de células observada durante a evolução do diabetes mellitus tipo 2 (DM 2) ocorra por apoptose deste tipo celular. As tiazolidinedionas (TZDs), uma classe de medicamentos utilizada no tratamento do DM 2, atuam como ligantes dos receptores ativados por proliferadores de peroxissomos (PPAR) e e promovem diminuição da resistência periférica à insulina. Embora existam estudos controversos, tem se especulado que as TZDs possam exercer efeitos diretos sobre as células pancreáticas, prevenindo a perda por apoptose e melhorando a sua viabilidade. O objetivo deste estudo foi avaliar os efeitos diretos da Pioglitazona (PIO) na concentração de 10 M sobre a viabilidade funcional e o índice de apoptose de ilhotas pancreáticas isoladas de ratos Wistar expostas a concentrações fisiológica (5,6 mM) e suprafisiológica (23 mM) de glicose durante 24, 48 e 72 horas. A viabilidade funcional foi avaliada pela análise da secreção de insulina estimulada por glicose e do conteúdo total de insulina nas ilhotas. O índice de apoptose foi avaliado pela medida da fragmentação do DNA, da expressão do RNAm dos genes Bcl2 (anti-apoptótico) e Bax (pró-apoptótico) e da atividade proteolítica da caspase-3 em ilhotas tratadas e não tratadas com a PIO. Em 5,6 mM de glicose, não se observou efeito significativo sobre a secreção de insulina, mas a avaliação do conteúdo total de insulina evidenciou uma diminuição transitória nas ilhotas tratadas com PIO por 24 horas, seguida por um aumento no conteúdo de insulina quando as ilhotas foram cultivadas por 48 e 72 horas em presença da droga. Em relação à avaliação da apoptose, observou-se uma diminuição na expressão do RNAm do gene Bax nas ilhotas tratadas com PIO por 24 horas, entretanto, após 48 e 72 horas, houve um aumento da expressão do RNAm deste gene nas ilhotas tratadas com a droga. Não foram observadas diferenças estatisticamente significativas na expressão do RNAm do gene Bcl2 em nenhum dos tempos estudados e a avaliação da apoptose determinada pela medida da fragmentação do DNA somente demonstrou uma diminuição do índice de apoptose após 48 horas de tratamento com a PIO. Em 23 mM de glicose, a PIO promoveu um aumento transitório na secreção de insulina estimulada por glicose e no conteúdo total de insulina (após 48 horas), no entanto, após 72 horas, observou-se diminuição significativa no conteúdo total de insulina. Em relação à apoptose, o tratamento com PIO determinou um aumento do índice de apoptose medido pela fragmentação do DNA e da atividade proteolítica da caspase-3 após 48 e 72 horas e uma diminuição da expressão do RNAm do gene Bcl2 nos tempos 24 e 48 horas. Os resultados do presente estudo sugerem que os efeitos diretos da PIO sobre as ilhotas pancreáticas murídeas em cultura variam de acordo com a concentração de glicose a qual as ilhotas estão expostas: em concentração fisiológica de glicose, a PIO parece exercer efeitos diretos benéficos, enquanto em concentração suprafisiológica de glicose, ela exerce efeitos diretos deletérios sobre a viabilidade funcional e o índice de apoptose de ilhotas pancreáticas murídeas em cultura. / The progressive decrease in -cell mass observed during the evolution of type 2 diabetes (T2DM) is believed to occur due to cell apoptosis. Thiazolidinediones (TZDs), a class of agents used for the treatment T2DM, act as ligands of the peroxisome proliferator-activated receptor (PPAR) and and decrease peripheral insulin resistance. Although still controversial, some studies have shown a direct effect of TZDs on pancreatic -cell, preventing cell loss due to apoptosis and improving their viability. The objective of this study was to evaluate the direct effects of 10 M Pioglitazone (PIO) on functional viability and apoptosis rate of islets isolated from Wistar rats exposed to physiological (5.6 mM) and supraphysiological (23 mM) glucose concentrations during 24, 48 and 72 hours. The functional viability was evaluated by the analysis of insulin secretion after glucose challenge and of islet total insulin content. Apoptosis rate was evaluated by measurement of DNA fragmentation, of Bcl2 (antiapoptotic) and Bax (proapoptotic) mRNA expression and of proteolytic activity of caspase-3 in pancreatic islets treated or not with PIO. At 5.6 mM glucose concentration, no significant effects in insulin secretion were observed, while a transitory decrease (after 24 hours) followed by an increase in total insulin content was observed in islets treated with PIO for 48 and 72 hours. Regarding apoptosis, a lower expression of Bax mRNA was detected in islets treated with PIO for 24 hours, followed, however, by an increase in the expression of this gene after 48 and 72 hours of drug exposition. PIO treatment did not promote significant changes in Bcl2 mRNA expression, while decreased the apoptosis rate measured by DNA fragmentation only after 48 hours of exposition. At 23 mM glucose concentration, PIO treatment elicited a transitory increase in insulin secretion after glucose challenge and in islet total insulin content after 48 hours followed by a decrease in the islet total insulin content after 72 hours. Concerning apoptosis, PIO treatment determined an increase in the apoptose rate measured by DNA fragmentation and by proteolytic activity of caspase-3 after 48 and 72 hours and a decrease in Bcl2 mRNA expression after 24 and 48 hours. These findings suggest that the direct effects of PIO on pancreatic islets depend on glucose concentration to which they are exposed: while under physiological glucose concentration the direct effects seem to be beneficial, under supraphysiological glucose concentration, PIO exerts direct deleterious effects on the functional viability and on the apoptosis rate of murine pancreatic islets.

