Differential Behaviors of Atrial Versus Ventricular Fibroblasts A Potential Role for Platelet-Derived Growth Factor in Atrial-Ventricular Remodeling Differences
TL;DR: Atrial fibroblasts behave differently than ventricular fibro Blasts over a range of in vitro and in vivo paradigms, with atrial Fibroblast showing enhanced reactivity that may explain greater atrial fibrotic responses.
Abstract: Background— In various heart disease paradigms, atria show stronger fibrotic responses than ventricles. The possibility that atrial and ventricular fibroblasts respond differentially to pathological stimuli has not been examined. Methods and Results— We compared various morphological, secretory, and proliferative response indexes of canine atrial versus ventricular fibroblasts. Cultured atrial fibroblasts showed faster cell surface area increases, distinct morphology at confluence, and greater α-smooth muscle actin expression than ventricular fibroblasts. Atrial fibroblast proliferation ([3H]thymidine incorporation) responses were consistently greater for a range of growth factors, including fetal bovine serum, platelet-derived growth factor (PDGF), basic fibroblast growth factor, angiotensin II, endothelin-1, and transforming growth factor-β1. Normal atrial tissue showed larger myofibroblast density compared with ventricular tissue, and the difference was exaggerated by congestive heart failure. Congesti...
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TL;DR: This study suggests that PDGF-B/PDGFR-β signaling, which promotes the proliferation and COL1 secretion of atrial fibroblasts, is an important contributor to atrial Fibrosis in AF and may represent a novel target for the intervention of AF.
Abstract: Objective: To explore the role of platelet-derived growth factor-B (PDGF-B)/platelet-derived growth factor receptor-β (PDGFR-β) signaling in chronic atrial fibril
13 citations
TL;DR: It is proposed that the time is opportune to reevaluate how these cells are named and described, particularly as they transition to myofibroblasts through discrete stages, and to address the confusion that currently exists in the literature as to the usage of terms like my ofibroblast.
Abstract: Fibroblasts have long been recognized as important stromal cells, playing key roles in synthesizing and maintaining the extracellular matrix, but historically were treated as a relatively uniform c...
12 citations
Cites background from "Differential Behaviors of Atrial Ve..."
...Atrial fibroblasts are present in higher density, have higher basal rates of ECM production, and show greater propensity to activation than ventricular fibroblasts – differences that are maintained in the failing heart (Burstein et al. 2008)....
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TL;DR: This proof-of-concept study using an in vitro experimental cell culture model identifies the protective role of simvastatin against TGF-β1-induced hVF transformation into activated myofibroblasts through activation of protein phosphatase, a novel target that can be therapeutically modulated to curb excessive cardiac fibrosis associated with maladaptive cardiac remodeling.
12 citations
TL;DR: Elevated big ET-1 levels is an independent predictor of long-term all-cause mortality, MAEs, and cardiovascular death in patients with AF and allowed a significant improvement in the accuracy of predicting both all- Cause mortality and MAEs.
12 citations
TL;DR: This review will focus on how TRPC3 affects AF pathogenesis by exploring the underlying mechanisms governing fibrosis associated with particular signaling proteins, ultimately highlighting the characteristics of TPRC3 that mark it as a novel therapeutic target for AF alleviation.
12 citations
Cites background from "Differential Behaviors of Atrial Ve..."
...There is clear evidence that atrial fibroblasts are more susceptible to driving the pathological processes of differentiation and proliferation than are ventricular fibroblasts (Burstein et al., 2008)....
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TL;DR: It is shown that cardiac fibrosis is associated with the emergence of fibroblasts originating from endothelial cells, suggesting an endothelial-mesenchymal transition (EndMT) similar to events that occur during formation of the atrioventricular cushion in the embryonic heart.
