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This document is a correction notice for an article titled "Consecutive-Day Ventricular and Atrial Cardiomyocyte Isolations from the Same Heart: Shifting the Cost-Benefit Balance of Cardiac Primary Cell Research." The correction addresses an error in the Materials and Methods section regarding the concentration of the digestion solution used in cell isolation. The correct concentration is provided in the correction notice. The authors assure that this correction does not affect the scientific conclusions of the study. [Extracted from the article]

The changes in the myocardial proteome and metabolome associated with left ventricular assist device (LVAD) therapy in patients with ischemic cardiomyopathy (ICM) are poorly characterized. We investigated the impact of mechanical unloading following LVAD therapy on the myocardial proteome and metabolome. Matched samples of 5 patients' myocardial tissue, harvested at the time of LVAD implant ("pre‐LVAD") or heart transplant ("post‐LVAD"), were studied by quantitative proteomics and metabolomics as well as being probed for T‐tubule structure and connexin‐43 distribution. Moreover, pre‐LVAD proteome profiles of ICM context were bioinformatically compared to pre‐LVAD proteome profiles of dilated cardiac myopathy (DCM). More than 2120 proteins were reliably identified and quantified in paired patient samples. LVAD therapy led to proteomic remodeling, including reduced levels of α‐1‐antichymotrypsin together with an overall decrease of immune response proteins and an increase of proteins involved in membrane biology. Metabolomics highlighted increased glucose and glucose‐6‐phosphate levels in the left ventricle upon LVAD therapy. Wheat germ agglutinin staining demonstrated improved T‐tubule structure. Connexin‐43 displayed a trend for more pronounced intercalated disc localization. In comparing pre‐LVAD proteome profiles of ICM context with pre‐LVAD proteome profiles of dilated cardiac myopathy (DCM), we noticed an overrepresentation in ICM of proteins associated with humoral immune response. Our findings underline an impact of LVAD therapy on left ventricular biology in ICM. The proteomic, metabolomic, and structural alterations described here are typically associated with cardiac recovery. On the molecular level, our findings indicate the possibility of cardiac remodeling under LVAD therapy in ICM. [ABSTRACT FROM AUTHOR]

Glucocorticoids are steroid hormones, essential in mammals to prepare for life after birth. Blood levels of glucocorticoids (cortisol in most mammals including humans; corticosterone in rats and mice) rise dramatically shortly before birth. This is mimicked clinically in the routine administration of synthetic glucocorticoids to pregnant women threatened by a preterm birth or to preterm infants to improve neonatal survival. Whilst effects on lung are well documented and essential for postnatal survival, those on heart are less well known. In this study, we review recent evidence for a crucial role of glucocorticoids in late gestational heart maturation. Either insufficient or excessive glucocorticoid exposure before birth may alter the normal glucocorticoid-regulated trajectory of heart maturation with potential life-long consequences. [ABSTRACT FROM AUTHOR]

Background: Cardiac hypertrophy compensates for increased biomechanical stress of the heart induced by prevalent cardiovascular pathologies but can result in heart failure if left untreated. Here, we hypothesized that the membrane fusion and repair protein dysferlin is critical for the integrity of the transverse-axial tubule (TAT) network inside cardiomyocytes and contributes to the proliferation of TAT endomembranes during pressure overload-induced cardiac hypertrophy., Methods: Stimulated emission depletion and electron microscopy were used to localize dysferlin in mouse and human cardiomyocytes. Data-independent acquisition mass spectrometry revealed the cardiac dysferlin interactome and proteomic changes of the heart in dysferlin-knockout mice. After transverse aortic constriction, we compared the hypertrophic response of wild-type versus dysferlin-knockout hearts and studied TAT network remodeling mechanisms inside cardiomyocytes by live-cell membrane imaging., Results: We localized dysferlin in a vesicular compartment in nanometric proximity to contact sites of the TAT network with the sarcoplasmic reticulum, a.k.a. junctional complexes for Ca 2+ -induced Ca 2+ release. Interactome analyses demonstrated a novel protein interaction of dysferlin with the membrane-tethering sarcoplasmic reticulum protein juncophilin-2, a putative interactor of L-type Ca 2+ channels and ryanodine receptor Ca 2+ release channels in junctional complexes. Although the dysferlin-knockout caused a mild progressive phenotype of dilated cardiomyopathy, global proteome analysis revealed changes preceding systolic failure. Following transverse aortic constriction, dysferlin protein expression was significantly increased in hypertrophied wild-type myocardium, while dysferlin-knockout animals presented markedly reduced left-ventricular hypertrophy. Live-cell membrane imaging showed a profound reorganization of the TAT network in wild-type left-ventricular myocytes after transverse aortic constriction with robust proliferation of axial tubules, which critically depended on the increased expression of dysferlin within newly emerging tubule components., Conclusions: Dysferlin represents a new molecular target in cardiac disease that protects the integrity of tubule-sarcoplasmic reticulum junctional complexes for regulated excitation-contraction coupling and controls TAT network reorganization and tubular membrane proliferation in cardiomyocyte hypertrophy induced by pressure overload., Competing Interests: None.

Aims: Patients with tetralogy of Fallot (TOF) are often affected by right ventricular fibrosis, which has been associated with arrhythmias. This study aimed to assess fibrosis distribution in right ventricular outflow tract (RVOT) myocardium of TOF patients to evaluate the utility of single histology-section analyses, and to explore the possibility of fibrosis quantification in unlabelled tissue by second harmonic generation imaging (SHGI) as an alternative to conventional histology-based assays., Methods and Results: We quantified fibrosis in 11 TOF RVOT samples, using a tailor-made automated image analysis method on Picrosirius red-stained sections. In a subset of samples, histology- and SHGI-based fibrosis quantification approaches were compared. Fibrosis distribution was highly heterogeneous, with significant and comparable variability between and within samples. We found that, on average, 67.8 mm2 of 10 µm thick, histologically processed tissue per patient had to be analysed for accurate fibrosis quantification. SHGI provided data faster and on live tissue, additionally enabling quantification of collagen anisotropy., Conclusion: Given the high intra-individual heterogeneity, fibrosis quantification should not be conducted on single sections of TOF RVOT myectomies. We provide an analysis algorithm for fibrosis quantification in histological images, which enables the required extended volume analyses in these patients., (© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.)