Heart failure is characterized by a debilitating decline in cardiac function1, and recent clinical trial results indicate that improving the contractility of heart muscle cells by boosting intracellular calcium handling might be an effective therapy2,3. microRNAs (miRs) are dysregulated with heart failure4,5 but whether they control contractility or constitute therapeutic targets remain speculative. Using high throughput, functional screening of the human microRNAome, we identified miRs that suppress intracellular calcium handling in heart muscle by interacting with mRNA encoding the sarcoplasmic reticulum calcium uptake pump SERCA2a. Of 875 miRs tested, miR-25 potently delayed calcium uptake kinetics in cardiomyocytes in vitro and was upregulated in heart failure, both in mice and humans. Whereas AAV9-mediated overexpression of miR-25 in vivo resulted in a significant loss of contractile function, injection of an antisense oligonucleotide (antagomiR) against miR-25 dramatically halted established heart failure in a mouse model, improving cardiac function and survival relative to a control antagomiR. These data reveal that increased expression of endogenous miR-25 contributes to declining cardiac function during heart failure and suggests that it might be targeted therapeutically to restore function.

BACKGROUND Cardiac fibrosis (CF) is associated with increased ventricular stiffness and diastolic dysfunction and is an independent predictor of long-term clinical outcomes of patients with heart failure (HF). We previously showed that the matricellular CCN5 protein is cardioprotective via its ability to inhibit CF and preserve cardiac contractility. OBJECTIVES This study examined the role of CCN5 in human heart failure and tested whether CCN5 can reverse established CF in an experimental model of HF induced by pressure overload. METHODS Human hearts were obtained from patients with end-stage heart failure. Extensive CF was induced by applying transverse aortic constriction for 8 weeks, which was followed by adeno-associated virus-mediated transfer of CCN5 to the heart. Eight weeks following gene transfer, cellular and molecular effects were examined. RESULTS Expression of CCN5 was significantly decreased in failing hearts from patients with end-stage heart failure compared to nonfailing hearts. Trichrome staining and myofibroblast content measurements revealed that the established CF had been reversed by CCN5 gene transfer. Anti-CF effects of CCN5 were associated with inhibition of the transforming growth factor beta signaling pathway. CCN5 significantly inhibited endothelial-mesenchymal transition and fibroblast-to-myofibroblast transdifferentiation, which are 2 critical processes for CF progression, both in vivo and in vitro. In addition, CCN5 induced apoptosis in myofibroblasts, but not in cardiomyocytes or fibroblasts, both in vivo and in vitro. CCN5 provoked the intrinsic apoptotic pathway specifically in myofibroblasts, which may have been due the ability of CCN5 to inhibit the activity of NFκB, an antiapoptotic molecule. CONCLUSIONS CCN5 can reverse established CF by inhibiting the generation of and enhancing apoptosis of myofibroblasts in the myocardium. CCN5 may provide a novel platform for the development of targeted anti-CF therapies.

Aims: Small ubiquitin-like modifier type 1 (SUMO-1) has been shown to play a critical role in the dysfunction of the cardiac isoform of sarcoplasmic reticulum calcium ATPase (SERCA2a) pump in the setting of heart failure. In cardiac hypertrophy, the role of SUMO-1 has not been defined and our study's goals were to examine the effects of modulating SUMO-1 on the hypertrophic response both in vitro and in vivo and to examine whether oxidative stress (during cardiac hypertrophy) is abrogated by SUMO-1 gene transfer. Results: In mice undergoing transverse aortic constriction (TAC), SUMO-1 levels increased slightly during the compensated stage of hypertrophy and then dropped sharply during the transition to heart failure. In isolated cardiomyocytes, SUMO-1 gene transfer inhibited the hypertrophic response in the presence of phenylephrine. Adeno-associated vector type 9 (AAV9) gene transfer of SUMO-1 prevented the heart from undergoing hypertrophy after TAC and prevented the development of left ventricular dysfunction. Furthermore, SUMO-1 gene transfer blocked the negative effects of H 2 O 2 on SERCA2a activity in cardiac myocytes, while in vivo indices of oxidative stress were decreased by SUMO-1 in cardiac hypertrophy and heart failure. Innovation and Conclusion: The results of this study indicate that post-translational modifications of SERCA2a caused by the toxic environment of the hypertrophied and failing myocardium can be prevented by SUMO-1.

We present the cases of eight patients (mean age 75 years; EuroSCORE II 17.0 ± 22.0) who underwent post-cardiotomy venovenous extracorporeal membrane oxygenation (ECMO) without heparinization due to serious bleeding. Three liver cirrhosis, two chronic hemodialysis, three redo sternotomy, and two urgent surgery cases were included. Respiratory ECMO Survival Prediction score was - 5.1 ± 4.2 (estimated survival rate: approximately 30%). Mean ECMO duration was 14 days with 9 circuit exchanges. Five patients were weaned from ECMO and three were discharged alive at 90 days (survival 37.5%). There was a case of pump-head thrombosis requiring urgent circuit exchange. All experienced bleeding complications without clinically apparent pulmonary thromboembolism. Disseminated Intravascular Coagulation scores (Pre 1.3 ± 0.8 vs. Post 3.8 ± 1.7; p < 0.05) significantly increased (N = 6). Post-cardiotomy ECMO without heparinization facilitated patient rescue at a reasonable survival rate. However, bleeding complications were still observed. More sophisticated management protocols are warranted.

Overexpression of cardiac sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2a) has been suggested as a strategic intervention for cardiac failure. However, its benefit in wild-type (WT) rats with normal SERCA2a levels seems to be small. To investigate whether it would be beneficial in a cardiac failure model with down-regulated SERCA2a levels, we made a cardiac hypertrophy model using isoproterenol infusion (1.2mgkg(-1)day(-1) for 1 or 4weeks; TG-ISO1w and TG-ISO4w, respectively) in SERCA2a transgenic (TG) rats and compared these rats with littermate WT rats that underwent the same treatments (WT-ISO1w and WT-ISO4w). We analyzed the left ventricular (LV) mechanoenergetics in the excised heart using our original cross-circulation system. The downward shift of curvilinear LV end-systolic pressure-volume relations (ESPVRs) observed in WT-ISO4w rats was abolished in TG-ISO4w rats. The slope and VO2 intercept of the VO2 (myocardial oxygen consumption per beat)-PVA (systolic pressure-volume area: total mechanical energy per beat) linear relation did not differ in any of the groups. The most important finding was a significantly smaller O2 cost of LV contractility in the TG-ISO4w group, which means that less O2 is needed to exert the same LV contractility, compared with the other groups. The increased ratio of SERCA2a/phospholamban returned to the level of the WT-control group only in the TG-ISO4w group. Longer-term up-regulation of mitochondrial transcription factor A for genes of mitochondrial enzymes producing ATP was observed in TG rats. In conclusion, longer-term overexpression of SERCA2a will be beneficial in the present cardiac failure model with down-regulated SERCA2a levels.