Abstract: Cardiac fibrosis, associated with a decreased extent of microvasculature and with disruption of normal myocardial structures, results from excessive deposition of extracellular matrix, which is mediated by the recruitment of fibroblasts. The source of these fibroblasts is unclear and specific anti-fibrotic therapies are not currently available. Here we show that cardiac fibrosis is associated with the emergence of fibroblasts originating from endothelial cells, suggesting an endothelial-mesenchymal transition (EndMT) similar to events that occur during formation of the atrioventricular cushion in the embryonic heart. Transforming growth factor-β1 (TGF-β1) induced endothelial cells to undergo EndMT, whereas bone morphogenic protein 7 (BMP-7) preserved the endothelial phenotype. The systemic administration of recombinant human BMP-7 (rhBMP-7) significantly inhibited EndMT and the progression of cardiac fibrosis in mouse models of pressure overload and chronic allograft rejection. Our findings show that EndMT contributes to the progression of cardiac fibrosis and that rhBMP-7 can be used to inhibit EndMT and to intervene in the progression of chronic heart disease associated with fibrosis.
1,908 citations
TL;DR: Experimental CHF strongly promotes the induction of sustained AF by causing interstitial fibrosis that interferes with local conduction, with important potential implications for understanding, treating, and preventing AF related to CHF.
Abstract: Background—Studies of atrial fibrillation (AF) due to atrial tachycardia have provided insights into the remodeling mechanisms by which “AF begets AF” but have not elucidated the substrate that initially supports AF before remodeling occurs. We studied the effects of congestive heart failure (CHF), an entity strongly associated with clinical AF, on atrial electrophysiology in the dog and compared the results with those in dogs subjected to rapid atrial pacing (RAP; 400 bpm) with a controlled ventricular rate (AV block plus ventricular pacemaker at 80 bpm). Methods and Results—CHF induced by 5 weeks of rapid ventricular pacing (220 to 240 bpm) increased the duration of AF induced by burst pacing (from 8±4 seconds in control dogs to 535±82 seconds; P<0.01), similar to the effect of 1 week of RAP (713±300 seconds). In contrast to RAP, CHF did not alter atrial refractory period, refractoriness heterogeneity, or conduction velocity at a cycle length of 360 ms; however, CHF dogs had a substantial increase in th...
1,343 citations
TL;DR: Cultured fetal and adult human fibroblasts maintained key features of HOX gene expression patterns established during embryogenesis, suggesting that HOX genes may direct topographic differentiation and underlie the detailed positional memory in fibro Blasts.
Abstract: A fundamental feature of the architecture and functional design of vertebrate animals is a stroma, composed of extracellular matrix and mesenchymal cells, which provides a structural scaffold and conduit for blood and lymphatic vessels, nerves, and leukocytes. Reciprocal interactions between mesenchymal and epithelial cells are known to play a critical role in orchestrating the development and morphogenesis of tissues and organs, but the roles played by specific stromal cells in controlling the design and function of tissues remain poorly understood. The principal cells of stromal tissue are called fibroblasts, a catch-all designation that belies their diversity. We characterized genome-wide patterns of gene expression in cultured fetal and adult human fibroblasts derived from skin at different anatomical sites. Fibroblasts from each site displayed distinct and characteristic transcriptional patterns, suggesting that fibroblasts at different locations in the body should be considered distinct differentiated cell types. Notable groups of differentially expressed genes included some implicated in extracellular matrix synthesis, lipid metabolism, and cell signaling pathways that control proliferation, cell migration, and fate determination. Several genes implicated in genetic diseases were found to be expressed in fibroblasts in an anatomic pattern that paralleled the phenotypic defects. Finally, adult fibroblasts maintained key features of HOX gene expression patterns established during embryogenesis, suggesting that HOX genes may direct topographic differentiation and underlie the detailed positional memory in fibroblasts.
1,055 citations
TL;DR: The two PDGF null phenotypes reveal analogous morphogenetic functions for myofibroblast-type cells in lung and kidney organogenesis, and show that PDGF-B is required in the ontogeny of kidney mesangial cells.
854 citations
TL;DR: TGF-beta induces proliferation of connective tissue cells at low concentrations by stimulating autocrine PDGF-AA secretion, which at higher concentrations of TGF- beta, is decreased by down-regulation of PDGF receptor alpha subunits and perhaps by direct growth inhibition.
760 citations