Directed cardiac differentiation of human pluripotent stem cells (hPSCs) enables disease modeling, investigation of human cardiogenesis, as well as large‐scale production of cardiomyocytes (CMs) for ...translational purposes. Multiple CM differentiation protocols have been developed to individually address specific requirements of these diverse applications, such as enhanced purity at a small scale or mass production at a larger scale. However, there is no universal high‐efficiency procedure for generating CMs both in two‐dimensional (2D) and three‐dimensional (3D) culture formats, and undefined or complex media additives compromise functional analysis or cost‐efficient upscaling. Using systematic combinatorial optimization, we have narrowed down the key requirements for efficient cardiac induction of hPSCs. This implied differentiation in simple serum and serum albumin‐free basal media, mediated by a minimal set of signaling pathway manipulations at moderate factor concentrations. The method was applicable both to 2D and 3D culture formats as well as to independent hPSC lines. Global time‐course gene expression analyses over extended time periods and in comparison with human heart tissue were used to monitor culture‐induced maturation of the resulting CMs. This suggested that hPSC‐CMs obtained with our procedure reach a rather stable transcriptomic state after approximately 4 weeks of culture. The underlying gene expression changes correlated well with a decline of immature characteristics as well as with a gain of structural and physiological maturation features within this time frame. These data link gene expression patterns of hPSC‐CMs to functional readouts and thus define the cornerstones of culture‐induced maturation. Stem Cells 2015;33:1456–1469
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disorder that causes sudden death and right ventricular heart failure in the young. Clinical data suggest that competitive ...sports may provoke ARVC in susceptible persons. Genetically, loss-of-function mutations in desmosomal proteins (plakophilin, desmoplakin, or plakoglobin) have been associated with ARVC. To test the hypothesis that reduced desmosomal protein expression causes ARVC, we studied the cardiac effects of heterozygous plakoglobin deficiency in mice.
Ten-month-old heterozygous plakoglobin-deficient mice (plakoglobin+/-) had increased right ventricular volume, reduced right ventricular function, and spontaneous ventricular ectopy (all P<0.05). Left ventricular size and function were not altered. Isolated, perfused plakoglobin+/- hearts had spontaneous ventricular tachycardia of right ventricular origin and prolonged right ventricular conduction times compared with wild-type hearts. Endurance training accelerated the development of right ventricular dysfunction and arrhythmias in plakoglobin+/- mice. Histology and electron microscopy did not identify right ventricular abnormalities in affected animals.
Heterozygous plakoglobin deficiency provokes ARVC. Manifestation of the phenotype is accelerated by endurance training. This suggests a functional role for plakoglobin and training in the development of ARVC.
Optogenetic control of the heart is an emergent technology that offers unparalleled spatio-temporal control of cardiac dynamics via light-sensitive ion pumps and channels (opsins). This fast-evolving ...technique holds broad scope in both clinical and basic research setting. Combination of optogenetics with optical mapping of voltage or calcium fluorescent probes facilitates 'all-optical' electrophysiology, allowing precise optogenetic actuation of cardiac tissue with high spatio-temporal resolution imaging of action potential and calcium transient morphology and conduction patterns. In this review, we provide a synopsis of optogenetics and discuss in detail its use and compatibility with optical interrogation of cardiac electrophysiology. We briefly discuss the benefits of all-optical cardiac control and electrophysiological interrogation compared to traditional techniques, and describe mechanisms, unique features and limitations of optically induced cardiac control. In particular, we focus on state-of-the-art setup design, challenges in light delivery and filtering, and compatibility of opsins with fluorescent reporters used in optical mapping. The interaction of cardiac tissue with light, and physical and computational approaches to overcome the 'spectral congestion' that arises from the combination of optogenetics and optical mapping are discussed. Finally, we summarize recent preclinical work applications of combined cardiac optogenetics and optical mapping approach.
