Serial changes in the three-dimensional aspect of the side-branch ostium jailed by a drug-eluting stent assessed by optical coherence tomography.

The present study investigated serial changes in the three-dimensional (3D) aspect of the jailed side-branch (SB) ostium. We evaluated 32 patients who underwent examination with optical coherence tomography (OCT) both at baseline and at follow-up. After reconstruction of the 3D images, we classified the configuration of overhanging struts at the SB orifice into three groups according to the 3D aspect of the jailing configuration. The number of compartments divided by the stent strut was counted. The side-branch flow area (SBFA), i.e., the area of the SB ostium except for jailing struts, was measured by cut-plane analysis. Forty-eight SBs of 25 patients were analyzed. Thirteen SBs were classified as the No-jail type (N-type), 19 as the Simple-jail type (S-type; no longitudinal link at the carina), and 16 as the Complex-jail type (C-type; had a link at the carina). In the N-type, the SBFA was significantly increased at follow-up (P = 0.018). In the C-type, the SBFA was significantly decreased at follow-up (P = 0.002). Percent reduction of SBFA in the C-type group was significantly greater than that in the N-type or S-type groups (S-type vs. C-type P = 0.002, N-type vs. C-type P < 0.001). 3D-OCT images showed that some of the compartments were filled with tissue. The number of compartments was significantly decreased at follow-up (P < 0.001). In the C-type group, the SBFA was significantly decreased and small compartments were filled with tissue. These findings suggest that stent jail complexity is associated with the progression of SB ostial stenosis.

A cell-penetrating phospholamban-specific RNA aptamer enhances Ca2+ transients and contractile function in cardiomyocytes.

The sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a (SERCA2a)-phospholamban (PLN) system of sarcoplasmic reticulum plays a pivotal role in regulation of intracellular Ca(2+) cycling in ventricular cardiomyocytes. Given that Ca(2+) cycling is impaired in heart failure, proteins that contribute to this process are potential targets for the treatment of this condition. We have now isolated PLN-specific aptamers with a phosphorothioate-modified backbone from a library of RNA molecules containing a randomized 40-nucleotide sequence by application of the systematic evolution of ligands by exponential enrichment (SELEX) protocol with a fusion protein containing the cytoplasmic region of human PLN. One of these aptamers was shortened to a 30-nucleotide oligomer (RNA-Apt30) without loss of function. RNA-Apt30 showed a high affinity for the cytoplasmic region of PLN (Kd=11 nM), but it did not bind to the phosphorylated form of PLN or to a phosphomimetic mutant. It also increased SERCA2a activity in isolated cardiac SR vesicles with an EC50 of 18 nM by relieving PLN-mediated inhibition. Conjugation of RNA-Apt30 to a cell-penetrating peptide allowed its delivery into adult rat cardiomyocytes, in which it enhanced both Ca(2+) transients and contractile function. These effects of the aptamer were also apparent in the presence of the ß-adrenergic receptor antagonist propranolol. This cell-penetrating PLN aptamer may thus provide a basis for the development of new therapeutic agents for heart failure without the need for gene transfer or a change in endogenous protein expression.

Heart failure-inducible gene therapy targeting protein phosphatase 1 prevents progressive left ventricular remodeling.

BACKGROUND: The targeting of Ca(2+) cycling has emerged as a potential therapy for the treatment of severe heart failure. These approaches include gene therapy directed at overexpressing sarcoplasmic reticulum (SR) Ca(2+) ATPase, or ablation of phospholamban (PLN) and associated protein phosphatase 1 (PP1) protein complexes. We previously reported that PP1ß, one of the PP1 catalytic subunits, predominantly suppresses Ca(2+) uptake in the SR among the three PP1 isoforms, thereby contributing to Ca(2+) downregulation in failing hearts. In the present study, we investigated whether heart-failure-inducible PP1ß-inhibition by adeno-associated viral-9 (AAV9) vector mediated gene therapy is beneficial for preventing disease progression in genetic cardiomyopathic mice. METHODS: We created an adeno-associated virus 9 (AAV9) vector encoding PP1ß short-hairpin RNA (shRNA) or negative control (NC) shRNA. A heart failure inducible gene expression system was employed using the B-type natriuretic protein (BNP) promoter conjugated to emerald-green fluorescence protein (EmGFP) and the shRNA sequence. AAV9 vectors (AAV9-BNP-EmGFP-PP1ßshRNA and AAV9-BNP-EmGFP-NCshRNA) were injected into the tail vein (2×10(11) GC/mouse) of muscle LIM protein deficient mice (MLPKO), followed by serial analysis of echocardiography, hemodynamic measurement, biochemical and histological analysis at 3 months. RESULTS: In the MLPKO mice, BNP promoter activity was shown to be increased by detecting both EmGFP expression and the induced reduction of PP1ß by 25% in the myocardium. Inducible PP1ßshRNA delivery preferentially ameliorated left ventricular diastolic function and mitigated adverse ventricular remodeling. PLN phosphorylation was significantly augmented in the AAV9-BNP-EmGFP-PP1ßshRNA injected hearts compared with the AAV9-BNP-EmGFP-NCshRNA group. Furthermore, BNP production was reduced, and cardiac interstitial fibrosis was abrogated at 3 months. CONCLUSION: Heart failure-inducible molecular targeting of PP1ß has potential as a novel therapeutic strategy for heart failure.