Orientador: Luiz Henrique de Araújo Machado / Resumo: O diabetes mellitus (DM) é uma das doenças que mais tem aumentado sua incidência na última década. As células-tronco mesenquimais derivadas de tecido adiposo (CTMs-TA) possuem características imunomoduladoras e reparadoras, sendo capazes de reverter efeitos sistêmicos da doença. Sendo assim, nosso trabalho teve como objetivo avaliar o impacto do transplante de CTMs-TA pelas vias intravenosa, intrapancreática e intra-capsular renal em ratos diabéticos e comparar a que melhor exerce efeito regenerador. Para o estudo, utilizamos 45 ratos, wistar, fêmeas, divididos em 5 grupos: GCS – controle sadio; GCD – controle diabético; GIV – diabético, via intravenosa; GIP – diabético, via intrapancreática; GIR – diabético, via cápsula renal. Para a indução, utilizamos uma única aplicação intraperitoneal (i.p) de Aloxana (120mg/kg), e após 3 dias, os animais foram submetidos ao transplante com as CTMs-TA (2x106cel/animal). Após 15 dias do transplante, os animais foram eutanasiados. O transplante de CTMs-TA pela cápsula renal foi capaz de reverter a hiperglicemia, além de restaurar o diâmetro das ilhotas e restabelecer a função das massa β-pancreática. Concluímos que a cápsula renal foi a que apresentou melhores resultados na regeneração morfofuncional do pâncreas diabético. As CTMs-TA utilizadas neste estudo foram capazes de exercer um importante efeito parácrino, podendo ser utilizadas como alternativa para a melhoria da qualidade de vida de indivíduos diabéticos. / Mestre

Several studies have shown cellular replacement therapy as a treatment strategy of myocardial infarction but results have been limited. Therefore, enhancing the therapeutic potential of stem cells injected into ischemic microenvironments by novel preconditioning (PC) techniques is critical for improving cellular therapy. Recent studies have shown that inhibition of phosphodiesterase-5 (PDE-5) is a powerful strategy to precondition the heart and cardiomyocytes against ischemia/reperfusion injury. We therefore tested the hypothesis that inhibition of PDE-5 with sildenafil (Viagra®) or selective knockdown with a silencing vector in adipose derived stem cells (ASCs) would improve their survival after ischemia/reoxygenation in vitro and enhance cardiac function following myocardial implantation in vivo. ASCs were treated with sildenafil or infected with PDE-5 silencing vector shRNA (shRNAPDE-5). The cells were subjected to simulated ischemia (SI) and reoxygenation (RO). Both sildenafil and shRNAPDE-5 significantly reduced cell injury, as shown by improved viability, decreased lactate dehydrogenase, and apoptosis. The preconditioned ASCs also demonstrated an increase in the release of growth factors including VEGF, b-FGF, and IGF. The protective effect against SI/RO injury was abolished by inhibition of protein kinase G (PKG) using both a pharmacological inhibitor and selective knockdown with shRNAPKG1α suggesting a PKG-mediated mechanism. To show the effect of preconditioned ASCs in vivo, adult male CD-1 mice underwent myocardial infarction (MI) by occlusion of the left descending coronary artery, followed by direct injection of PBS (control), non-preconditioned ASCs, or preconditioned ASCs (4x105) ASCs into the left ventricle (LV). Preconditioned ASC-treated hearts showed consistently superior cardiac function by all measures as compared with PBS and non-preconditioned ASCs after 4 weeks of treatment. Post-mortem histological analysis demonstrated that preconditioned ASC-treated mice had significantly reduced fibrosis, increased vascular density and reduced resident myocyte apoptosis as compared to mice receiving non-preconditioned ASCs or PBS. VEGF, b-FGF, and Ang-1 were also significantly elevated 4 weeks after cell therapy with preconditioned ASCs. Our data suggests that genetic or pharmacological inhibition of PDE-5 is a powerful new approach to improve stem cell therapy following myocardial infarction.