RESUMEN
There are a limited number of therapies available to prevent heart failure following myocardial infarction. One novel therapy that is currently being pursued is the implantation of cardiac progenitor cells (CPCs); however, their responses to oxidative stress during differentiation have yet to be elucidated. The objective of this study was to determine the effect of hydrogen peroxide (H2O2) treatment on CPC differentiation in vitro, as well as the effect of H2O2 preconditioning before implantation following ischemia-reperfusion (I/R) injury. CPCs were isolated and cloned from adult rat hearts, and then cultured in the absence or presence of H2O2 for 2 or 5 days. CPC survival was assessed with Annexin V, and cellular differentiation was evaluated through mRNA expression for cardiogenic genes. We found that 100 µM H2O2 decreased serum withdrawal-induced apoptosis by at least 45% following both 2 and 5 days of treatment. Moreover, 100 µM H2O2 treatment for 2 days significantly increased endothelial and smooth muscle markers compared to time-matched untreated CPCs. However, continued H2O2 treatment significantly decreased these markers. Left ventricular cardiac function was assessed 28 days after I/R and I/R with the implantation of Luciferase/GFP(+) CPCs, which were preconditioned with 100 µM H2O2 for 2 days. Hearts implanted with Luciferase/GFP(+) CPCs had significant improvement in both positive and negative dP/dT over I/R. Furthermore, cardiac fibrosis was significantly decreased in the preconditioned cells versus both I/R alone and I/R with control cells. We also observed a significant increase in endothelial cell density in the preconditioned CPC hearts compared to untreated CPC hearts, which also coincided with a higher density of Luciferase(+) vessels. These findings suggest that preconditioning of CPCs with H2O2 for 2 days stimulates neoangiogenesis in the peri-infarct area following I/R injury and could be a viable therapeutic option to prevent heart failure.
Asunto(s)
Insuficiencia Cardíaca/prevención & control , Peróxido de Hidrógeno/farmacología , Infarto del Miocardio/tratamiento farmacológico , Daño por Reperfusión/tratamiento farmacológico , Células Madre/efectos de los fármacos , Animales , Apoptosis/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Células Cultivadas , Fibrosis/tratamiento farmacológico , Expresión Génica , Insuficiencia Cardíaca/tratamiento farmacológico , Peróxido de Hidrógeno/metabolismo , Precondicionamiento Isquémico Miocárdico/métodos , Masculino , Contracción Miocárdica/efectos de los fármacos , Neovascularización Fisiológica/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Células Madre/metabolismo , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
The causality of the associations between cellular and mechanical mechanisms of abdominal aortic aneurysm (AAA) formation has not been completely defined. Because reactive oxygen species are established mediators of AAA growth and remodeling, our objective was to investigate oxidative stress-induced alterations in aortic biomechanics and microstructure during subclinical AAA development. We investigated the mechanisms of AAA in an angiotensin II (ANG II) infusion model of AAA in apolipoprotein E-deficient (apoE(-/-)) mice that overexpress catalase in vascular smooth muscle cells (apoE(-/-)xTg(SMC-Cat)). At baseline, aortas from apoE(-/-)xTg(SMC-Cat) exhibited increased stiffness and the microstructure was characterized by 50% more collagen content and less elastin fragmentation. ANG II treatment for 7 days in apoE(-/-) mice altered the transmural distribution of suprarenal aortic circumferential strain (quantified by opening angle, which increased from 130 ± 1° at baseline to 198 ± 8° after 7 days of ANG II treatment) without obvious changes in the aortic microstructure. No differences in aortic mechanical behavior or suprarenal opening angle were observed in apoE(-/-)xTg(SMC-Cat) after 7 days of ANG II treatment. These data suggest that at the earliest stages of AAA development H(2)O(2) is functionally important and is involved in the control of local variations in remodeling across the vessel wall. They further suggest that reduced elastin integrity at baseline may predispose the abdominal aorta to aneurysmal mechanical remodeling.
