Xie Xudong, Liu Yanrong, Gao Shilong, Wu Bifeng, Hu Xiaosheng, Chen Junzhu
Department of Cardiology, First Affiliated Hospital, Medical School of Zhejiang University.
Circ J. 2014;78(2):338-44. doi: 10.1253/circj.cj-13-0776. Epub 2013 Nov 7.
Chronic atrial fibrillation (AF) is characterized by a remodeling process with prominent atrial fibrosis. Fibrocytes, a bone marrow-derived population of fibroblast-like cells, have been placed at the center of a number of fibrosing conditions. The purpose of this study was to evaluate the contribution of fibrocytes to atrial fibrosis in patients with chronic AF and the possible mechanisms.
We enrolled 22 consecutive valvular heart disease patients with chronic AF (>6 months: CAF group) and 15 valvular heart disease patients in sinus rhythm served as controls (SR group). Left atrial tissue samples were obtained during cardiac surgery. The infiltration of fibrocytes into the atrial interstitium was observed by confocal microscopy. The number of atrial fibrocytes was approximately three-fold higher in the CAF group compared with the SR controls, and positively correlated with both the atrial collagen volume fraction (r=0.713; P=0.0002) and the left atrial volume index (r=0.631; P=0.002). In the peripheral blood samples collected before the operation, approximately 2.5-fold higher percentage of circulating fibrocytes was identified in the CAF group. These fibrocytes showed a stronger proliferative capacity (≍2.5-fold) and higher level expression of collagen I and α-SMA (≍2-fold and 4-fold, respectively) compared with the SR controls.
The results suggested that fibrocytes may be involved in atrial fibrosis in chronic AF through enhanced profibrotic characteristics.
慢性心房颤动（AF）的特征是伴有显著心房纤维化的重塑过程。纤维细胞是一种源自骨髓的成纤维细胞样细胞群体，在多种纤维化疾病中处于核心地位。本研究的目的是评估纤维细胞对慢性AF患者心房纤维化的作用及可能机制。
我们连续纳入了22例患有慢性AF（>6个月）的瓣膜性心脏病患者（CAF组）和15例处于窦性心律的瓣膜性心脏病患者作为对照组（SR组）。在心脏手术期间获取左心房组织样本。通过共聚焦显微镜观察纤维细胞向心房间质的浸润情况。与SR对照组相比，CAF组的心房纤维细胞数量高出约三倍，且与心房胶原容积分数（r = 0.713；P = 0.0002）和左心房容积指数（r = 0.631；P = 0.002）均呈正相关。在术前采集的外周血样本中，CAF组循环纤维细胞的百分比高出约2.5倍。与SR对照组相比，这些纤维细胞表现出更强的增殖能力（约2.5倍）以及更高水平的I型胶原和α - SMA表达（分别约为2倍和4倍）。
结果表明，纤维细胞可能通过增强促纤维化特性参与慢性AF的心房纤维化过程。
