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Increased length-dependent activation of human engineered heart tissue after chronic α1A-adrenergic agonist treatment: testing a novel heart failure therapy

ABSTRACT: Chronic stimulation of cardiac a1A-adrenergic receptors (a1A-ARs) improves symptoms in multiple preclinical models of heart failure. However, the translational significance remains unclear. This study tested the effects of chronic a1A-AR stimulation on human engineered heart tissue (EHT). EHTs were created from thin slices of decellularized pig myocardium seeded with human induced pluripotent stem cell (iPSC)-derived cardiomyocytes and fibroblasts. Using a paired experimental design, EHTs were cultured for 3 wk., mechanically tested, cultured again for 2 wk. with a1A-AR agonist A61603 (10 nM) or vehicle control, and retested after drug washout for 24-hr. Separate control experiments determined the effects of EHT age (3-5 wk.) or repeat mechanical testing. We found that chronic A61603 treatment caused a 25% increase of length-dependent activation (LDA) of contraction compared to vehicle treatment (n=7/group, P=0.035). EHT force was not increased after chronic A61603 treatment. However, after vehicle treatment, EHT force was increased 35% relative to baseline testing (n=7/group, P=0.022), suggesting EHT maturation. Control experiments showed increased EHT force resulted from repeat mechanical testing, not from EHT aging. RNA-seq analysis confirmed the a1A-AR is expressed in human EHTs and found chronic A61603 treatment affected gene expression in biological pathways which are known to be activated by a1A-ARs, including the MAP kinase signaling pathway. In conclusion, chronic stimulation of the a1A-AR, a promising preclinical target for treating heart failure, gave mixed results in human EHTs. Chronic a1A-AR stimulation had a positive effect (increased LDA) but potentially, a negative effect (lower EHT force). The translational significance of these findings requires further study.

ORGANISM(S): Homo sapiens

PROVIDER: GSE216439 | GEO | 2023/01/01

REPOSITORIES: GEO

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Project description:Background: Cardiomyocytes (CMs) induced from human induced pluripotent stem cells (hiPSCs) by traditional methods are a mix of atrial and ventricular CMs and many other non-cardiomyocytes. Retinoic acid (RA) plays an important role in regulation of the spatiotemporal development of the embryonic heart and high concentrations of RA have been shown to steer differentiation towards atrial CMs, whereas lower concentrations of RA promote a more ventricular-like CM profile. Aim: Create engineered heart tissue (EHT) with left and right ventricular phenotype from hiPSCs by intervening with specific concentrations of retinoic acid (RA) during hiPSC differentiation towards CM. Methods: hiPSC were derived by reprogramming skin fibroblasts. Different concentrations of RA (Control group without RA, LRA group with 0.05 µM and HRA group with 0.1 µM) were administered during third to sixth days of the differentiation process. Engineered heart tissues (EHTs) were generated by assembling CMs derived from hiPSC (hiPSC-CM) at high cell density in a low collagen hydrogel. The maturation and growth of EHTs were induced in a customized biomimetic tissue culture system, that provides continuous electrical stimulation, medium agitation and stretch. The function of CMs and EHTs was analyzed under different conditions. Finally, RNA extraction and tissue fixation were performed on CMs and EHTs for RT-qPRC and immunofluorescence staining analysis. RNA sequencing was conducted on EHTs to examine how RA affects both the function and structure of EHT. Results: In the HRA group, hiPSC-CMs exhibited the first onset of beating and showed the highest expression of maturity genes MYH7 and cTnT. The expression of TBX5, NKX2.5 and CORIN, which are the marker genes for left ventricular CMs, was also the highest in the HRA group. The transcription factor MEF2C associated with RA and ventricular development genes, NPPA and MYH7, were highly expressed in the HRA group, while GATA4 was less expressed in the HRA group. In terms of EHT, the HRA group displayed the highest contraction force, the lowest beating frequency, and the highest sensitivity to hypoxia and isoprenaline, which means it was more functionally similar to the left ventricle. The expression of TBX5 and NKX2.5 was found to be the highest expression in the HRA group of EHT, while expression of TBX20 and ISL1 was found to be the highest expression in control group. When the electrical stimulation frequency of EHT in the HRA group was raised, it correspondingly increased its contractile force. The heightened contractility of EHT within the HRA group can be attributed to the promotion of augmented extracellular matrix strength by RA. Conclusion: By interfering with the differentiation process of hiPSC with a specific concentration of RA at a specific time, we were able to successfully induce CMs and EHT with a phenotype similar to that of the left ventricle or right ventricle. Our research paved the way for future studies on in vitro left ventricular or right ventricular function, personalized drug screening, and precision medicine.

