Recirculating cardiac delivery of AAV2/1SERCA2a improves myocardial function in an experimental model of heart failure in large animals
Byrne MJ, Power JM, Preovolos A, Mariani JA, Hajjar RJ, Kaye DM
Gene Therapy, December 2008
Abnormal excitation-contraction coupling is a key pathophysiologic component of heart failure (HF), and at a molecular level reduced expression of the sarcoplasmic reticulum (SR) Ca(2+) ATPase (SERCA2a) is a major contributor. Previous studies in small animals have suggested that restoration of SERCA function is beneficial in HF. Despite this promise, the means by which this information might be translated into potential clinical application remains uncertain. Using a recently established cardiac-directed recirculating method of gene delivery, we administered adeno-associated virus 2 (AAV2)/1SERCA2a to sheep with pacing-induced HF. We explored the effects of differing doses of AAV2/1SERCA2a (low 1 x 10(10) d.r.p.; medium 1 x 10(12) d.r.p. and high 1 x 10(13) d.r.p.) in conjunction with an intra-coronary delivery group (2.5 x 10(13) d.r.p.). At the end of the study, haemodynamic, echocardiographic, histopathologic and molecular biologic assessments were performed.

Prevention of Ventricular Arrhythmias With Sarcoplasmic Reticulum Ca2+ ATPase Pump Overexpression in a Porcine Model of Ischemia Reperfusion
Prunier F, Kawase Y, Gianni D, Scapin C, Danik SB, Ellinor PT, Hajjar RJ, Del Monte F
Circulation: Heart Failure, August 2008
Ventricular arrhythmias are life-threatening complications of heart failure and myocardial ischemia. Increased diastolic Ca2+ overload occurring in ischemia leads to after depolarizations and after contractions that are responsible for cellular electric instability. We inquired whether sarcoplasmic reticulum Ca2+ ATPase pump (SERCA2a) overexpression could reduce ischemic ventricular arrhythmias by modulating Ca2+ overload. SERCA2a overexpression in pig hearts was achieved by intracoronary gene delivery of adenovirus in the 3 main coronary arteries. Homogeneous distribution of the gene was obtained through the left ventricle. After gene delivery, the left anterior descending coronary artery was occluded for 30 minutes to induce myocardial ischemia followed by reperfusion. We compared this model with a model of permanent coronary artery occlusion.

Elevated Afterload, Neuroendocrine Stimulation, and Human Heart Failure Increase BNP Levels and Inhibit Preload-Dependent SERCA Upregulation
Circulation: Heart Failure, August 2008
In heart failure, brain-type natriuretic peptide (BNP) is elevated and the sarcoplasmic reticulum Ca2+-ATPase (SERCA) downregulated. We previously showed that preload-induced SERCA-upregulation is suppressed by exogenous BNP.  Here we tested the hypothesis that afterload and neurohumoral activation would counterregulate preload-dependent SERCA upregulation through BNP, which finally results in decreased SERCA levels. We studied the effects of 6 hours preload, afterload, and isoproterenol stimulation on BNP and SERCA mRNA expression in rabbit and human failing muscles strips. Preload resulted in a pronounced upregulation of SERCA by 149% (isotonic versus slack, P<0.01). This upregulation was largely suppressed in afterloaded muscles (isometric versus slack: +32%; P<0.05). Similarly, presence of isoproterenol prevented SERCA upregulation in isotonic muscles. Afterload and isoproterenol resulted in a pronounced increase in BNP expression compared with slack by 225% (P<0.05) and 198% (P<0.01), respectively. Isoproterenol also increased expression of phospholamban by 84% (P<0.01). SERCA upregulation in preloaded muscles is associated with frequency-dependent potentiation of contractile force, which is absent in afterloaded muscles. In failing human myocardium, BNP expression was upregulated compared with nonfailing (+631%; P<0.05). Neither unloading nor preload or afterload induced a change in SERCA or BNP expression after 6 hours.

The Management of Heart Failure:  The Past, the Present, and the Future
Braunwald, E.
Circulation: Heart Failure, May 2008
It is an honor to contribute to this inaugural issue of Circulation: Heart Failure and to provide some personal reflections on the management of heart failure (HF). I will comment on the past and the present and will venture to makes some predictions about the future of this important subject.

