Congestive Heart Failure Effects on Atrial Fibroblast Phenotype: Differences between Freshly-Isolated and Cultured Cells

Dawson, Kristin; Wu, Chia-Tung; Qi, Xiao Yan; Nattel, Stanley

doi:10.1371/journal.pone.0052032

Cited by 33 publications

(37 citation statements)

References 38 publications

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“…The downregulation of I Kv,fb reported here is similar to our observations in previous work, both in fibroblasts from HF animals and occurring spontaneously under cell-culture conditions (22,24). We are not aware of any previous reports of I Kir,fb remodeling in HF.…”

Section: Relation To Previous Studies Of Fibroblast Ion Currentssupporting

confidence: 91%

“…The properties of I Kir,fb and I Kv,fb described in this work are grossly similar to those reported in prior studies of rat (29), canine (22,24), and human (30) fibroblasts. The downregulation of I Kv,fb reported here is similar to our observations in previous work, both in fibroblasts from HF animals and occurring spontaneously under cell-culture conditions (22,24).…”

Section: Relation To Previous Studies Of Fibroblast Ion Currentssupporting

confidence: 86%

“…Here, we examined the remodeling of K þ currents in fibroblasts freshly isolated from dogs with an AF substrate associated with heart failure (HF). Freshly isolated fibroblasts were used to preclude the effects of cell culture, which can obscure the fibroblast remodeling phenotype caused by HF (22). We then implemented these experimental findings in a mathematical model based on previous work (23) to investigate the potential effects of fibroblast electrical remodeling on atrial cardiomyocyte electrophysiological properties and arrhythmogenesis, assuming cardiomyocyte-fibroblast electrical coupling.…”

Section: Introductionmentioning

confidence: 99%

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Fibroblast Electrical Remodeling in Heart Failure and Potential Effects on Atrial Fibrillation

Aguilar

Huang

et al. 2014

Biophysical Journal

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Fibroblasts are activated in heart failure (HF) and produce fibrosis, which plays a role in maintaining atrial fibrillation (AF). The effect of HF on fibroblast ion currents and its potential role in AF are unknown. Here, we used a patch-clamp technique to investigate the effects of HF on atrial fibroblast ion currents, and mathematical computation to assess the potential impact of this remodeling on atrial electrophysiology and arrhythmogenesis. Atrial fibroblasts were isolated from control and tachypacing-induced HF dogs. Tetraethylammonium-sensitive voltage-gated fibroblast current (IKv,fb) was significantly downregulated (by ?44%), whereas the Ba(2+)-sensitive inward rectifier current (IKir,fb) was upregulated by 79%, in HF animals versus controls. The fibroblast resting membrane potential was hyperpolarized (?53 ± 2 mV vs. ?42 ± 2 mV in controls) and the capacitance was increased (29.7 ± 2.2 pF vs. 17.8 ± 1.4 pF in controls) in HF. These experimental findings were implemented in a mathematical model that included cardiomyocyte-fibroblast electrical coupling. IKir,fb upregulation had a profibrillatory effect through shortening of the action potential duration and hyperpolarization of the cardiomyocyte resting membrane potential. IKv,fb downregulation had the opposite electrophysiological effects and was antifibrillatory. Simulated pharmacological blockade of IKv,fb successfully terminated reentry under otherwise profibrillatory conditions. We conclude that HF induces fibroblast ion-current remodeling with IKv,fb downregulation and IKir,fb upregulation, and that, assuming cardiomyocyte-fibroblast electrical coupling, this remodeling has a potentially important effect on atrial electrophysiology and arrhythmogenesis, with the overall response depending on the balance of pro- and antifibrillatory contributions. These findings suggest that fibroblast K(+)-current remodeling is a novel component of AF-related remodeling that might contribute to arrhythmia dynamics.

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Section: Relation To Previous Studies Of Fibroblast Ion Currentssupporting

confidence: 91%

Section: Relation To Previous Studies Of Fibroblast Ion Currentssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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Fibroblast Electrical Remodeling in Heart Failure and Potential Effects on Atrial Fibrillation

Aguilar

Huang

et al. 2014

Biophysical Journal

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“…7 Hearts were removed after intra-atrial injection of heparin (10 000 U) and immersed in 2 mmol/L of Ca 2+ -containing Tyrode solution. The left coronary artery was cannulated, and the LA tissue was perfused with 2 mmol/L of Ca 2+ Tyrode solution (37°C, 100% O 2 ), then with Ca 2+ -free Tyrode solution (≈10 minutes), followed by ≈60-minute perfusion with the same solution containing collagenase (≈0.48 mg/mL; CLSII, Worthington, OH) and 0.1% bovine serum albumin (Sigma).…”

Section: Fibroblast Isolation and Culturementioning

confidence: 99%

“…Freshly isolated fibroblasts were then separated; 1 aliquot was flash-frozen in liquid N 2 and stored for biochemical studies, and the remaining cells were cultured on noncoated glass coverslips. 7 Fibroblasts were incubated in 5% CO 2 /95% O 2 humidified air (37°C). A medium change was performed 4 hours after plating to remove any dead cells and debris, and the medium was changed every 24 hours.…”