O adenocarcinoma de ducto pancreático (PDAC) é a quarta causa de morte em decorrência de neoplasias nos países ocidentais. Atualmente, a cirurgia ressectiva é a única possibilidade de cura para a doença, porém, a recidiva tumoral acontece em menos de um ano após a intervenção cirúrgica, mesmo com a quimioterapia adjuvante. A terapia fotodinâmica (PDT) é uma alternativa promissora no tratamento do câncer. No entanto, pouco se sabe sobre o uso da PDT em tumores pancreáticos. Portanto, o objetivo deste trabalho foi avaliar a eficiência da PDT com o azul de metileno (MB) como fotossensibilizador (MB-PDT) em induzir a morte de linhagens de PDAC humanas (AsPC-1, Panc-1, MIAPaCa-2 e BxPC-3) e estudar a contribuição de vias de necrose regulada nos efeitos citotóxicos da terapia sobre estes modelos. Os resultados obtidos mostraram que a MB-PDT foi capaz de induzir a morte massiva das células de PDAC. Além disso, eles indicaram que há dois perfis de susceptibilidade entre as quatro linhagens estudadas quando submetidas a MBPDT com 4,5 J/cm2 de energia e 6min de irradiação. De acordo com os dados apresentados, a diferença nas sensibilidades das linhagens à terapia não está associada à diferenças na capacidade de incorporação do MB ou na localização sub-celular do fotossensibilizador nas diferentes células, uma vez que a localização é, predominantemente, lisossomal em todas elas. Adicionalmente, mostrou-se que as linhagens menos susceptíveis ao tratamento, MIAPaCa-2 e Panc-1, apresentam níveis significativamente menores de RIPK3 e MLKL, dois dos componentes do necrossomo, essenciais para a execução da necroptose. Além disso, foi visto que a MB-PDT induz um aumento de fosforilação de MLKL em AsPC-1, demonstrando a ativação da necroptose após a terapia nestas células, mas não em MIAPaCa-2 (menos responsiva à terapia com 4,5 J/cm2 deenergia e 6min de tempo de irradiação). Ainda, a inibição da via de sinalização necroptótica diminuiu significativamente as porcentagens de morte das células mais susceptíveis (BxPC-3 e AsPC-1), não alterando a resposta de Panc-1 e MIAPaCa-2, corroborando a ativação e importância da necroptose para a citotoxicidade da MB-PDT. Finalmente, neste trabalho foi mostrado que o aumento do tempo de irradiação, mantendo-se a quantidade total de energia aplicada no tratamento, melhora a eficiência da MB-PDT em induzir a morte das células que apresentam limitações para executar a necroptose, sugerindo que mais de uma via de morte esteja sendo ativada após a terapia e que o tempo de irradiação atuaria modulando esta ativação. Complementarmente, foi mostrado que os tempos maiores de irradiação aumentam o estresse oxidativo intracelular que é acompanhado por uma diminuição significativa do conteúdo intracelular de glutationa reduzida (GSH), indicando, preliminarmente, que a ferroptose pode estar sendo acionada após os protocolos mais longos de irradiação. Coletivamente, os resultados apresentados neste trabalho confirmam a eficiência da MB-PDT no tratamento de diferentes linhagens de PDAC, indicando que a necroptose está sendo ativada e contribuindo para a citotoxicidade da terapia sobre as células que não apresentam resistência à esta via de morte. Ainda, eles demonstram que o aumento do tempo de irradiação pode transpor a barreira de resistência de algumas linhagens à terapia, provavelmente por induzir a ativação de outras vias de necrose regulada, mostrando a importância da otimização do protocolo de tratamento no aumento da eficiência da MB-PDT sobre os tumores de pâncreas. Finalmente, os resultados confirmam a MB-PDT como alternativa eficaz no tratamento do PDAC, apresentando um amplo espectro de atuação sobre subtipos