No description available.

No description available.

Micro-encapsulation of heart explant-derived stem cells (EDCs) within protective nanoporous gel (NPG) cocoons improves cardiac function and long-term retention of transplanted cells after ischemic injury by limiting detachment induced cell death and vascular clearance of intramyocardial injected cells. Although cocooned EDCs boost cardiac function, the fundamental mechanism is unclear. Here, we investigate the effects of altering cocoon stiffness and size on human EDC mediated repair of damaged myocardium using an immunodeficient mouse model of ischemic cardiomyopathy. First, we found that increasing cocoon stiffness by altering NPG content boosted cell viability and migration; effectively forcing cocooned cells to adopt a migratory, invasive phenotype. Although cocooning improved retention of transplanted cells, increasing cocoon stiffness had no additional effects on long-term engraftment despite markedly improving cardiac function and fibrosis after myocardial infarction. Given increased cocoon stiffness boosted the production and microRNA cargo within EDC nanovesicles, the observed benefits in post-ischemic function are likely dependent more on paracrine production of transplanted cells rather than simply increasing the number of cells retained. The effect of cocoon diameter on EDC phenotype and cell mediated repair of ischemic myocardium was evaluated using microfluidic-based cocooning enabling deterministic encapsulation within defined cocoon size and intracapsular cell number while maintaining a fixed cocoon stiffness. Increased cocoon size enhanced post-ischemic cardiac function by reducing clearance of transplanted cells and increased paracrine stimulation of endogenous repair. The latter being attributable to microfluidic cocooning closely following the expected Poisson distribution with smaller cocoons having a greater proportion of single cells while larger cocoons contained greater proportions of multicellular aggregates which enhanced cell-cell interactions to increase the amount and breadth of cytokines/nanoparticles delivered to injured myocardium. In conclusion, altering the biophysical properties of NPG surrounding cocooned cells provides a straightforward means of boosting the regenerative potential of heart EDCs for repair of injured myocardium.

Made available in DSpace on 2015-04-20T12:31:47Z (GMT). No. of bitstreams: 1 Jaime Arnez.pdf: 2202191 bytes, checksum: 2925f1eec50bb2ccb5e644dc0dad1780 (MD5) Previous issue date: 2013-03-30 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Heart failure (HF) affects approximately 2% of the world population. Ischemic cardiomyopathy accounts for two-thirds of cases of HF, which, when established, leads to physical limitations, multiple hospital admissions, declining quality of life, and increasing morbidity and mortality. Therapeutic alternatives range from pharmacological treatment to heart transplantation. Modern reperfusion strategies and advanced pharmacotherapeutic management have contributed to increase the survival of patients with ischemic cardiomyopathy, but none of these treatment strategies can reverse damage to cardiomyocytes or recover lost vasculature. Within this context, the concept of regenerative medicine, using stem cells (SC) for tissue repair, may become a reality. Mobilization and implantation of autologous, CD34+ hematopoietic SCs may improve myocardial function and perfusion. A total of 15 patients with severe ischemic cardiomyopathy, not eligible for other therapeutic alternatives, received autologous CD34+ cells collected from peripheral blood (PB) after G-CSF mobilization. SCs collected from PB were implanted in the myocardium using two routes (intracoronary and via the coronary sinus). All patients underwent clinical, laboratory, and imaging-based assessment to evaluate left ventricular function, perfusion and voltage. All patients were reevaluated after 4 months of post-implantation follow-up. Of the 15 initial patients, two died during follow-up (late post-implantation mortality). The different variables analyzed at 4-month follow-up showed improvement in functional classification (p=0.014), angina score (CCS) (p=0.006), the six-minute walk test (p=0.005), and quality of life (p=0.003). There was minor improvement in ejection fraction, as analyzed by echocardiography and magnetic resonance imaging, without reaching statistical significance (p=0.062 and p=0.0397 respectively); myocardial perfusion scintigraphy showed a non-significant improvement in viability (20.79% to 27.14%, p=0.390). Electroanatomic mapping of the left ventricle did not show any significant changes in electrical activity (p=0.767). CD34+ SC implantation into the myocardium using two routes simultaneously is a safe procedure. At 4-month follow-up, patients experienced improvement in symptoms and quality of life, but without significant improvement in left ventricular function, perfusion and voltage. Key words: Cell therapy, G-CSF, CD34+, ischemic cardiomyopathy / A insuficiência cardíaca (IC) acomete aproximadamente 2% da população mundial. A cardiopatia isquêmica é responsável por 2/3 da IC, a qual, quando estabelecida, implica limitações físicas, repetidas internações hospitalares, piora da qualidade de vida e aumento da morbimortalidade. As alternativas terapêuticas variam desde o tratamento farmacológico até o transplante cardíaco. Modernas estratégias de reperfusão e avançadas condutas farmacológicas têm propiciado um aumento na sobrevida dos pacientes com cardiopatia isquêmica, porém nenhuma estratégia de tratamento recupera o dano aos cardiomiócitos e à vasculatura perdida; é nesse sentido que o conceito de medicina regenerativa utilizando células-tronco (CT) para o reparo de tecidos pode tornar-se realidade. A mobilização e implante autólogo de CT hematopoéticas CD34+ podem melhorar a função e perfusão. Um total de 15 pacientes com cardiopatia isquêmica grave, inelegíveis para outra alternativa terapêutica, receberam células autólogas CD34+ coletadas de sangue periférico (SP), previamente mobilizadas com fator de estimulação de colônias de granulócitos (G-CSF). As CT coletadas de SP foram implantadas no miocárdio utilizando duas vias (intracoronariana e seio coronariano). Realizou-se em todos os pacientes uma avaliação clínica, laboratorial e exames complementares de imagem para avaliar função, perfusão e voltagem do ventrículo esquerdo. Após 4 meses de seguimento pós-implante, todos os pacientes foram reavaliados. Dos 15 pacientes incluídos, dois foram a óbito durante o seguimento (pós-implante tardio). As diferentes variáveis analisadas no seguimento de 4 meses mostraram uma melhora na classe funcional (p = 0,014), escore de angina (Canadian Cardiovascular Society) (p = 0,006), teste da caminhada de 6 minutos (p = 0,005) e qualidade de vida (p = 0,003). A fração de ejeção analisada por ecocardiograma e ressonância magnética mostrou uma discreta melhora, porém sem significância estatística (p = 0,062 e p = 0,0397); a cintilografia do miocárdio mostrou uma melhora da viabilidade, porém sem significância (20,79 para 27,14%; p = 0,390); a atividade elétrica do ventrículo esquerdo realizada através do mapeamento eletroanatômico não mostrou alterações significativas (p = 0,767). O implante de CT CD34+ no miocárdio utilizando duas vias simultâneas é seguro. No seguimento de 4 meses os pacientes apresentaram uma melhora em relação à sintomatologia e qualidade de vida, porém sem melhora significativa na função, perfusão e voltagem do ventrículo esquerdo

