Neonatal injury models: integral tools to decipher the molecular basis of cardiac regeneration

Myocardial injury often leads to heart failure due to the loss and insufficient regeneration of resident cardiomyocytes. The low regenerative potential of the mammalian heart is one of the main drivers of heart failure progression, especially after myocardial infarction accompanied by large contractile muscle loss. Preclinical therapies for cardiac regeneration are promising, but clinically still missing. Mammalian models represent an excellent translational in vivo platform to test drugs and treatments for the promotion of cardiac regeneration. Particularly, short-lived mice offer the possibility to monitor the outcome of such treatments throughout the life span. Importantly, there is a short period of time in newborn mice in which the heart retains full regenerative capacity after cardiac injury, which potentially also holds true for the neonatal human heart. Thus, in vivo neonatal mouse models of cardiac injury are crucial to gain insights into the molecular mechanisms underlying the cardiac regenerative processes and to devise novel therapeutic strategies for the treatment of diseased adult hearts. Here, we provide an overview of the established injury models to study cardiac regeneration. We summarize pioneering studies that demonstrate the potential of using neonatal cardiac injury models to identify factors that may stimulate heart regeneration by inducing endogenous cardiomyocyte proliferation in the adult heart. To conclude, we briefly summarize studies in large animal models and the insights gained in humans, which may pave the way toward the development of novel approaches in regenerative medicine

Circulating cardiovascular microRNAs in critically ill COVID ‐19 patients Short title: microRNA signatures in COVID ‐19

Aims: Corona virus disease 2019 (COVID-19) is a still growing pandemic, causing many deaths and socio-economic damage. Elevated expression of the SARS-CoV-2 entry receptor ACE2 on cardiac cells of patients with heart diseases may be related to cardiovascular burden. We have thus analysed cardiovascular and inflammatory microRNAs (miRs), sensitive markers of cardiovascular damage, in critically ill, ventilated patients with COVID-19 or Influenza associated acute respiratory distress syndrome (Influenza-ARDS) admitted to intensive care unit (ICU) and healthy controls. Methods and results: Circulating miRs (miR-21, miR-126, miR-155, miR-208a and miR-499) were analyzed in a discovery cohort consisting of patients with mechanically-ventilated COVID-19 (n = 18) and healthy controls (n = 15). A validation study was performed in an independent cohort of mechanically-ventilated COVID-19 patients (n = 20), Influenza-ARDS patients (n = 13) and healthy controls (n = 32). In both cohorts RNA was isolated from serum and cardiovascular disease/inflammatory-relevant miR concentrations were measured by miR-specific TaqMan PCR analyses. In both the discovery and the validation cohort, serum concentration of miR-21, miR-155, miR-208a and miR-499 were significantly increased in COVID-19 patients compared to healthy controls. Calculating the area under the curve (AUC) using ROC-analysis miR-155, miR-208a and miR-499 showed a clear distinction between COVID-19 and Influenza-ARDS patients. Conclusion: In this exploratory study, inflammation and cardiac myocyte-specific miRs were upregulated in critically ill COVID-19 patients. Importantly, miR profiles were able to differentiate between severely ill, mechanically-ventilated Influenza-ARDS and COVID-19 patients, indicating a rather specific response and cardiac involvement of COVID-19. Keywords: ARDS; COVID-19; SARS-CoV-2; biomarker; influenza; microRNA