Asunto(s)
Aorta Abdominal/enzimología , Aneurisma de la Aorta Abdominal/enzimología , Aneurisma de la Aorta Abdominal/prevención & control , Presión Sanguínea , Catalasa/metabolismo , Peróxido de Hidrógeno/metabolismo , Análisis de Varianza , Angiotensina II , Animales , Aorta Abdominal/patología , Aorta Abdominal/fisiopatología , Aneurisma de la Aorta Abdominal/inducido químicamente , Aneurisma de la Aorta Abdominal/genética , Aneurisma de la Aorta Abdominal/patología , Aneurisma de la Aorta Abdominal/fisiopatología , Apolipoproteínas E/deficiencia , Apolipoproteínas E/genética , Fenómenos Biomecánicos , Catalasa/genética , Colágeno/metabolismo , Modelos Animales de Enfermedad , Elastina/metabolismo , Ratones , Ratones Noqueados , Ratones Transgénicos , Estrés Mecánico , Factores de Tiempo , Regulación hacia ArribaRESUMEN
BACKGROUND: Reactive oxygen species, such as hydrogen peroxide (H(2)O(2)), contribute to progression of dysfunction after myocardial infarction (MI). However, chronic overexpression studies do not agree with acute protein delivery studies. The purpose of the present study was to assess the temporal role of cardiomyocyte-derived H(2)O(2) scavenging on cardiac function after infarction using an inducible system. METHODS AND RESULTS: We developed a tamoxifen-inducible, cardiomyocyte-specific, catalase-overexpressing mouse. Catalase overexpression was induced either 5 days before or after MI. Mice exhibited a 3-fold increase in cardiac catalase activity that was associated with a significant decrease in H(2)O(2) levels at both 7 and 21 days. However, cardiac function improved only at the later time point. Proinflammatory and fibrotic genes were acutely upregulated after MI, but catalase overexpression abolished the increase despite no acute change in function. This led to reduced overall scar formation, with lower levels of Collagen 1A and increased contractile Collagen 3A expression at 21 days. CONCLUSIONS: In contrast to prior studies, there were no acute functional improvements with physiological catalase overexpression before MI. Scavenging of H(2)O(2), however, reduced proinflammatory cytokines and altered cardiac collagen isoforms, associated with an improvement in cardiac function after 21 days. Our results suggest that sustained H(2)O(2) levels rather than acute levels immediately after MI may be critical in directing remodeling and cardiac function at later time points.
Asunto(s)
Catalasa/genética , Catalasa/metabolismo , Infarto del Miocardio/metabolismo , Miocardio/metabolismo , Recuperación de la Función/fisiología , Animales , Catalasa/efectos de los fármacos , Colágeno Tipo I/metabolismo , Colágeno Tipo III/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Peróxido de Hidrógeno/metabolismo , Masculino , Ratones , Ratones Transgénicos , Modelos Animales , Infarto del Miocardio/fisiopatología , Tamoxifeno/farmacologíaRESUMEN
OBJECTIVE: Current understanding of shear-sensitive signaling pathways has primarily been studied in vitro largely because of a lack of adequate in vivo models. Our objective was to develop a simple and well-characterized murine aortic coarctation model to acutely alter the hemodynamic environment in vivo and test the hypothesis that endothelial inflammatory protein expression is acutely upregulated in vivo by low-magnitude oscillatory wall shear stress (WSS). METHODS AND RESULTS: Our model uses the shape memory response of nitinol clips to reproducibly induce an aortic coarctation and allow subsequent focal control over WSS in the aorta. We modeled the corresponding hemodynamic environment using computational fluid dynamics and showed that the coarctation produces low-magnitude oscillatory WSS distal to the clip. To assess the biological significance of this model, we correlated WSS to inflammatory protein expression and fatty streak formation. Vascular cell adhesion molecule-1 expression and fatty streak formation were both found to increase significantly in regions corresponding to acutely induced low-magnitude oscillatory WSS. CONCLUSIONS: We have developed a novel aortic coarctation model that will be a useful tool for analyzing the in vivo molecular mechanisms of mechanotransduction in various murine models.