Reversal of cardiac dysfunction after long-term expression of SERCA2a by gene transfer in a pre-clinical model of heart failure
Kawase Y, Ly HQ, Prunier F, Lebeche D, Shi Y, Jin H, Hadri L, Yoneyama R, Hoshino K, Takewa Y, Sakata S, Peluso R, Zsebo K, Gwathmey JK, Tardif JC, Tanguay JF, Hajjar RJ.
Journal of the American College of Cardiology, March 2008
The aim of this study was to examine the effects of sarcoplasmic reticulum Ca(2+) ATPase (SERCA2a) gene transfer in a swine heart failure (HF) model. Reduced expression and activity of SERCA2a have been documented in HF. Prior studies have reported the beneficial effects of short-term SERCA2a overexpression in rodent models. However, the effects of long-term expression of SERCA2a in pre-clinical large animal models are not known. Yorkshire-Landrace pigs were used (n = 16) to create volume overload by percutaneously severing chordae tendinae of the mitral apparatus with a bioptome to induce mitral regurgitation.

Transcoronary gene transfer of SERCA2a increases coronary blood flow and decreases cardiomyocyte size in a type II diabetic rat model
Sakata S, Lebeche D, Sakata Y, Sakata N, Chemaly ER, Liang L, Nakajima-Takenaka C, Tsuji T, Konishi N, del Monte F, Hajjar RJ, Takaki M
The American Journal of Physiology - Heart and Circulatory Physiology, September 2006
The Otsuka Long-Evans Tokushima Fatty rat is an animal model of type II diabetes mellitus (DM), which is characterized by diastolic dysfunction associated with decreased sarcoplasmic reticulum Ca2+-ATPase (SERCA2a). The aim of this study was to examine whether gene transfer of SERCA2a can influence coronary blood flow and cardiomyocyte diameter in this model. DM rats were injected with adenovirus carrying SERCA2a (DM+SERCA) or Agalactosidase gene (DM+_Gal). Coronary blood flow was measured in cross-circulated excised hearts 3 days after infection. Although in all groups coronary blood flow remained unchanged even if left ventricular (LV) volume or intracoronary Ca2+ infusion was increased, DM+SERCA group showed a sustained increase in coronary blood flow compared with other groups. This result suggests that the sustained high coronary blood flow is a specific response in SERCA2a-overexpressed hearts. Although LV weight/body weight (LV/BW) ratio and cardiomyocyte diameter were higher in DM and DM+_Gal groups than in non-DM, in DM+SERCA group they were restored back to non-DM size. The percentage of collagen area in these 3 DM groups was significantly higher than that of non-DM, and there were no significant differences in collagen area percentage among the 3 DM groups.

Transcriptional changes following restoration of SERCA2a levels in failing rat hearts
del Monte F, Dalal R, Tabchy A, Couget J, Bloch KD, Peterson R, Hajjar RJ
The FASEB Journal, September 2004
Heart failure is characterized at the cellular level by impaired contractility and abnormal Ca2+ homeostasis. We have previously shown that restoration of a key enzyme that controls intracellular Ca(2+) handling, the sarcoplasmic reticulum Ca2+ ATPase (SERCA2a), induces functional improvement in heart failure. We used high-density oligonucleotide arrays to explore the effects of gene transfer of SERCA2a on genetic reprogramming in a model of heart failure. A total of 1,300 transcripts were identified to be unmodified by the effect of virus alone. Of those, 251 transcripts were found to be up- or down-regulated upon failure. A total of 51 transcripts which were either up--(27) or down--(24) regulated in heart failure were normalized to the nonfailing levels by the restoration of SERCA2a by gene transfer. The microarray analysis identified new genes following SERCA2a restoration in heart failure, which will give us insights into their role in the normalization of multiple pathways within the failing cell.