Leukocyte telomere length correlates with hypertrophic cardiomyopathy severity

Telomere length is a marker of biological aging. Short leukocyte telomere length has been associated with various conditions including cardiovascular disorders. Here, we evaluated if patients with hypertrophic cardiomyopathy have altered leukocyte telomere length and whether this is associated with disease severity. A quantitative polymerase chain reaction-based method was used to measure peripheral blood leukocyte telomere length in 59 healthy control subjects and a well-characterized cohort of 88 patients diagnosed with hypertrophic cardiomyopathy: 32 patients with non-obstructive cardiomyopathy (HNCM) and 56 patients with obstructive cardiomyopathy (HOCM). We observed shorter leukocyte telomeres in both HNCM and HOCM patients compared to healthy controls. Furthermore, leukocyte telomere length was inversely associated with HCM even after adjusting for age and sex. Telomere length of HOCM patients was also inversely correlated with left ventricular outflow tract obstruction. Therefore, HOCM patients were categorized by tertiles of telomere length. Patients in the first tertile (shortest telomeres) had a significantly increased left ventricular posterior wall thickness at end-diastole and higher left ventricular outflow tract gradients, whereas the left ventricular end-diastolic diameter was lower compared with patients in the second and third tertile. In summary, telomere length is associated with the severity of the disease in the HOCM subtype.This work was supported by Deutsche Forschungsgemeinschaft (grant number BA5631/2-1 to CB), the Hannover Medical School REBIRTH Excellence cluster (to TT and JB) and the KFO311 (to TT and JB). DdG-C was recipient of a Juan de la Cierva-Incorporación grant from the Ministerio de Economía y Competitividad (IJCI-2016-29393). CIBER Cardiovascular (CB16/11/00403 to DdG-C) is a project of the Instituto de Salud Carlos III.Peer reviewe

Blood-based microRNA profiling in patients with cardiac amyloidosis.

INTRODUCTION:Amyloidosis is caused by dysregulation of protein folding resulting in systemic or organ specific amyloid aggregation. When affecting the heart, amyloidosis can cause severe heart failure, which is associated with a high morbidity and mortality. Different subtypes of cardiac amyloidosis exist e.g. transthyretin cardiac amyloidosis and senile cardiac amyloidosis. Today, diagnostics is primarily based on cardiac biopsies and no clinically used circulating blood-based biomarkers existing. Therefore, our aim was to identify circulating microRNAs in patients with different forms of amyloidosis. METHODS:Blood was collected from healthy subjects (n = 10), patients with reduced ejection fraction (EF < 35%; n = 10), patients affected by transthyretin cardiac amyloidosis (n = 13) as well as senile cardiac amyloidosis (n = 11). After performing TaqMan array profiling, promising candidates, in particular miR-99a-5p, miR-122-5p, miR-27a-3p, miR-221-3p, miR-1180-3p, miR-155-5p, miR-339-3p, miR-574-3p, miR-342-3p and miR-329-3p were validated via quantitative real time PCR. RESULTS:The validation experiments revealed a significant upregulation of miR-339-3p in patients affected with senile cardiac amyloidosis compared to controls. This corresponded to the array profiling results. In contrast, there was no deregulation in the other patient groups. CONCLUSION:MiR-339-3p was increased in blood of patients with senile cardiac amyloidosis. Therefore, miR-339-3p is a potential candidate as biomarker for senile cardiac amyloidosis in future studies. Larger patient cohorts should be investigated

Serum circular RNAs act as blood-based biomarkers for hypertrophic obstructive cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is one of the most common hereditary heart diseases and is associated with a high risk of sudden cardiac death. HCM is characterized by pronounced hypertrophy of cardiomyocytes, fiber disarray and development of fibrosis and can be divided into a non-obstructive (HNCM) and obstructive form (HOCM) therefore requiring personalized therapeutic therapies. In the present study, we investigated the expression patterns of several circulating circular RNAs (circRNAs) as potential biomarkers in patients with HCM. We included 64 patients with HCM and 53 healthy controls to the study and quantitatively measured the expression of a set of circRNAs already known to be associated with cardiac diseases (circDNAJC6) and/or being highly abundant in blood (circTMEM56 and circMBOAT2). Abundancy of circRNAs was then correlated to relevant clinical parameters. Serum expression levels of circRNAs DNAJC6, TMEM56 and MBOAT2 were downregulated in patients with HCM. The inverse association between circRNA levels and HCM remained unchanged even after adjusting for confounding factors. All circRNAs, evaluated separately or in combination, showed a robust discrimination capacity when comparing control subjects with HCM, HNCM or HOCM patients (AUC from 0.722 to 0.949). Two circRNAs, circTMEM56 and circDNAJC6, significantly negatively correlated with echocardiographic parameters for HOCM. Collectively, circulating circRNAs DNAJC6, TMEM56 and MBOAT2 can distinguish between healthy and HCM patients. In addition, circTMEM56 and circDNAJC6 could serve as indicators of disease severity in patients with HOCM. Thus, circRNAs emerge as novel biomarkers for HCM facilitating the clinical decision making in a personalized manner.This work was supported by Junge Akademie, MHH (to K.S.), ERC grant Longheart (to T.T.) and Deutsche Forschungsgemeinschaft, TRR_267 (to T.T.) and KFO311 (to T.T. and J.B. (D.d.G.C. was a recipient of a Juan de la Cierva-Incorporación grant from the Ministry of Science Innovation and Universities (IJCI-2016-29393). CIBER Cardiovascular (CB16/11/00403 to DdG-C) is a project from Carlos III Health Institute