tumorais resistentes à vias clássicas de morte celular, uma característica importante no contexto de uma terapia anti-cancer. / Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of death due to neoplasms in western countries. Currently, resective surgery is the only therapetical approach to cure this disease, but tumor´s recurrence occurs less than one year after the surgery, even with adjuvant chemotherapy. Photodynamic therapy (PDT) is a promising alternative for the cancer treatment. However, the efficacy of PDT to treat pancreatic tumors as well as the mechanisms involved in the induction of tumorigenic cell death remain unclear. For this purpose, in this study, we set out to evaluate the efficacy of PDT using methylene blue (MB) as a photosensitizer (MB-PDT), in inducing death of human PDAC derived cell lines (AsPC-1, Panc-1, MIAPaCa-2 and BxPC-3) and to deeper investigate the contribution of necroptosis to the cytotoxic effects of the therapy. We observed that MB-PDT was able to induce massive death of PDAC cells. Moreover, our results indicated that upon MB-PDT (4.5 J/cm2 energy and 6min of irradiation time), there were two susceptibility profiles among the four cell lines studied. Data also showed that this differential profile of cell response was neither associated with the differences in the MB incorporation capacity nor with the subcellular location of the photosensitizer, since the localization was predominantly lysosomal in all of tested cell lines. In addition, less susceptible cells, MIAPaCa-2 and Panc-1, showed significantly lower levels of RIPK3 and MLKL, two of the necrosome components, essential for triggering necroptosis. Furthermore, while MB-PDT (4.5 J/cm2 and 6min of irradiation) has been able to increase MLKL´s phosphorylation levels, an essential step in necroptosis induction, in AsPC-1cells, less responsive MIAPaCa-2 cells presented no variations on the phosphorylation state of this pseudokinase. Moreover, pharmacological inhibition of the necroptotic signaling pathway significantly decreased cell death percentages of the most susceptible cells (BxPC-3 andAsPC-1), without altering the response of Panc-1 and MIAPaCa-2, corroborating that activation of necroptosis was strongly involved in the cytotoxicity of MB-PDT. Finally, this work showed that increasing the irradiation time improved the efficacy of MB-PDT in killing cells which display limitations to perform necroptosis, suggesting that the irradiation time would be modulating the degree of oxidative stress generated and this stimuli would in turn, be responsible for triggering other regulated cell death pathways in a RIKP3 and MLKL independent way. Indeed, this increase in oxidative stress was accompanied by a significant decrease in GSH, a global indicatior of less antioxidant cell capacity, preliminarily pointing at the induction of ferroptosis by longer irradiation protocols. In summary, we demonstrated that MB-PDT is able to induce cell death in different PDAC cell lines and that different regulated cell death mechanisms are being activated upon MB-PDT induction. Furthermore, it was demonstrated that increased irradiation time may overcome the resistance barrier of some cell lines, probably inducing the activation of other regulated cell death pathways, showing the importance of optimizing the irradiation protocol in order to maximize the efficacy of the therapy. Finally, our observations point MB-PDT as an alternative and effective therapy for pancreatic cancer treatment, displaying a broad-spectrum action on tumors displaying different resistance mechanisms to classic cell death pathways, a desired property for improving an anticancer therapy.

