Background: Cardiac development is a complex developmental process. The early cardiac straight tube is composed of an external myocardial layer and an internal endocardial lining. Soon after rightward looping, the embryonic heart becomes externally covered by a new epithelial lining, the embryonic epicardium. A subset of these embryonic epicardial cells migrate and colonize the embryonic myocardium, contributing to distinct cell types. In recent years, our understanding of the molecular mechanisms that govern proepicardium and embryonic epicardium formation has greatly increased. We have recently witnessed a novel layer of complexity governing gene regulation with the discovery of non-coding RNAs. Our laboratory recently identified three distinct lncRNAs, adjacent to the Wt1, Bmp4 and Fgf8 chicken gene loci, with enhanced expression in the proepicardium that are distinctly regulated by Bmp, Fgf and thymosin 4, providing support of their plausible implication in epicardial formation. Methods: Expression of lncRNAs was analyzed in different chicken and mouse tissues as well as their subcellular distribution in chicken proepicardial, epicardial, ventricle explants and in different murine cardiac cell types. lncRNA transcriptional regulation was analyzed by using siRNAs and expression vectors of different transcription factors in chicken and mouse. Antisense oligonucleotides were used to inhibit Gm14014 expression. Cardiac injury was induced ex vivo in mouse ventricle explants by cryoinjury. Furthermore, RT-qPCR, immunocytochemistry, RNA pulldown, Western blot, viability and cell migration assays were conducted to investigate the biological function of Wt1_76127 and Gm14014. Results: We demonstrated that Wt1_76127 in chicken and its evolutionarily conserved homologue Gm14014 in mice are widely distributed in different embryonic and adult tissues and distinctly regulated by cardiac enriched transcription factors, particularly Mef2c and Nkx2.5. Gm14014 is distinctly regulated in mouse ventricular cryoinjury ex vivo models, displaying a negative correlation with epicardial and epithelial to mesenchymal transition markers. Furthermore, silencing assays demonstrated that mouse Gm14014, but not chicken Wt1_76127, is essential for epicardial, but not endocardial or myocardial cell migration. Such process is governed by partnering with Myl9, promoting cytoskeletal remodeling. Conclusion: Our data evidence that Gm14014 plays a pivotal role in epicardial cell migration essential for heart regeneration.

Objectives: To evaluate atrial fibrillation (AF) recurrence and Sarcoplasmic Endoplasmic Reticulum Calcium ATPase (SERCA) levels in patients treated by epicardial thoracoscopic ablation for persistent AF. Background: Reduced levels of SERCA have been reported in the peripheral blood cells of patients with AF. We hypothesize that SERCA levels can predict the response to epicardial ablation. Methods: We designed a prospective, multicenter observational study to recruit, from October 2014 to June 2016, patients with persistent AF receiving an epicardial thoracoscopic pulmonary vein isolation. Results: We enrolled 27 patients; responders patients (n=15) did not present AF recurrence after epicardial ablation at 1-year follow-up. These patients displayed a marked remodeling of the left atrium, with a significant reduction of inflammatory cytokines, B type Natriuretic Peptide (BNP), and over expression of SERCA as compared to baseline and to non-responders (p<0.05). Furthermore, mean AF duration (HR 1.235 [1.037-1.471], p<0.05), LAV (HR 1.755 [1.126-2.738], p<0.05), BNP (HR 1.945 [1.895-1.999], p<0.05), and SERCA (HR 1.763 [1.167-2.663], p<0.05) were predictive of AF recurrence. Conclusions: Our data indicate that baseline values of SERCA in patients with persistent AF might be predictive of failure to epicardial ablative approach. Intriguingly, epicardial ablation was associated with increased levels of SERCA in responders. Therefore, SERCA might be an innovative therapeutic target to improve the response to epicardial ablative treatments.

Atrial fibrillation (AF) is a common cardiac arrhythmia associated with significant morbidity and mortality. The role of epicardial adipose tissue (EAT), particularly in the left atrium, has garnered attention in the pathophysiology of AF. This review aims to provide an overview of the association between the thickness of left atrial epicardial adipose tissue (LA-EAT) and the incidence of AF, while exploring the arrhythmogenic effects of LA-EAT and the impact of epicardial fat tissue changes with age and in pathological conditions. A comprehensive search of PubMed was conducted, and relevant studies were selected based on their inclusion criteria. The findings suggest that increased LA-EAT thickness is associated with an elevated risk of AF, potentially mediated through inflammatory and proarrhythmic effects. Age-related changes in epicardial fat tissue and alterations in pathological conditions, such as obesity, metabolic syndrome, and cardiovascular diseases, further contribute to the development and progression of AF. Further research is needed to deepen our understanding of these mechanisms and their clinical implications.