IntroductionAortic stenosis (AS) is common affecting >13% of adults over the age of 75 years. In people who develop symptoms, without valve replacement, prognosis is dismal with mortality as high as ...50% at 1 year. In asymptomatic patients, the timing of valve intervention is less well defined and a strategy of watchful waiting is recommended. Many, however, may develop symptoms and attribute this to age related decline, rather than worsening AS. Timely intervention in asymptomatic severe AS is critical, since delayed intervention often results in poor outcomes. Proactive surveillance of symptoms, quality of life and functional capacity should enable timely identification of people who will benefit from aortic valve replacement. There are no data however, to support the clinical and cost effectiveness of such an approach in a healthcare setting in the UK. The aim of this pilot trial is to test the feasibility of a full-scale randomised controlled trial (RCT) to determine the utility of proactive surveillance in people with asymptomatic severe AS to guide the timing of intervention.Methods and analysisAPRAISE-AS is a multi-centre, non-blinded, two-arm, parallel group randomised controlled trial of up to 66 participants aged >18 years with asymptomatic severe AS. Participants will be randomised to either standard care or standard care supplemented with the APRAISE-AS intervention. Primary outcomes will capture; adherence to and participant acceptability of the intervention, recruitment and retention rates, and completeness of data collection. The findings will be used to inform the sample size and most appropriate outcome measure(s) for a full-scale RCT and health economic evaluation.Ethics and disseminationEthical approval was granted by the Black Country REC, reference: 22/WM/0214. Results will be submitted for publication in peer-reviewed journals and disseminated at local, regional and national meetings where appropriate.Trial registration number ISRCTN19413194 registered on 14.07.2023.
Abstract
Aims
Study sex-differences in efficacy and safety of atrial fibrillation (AF) ablation.
Methods and results
We assessed first AF ablation outcomes on continuous anticoagulation in 633 ...patients 209 (33%) women and 424 (67%) men in a pre-specified subgroup analysis of the AXAFA-AFNET 5 trial. We compared the primary outcome (death, stroke or transient ischaemic attack, or major bleeding) and secondary outcomes change in quality of life (QoL) and cognitive function 3 months after ablation. Women were older (66 vs. 63 years, P < 0.001), more often symptomatic, had lower QoL and a longer history of AF. No sex differences in ablation procedure were found. Women stayed in hospital longer than men (2.1 ± 2.3 vs. 1.6 ± 1.3 days, P = 0.004). The primary outcome occurred in 19 (9.1%) women and 26 (6.1%) men, P = 0.19. Women experienced more bleeding events requiring medical attention (5.7% vs. 2.1%, P = 0.03), while rates of tamponade (1.0% vs. 1.2%) or intracranial haemorrhage (0.5% vs. 0%) did not differ. Improvement in QoL after ablation was similar between the sexes 12-item Short Form Health Survey (SF-12) physical 5.1% and 5.9%, P = 0.26; and SF-12 mental 3.7% and 1.6%, P = 0.17. At baseline, mild cognitive impairment according to the Montreal Cognitive Assessment (MoCA) was present in 65 (32%) women and 123 (30%) men and declined to 23% for both sexes at end of follow-up.
Conclusion
Women and men experience similar improvement in QoL and MoCA score after AF ablation on continuous anticoagulation. Longer hospital stay, a trend towards more nuisance bleeds, and a lower overall QoL in women were the main differences observed.
Large-scale screening for atrial fibrillation (AF) requires reliable methods to identify at-risk populations. Using an experimental semi-quantitative biomarker assay, B-type natriuretic peptide (BNP) ...and fibroblast growth factor 23 (FGF23) were recently identified as the most suitable biomarkers for detecting AF in combination with simple morphometric parameters (age, sex, and body mass index BMI). In this study, we validated the AF model using standardised, high-throughput, high-sensitivity biomarker assays.
For this study, 1,625 consecutive patients with either (1) diagnosed AF or (2) sinus rhythm with CHA2DS2-VASc score of 2 or more were recruited from a large teaching hospital in Birmingham, West Midlands, UK, between September 2014 and February 2018. Seven-day ambulatory ECG monitoring excluded silent AF. Patients with tachyarrhythmias apart from AF and incomplete cases were excluded. AF was diagnosed according to current clinical guidelines and confirmed by ECG. We developed a high-throughput, high-sensitivity assay for FGF23, quantified plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) and FGF23, and compared results to the previously used multibiomarker research assay. Data were fitted to the previously derived model, adjusting for differences in measurement platforms and known confounders (heart failure and chronic kidney disease). In 1,084 patients (46% with AF; median Q1, Q3 age 70 60, 78 years, median Q1, Q3 BMI 28.8 25.1, 32.8 kg/m2, 59% males), patients with AF had higher concentrations of NT-proBNP (median Q1, Q3 per 100 pg/ml: with AF 12.00 4.19, 30.15, without AF 4.25 1.17, 15.70; p < 0.001) and FGF23 (median Q1, Q3 per 100 pg/ml: with AF 1.93 1.30, 4.16, without AF 1.55 1.04, 2.62; p < 0.001). Univariate associations remained after adjusting for heart failure and estimated glomerular filtration rate, known confounders of NT-proBNP and FGF23. The fitted model yielded a C-statistic of 0.688 (95% CI 0.656, 0.719), almost identical to that of the derived model (C-statistic 0.691; 95% CI 0.638, 0.744). The key limitation is that this validation was performed in a cohort that is very similar demographically to the one used in model development, calling for further external validation.