Project description:Aims: The sympathetic nervous system regulates numerous critical aspects of mitochondrial function in the heart through activation of adrenergic receptors (ARs) on cardiomyocytes. Chronic β-AR activation causes maladaptive alterations in cardiomyocyte metabolism that contribute to the pathobiology of heart failure. In contrast, mounting evidence suggests that a1-ARs, particularly the a1A subtype, are cardioprotective and may mitigate the deleterious effects of chronic β-AR activation by shared endogenous catecholamine ligands. The mechanisms through which a1A-ARs exert their cardioprotective effects remain unclear. Here we tested the hypothesis that a1A-ARs adaptively regulate cardiomyocyte oxidative metabolism in both the uninjured and failing heart. Methods: We characterized the effects of global α1A-AR genetic deletion on mitochondrial function and metabolism in the uninjured mouse heart using high resolution respirometry, substrate-specific electron transport chain (ETC) enzyme assays, transmission electron microscopy (TEM), proteomics, and lipidomics. We then compared the effects of α1A- and β-AR agonist treatment on ETC enzyme activity and oxidative stress in vivo and in vitro. We subjected wild type and cardiomyocyte-specific α1A-KO mice to permanent left coronary artery (LCA) ligation and used RNAseq to compare the transcriptomic response. Results: We found that isolated cardiac mitochondria from mice with global α1A-AR genetic deletion (α1A-KO) had deficits in fatty acid-dependent respiration and ETC enzyme activity. TEM revealed abnormalities of mitochondrial morphology characteristic of these functional deficits. The selective α1A-AR agonist A61603 (100 ng/kg/d, 3d) enhanced fatty acid oxidation (FAO) in isolated cardiac mitochondria while increasing expression and activity of the mitochondrial trifunctional protein, a critical FAO mediator. The β-AR agonist isoproterenol enhanced oxidative stress in vitro and this adverse effect was mitigated by A61603. RNAseq revealed broad basal deficits in pathways related to mitochondria and OXPHOS in cardiomyocyte-specific α1A-KO mice; these differences were exaggerated by LCA ligation. A61603 enhanced ETC Complex I activity and protected contractile function following myocardial infarction. Conclusions: Collectively, these novel findings position α1A-ARs as critical regulators of cardiomyocyte metabolism in the basal state and suggest that metabolic mechanisms may underlie the protective effects of α1A-AR activation in the failing heart.

Project description:Rationale Hypertrophic cardiomyopathy (HCM) is the most common cardiac genetic disorder caused by sarcomeric gene variants and is associated with left ventricular hypertrophy and diastolic dysfunction. The role of the microtubule network has recently gained interest with findings that microtubule detyrosination (dTyr-MTs) is markedly elevated in heart failure. Acute reduction of dTyr-MTs by inhibition of the detyrosinase (VASH/SVBP complex) or activation of the tyrosinase (tubulin tyrosine ligase, TTL) markedly improved contractility and reduced stiffness in human failing cardiomyocytes, presenting a new perspective for HCM treatment. Objective In this study, we tested the impact of chronic tubulin tyrosination in a HCM mouse model (Mybpc3-knock-in; KI), in human HCM cardiomyocytes, and in SVBP-deficient human engineered heart tissues (EHTs). Methods and Results AAV9-mediated TTL transfer was applied in neonatal wild-type (WT) rodents, in 3-week-old KI mice, and in HCM human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes. We show: i) TTL for 6 weeks dose-dependently reduced dTyr-MTs and improved contractility without affecting cytosolic calcium transients in WT cardiomyocytes. ii) TTL for 12 weeks reduced the abundance of dTyr-MTs in the myocardium, improved diastolic filling, compliance, cardiac output, and stroke volume in KI mice. iii) TTL for 10 days normalized cell area in HCM hiPSC-cardiomyocytes. iv) TTL overexpression activates transcription of several tubulin isoforms, and omics GO analysis revealed enrichment of components of the cytoskeleton, sarcomere Z-disc, mitochondria, and intercalated disc in KI mice. v) SVBP-deficient EHTs exhibited reduced dTyr-MT levels, higher force, and faster relaxation than TTL-deficient and WT EHTs. RNA-seq and mass spectrometry analysis revealed distinct enrichment of cardiomyocyte components and pathways in SVBP-KO vs. TTL-KO EHTs. Conclusion This study provides the first proof-of-concept that chronic activation of tubulin tyrosination in HCM mice and in human EHTs improves heart function and holds promise for targeting the non-sarcomeric cytoskeleton in heart disease.

Project description:Background: The phospholamban (PLN) p.Arg14del mutation belongs to the established causes of dilated cardiomyopathy, with the molecular disease mechanisms incompletely understood. We used human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes, CRISPR/Cas9 gene editing and patient heart samples to investigate the molecular pathomechanisms of PLN p.Arg14del cardiomyopathy. Methods and results: Patient dermal fibroblasts carrying the PLN p.Arg14del mutation were reprogrammed into hiPSC, isogenic controls were established by CRISPR/Cas9. Cells were differentiated into cardiomyocytes and characterized in 2D and 3D-engineered heart tissue (EHT) format. Mutant cardiomyocytes revealed significantly prolonged Ca2+ transient decay time, Ca2+-load dependent irregular beating pattern and lower peak force compared to isogenic controls. While this data support the reported super-inhibitory effect of PLN p.Arg14del on the sarcoplasmic/endoplasmic reticulum Ca2+ ATPase, an unchanged SR Ca2+ content argued against disturbed SR Ca2+ cycling as the sole cause of contractile dysfunction. Label-free proteomic analysis of p.Arg14del EHTs revealed less endoplasmic reticulum (ER), ribosomal and mitochondrial proteins. Electron microscopy showed dilation of the rough ER, large lipid droplets in close association with mitochondria and reduced mitochondrial number. Follow-up experiments confirmed impairment of the rough ER/mitochondria compartment and enhanced oxidative stress in PLN p.Arg14del. Relevance for human disease was demonstrated by immunohistochemistry of human heart samples. PLN p.Arg14del end-stage heart failure samples revealed perinuclear aggregates positive for ER marker proteins and oxidative stress in comparison to ischemic heart failure - and non-failing donor heart samples. Surprisingly, transduction of PLN p.Arg14del EHTs with the Ca2+ binding protein GCaMP6f reversed the contractile, molecular and morphological disease phenotype. Conclusion: This study identified impairment of the rough ER/mitochondria compartment without SR dysfunction as a novel disease mechanism underlying PLN p.Arg14del cardiomyopathy. The pathology was improved by Ca2+-scavenging, suggesting impaired local Ca2+ cycling as an important disease culprit.

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Increased length-dependent activation of human engineered heart tissue after chronic α1A-adrenergic agonist treatment: testing a novel heart failure therapy

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