Dans le cas d'une tumeur pancréatique, la chirurgie d'exérèse est le traitement de première intention lorsqu'elle est possible. Les pancréatectomies sont des actes à haut risque, entraînant un taux de morbidité de 50%. L'une des complications les plus graves est l'apparition de fistules pancréatiques (FP) qui surviennent dans 15 à 20 % des cas, pour lesquelles il n'existe aucune solution de prévention. Cette thèse porte sur l'élaboration d'un biomatériau pour la prévention des FP. Le cahier des charges, défini avec l'équipe chirurgicale, nous a orienté vers un dispositif médical sous forme de pansement absorbant, présentant des propriétés mécaniques adaptées, ainsi qu'une résistance aux enzymes pancréatiques serait intéressant. Un biomatériau constitué de deux couches a été imaginé : 1) une matrice absorbante constituée d'un complexe polyélectrolyte (PEC) sous forme de film, 2) une couche supérieure imperméable permettant de limiter la diffusion des enzymes pancréatiques dans le milieu péritonéal ; afin de répondre aux spécifications demandées par l'équipe médicale. La première partie de ce travail a porté sur l'optimisation de la mise en forme de la matrice sous forme de film à partir de PEC d'alginate (ALG) et de chitosane (CHI) présentant différents ratio de polymères (ALG-CHI 50/50 et ALG-CHI 63/37). L'influence de la technique d'homogénéisation des PEC, sous ultra-turrax (UT) ou au Stephan (ST) a été étudiée sur les propriétés physico-chimiques des films obtenus. Les propriétés de biodégradation, de gonflement et de cytotoxicité sont principalement influencées par le ratio des polymères. En revanche, leurs structure et propriétés mécaniques sont essentiellement influencées par la technique d'homogénéisation utilisée lors de l'élaboration du PEC. Au vu de ces résultats, le choix de la matrice au contact de l'anastomose ou de la tranche pancréatique s'est arrêté sur le PEC ALG-CHI 63/37 UT. La deuxième partie de cette thèse a été consacrée à l'incorporation d'une couche imperméable à la surface supérieure du film. Deux polymères ont été testés : l'acide polylactique (PLA) et le polycaprolactone (PCL). Ils ont été incorporés après fonctionnalisation de la surface du film. La matrice ALG-CHI 63/37 UT recouverte de PLA présente une surface plus hydrophobe, des propriétés mécaniques adaptées, une bonne résistance aux enzymes pancréatiques tout en possédant des propriétés de gonflement intéressantes. Le biomatériau ainsi obtenu est un bon candidat qui répond au cahier des charges d'un pansement indiqué pour la prévention des fistules pancréatiques. / Resection surgery is the first-line treatment indicated for pancreatic tumor. The morbidity of this surgery is high with a complication rate around 50%. One of the most serious complications is the occurrence of pancreatic fistula (PF), which occurs in 15-20% of cases. To date, no biomaterial available on the market is indicated for the prevention of the onset of PF following pancreatectomy. This project focuses on the development of a biomaterial for the prevention of PF. Specifications identified by the surgical team oriented us to ward an absorbent dressing with sufficient mechanical properties and pancreatic enzymes resistance. A biomaterial made up of two layers was designed: 1) an absorbent matrix, in the form of a film, constituted by a polyelectrolyte complex (PEC), 2) an impermeable backing layer expected to limit the diffusion of the pancreatic enzymes into the peritoneal medium; to meet surgeons' specifications. The first part of this work focused on the optimization of the preparation of the matrix, composed of alginate (ALG) and chitosan (CHI) PECs films with different polymer ratios (ALG-CHI 50/50and ALG-CHI 63/37). The influence of the technique of homogenization of PEC, ultra-turrax (UT) or Stephan (ST) was studied on the physicochemical properties of the films. Biodegradation, swelling and cytotoxicity were shown to be mainly influenced by the ratio of polymers used. On the other hand, structure and mechanical properties are mainly influenced by the homogenization technique. With these results, the choice of the matrix to pancreatic application was set as the PEC ALG-CHI 63/37 UT. The second part of the present work was devoted to the incorporation of an impermeable backing layer on the upper film surface. Two polymers were evaluated: polylactic acid (PLA) and polycaprolactone (PCL). They were incorporated after the functionalization of the film surface. The PLA-coated ALG-CHI 63/37 UT matrix led to more hydrophobic surfaces, as well as adaptated mechanical properties and resistance to pancreatic enzymes with interesting swelling properties. The obtained biomaterial is a promising candidate responding to the specifications for a dressing indicated for the prevention of PF.

