title: Congestive heart failure effects on atrial fibroblast phenotype: differences between freshly-isolated and cultured cells.
abstract: BACKGROUND
  Fibroblasts are important in the atrial fibrillation (AF) substrate resulting from congestive heart failure (CHF). We previously noted changes in in vivo indices of fibroblast function in a CHF dog model, but could not detect changes in isolated cells. This study assessed CHF-induced changes in the phenotype of fibroblasts freshly isolated from control versus CHF dogs, and examined effects of cell culture on these differences.
  
  
  RESULTS
  Left-atrial fibroblasts were isolated from control and CHF dogs (ventricular tachypacing 240 bpm × 2 weeks). Freshly-isolated fibroblasts were compared to fibroblasts in primary culture. Extracellular-matrix (ECM) gene-expression was assessed by qPCR, protein by Western blot, fibroblast morphology with immunocytochemistry, and K(+)-current with patch-clamp. Freshly-isolated CHF fibroblasts had increased expression-levels of collagen-1 (10-fold), collagen-3 (5-fold), and fibronectin-1 (3-fold) vs. control, along with increased cell diameter (13.4 ± 0.4 µm vs control 8.4 ± 0.3 µm) and cell spreading (shape factor 0.81 ± 0.02 vs. control 0.87 ± 0.02), consistent with an activated phenotype. Freshly-isolated control fibroblasts displayed robust tetraethylammonium (TEA)-sensitive K(+)-currents that were strongly downregulated in CHF. The TEA-sensitive K(+)-current differences between control and CHF fibroblasts were attenuated after 2-day culture and eliminated after 7 days. Similarly, cell-culture eliminated the ECM protein-expression and shape differences between control and CHF fibroblasts.
  
  
  CONCLUSIONS
  Freshly-isolated CHF and control atrial fibroblasts display distinct ECM-gene and morphological differences consistent with in vivo pathology. Culture for as little as 48 hours activates fibroblasts and obscures the effects of CHF. These results demonstrate potentially-important atrial-fibroblast phenotype changes in CHF and emphasize the need for caution in relating properties of cultured fibroblasts to in vivo systems.
authors.affiliation: Research Center, Montreal Heart Institute, Montreal, Quebec, Canada.
authors.forename: Kristin
authors.initials: K
authors.lastname: Dawson
authors.forename: Chia-Tung
authors.initials: CT
authors.lastname: Wu
authors.forename: Xiao Yan
authors.initials: XY
authors.lastname: Qi
authors.forename: Stanley
authors.initials: S
authors.lastname: Nattel
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003094:Collagen / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D004285:Dogs; D015536:Down-Regulation; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology*; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006325:Heart Atria / Q000378:metabolism / Q000473:pathology; D006333:Heart Failure / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008297:Male; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D011188:Potassium / Q000378:metabolism
chemical_list: D005353:Fibronectins; D003094:Collagen; D011188:Potassium