Circulation, 2010, Vol.122(21_MeetingAbstracts Suppl 1)
Introduction: To identify novel cardioprotective genes we developed an innovative functional selection approach, based on in vivo gene transfer of cDNA libraries using AAV vectors.Hypothesis: To support the feasibility of in vivo functional screening, we used a pool of AAV expressing 50 different hormones and growth factors and assessed the hypothesis that the clones enriched by selective pressure effectively promoted cardiac function.Methods: After cardiac injection (n=50) of the AAV pool, animals were subjected to myocardial infarction. After 15 days, persisting vector DNA was recovered, recloned into AAV and used for subsequent cycles of functional selection. Individual AAV vectors expressing the selected clones were eventually tested for cardioprotective activity in vitro on primary cardiomyocytes and in mouse models of cardiac fibrosis (isoproterenol i.p. 200 mg/Kg) or myocardial infarction by echocardiography, morphometric and molecular analysis (n=10 per group).Results: In vivo functional selection led to marked enrichment for surviving cardiomyocytes expressing Ghrelin, a neuro-hormone secreted upon starvation. In vitro, transduction with AAV-Ghrelin resulted in improved survival of cardiomyocytes after isoproterenol (〉90% vs 60% vs 〈10%) treatment (p〈0.02). In vivo, AAV-Ghrelin preserved cardiac function upon isoproterenol injection, resulting in decreased heart rate (464±50 and 342±12 bpm in AAV-empty and AAV-Ghrelin, respectively), paralleled by a reduced up-regulation of a few novel markers of heart failure, such as miR-21 and MMP-2.Conclusions: In conclusion, these results support the feasibility of our innovative in vivo selection approach and identify Ghrelin as a novel and powerful molecule protecting from cardiac apoptosis and providing benefit upon cardiac damage.
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