Age, sex, and BMI combined with elevated NT-proBNP and elevated FGF23, quantified on a high-throughput platform, reliably identify patients with AF.
Registry IRAS ID 97753 Health Research Authority (HRA), United Kingdom.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Early detection of atrial fibrillation (AF) enables initiation of anticoagulation and early rhythm control therapy to reduce stroke, cardiovascular death, and heart failure. In a cross-sectional, ...observational study, we aimed to identify a combination of circulating biomolecules reflecting different biological processes to detect prevalent AF in patients with cardiovascular conditions presenting to hospital. Twelve biomarkers identified by reviewing literature and patents were quantified on a high-precision, high-throughput platform in 1485 consecutive patients with cardiovascular conditions (median age 69 years Q1, Q3 60, 78; 60% male). Patients had either known AF (45%) or AF ruled out by 7-day ECG-monitoring. Logistic regression with backward elimination and a neural network approach considering 7 key clinical characteristics and 12 biomarker concentrations were applied to a randomly sampled discovery cohort (n = 933) and validated in the remaining patients (n = 552). In addition to age, sex, and body mass index (BMI), BMP10, ANGPT2, and FGF23 identified patients with prevalent AF (AUC 0.743 95% CI 0.712, 0.775). These circulating biomolecules represent distinct pathways associated with atrial cardiomyopathy and AF. Neural networks identified the same variables as the regression-based approach. The validation using regression yielded an AUC of 0.719 (95% CI 0.677, 0.762), corroborated using deep neural networks (AUC 0.784 95% CI 0.745, 0.822). Age, sex, BMI and three circulating biomolecules (BMP10, ANGPT2, FGF23) are associated with prevalent AF in unselected patients presenting to hospital. Findings should be externally validated. Results suggest that age and different disease processes approximated by these three biomolecules contribute to AF in patients. Our findings have the potential to improve screening programs for AF after external validation.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Understanding the mechanism of re-entrant arrhythmias in the past 30 years has allowed the development of almost curative therapies for many rhythm disturbances. The complex, polymorphic arrhythmias ...of atrial fibrillation (AF) and sudden death are, unfortunately, not yet well understood, and hence still in need of adequate therapy. AF contributes markedly to morbidity and mortality in aging Western populations. In the past decade, many genetically altered murine models have been described and characterized. Here, we review genetically altered murine models of AF; powerful tools that will enable a better understanding of the mechanisms of AF and the assessment of novel therapeutic interventions.
Aims
Increasing evidence indicates that congenital long QT syndromes (LQTSs) promote atrial fibrillation. The atrial action potential (AP) has a short plateau, and whether LQTS atrial cardiomyocytes ...generate triggered activity via early afterdepolarizations (EADs) is unclear. Atrial cellular arrhythmia mechanisms have not been defined in congenital LQTS. Therefore, we studied atrial cardiomyocyte electrophysiology in mice with an LQTS3 SCN5A inactivation-impairing mutation (ΔKPQ heterozygotes).
Methods and results
Peak and late Na+ current (I
NaP and I
NaL) were measured with whole-cell patch clamp in left atrial (LA) cardiomyocytes. APs were recorded in multicellular LA preparations with floating microelectrodes. I
NaL was increased by 110% in LA cardiomyocytes of ΔKPQ mice, whereas I
NaP was unchanged. AP duration (APD) was prolonged over all frequencies in ΔKPQ mice, but particularly at lower frequencies e.g. APD90 at 0.5 Hz: 197 ± 8 ms vs. wild-type (WT) 82 ± 2 ms, P< 0.001. EADs occurred at 0.5 Hz in 10/18 ΔKPQ (56%) vs. 1/10 WT (10%) atria (P< 0.05). EADs immediately preceded premature APs in other LA regions, suggesting triggered activity. Ranolazine preferentially inhibited I
NaL (50% inhibitory concentration: 12.5 vs. 151.8 µM for I
NaP) in ΔKPQ myocytes. At 10 µM, ranolazine shortened APD (e.g. APD90 at 0.5 Hz to 122 ± 4 ms, P= 0.01) without changing APD in WT and suppressed EAD occurrence and triggered activity (from 10/18 to 1/9 preparations, 11%, P< 0.05).
Conclusion
This study implicates increased I
NaL in excessive atrial APD prolongation and arrhythmic EAD occurrence in a congenital LQTS3 mouse model. Our observations provide the first direct demonstration of atrial EADs and triggered activity in a genetically defined animal model of human LQTS and have potential clinically-relevant mechanistic and therapeutic implications.
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