Novel technique of aortic banding followed by gene transfer during hypertrophy and heart failure

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Abstract
Aortic banding in the rat has become a popular method to induce left ventricular (LV) hypertrophy and heart failure. However, because of often extensive intrathoracic adhesions and inflammatory cell infiltrates resulting from the traditional surgical approach, an uncomplicated second thoracic incision for genetic manipulation is impeded. In this study, we describe a novel surgical technique of aortic banding which avoids opening the sternum and thereby avoids adhesions and surgery-related inflammation. Placing a clip on the ascending aorta using a suprasternal approach in Sprague-Dawley rats created proximal aortic constriction. The present study was initiated to determine whether a replication-deficient adenovirus would enable efficient gene transfer to adult cardiac myocytes undergoing hypertrophy and transitioning to heart failure. Echocardiography performed at week 24 revealed significant concentric hypertrophy and increased fractional shortening followed by LV dilatation with decreased fractional shortening after 27 wk of banding. An adenoviral solution encoding for the reporter green fluorescent protein gene (GFP) was delivered to the heart. Fluorescent microscopy revealed global gene expression throughout hypertrophied and failing hearts. Our studies demonstrate that a novel suprasternal approach can be applied to create an LV hypertrophy model followed by heart failure which also allows investigators to perform genetic manipulations in vivo through gene transfer without the complication of adhesions and surgical trauma-induced inflammation. Furthermore, our approach to delivery of transgenes results in homogenous gene expression in both hypertrophied and failing hearts.