Hydrogen sulfide (H2S) is a gasotransmitter that has shown cardioprotective effects in the setting of myocardial injury such as acute myocardial infarction (MI) and pressure overload-induced heart failure. However, there are shortcomings in precision and control release from the use of traditional formulations of H2S in the form of inorganic salts. In this thesis, we sought to determine if the novel, orally active, slow-releasing H2S-compound SG1002 plays a role in attenuating MI-induced left ventricular (LV) dysfunction and adverse remodeling. We also evaluated the effect of SG1002 on changes in ECG parameters such as QT interval, in addition to 28-day survival post MI. SG1002 protects against ischemic cardiomyopathy in mice by mitigating LV dysfunction as measured by echocardiography and decreasing LV scar size as measured by histopathological methods. The improvement in survival might be due to the reduction in QT interval prolongation hence lessening the likelihood of forming lethal arrhythmias post MI. Western blot analyses of SG1002 treated mice showed restoration of VEGF levels indicating a pivotal role played by pro-angiogenic signaling in the improvement of cardiac function and attenuation of adverse remodeling. We propose that SG1002 can be a promising pharmacotherapeutic means for the treatment of ischemic heart failure.

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第13380号 / 論医博第2214号 / 新制||医||1047(附属図書館) / 京都大学大学院医学研究科外科系専攻 / (主査)教授 山下 潤, 教授 木村 剛, 教授 浅野 雅秀 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

Dilated (DCM) and ischemic cardiomyopathies (ICM) are associated with cardiac remodeling, where the ubiquitin–proteasome system (UPS) holds a central role. Little is known about the UPS and its alterations in patients suffering from DCM or ICM. The aim of this study is to characterize the UPS activity in human heart tissue from cardiomyopathy patients. Myocardial tissue from ICM (n = 23), DCM (n = 28), and control (n = 14) patients were used to quantify ubiquitinylated proteins, E3-ubiquitin-ligases muscle-atrophy-F-box (MAFbx)/atrogin-1, muscle-RING-finger-1 (MuRF1), and eukaryotic-translation-initiation-factor-4E (eIF4E), by Western blot. Furthermore, the proteasomal chymotrypsin-like and trypsin-like peptidase activities were determined fluorometrically. Enzyme activity of NAD(P)H oxidase was assessed as an index of reactive oxygen species production. The chymotrypsin- (p = 0.71) and caspase-like proteasomal activity (p = 0.93) was similar between the groups. Trypsin-like proteasomal activity was lower in ICM (0.78 ± 0.11 µU/mg) compared to DCM (1.06 ± 0.08 µU/mg) and control (1.00 ± 0.06 µU/mg; p = 0.06) samples. Decreased ubiquitin expression in both cardiomyopathy groups (ICM vs. control: p < 0.001; DCM vs. control: p < 0.001), as well as less ubiquitin-positive deposits in ICM-damaged tissue (ICM: 4.19% ± 0.60%, control: 6.28% ± 0.40%, p = 0.022), were detected. E3-ligase MuRF1 protein expression (p = 0.62), NADPH-oxidase activity (p = 0.63), and AIF-positive cells (p = 0.50). Statistical trends were detected for reduced MAFbx protein expression in the DCM-group (p = 0.07). Different levels of UPS components, E3 ligases, and UPS activation markers were observed in myocardial tissue from patients affected by DCM and ICM, suggesting differential involvement of the UPS in the underlying pathologies.

