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Intratracheal Gene Delivery of SERCA2a Ameliorates Chronic Post-Capillary Pulmonary Hypertension: A Large Animal Model.

ABSTRACT: BACKGROUND:Pulmonary hypertension (PH) is characterized by pulmonary arterial remodeling that results in increased pulmonary vascular resistance, right ventricular (RV) failure, and premature death. Down-regulation of sarcoplasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) in the pulmonary vasculature leads to perturbations in calcium ion (Ca(2+)) homeostasis and transition of pulmonary artery smooth muscle cells to a proliferative phenotype. OBJECTIVES:We assessed the feasibility of sustained pulmonary vascular SERCA2a gene expression using aerosolized delivery of adeno-associated virus type 1 (AAV1) in a large animal model of chronic PH and evaluated the efficacy of gene transfer regarding progression of pulmonary vascular and RV remodeling. METHODS:A model of chronic post-capillary PH was created in Yorkshire swine by partial pulmonary vein banding. Development of chronic PH was confirmed hemodynamically, and animals were randomized to intratracheal administration of aerosolized AAV1 carrying the human SERCA2a gene (n = 10, AAV1.SERCA2a group) or saline (n = 10). Therapeutic efficacy was evaluated 2 months after gene delivery. RESULTS:Transduction efficacy after intratracheal delivery of AAV1 was confirmed by ?-galactosidase detection in the distal pulmonary vasculature. Treatment with aerosolized AAV1.SERCA2a prevented disease progression as evaluated by mean pulmonary artery pressure, vascular resistance, and limited vascular remodeling quantified by histology. Therapeutic efficacy was supported further by the preservation of RV ejection fraction (p = 0.014) and improvement of the RV end-diastolic pressure-volume relationship in PH pigs treated with aerosolized AAV1.SERCA2a. CONCLUSIONS:Airway-based delivery of AAV vectors to the pulmonary arteries was feasible, efficient, and safe in a clinically relevant chronic PH model. Vascular SERCA2a overexpression resulted in beneficial effects on pulmonary arterial remodeling, with attendant improvements in pulmonary hemodynamics and RV performance, and might offer therapeutic benefit by modifying fundamental pathophysiology in pulmonary vascular diseases.

SUBMITTER: Aguero J

PROVIDER: S-EPMC6019268 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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Intratracheal Gene Delivery of SERCA2a Ameliorates Chronic Post-Capillary Pulmonary Hypertension: A Large Animal Model.

Aguero Jaume J Ishikawa Kiyotake K Hadri Lahouaria L Santos-Gallego Carlos G CG Fish Kenneth M KM Kohlbrenner Erik E Hammoudi Nadjib N Kho Changwon C Lee Ahyoung A Ibáñez Borja B García-Alvarez Ana A Zsebo Krisztina K Maron Bradley A BA Plataki Maria M Fuster Valentin V Leopold Jane A JA Hajjar Roger J RJ

Journal of the American College of Cardiology 20160501 17

<h4>Background</h4>Pulmonary hypertension (PH) is characterized by pulmonary arterial remodeling that results in increased pulmonary vascular resistance, right ventricular (RV) failure, and premature death. Down-regulation of sarcoplasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) in the pulmonary vasculature leads to perturbations in calcium ion (Ca(2+)) homeostasis and transition of pulmonary artery smooth muscle cells to a proliferative phenotype.<h4>Objectives</h4>We assessed the feasibility of su ...[more]

PMID: 27126531

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Project description:BackgroundPulmonary hypertension (PH) is a common and morbid complication of left heart disease with 2 subtypes: isolated post-capillary pulmonary hypertension (Ipc-PH) and combined post-capillary and pre-capillary pulmonary hypertension (Cpc-PH). Little is known about the clinical or physiological characteristics that distinguish these 2 subphenotypes or if Cpc-PH shares molecular similarities to pulmonary arterial hypertension (PAH).ObjectivesThe goal of this study was to test the hypothesis that the hemodynamic and genetic profile of Cpc-PH would more closely resemble PAH than Ipc-PH.MethodsVanderbilt University's electronic medical record linked to a DNA biorepository was used to extract demographic characteristics, clinical data, invasive hemodynamic data, echocardiography, and vital status for all patients referred for right heart catheterization between 1998 and 2014. Shared genetic variants between PAH and Cpc-PH compared with Ipc-PH were identified by using pre-existing single-nucleotide polymorphism data.ResultsA total of 2,817 patients with PH (13% Cpc-PH, 52% Ipc-PH, and 20% PAH) were identified. Patients with Cpc-PH were on average 6 years younger, with more severe pulmonary vascular disease than patients with Ipc-PH, despite similar comorbidities and prevalence, severity, and chronicity of left heart disease. After adjusting for relevant covariates, the risk of death was similar between the Cpc-PH and Ipc-PH groups (hazard ratio: 1.14; 95% confidence interval: 0.96 to 1.35; p = 0.15) when defined according to diastolic pressure gradient. We identified 75 shared exonic single-nucleotide polymorphisms between Cpc-PH and PAH enriched in pathways involving cell structure, extracellular matrix, and immune function. These genes are expressed, on average, 32% higher in lungs relative to other tissues.ConclusionsPatients with Cpc-PH develop pulmonary vascular disease similar to patients with PAH, despite younger age and similar prevalence of obesity, diabetes mellitus, and left heart disease compared with patients with Ipc-PH. An exploratory genetic analysis in Cpc-PH identified genes and biological pathways in the lung known to contribute to PAH pathophysiology, suggesting that Cpc-PH may be a distinct and highly morbid PH subphenotype.