A Diabetes mellitus em cães é cada vez mais frequente, decorrente de fatores genéticos e/ou ambientais, como um distúrbio endócrino que, de forma semelhante à que ocorre em humanos, falha no controle adequado de glicose no sangue, desencadeia a hiperglicemia, glicosúria e perda de peso. A terapia celular utilizando as células beta-pancreáticas tem sido alvo de estudos, devido à grande demanda de novos casos de Diabetes mellitus e à falta de órgãos para transplantes em humanos e animais. Acredita-se que a ciência possa responder e inovar em tratamentos, encontrando a possível cura para esta doença complexa. Portanto, o objetivo deste estudo foi obter e caracterizar células derivadas do pâncreas fetal canino de animais com idades compreendidas entre 50 e 60 dias de gestação. As células pancreáticas de fetos caninos apresentam morfologia fibroblastóide e crescimento em monocamada em cultivo, apresentam células pluripotentes e proliferativas, não são tumorigênicas e apresentam expressão de PDX1, um fator de transcrição que tem papel importante na ativação do gene promotor da insulina. O pâncreas possui inervação simpática, observado por fibras nervosas TH+. Histologicamente, o pâncreas fetal canino apresenta ácinos num estágio de organização avançado, com parênquima semelhante ao encontrado no cão adulto. As ilhotas pancreáticas são distribuídas no tecido de maneira irregular, organizando-se em pequenos aglomerados de células por entre os ácinos, especialmente próximas aos vasos sanguíneos. A coloração com Ditizona permitiu inferir a presença de insulina no tecido pancreático, o que foi comprovado mediante técnica de imunofluorescência, além da presença de células que expressam o hormônio somatostatina. Os resultados desta investigação indicam que o pâncreas fetal canino demonstra características favoráveis para ser uma fonte viável de células para estudos aplicados à terapia celular em cães. Outras investigações referentes à comprovação da produção de insulina in vitro por essas células se fazem necessárias / Diabetes mellitus in dogs is increasingly common, due to genetic and/or environmental factors such as an endocrine disorder, similarly to what occurs in humans, failure to adequately control blood glucose triggers hyperglycemia, glycosuria and weight loss. Cell therapy using the pancreatic beta cells has been the subject of studies, due to the great demand of new cases of diabetes mellitus and the lack of organs for transplants in humans and animals. It is believed that science can respond and innovate treatments, finding a possible cure for this disease complex. Therefore, the objective of this study was to obtain and characterize derived cells from canine fetal pancreas, of animals aged between 50 and 60 days of gestation. The pancreatic cells of canine fetuses exhibit fibroblastoid morphology and growth in monolayer culture, exhibit pluripotent and proliferative cells, are not tumorigenic and have PDX1 expression, a transcription factor that plays an important role in the activation of the insulin gene promoter. The pancreas has sympathetic innervation observed by TH+ nerve fibers. Histologically, the fetal pancreatic acini canine presents an advanced stage organization with similar parenchyma that found in adult dog. The pancreatic islets are distributed in the fabric unevenly, organizing themselves into small clusters of cells through the acini, especially close to the blood vessels. Staining with Dithizone allowed inferring the presence of insulin in the tissue, which was confirmed by immunofluorescence, in addition to cells that express somatostatin. The results of this investigation indicate that the canine fetal pancreas shows favorable characteristics to be a feasible source of cells for cell therapy applied to studies in dogs. Further investigation regarding the evidence of in vitro production of insulin by these cells are required

Não é claro como o receptor de glicocorticóide (GR) contrarregula a atividade do STAT5 na transição da gestação para a lactação. Dexras1 é uma pequena proteína G ativada por dexametasona (DEX), que regula morfologia celular, crescimento, etc. Neste estudo detectamos a expressão de Dexras1 em células beta de ilhotas pancreáticas. DEX induz a expressão de Dexras1 em células RINm5F, que está aumentada na gestação e diminuída na lactação. A expressão protéica de 11<font face=\"Symbol\">&#946HSD1, enzima ativadora de glicocorticóides (GCs), segue esse perfil. A ligação tanto do GR como do STAT5, analisada por ChIP assay, ao promotor do gene da Dexras1 aumentada por DEX é revertida por prolactina (PRL), e está diminuída e aumentada na gestação e lactação, respectivamente. DEX induz a associação ao GR, fosforilação e translocação nuclear do STAT5b. O silenciamento gênico de Dexras1 promoveu aumento da secreção de insulina, e aumentou os níveis de pERK1/2, pCREB, pPKC<font face=\"Symbol\">&#948 e PKA. Sendo assim, a regulação de Dexras1 por PRL e GCs contribui para a secreção de insulina característica do periparto. / It is not clear how glucocorticoid receptor (GR) counteracts STAT5 activity during the transition of pregnancy to lactation. Dexras1 is a small G protein activated by dexamethasone (DEX) that controls cell morphology, growth, etc. In the present study we detected Dexras1 expression in pancreatic beta cell. DEX induces Dexras1 expression in RINm5F cells, which is increased in pregnancy and decreased in lactation. The expression of 11<font face=\"Symbol\">&#946HSD1, the glucocorticoids (GCs) activating enzyme, followed Dexras1 profile in pancreatic islet. Both GR and STAT5b bindings to Dexras1 gene promoter, analyzed by ChIP assay, are increased by DEX and PRL counteracts this effect. Both bindings are decreased in pregnancy and increased in lactation. DEX induces STAT5b association to GR, phosphorylation and nuclear translocation. Dexras1 knockdown using small interference RNA (si-RNA) promoted an increase in insulin secretion, as well as increased levels of pERK1/2, pCREB, pPKC<font face=\"Symbol\">&#948 and PKA. Thus, Dexras1 regulation by PRL and GCs contributes to insulin secretion during peripartum.

