Bursac N, Parker K K, Iravanian S, Tung L
Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, Md 21205, USA.
Circ Res. 2002 Dec 13;91(12):e45-54. doi: 10.1161/01.res.0000047530.88338.eb.
Structural and functional cardiac anisotropy varies with the development, location, and pathophysiology in the heart. The goal of this study was to design a cell culture model system in which the degree, change in fiber direction, and discontinuity of anisotropy can be controlled over centimeter-size length scales. Neonatal rat ventricular myocytes were cultured on fibronectin on 20-mm diameter circular cover slips. Structure-function relationships were assessed using immunostaining and optical mapping. Cell culture on microabraded cover slips yielded cell elongation and coalignment in the direction of abrasion, and uniform, macroscopically continuous, elliptical propagation with point stimulation. Coarser microabrasion (wider and deeper abrasion grooves) increased longitudinal (23.5 to 37.2 cm/s; r=0.66) and decreased transverse conduction velocity (18.1 to 9.2 cm/s; r=-0.84), which resulted in increased longitudinal-to-transverse velocity anisotropy ratios (1.3 to 3.7, n=61). A thin transition zone between adjacent uniformly anisotropic areas with 45 degrees or 90 degrees difference in fiber orientation acted as a secondary source during 2x threshold field stimulus. Cell culture on cover slips micropatterned with 12- or 25- micro m wide fibronectin lines and previously coated with decreasing concentrations of background fibronectin yielded transition from continuous to discontinuous anisotropic architecture with longitudinally oriented intercellular clefts, decreased transverse velocity (16.9 to 2.6 cm/s; r=-0.95), increased velocity anisotropy ratios (1.6 to 5.6, n=70), and decreased longitudinal velocity (36.4 to 14.6 cm/s; r=-0.85) for anisotropy ratios >3.5. Cultures of cardiac myocytes with controlled degree, uniformity and continuity of structural, and functional anisotropy may enable systematic 2-dimensional in vitro studies of macroscopic structure-related mechanisms of reentrant arrhythmias. The full text of this article is available at http://www.circresaha.org.
心脏的结构和功能各向异性会随着心脏的发育、位置以及病理生理学情况而发生变化。本研究的目的是设计一种细胞培养模型系统，在该系统中，各向异性的程度、纤维方向的变化以及各向异性的不连续性能够在厘米级的长度尺度上得到控制。将新生大鼠心室肌细胞培养在直径为20毫米的圆形盖玻片上的纤连蛋白上。使用免疫染色和光学映射评估结构-功能关系。在微磨损的盖玻片上进行细胞培养，细胞会在磨损方向上伸长并排列成束，并且在点刺激时会产生均匀、宏观连续的椭圆形传播。更粗糙的微磨损（更宽更深的磨损沟槽）会增加纵向传导速度（从23.5厘米/秒增加到37.2厘米/秒；r = 0.66）并降低横向传导速度（从18.1厘米/秒降低到9.2厘米/秒；r = -0.84），这导致纵向与横向速度各向异性比率增加（从1.3增加到3.7，n = 61）。在相邻的均匀各向异性区域之间，纤维方向相差45度或90度的薄过渡区在2倍阈值场刺激期间充当次级源。在预先用浓度逐渐降低的背景纤连蛋白包被、并用12微米或25微米宽的纤连蛋白线进行微图案化的盖玻片上进行细胞培养，会产生从连续到不连续的各向异性结构转变，伴有纵向排列的细胞间裂隙，横向速度降低（从16.9厘米/秒降低到2.6厘米/秒；r = -0.95），速度各向异性比率增加（从1.6增加到5.6，n = 70），并且对于各向异性比率>3.5，纵向速度降低（从36.4厘米/秒降低到14.6厘米/秒；r = -0.85）。具有可控的结构和功能各向异性程度、均匀性和连续性的心肌细胞培养，可能有助于对折返性心律失常的宏观结构相关机制进行系统的二维体外研究。本文全文可在http://www.circresaha.org获取。