The relationship between epicardial adipose tissue (EAT) and atrial fibrillation (AF) has gained interest in recent years. Previous literature on the topic presents great heterogeneity, focusing especially on computed tomog-raphy imaging. Aim of the present study is to determine whether an increased volume of left atrial (LA) EAT evaluated at routine pre-procedural cardiac magnetic resonance imaging (MRI) relates to AF recurrences after catheter ablation. 50 patients undergoing AF cryoballoon ablation and pre-procedural cardiac MRI allowing quantification of LA EAT were enrolled. In one patient segmentation of LA EAT could not be achieved. After a median follow-up of 16.0 months, AF recurrences occurred in 17 patients (34%). Absolute volume of EAT was not different in patients with and without AF recurrences (10.35 ml vs. 10.29 ml; p-value=0.963), whereas volume of EAT indexed on the LA (EATi) was lower, albeit non statistically significant, in patients free from arrhythmias (12.77% vs. 14.06%; p-value=0.467). Receiver operating characteristic curve testing the ability of EATi to predict AF recurrence after catheter ablation showed sub-optimal performance (AUC: 0.588). The finest identified cut-off of EATi was 10.65%, achieving a sensitivity of 0.5, a specificity of 0.82, a positive predictive value of 0.59 and a negative predictive value of 0.76. Patients with values of EATi lower than 10.65% showed greater survival free from arrhythmias than patients with values above this cut-off (84% vs. 48%; p-value=0.04). In conclusion, indexed LA EAT volume evaluated at cardiac MRI independently relates to arrhythmia recurrence after AF cryoballoon ablation.

Vascular inflammation is recognized as the primary trigger of acute coronary syndrome (ACS). However, current noninvasive methods are not capable of accurately detecting coronary inflammation. Epicardial adipose tissue (EAT) and pericoronary adipose tissue (PCAT), in addition to their role as an energy reserve system, have been found to contribute to the development and progression of coronary artery calcifica-tion, inflammation, and plaque vulnerability. They also participate in the vascular re-sponse during ischemia, sympathetic stimuli, and arrhythmia. As a result, the evalua-tion of EAT and PCAT using imaging techniques such as computed tomography (CT), cardiac magnetic resonance (CMR), and nuclear imaging has gained significant atten-tion. PCAT-CT attenuation, which measures the average CT attenuation in Hounsfield units (HU) of the adipose tissue, reflects adipocyte differentiation/size and leukocyte infiltration. It is emerging as a marker of tissue inflammation and has shown prognos-tic value in coronary artery disease (CAD), being associated with plaque development, vulnerability, and rupture. In patients with acute myocardial infarction (AMI), an in-flammatory pericoronary microenvironment promoted by dysfunctional EAT/PCAT has been demonstrated, and more recently, it has been associated with plaque rupture in non-ST-segment elevation myocardial infarction (NSTEMI). Endothelial dysfunc-tion, known for its detrimental effects on coronary vessels and its association with plaque progression, is bidirectionally linked to PCAT. PCAT modulates the secretory profile of endothelial cells in response to inflammation and also plays a crucial role in regulating vascular tone in the coronary district. Consequently, dysregulated PCAT has been hypothesized to contribute to type 2 myocardial infarction with non-obstructive coronary arteries (MINOCA) and coronary vasculitis. Recently, quan-titative measures of EAT derived from coronary CT angiography (CCTA) have been included in artificial intelligence (AI) models for cardiovascular risk stratification. These models have shown incremental utility in predicting major adverse cardiovas-cular events (MACE) compared to plaque characteristics alone. Therefore, the analysis of PCAT and EAT, particularly through PCAT-CT attenuation, appears to be a safe, valuable, and sufficiently specific noninvasive method for accurately identifying cor-onary inflammation and subsequent high-risk plaque. These findings have been sup-ported by biopsy and in vivo evidence. Although speculative, these pieces of evidence open the door to a fascinating new strategy in cardiovascular risk stratification. The incorporation of PCAT and EAT analysis, mainly through PCAT-CT attenuation, could potentially lead to improved risk stratification and guide early targeted primary pre-vention and intensive secondary prevention in patients at higher risk of cardiac events.

Bone marrow-derived mesenchymal stem cells (BMSCs) have been considered a promising therapeutic approach to cardiovascular disease. This study intends to compare the effect of BMSCs through a standard active cardiac support device (ASD) and intravenous injection on global myocardial injury induced by isoproterenol. BMSCs were cultured in vitro, and the transplanted cells were labeled with a fluorescent dye CM-Dil. Isoproterenol (ISO) was injected into the rats; two weeks later, the labeled cells were transplanted into ISO-induced heart-injury rats through the tail vein or ASD device for five days. The rats were sacrificed on the first day, the third day, and the fifth day after transplantation to observe the distribution of cells in the myocardium by fluorescence microscopy. The hemodynamic indexes of the left ventricle were measured before sacrificing. H&E staining and Masson’s trichrome staining were used to evaluate the cardiac histopathology. In the ASD groups, after three days of transplantation, there were many BMSCs on the epicardial surface, and after five days of transplantation, BMSCs were widely distributed in the ventricular muscle. But in the intravenous injection group, there were no labeled-BMSCs distributed. In the ASD+BMSCs-three days treated group and ASD+BMSCs -five days-treated group, left ventricular systolic pressure (LVSP), the maximum rate of left ventricular pressure rise (+dP/dt), the maximum rate of left ventricular pressure decline (-dP/dt) increased compared with model group and intravenous injection group (P<0.05). By giving BMSCs through ASD device, cells can rapidly and widely distribute in the myocardium and significantly improve heart function.