Cyclin A2 (Ccna2), normally silenced after birth in the mammalian heart, can induce cardiac repair in small-animal models of myocardial infarction. We report that delivery of the Ccna2 gene to infarcted porcine hearts invokes a regenerative response. We used a catheter-based approach to occlude the left anterior descending artery in swine, which resulted in substantial myocardial infarction. A week later, we performed left lateral thoracotomy and injected adenovirus carrying complementary DNA encoding CCNA2 or null adenovirus into peri-infarct myocardium. Six weeks after treatment, we assessed cardiac contractile function using multimodality imaging including magnetic resonance imaging, which demonstrated ~18% increase in ejection fraction of Ccna2-treated pigs and ~4% decrease in control pigs. Histologic studies demonstrate in vivo evidence of increased cardiomyocyte mitoses, increased cardiomyocyte number, and decreased fibrosis in the experimental pigs. Using time-lapse microscopic imaging of cultured adult porcine cardiomyocytes, we also show that Ccna2 elicits cytokinesis of adult porcine cardiomyocytes with preservation of sarcomeric structure. These data provide a compelling framework for the design and development of cardiac regenerative therapies based on cardiomyocyte cell cycle regulation.

AimsMammalian myocardium has a finite but limited capacity to regenerate. Experimentally stimulating proliferation of cardiomyocytes with extracellular regeneration factors like periostin enhances cardiac repair in rodents. The aim of this study was to develop a safe method for delivering regeneration factors to the heart and to test the functional and structural effects of periostin peptide treatment in a large animal model of myocardial infarction (MI).Methods and ResultsWe developed a controlled release system to deliver recombinant periostin peptide into the pericardial space. A single application of this method was performed two days after experimental MI in swine. Animals were randomly assigned to receive either saline or periostin peptide. Experimental groups were compared at baseline, day 2, 1 month and 3 months. Treatment with periostin peptide increased the EF from 31% to 41% and decreased by 22% the infarct size within 12 weeks. Periostin peptide-treated animals had newly formed myocardium strips within the infarct scar, leading to locally improved myocardial function. In addition the capillary density was increased in animals receiving periostin. However, periostin peptide treatment increased myocardial fibrosis in the remote region at one week and 12 weeks post-treatment.ConclusionOur study shows that myocardial regeneration through targeted peptides is possible. However, in the case of periostin the effects on cardiac fibrosis may limit its clinical application as a viable therapeutic strategy.

No abstract

No abstract