RESUMO
"Epigenetherapy" alters epigenetic status of the targeted chromatin and modifies expression of the endogenous therapeutic gene. In this study we used lentiviral in vivo delivery of small hairpin RNA (shRNA) into hearts in a murine infarction model. shRNA complementary to the promoter of vascular endothelial growth factor (VEGF-A) was able to upregulate endogenous VEGF-A expression. Histological and multiphoton microscope analysis confirmed the therapeutic effect in the transduced hearts. Magnetic resonance imaging (MRI) showed in vivo that the infarct size was significantly reduced in the treatment group 14 days after the epigenetherapy. Importantly, we show that promoter-targeted shRNA upregulates all isoforms of endogenous VEGF-A and that an intact hairpin structure is required for the shRNA activity. In conclusion, regulation of gene expression at the promoter level is a promising new treatment strategy for myocardial infarction and also potentially useful for the upregulation of other endogenous genes.
Assuntos
Epigênese Genética , Infarto do Miocárdio/genética , Infarto do Miocárdio/patologia , Regulação para Cima/genética , Fator A de Crescimento do Endotélio Vascular/genética , Animais , Sequência de Bases , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Metilação de DNA , Inativação Gênica , Sequências Repetidas Invertidas/genética , Masculino , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Infarto do Miocárdio/metabolismo , Fosfoproteínas/metabolismo , Regiões Promotoras Genéticas/genética , Isoformas de Proteínas/genética , RNA Interferente Pequeno/genética , Transcrição Gênica/genética , Ativação TranscricionalRESUMO
Longitudinal relaxation time in the rotating frame (T1ρ) was measured using continuous wave irradiation in normal and infarcted mouse myocardium in vivo. Significant increase in T1ρ was found after 7 days of infarction when compared with reference myocardium or in myocardium before infarction. Cine MRI and histology were performed to verify the severity of infarction. The time course of T1ρ in the infarct fits better with granulation and scar tissue formation than necrosis and edema. The results of the study show that T1ρ could potentially be a noninvasive quantitative marker for tissue remodeling after ischemic damage.