Project description:BACKGROUND:Pulmonary arterial hypertension (PAH) is characterized by dysregulated proliferation of pulmonary artery smooth muscle cells leading to (mal)adaptive vascular remodeling. In the systemic circulation, vascular injury is associated with downregulation of sarcoplasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) and alterations in Ca(2+) homeostasis in vascular smooth muscle cells that stimulate proliferation. We, therefore, hypothesized that downregulation of SERCA2a is permissive for pulmonary vascular remodeling and the development of PAH. METHODS AND RESULTS:SERCA2a expression was decreased significantly in remodeled pulmonary arteries from patients with PAH and the rat monocrotaline model of PAH in comparison with controls. In human pulmonary artery smooth muscle cells in vitro, SERCA2a overexpression by gene transfer decreased proliferation and migration significantly by inhibiting NFAT/STAT3. Overexpresion of SERCA2a in human pulmonary artery endothelial cells in vitro increased endothelial nitric oxide synthase expression and activation. In monocrotaline rats with established PAH, gene transfer of SERCA2a via intratracheal delivery of aerosolized adeno-associated virus serotype 1 (AAV1) carrying the human SERCA2a gene (AAV1.SERCA2a) decreased pulmonary artery pressure, vascular remodeling, right ventricular hypertrophy, and fibrosis in comparison with monocrotaline-PAH rats treated with a control AAV1 carrying ?-galactosidase or saline. In a prevention protocol, aerosolized AAV1.SERCA2a delivered at the time of monocrotaline administration limited adverse hemodynamic profiles and indices of pulmonary and cardiac remodeling in comparison with rats administered AAV1 carrying ?-galactosidase or saline. CONCLUSIONS:Downregulation of SERCA2a plays a critical role in modulating the vascular and right ventricular pathophenotype associated with PAH. Selective pulmonary SERCA2a gene transfer may offer benefit as a therapeutic intervention in PAH.

Project description:BackgroundPulmonary arterial hypertension (PAH) results in right ventricular (RV) failure, electro-mechanical dysfunction and heightened risk of sudden cardiac death (SCD), although exact mechanisms and predisposing factors remain unclear. Because impaired chronotropic response to exercise is a strong predictor of early mortality in patients with PAH, we hypothesized that progressive elevation in heart rate can unmask ventricular tachyarrhythmias (VT) in a rodent model of monocrotaline (MCT)-induced PAH. We further hypothesized that intra-tracheal gene delivery of aerosolized AAV1.SERCA2a (AAV1.S2a), an approach which improves pulmonary vascular remodeling in PAH, can suppress VT in this model.ObjectiveTo determine the efficacy of pulmonary AAV1.S2a in reversing electrophysiological (EP) remodeling and suppressing VT in PAH.MethodsMale rats received subcutaneous injection of MCT (60 mg/kg) leading to advanced PAH. Three weeks following MCT, rats underwent intra-tracheal delivery of aerosolized AAV1.S2a (MCT + S2a, N = 8) or saline (MCT, N = 9). Age-matched rats served as controls (CTRL, N = 7). The EP substrate and risk of VT were determined using high-resolution optical action potential (AP) mapping ex vivo. The expression levels of key ion channel subunits, fibrosis markers and hypertrophy indices were measured by RT-PCR and histochemical analyses.ResultsOver 80% of MCT but none of the CTRL hearts were prone to sustained VT by rapid pacing (P < .01). Aerosolized gene delivery of AAV1.S2a to the lung suppressed the incidence of VT to <15% (P < .05). Investigation of the EP substrate revealed marked prolongation of AP duration (APD), increased APD heterogeneity, a reversal in the trans-epicardial APD gradient, and marked conduction slowing in untreated MCT compared to CTRL hearts. These myocardial EP changes coincided with major remodeling in the expression of K and Ca channel subunits, decreased expression of Cx43 and increased expression of pro-fibrotic and pro-hypertrophic markers. Intra-tracheal gene delivery of aerosolized AAV1 carrying S2a but not luciferase resulted in selective upregulation of the human isoform of SERCA2a in the lung but not the heart. This pulmonary intervention, in turn, ameliorated MCT-induced APD prolongation, reversed spatial APD heterogeneity, normalized myocardial conduction, and suppressed the incidence of pacing-induced VT. Comparison of the minimal conduction velocity (CV) generated at the fastest pacing rate before onset of VT or at the end of the protocol revealed significantly lower values in untreated compared to AAV1.S2a treated PAH and CTRL hearts. Reversal of EP remodeling by pulmonary AAV1.S2a gene delivery was accompanied by restored expression of key ion channel transcripts. Restored expression of Cx43 and collagen but not the pore-forming Na channel subunit Nav1.5 likely ameliorated VT by improving CV at rapid rates in PAH.ConclusionAerosolized AAV1.S2a gene delivery selectively to the lungs ameliorates myocardial EP remodeling and VT susceptibility at rapid heart rates. Our findings highlight for the first time the utility of a non-cardiac gene therapy approach for arrhythmia suppression.

Dataset Information

Intratracheal Gene Delivery of SERCA2a Ameliorates Chronic Post-Capillary Pulmonary Hypertension: A Large Animal Model.

Publications

Intratracheal Gene Delivery of SERCA2a Ameliorates Chronic Post-Capillary Pulmonary Hypertension: A Large Animal Model.

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