No description available.

Le syndrome d’apnées obstructives du sommeil (SAOS) est un problème de santé publique majeure affectant 6-13% de la population d’âge moyen. Des études épidémiologiques et l’accumulation de données cliniques ont montré que le SAOS joue un rôle important dans l’initiation et la progression des pathologies cardiovasculaires (CV) comme l’infarctus du myocarde (IM). Les patients hospitalisés post-IM présentent une prévalence pour le SAOS de l’ordre de 50%. De plus, le SAOS augmente la vulnérabilité du cœur à l’infarctus, ce qui se traduit par une taille d’IM plus grande, une ischémie myocardique prolongée, et une aggravation des évènements cardiovasculaires au long-terme, prédisposant les patients apnéiques à des infarctus surnuméraires, à l’insuffisance cardiaque (IC) et au décès. Il semble donc important de comprendre précisément les mécanismes impliqués dans cette susceptibilité accrue à l’ischémie myocardique afin de proposer de nouvelles cibles thérapeutiques et améliorer la prise en charge du risque CV chez les patients apnéiques. L’hypoxie intermittente chronique (HI) est le substrat physiopathologique majeur des complications CV du SAOS via l’activation de mécanismes physiopathologiques variés, tels que l’inflammation, le stress oxydant ou encore l’activation sympathique. Ce travail de thèse avait pour but de 1) caractériser la réponse aigue et chronique à l’IM chez des animaux exposés à l’HI, 2) de disséquer les mécanismes cellulaires impliqués dans la susceptibilité accrue à l’IM chez ces mêmes animaux.Nos travaux ont confirmé que l’HI induit une majoration de la taille d’infarctus suite à un évènement ischémique aigue et aggrave le remodelage cardiaque et la dysfonction contractile dans un modèle de cardiopathie ischémique chronique chez le rat. Nous avons également mis en évidence que l’HI induisait dans ce contexte une hyperactivation sympathique persistante, un stress du RE proapoptotique et l’activation du facteur de transcription HIF-1 contribuant à l’augmentation de la vulnérabilité du cœur à l’infarctus et l’aggravation post-IM des complications cardiaques au long-terme. Ces différents facteurs pourraient représenter des biomarqueurs intéressants pour prédire le risque CV chez les patients apnéiques sévères et pourraient être considérés comme des pistes thérapeutiques potentielles pour améliorer la prise en charge des patients SAOS à haut risque CV. / Obstructive sleep apnea syndrome (OSA) is a common disease that affects 6-13% of the middle-aged population. Epidemiological and clinical data support the notion that OSA has a role in the initiation or progression of several cardiovascular (CV) diseases, including myocardial infarction (MI). Indeed, patients hospitalized with acute MI present high prevalence for OSA. Furthermore, OSA is known to major infarct size in patients that persists over time and aggravates long-term adverse events post-MI, as reinfarction, heart failure (HF) and death. OSA is characterized by intermittent hypoxia (IH) which results in desaturation-reoxygenation sequences and appears to be the major consequence of OSA in term of cardiovascular alterations associated with apneas. However, the mechanisms remain unclear. Therefore, the understanding of pathophysiologic mechanisms involved in cardiac disorders is a research priority for OSA in order to develop new therapeutic targets and improve the management of CV risk in apneic patients. There are growing evidences suggesting a major role of endoplasmic reticulum (ER) stress and HIF-1 activation in the vulnerability to acute ischemic events and in long-term adverse complications associated with prolonged MI. Furthermore, the progression of ischemic cardiomyopathy following MI is also associated with activation of the sympathetic nervous system which substantially contributes to cardiac alterations. Furthermore, these are three mechanisms known to be activated with IH. This project aimed 1) to assess the IH-induced acute and chronic cardiac alterations following MI, 2) to study the implication of cellular mechanisms involved in the adverse ischemic events related to OSA.We have shown that IH increases infarct size following acute MI and aggravates cardiac remodeling and contractile dysfunction in a rat model of chronic ischemic cardiomyopathy. In these contexts, IH is associated with a sympathetic over activity, a proapoptotic ER stress and the activation of HIF-1, which substantially contribute to increased heart vulnerability to infarction and worsening of long-term heart complications post-MI. These different factors may represent interesting biomarkers for predicting CV risk in severe apneic patients and may be considered as potential therapeutic targets to improve the management of OSA patients with high CV risks.