Apart from CFRD, low cognitive skill index (CSI) was also found in CF patients and was attributed the lacking of vitamin E. Since it is known that insulin plays a role in the learning and memory, decreased plasma insulin level in CF patients is an alternative mechanism for impaired cognitive function. Although numerous studies have found that insulin can improve learning and memory, the mechanism of it is not well understood. In this study, we investigated the effect of insulin on the expression of hippocampal early-phase long-term potentiation (E-LTP) in the immature rats. Hippocampal brain slices were acutely prepared from 10-12 days and 2 months old rats and field excitatory postsynaptic potentials (tEPSCs) were recorded from CA1 region by a multi-electrode in vitro recording system. In the control group, the hippocampal slices of neonatal rats showed no increase in the magnitude of fEPSC after conventional high frequency stimulation (HFS). After pretreatment of the slices with 0.08ng/ml insulin for over one hour, there was no significant change in the magnitude of E-LTP. However, when the insulin concentration increased to 0.8ng/ml, a significant increase in the magnitude of E-LTP was observed. On the contrary, any doses of insulin failed to affect the magnitude of E-LTP of mature rats. These results suggested that insulin could dose-dependently facilitate the production of E-LTP in the hippocampus of infant rats. Application of AG-1024, an inhibitor of insulin receptor, largely abolished the insulin-dependent E-LTP in immature rats rather than adult rats, indicating the involvement of insulin signaling pathway in the insulin effect. On the other hand, increasing the concentration of glucose from 11mM to 22 or 33 mM did not facilitate the E-LTP and application of indinavir, a blocker of insulin-sensitive glucose transporter-4, did not inhibit the effect of insulin. Therefore, it is unlikely that the facilitory action of insulin on E-LTP is via an indirect effect on glucose homeostasis or utilization. Pretreatment with the MAPK pathway inhibitor PD98059 blocked insulin-mediated E-LTP facilitation. Furthermore, the tetanic stimulation induced a significant increase in the level of phosphorylated p42MAPK in the insulin-treated hippocampus than that in the control group. In conclusion, our results suggested that insulin could facilitate the production of hippocampal E-LTP in infant rats, which may play an important role in modulating the expression of LTP in the developing brain and perhaps is an underlying mechanism for the improving effect of insulin on learning and memory. Since insulin plays an important role in the developing brain, perhaps the deficiency of insulin effect resulted from CF patients induces the impairment of cognitive function. / Cystic fibrosis (CF), which is caused by the deficiency of cystic fibrosis transmembrne conductance regulator (CFTR), is the most common autosomal recessive systemic disease with an incidence of 1: 2500 in Caucasians. Cystic fibrosis-related diabetes (CFRD), as one of the complications of CF patients, is regarded as one of the leading co-morbidity in CF patients. The mechanism ofCFRD is attributed to the reduced number of islets due to pancreatic fibrosis caused by the loss of CFTR in pancreatic duct. However, the above mechanism failed to explain the dynamics of insulin secretion induced by glucose tolerance test (GTT) in some CF patients and therefore, we were forced to re-consider the mechanism for the pathogenesis of CFRD. Interestingly, the following facts imply that perhaps there is another mechanism for the onset of CFRD: decreased insulin secretion and decreased plasma HCO3 - concentration was observed in the metabolic acidosis disease, plasma HCO3- level increased accompanied by the elevation of plasma insulin after food intake and CFTR accounted for HCO3 - transport in many epithelial cells. These facts promoted