Improvement in survival and cardiac metabolism after gene transfer of sarcoplasmic reticulum Ca(2+)-ATPase in a rat model of heart failure
del Monte F, Williams E, Lebeche D, Schmidt U, Rosenzweig A, Gwathmey JK, Lewandowski ED, Hajjar RJ
Circulation, September 2001
In heart failure, sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA2a) activity is decreased, resulting in abnormal calcium handling and contractile dysfunction. We have previously shown that increasing SERCA2a expression by gene transfer improves ventricular function in a rat model of heart failure created by ascending aortic constriction. In this study, we tested the effects of gene transfer of SERCA2a on survival, left ventricular (LV) volumes, and metabolism. By 26 to 27 weeks after aortic banding, all animals developed heart failure (as documented by >25% decrease in fractional shortening) and were randomized to receive either an adenovirus carrying the SERCA2a gene (Ad.SERCA2a) or control virus (Ad.betagal-GFP) by use of a catheter-based technique. Sham-operated rats, uninfected or infected with either Ad.betagal-GFP or Ad.SERCA2a, served as controls. Four weeks after gene transfer, survival in rats with heart failure treated with Ad.betagal-GFP was 9%, compared with 63% in rats receiving Ad.SERCA2a. LV volumes were significantly increased in heart failure (0.64+/-0.05 versus 0.35+/-0.03 mL, P<0.02). Overexpression of SERCA2a normalized LV volumes (0.46+/-0.07 mL) in the failing hearts. (31)P NMR analysis showed a reduced ratio of phosphocreatine to ATP content in failing+Ad.betagal-GFP compared with sham+Ad.betagal-GFP (0.82+/-0.13 versus 1.38+/-0.14, P<0.01). Overexpression of SERCA2a in failing hearts improved the phosphocreatine/ATP ratio (1.23+/-0.28).

Disruption of a single copy of the SERCA2 gene results in altered Ca2+ homeostasis and cardiomyocyte function
Ji Y, Lalli MJ, Babu GJ, Xu Y, Kirkpatrick DL, Liu LH, Chiamvimonvat N, Walsh RA, Shull GE, Periasamy M
The Journal of Biological Chemistry, December 2000
A mouse model carrying a null mutation in one copy of the sarcoplasmic reticulum (SR) Ca(2+)-ATPase isoform 2 (SERCA2) gene, in which SERCA2 protein levels are reduced by approximately 35%, was used to investigate the effects of decreased SERCA2 level on intracellular Ca(2+) homeostasis and contractile properties in isolated cardiomyocytes. When compared with wild-type controls, SR Ca(2+) stores and Ca(2+) release in myocytes of SERCA2 heterozygous mice were decreased by approximately 40-60% and approximately 30-40%, respectively, and the rate of myocyte shortening and relengthening were each decreased by approximately 40%. However, the rate of Ca(2+) transient decline (tau) was not altered significantly, suggesting that compensation was occurring in the removal of Ca(2+) from the cytosol. Phospholamban, which inhibits SERCA2, was decreased by approximately 40% in heterozygous hearts, and basal phosphorylation of Ser-16 and Thr-17, which relieves the inhibition, was increased approximately 2- and 2.1-fold.

Targeted overexpression of the sarcoplasmic reticulum Ca2+-ATPase increases cardiac contractility in transgenic mouse hearts
Baker DL, Hashimoto K, Grupp IL, Ji Y, Reed T, Loukianov E, Grupp G, Bhagwhat A, Hoit B, Walsh R, Marban E, Periasamy M
Circulation Research, October 1998
Cardiac hypertrophy and heart failure are known to be associated with a reduction in Ca2+-ATPase pump levels of the sarcoplasmic reticulum (SR). To determine whether, and to what extent, alterations in Ca2+ pump numbers can affect contraction and relaxation parameters of the heart, we have overexpressed the cardiac SR Ca2+-ATPase specifically in the mouse heart using the alpha-myosin heavy chain promoter. Analysis of 2 independent transgenic lines demonstrated that sarco(endo)plasmic reticulum Ca2+-ATPase isoform (SERCA2a) mRNA levels were increased 3.88+/-0. 4-fold and 7.90+/-0.2-fold over those of the control mice. SERCA2a protein levels were increased by 1.31+/-0.05-fold and 1.54+/-0. 05-fold in these lines despite high levels of mRNA, suggesting that complex regulatory mechanisms may determine the SERCA2a pump levels. The maximum velocity of Ca2+ uptake (Vmax) was increased by 37%, demonstrating that increased pump levels result in increased SR Ca2+ uptake function. However, the apparent affinity of the SR Ca2+-ATPase for Ca2+ remains unchanged in transgenic hearts. To evaluate the effects of overexpression of the SR Ca2+ pump on cardiac contractility, we used the isolated perfused work-performing heart model.