Section: Fibroblast Isolation and Culturementioning

confidence: 99%

Fibroblast Inward-Rectifier Potassium Current Upregulation in Profibrillatory Atrial Remodeling

Huang

Ördög

et al. 2015

Circulation Research

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Rationale: Fibroblasts are involved in cardiac arrhythmogenesis and contribute to the atrial fibrillation substrate in congestive heart failure (CHF) by generating tissue fibrosis. Fibroblasts display robust ion currents, but their functional importance is poorly understood. Objective: To characterize atrial fibroblast inward-rectifier K + current ( I K1 ) remodeling in CHF and its effects on fibroblast properties. Methods and Results: Freshly isolated left atrial fibroblasts were obtained from controls and dogs with CHF (ventricular tachypacing). Patch clamp was used to record resting membrane potential (RMP) and I K1 . RMP was significantly increased by CHF (from −43.2±0.8 mV, control, to −55.5±0.9 mV). CHF upregulated I K1 (eg, at −90 mV from −1.1±0.2 to −2.7±0.5 pA/pF) and increased the expression of KCNJ2 mRNA (by 52%) and protein (by 80%). Ba 2+ (300 μmol/L) decreased the RMP and suppressed the RMP difference between controls and dogs with CHF. Store-operated Ca 2+ entry (Fura-2-acetoxymethyl ester) and fibroblast proliferation (flow cytometry) were enhanced by CHF. Lentivirus-mediated overexpression of KCNJ2 enhanced I K1 and hyperpolarized fibroblasts. Functional KCNJ2 suppression by lentivirus-mediated expression of a dominant negative KCNJ2 construct suppressed I K1 and depolarized RMP. Overexpression of KCNJ2 increased Ca 2+ entry and fibroblast proliferation, whereas the dominant negative KCNJ2 construct had opposite effects. Fibroblast hyperpolarization to mimic CHF effects on RMP enhanced the Ca 2+ entry. MicroRNA-26a, which targets KCNJ2, was downregulated in CHF fibroblasts. Knockdown of endogenous microRNA-26 to mimic CHF effects unregulated I K1 . Conclusions: CHF upregulates fibroblast KCNJ2 expression and currents, thereby hyperpolarizing RMP, increasing Ca 2+ entry, and enhancing atrial fibroblast proliferation. These effects are likely mediated by microRNA-26a downregulation. Remodeling-induced fibroblast KCNJ2 expression changes may play a role in atrial fibrillation promoting fibroblast remodeling and structural/arrhythmic consequences.

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Mechanosensitive molecular mechanisms of myocardial fibrosis in living myocardial slices

et al. 2022

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Aims Altered mechanical load in response to injury is a main driver of myocardial interstitial fibrosis. No current in vitro model can precisely modulate mechanical load in a multicellular environment while maintaining physiological behaviour. Living myocardial slices (LMS) are a 300 μm-thick cardiac preparation with preserved physiological structure and function. Here we apply varying degrees of mechanical preload to rat and human LMS to evaluate early cellular, molecular, and functionality changes related to myocardial fibrosis. Methods and resultsLeft ventricular LMS were obtained from Sprague Dawley rat hearts and human cardiac samples from healthy and failing (dilated cardiomyopathy) hearts. LMS were mounted on custom stretchers and two degrees of diastolic load were applied: physiological sarcomere length (SL) (SL = 2.2 μm) and overload (SL = 2.4 μm). LMS were maintained for 48 h under electrical stimulation in circulating, oxygenated media at 37°C. In overloaded conditions, LMS displayed an increase in nucleus translocation of Yes-associated protein (YAP) and an up-regulation of mechanotransduction markers without loss in cell viability. Expression of fibrotic and inflammatory markers, as well as Collagen I deposition were also observed. Functionally, overloaded LMS displayed lower contractility (7.48 ± 3.07 mN mm À2 at 2.2 SL vs. 3.53 ± 1.80 mN mm À2 at 2.4 SL). The addition of the profibrotic protein interleukin-11 (IL-11) showed similar results to the application of overload with enhanced fibrosis (8% more of collagen surface coverage) and reduced LMS contractility at physiological load. Conversely, treatment with the Transforming growth factor β receptor (TGF-βR) blocker SB-431542, showed down-regulation of genes associated with mechanical stress, prevention of fibrotic response and improvement in cardiac function despite overload (from 2.40 ± 0.8 mN mm À2 to 4.60 ± 1.08 mN mm À2 ). Conclusions The LMS have a consistent fibrotic remodelling response to pathological load, which can be modulated by a TGF-βR blocker. The LMS platform allows the study of mechanosensitive molecular mechanisms of myocardial fibrosis and can lead to the development of novel therapeutic strategies.

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Congestive Heart Failure Effects on Atrial Fibroblast Phenotype: Differences between Freshly-Isolated and Cultured Cells

Cited by 33 publications

References 38 publications

Fibroblast Electrical Remodeling in Heart Failure and Potential Effects on Atrial Fibrillation

Fibroblast Electrical Remodeling in Heart Failure and Potential Effects on Atrial Fibrillation

Fibroblast Inward-Rectifier Potassium Current Upregulation in Profibrillatory Atrial Remodeling

Mechanosensitive molecular mechanisms of myocardial fibrosis in living myocardial slices

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