us to hypothesize that the loss of HCO3--induced insulin secretion resulting from the deficiency of CFTR is an alternative mechanism for the onset of CFRD. Our results showed that HCO3- could induce insulin secretion of isolated islets from rats. Ca2+ imaging revealed that HCO3- dose-dependently induced an increase in intracellular Ca2+ ([Ca2+] i) in RIN-5F cells, an insulin-secreting cell line. Removal of extracellular Ca2+ or addition of nifedipine, the blocker of L-type Ca 2+ channel, decreased the effect of HCO3- significantly, indicating the activation of L-type Ca2+ channel during HCO3- stimulation. The inhibitory effect of BaCl2 implied the involvement of K+ channel. The results that HCO3--induced increase in [Ca 2+]i was reduced by PKA inhibitor and sAC blocker demonstrated that the pathway of sAC-cAMP-PKA-ATP-sentitive K+ channel (K ATP channel) was responsible for the effect of HCO3 -. The reduction of extracellular Cl- or the inhibitor of anion exchanger (AE) inhibited the [Ca2+]i increase induced by HCO3- significantly but the omission of external Na+ failed. The facts that CFTR blocker decreased the effect of HCO3- markedly and the expression of CFTR in RIN-5F cells revealed by western blotting suggested the CFTR-mediated HCO3- transport. These results suggested that HCO 3- could induce insulin secretion in a CFTR-dependent manner, which provided a new insight into the understanding of pathogenesis of CFRD and paved the way for the therapy of CFRD. / Zhao, Wenchao. / "November 2010." / Advisers: Chang Chan; Wing Ho Yung. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 115-138). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Pancreatic cancer is one of the most devastating human cancers with the lowest survival rate among 24 commonly diagnosed cancers. It is the seventh and the sixth leading cause of cancer-related deaths in the world and Hong Kong respectively. The current pancreatic cancer treatment options, have limited efficacy and undesirable side effects. Because of the high mortality rate and unsatisfactory treatment outcome, it is necessary to develop new strategies for pancreatic cancer therapy. / In human, an abundant arginine reserve is known to be crucial for tumor cell proliferation. Arginine is a semi-essential amino acid because most of the somatic cells can re-synthesize it from other metabolites like citrulline in urea cycle. However, arginine auxotrophy is observed in certain tumors, such as hepatocarcinoma, melanoma and sarcoma, where restriction or depletion of arginine will lead to tumor death. Further studies have found that deficiency in either argininosuccinate synthetase 1 (ASS1) or ornithine transcarbamylase (OTC) expression contributes to arginine auxotrophy in these tumors. These findings implicated the potential of using arginine deprivation as a novel pancreatic cancer treatment strategy. / PEG-BCT-100 is a pegylated recombinant human arginase that metabolizes arginine into urea and ornithine. This study examined the preclinical anti-tumor efficacy of PEG-BCT-100 and the underlying mechanism in pancreatic cancer. Six pancreatic cancer cell lines AsPC-1, BxPC-3, CFPAC-1, Capan-2, MIA PaCa-2 and Panc10.05 were used as in vitro cell model. Cell growth was either completely stopped or dramatically reduced in arginine-free medium, suggesting pancreatic cancer cells were arginine auxotrophic. The protein and mRNA expression levels of the ASS1, OTC and argininosuccinate lyase (ASL), which are enzymes involved in arginine, were studied. The results showed that ASL was highly expressed in all cell lines, suggesting it is not an essential regulator in arginine auxotrophy in pancreatic cancer. On the other hand, ASS1 was only detected in BxPC-3 and CFPAC-1, while OTC was undetectable in all cell lines in both mRNA and protein levels. The effect of PEG-BCT-100 was illustrated via cell cycle progression, cell proliferation and viability. Single drug effect combining PEG-BCT-100 with other anti-tumor drugs, such as 5-FU and gemcitabine, was further explored. Synergistic effect of PEG-BCT-100 and gemcitabine under combination of PEG-BCT-100 and gemcitabine was observed in CFPAC-1 and MIA PaCa-2. Overexpression of OTC and ASS1 decreased the sensitivity of towards PEG-BCT-100 significantly. Taken together, OTC deficiency is a potential indicative marker for the sensitivity of arginine depletion treatment in pancreatic cancer. / 胰腺癌是最具毀滅性的人類癌症之一，在二十四種常見的癌症中，它有着最低的存活率。