Abstract 14905: Fibrocytes Are Involved in Atrial Fibrosis in Patients With Chronic Atrial Fibrillation
Introduction: Chronic atrial fibrillation (AF) is characterized by a remodeling process, which involves prominent atrial fibrosis. Fibrocytes are a distinct population of blood-borne cells that coexpress hematopoietic cell antigens and fibroblast products,which have been shown to contribute to organ fibrosis.
Hypothesis: The purpose of this study was to test the hypothesis that fibrocytes may contribute to the atrial fibrosis in patients with chronic AF.
Methods: We investigated the presence of fibrocytes co-expressing CD34 and pro-collagen I immunohistochemically in atrial biopsy specimens from 13 valvular heart disease patients with chronic AF (CAF, > 6 months). Nine valvular heart disease patients with sinus rhythm were served as matched control (SR). The number of circulating fibrocytes in peripheral blood was identified by flow cytometry. The expressions of collagen I and a-SMA were detected by Western Blotting. We investigated the correlation between fibrocytes counts and left atrial diameter.
Results: The infiltration of fibrocytes was observed in the atrial interstitium. The number of interstitial fibrocytes in patients with CAF was higher that in patients with SR (7.1±2.3 VS 3.3±2.0 per visual field, p<0.05). A higher percentage of circulating fibrocytes was significantly identified in CAF than that in SR (5.8±[2.1]×104 VS 1.9±[1.0]×104 cells/ml, p<0.05). The collagen I and a-SMA levels in circulating fibrocytes were about 5-fold and 3-fold higher, respectively, in CAF compared to those in SR (both p<0.05). A significant positive correlation was evident between the number of interstitial fibrocytes and left atrial diameter in CAF group (r=0.53, p<0.05).
Conclusions: Circulating firocytes might be involved in atrial interstitial fibrosis in patients with chronic AF and be useful as a clinical marker for atrial remodeling progression.
- © 2010 by American Heart Association, Inc.