Circulating microRNAs in Symptomatic and Asymptomatic Carotid Stenosis

Background: Specific microRNAs (miRs) have been implicated in the pathophysiology of atherosclerosis and may represent interesting diagnostic and therapeutic targets in carotid stenosis. We hypothesized that the levels of specific circulating miRs are altered in patients with symptomatic carotid stenosis (sCS) in comparison to those in patients with asymptomatic carotid stenosis (aCS) planned to undergo carotid endarterectomy (CEA). We also studied whether miR levels are associated with plaque vulnerability and stability over time after CEA. Methods: Circulating levels of vascular-enriched miR-92a, miR-126, miR-143, miR-145, miR-155, miR-210, miR-221, miR-222, and miR-342-3p were determined in 21 patients with sCS and 23 patients with aCS before CEA and at a 90-day follow-up. Transcranial Doppler ultrasound for detection of microembolic signals (MES) in the ipsilateral middle cerebral artery was performed prior to CEA. Carotid plaques were histologically analyzed. Results: Mean levels of miRs were not considerably different between groups and were only marginally higher in sCS than aCS concerning miR-92a, miR-210, miR-145, and miR-143 with the best evidence concerning miR-92a. After adjustment for vascular risk factors and statin pre-treatment, the effect sizes remained essentially unchanged. At follow-up, however, these modest differences remained uncorroborated. There were no relevant associations between miR-levels and MES or histological plaque vulnerability features. Conclusions: This study does not provide evidence for strong associations between specific circulating miRs and symptomatic state in a collective of comprehensively characterized patients with carotid stenosis. Further work is needed to elucidate the role of circulating miRs as targets in advanced carotid atherosclerosis

miR−21 and NT-proBNP Correlate with Echocardiographic Parameters of Atrial Dysfunction and Predict Atrial Fibrillation

This study aimed to investigate the association of circulating biomarkers with echocardiographic parameters of atrial remodelling and their potential for predicting atrial fibrillation (AF). In patients with and without AF (n = 21 and n = 60) the following serum biomarkers were determined: soluble ST2 (sST2), Galectin&minus;3 (Gal-3), N-terminal pro-brain natriuretic peptide (NT-proBNP), microRNA (miR)&minus;21, &minus;29a, &minus;133a, &minus;146b and &minus;328. Comprehensive transthoracic echocardiography was performed in all participants. Biomarkers were significantly altered in patients with AF. The echocardiographic parameter septal PA-TDI, indicating left atrial (LA) remodelling, correlated with concentrations of sST2 (r = 0.249, p = 0.048), miR&minus;21 (r = &minus;0.277, p = 0.012), miR&minus;29a (r = &minus;0.269, p = 0.015), miR&minus;146b (r = &minus;0.319, p = 0.004) and miR&minus;328 (r = &minus;0.296, p = 0.008). In particular, NT-proBNP showed a strong correlation with echocardiographic markers of LA remodelling and dysfunction (septal PA-TDI: r = 0.444, p &lt; 0.001, LAVI/a&rsquo;: r = 0.457, p = 0.001, SRa: r = 0.581, p &lt; 0.001). Multivariate Cox regressions analysis highlighted miR&minus;21 and NT-proBNP as predictive markers for AF (miR&minus;21: hazard ratio (HR) 0.16; 95% confidence interval (CI) 0.04&ndash;0.7, p = 0.009; NT-proBNP: HR 1.002 95%CI 1.001&ndash;1.004, p = 0.006). Combination of NT-proBNP and miR&minus;21 had the best accuracy to discriminate patients with AF from those without AF (area under the curve (AUC)= 0.843). Our findings indicate that miR&minus;21 and NT-proBNP correlate with echocardiographic parameters of atrial remodeling and predict AF, in particular if combined