儘管不在發病率最高的十種癌症中，胰腺癌仍舊是世界第七大致死癌症，以及香港第六大致死癌症。手術治療，放射治療，以及化學藥物治療是現今常用的胰腺癌治療手段，但是這些療法不是限制繁多，就是收效甚微，並常常伴有強烈的副作用。由於胰腺癌具有很高的致死率以及缺乏有效的治療方法，所以新的治療策略亟待開發。 / 於人類而言，精氨酸是一種半必需氨基酸，因爲它可以通過尿素循環中的其他代謝產物，如鳥氨酸以及瓜氨酸，重新合成。然而，精氨酸缺陷出現在多種腫瘤中，像肝癌，黑色素瘤，以及血癌。限制或者減少精氨酸的供應會導致這些腫瘤死亡。除此之外，腫瘤細胞的快速生長也依賴於充足的精氨酸。進一步的研究表明，在這些腫瘤中，精氨琥珀酸合成酶1（ASS1）或者鳥氨酸氨甲醯基轉移酶（OTC）的任意一個缺乏都會導致精氨酸缺陷。本文將探討將剝奪精氨酸作爲一種新策略來治療胰腺癌的可行性。 / PEG-BCT-100又名金氨素，是一種聚乙二醇化重組人精氨酸酶，它可以催化精氨酸分解爲尿素和鳥氨酸。我們研究了PEG-BCT-100在胰腺癌細胞中的抗癌效果以及探討了與其相關的作用機理。在我們的研究中，AsPC-1, BxPC-3, CFPAC-1, Capan-2, MIA PaCa-2以及Panc10.05這六個細胞株用作體外的細胞模型。爲了評估PEG-BCT-100治療胰腺癌的可行性，我們首先調查了精氨酸對胰腺癌細胞的重要性。通過將這些胰腺癌細胞培養在有精氨酸供應和沒有精氨酸供應的完全培養基中，我們發現剝奪精氨酸能完全停止或者極大地減少了胰腺癌細胞的生長。這說明了這些胰腺癌細胞也都是精氨酸營養缺陷型的細胞。通過蛋白印跡和實時定量聚合酶鏈式反應實驗，我們進一步研究了精氨酸代謝相關基因在這些胰腺癌細胞中的表達水平。結果表明，精氨琥珀酸裂解酶（ASL）在全部的六條細胞系中都有被檢測到。ASS1只出現在BxPC-3和CFPAC-1中。然而在全部的細胞中，無論是蛋白質水平還是mRNA水平，OTC都沒有被檢測到。緊接着，我們研究了PEG-BCT-100在胰腺癌細胞活力，細胞增殖，細胞週期以及細胞凋亡等方面的影響。結果表明，PEG-BCT-100可以從多個方面抑制胰腺癌細胞。我們還嘗試探索了PEG-BCT-100與其他胰腺癌治療藥物在胰腺癌細胞中的聯合使用效果。然後發現PEG-BCT-100與吉西他滨（gemcitabine）聯合使用具有協同效果。最後，我們構建了四種不同表達類型的MIA PaCa-2細胞模型：（ASS1-/OTC-）, (ASS1-/OTC+), (ASS1+/OTC-)以及(ASS1+/OTC+)。接着我們測試了PEG-BCT-100在這些細胞模型中的效果。結果表明，同時在MIA PaCa-2細胞中表達ASS1和OTC可以明顯地提高其對PEG-BCT-100的抗性，單表達其中一個基因對PEG-BCT-100的抗性也有些許提高，但效果不如雙表達明顯。 / 總而言之，對於胰腺癌細胞而言，精氨酸是必不可少的。PEG-BCT-100有很明顯的胰腺癌效果。在胰腺癌中，OTC的表達情況可以作爲預估PEG-BCT-100治療效果的重要生物標誌。 / Deng, Haohao. / Thesis M.Phil. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 111-117). / Abstracts also in Chinese. / Title from PDF title page (viewed on 14, October, 2016). / Deng, Haohao. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

Pancreatic Ductal Adenocarcinoma (PDAC) affects approximately 8000 people every year in the UK and is the fifth leading cause of cancer related death. At a molecular level PDAC is characterized by a significant immune infiltrate. Tumour-associated macrophages (TAMs) infiltrate the tumour and contribute to a worse prognosis by promoting growth, metastasis and resistance to chemotherapy. TAMs are derived from circulating ‘classical’ CD14++ CD16- monocytes in the peripheral blood. Current work in murine models suggests targeting monocyte recruitment in PDAC can reduce TAM infiltration and disease burden therefore improving survival. This project aims to identify markers specific to monocytes from PDAC patients and to investigate their biological relevance and potential for therapeutic intervention. Gene expression and metabolomics analysis was carried out on classical CD14++ CD16- monocytes from locally advanced PDAC patients and age matched healthy donors. Transcriptomic profiling revealed a significantly altered gene expression profile in classical monocytes from patients and genes with the highest fold change difference were chosen for validation using qPCR. Validated gene targets were investigated further in vitro and large-scale gene expression analysis from pancreatic tumours assessed. The results from my work demonstrate that the gene expression profile of classical monocytes from PDAC patients is significantly different compared to healthy volunteers. Identification and validation of up-regulated genes and their biological relevance may represent a relevant novel novel biomarker or therapeutic strategyies to target monocytes and myeloid recruitment in cancer.

Li, Chi Han Samson. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 158-175). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.