Morphological, Electrophysiological and Molecular Analysis of the Cardiomyocytes Defferentiated From Bone Marrow Mesenchymal Stem Cells

我们从小鼠骨髓基质细胞中分离出一株心肌细胞系。经5-氮胞苷处理后，约30%的细胞形态发生改变，1周后与相邻细胞连接，2周后形成肌管样结构并开始自发搏动，3周后同步搏动。表达ANP和BNP。电子显微镜下可见心肌细胞样超微结构，包括典型的肌节和心房颗粒。这些细胞有几种类型的动作电位：窦房结样动作电位和心室细胞样动作电位。所有细胞都有较长的动作电位持续时间或平台，静息膜电位相对较浅，舒张期晚期慢去极化。肌球蛋白重链、肌球蛋白轻链和α-肌动蛋白等收缩蛋白基因的同工型分析表明，在5-氮胞苷治疗前，它们的肌肉NKX2.5/CSx、GATA4、TEF-1和MEF-2C基因表达，治疗后表达MEF-2A和MEF-2D。使用成人组织作为心肌细胞的来源，使该系统特别适合于心脏病基因治疗策略的开发。该新细胞系为研究心肌细胞分化提供了有力的模型。

We have isolated a cardiomyogenic cell line from murine bone marrow stromal cells. The cells showed a fibroblast-like morphology, but the morphology changed after 5-azacytidine treatment in approximately 30% of the cells; they connected with adjoining cells after 1 week, formed myotube-like structures and began spontaneous beating after 2 weeks, and beat synchronously after 3 weeks. The expressed ANP and BNP. Electron microscopy revealed a cardiomyocyte-like ultrastructure including typical sarcomeres and atrial granules. These cells had several types of action potentials; sinus node-like and ventricular cell-like action potentials. All cells had a long action potential duration or plateau, a relatively shallow resting membrane potential, and a pacemaker-like late diastolic slow depolarization. Analysis of the isoform of contractile protein genes, such as myosin heavy chain, myosin light chain and α-actin, indicated that their muscle Nkx2.5/Csx, GATA4, TEF-1 and MEF-2C mRNA before 5-azacytidine treatment, and expressed MEF-2A and MEF-2D after treatment. The use of adult tissues as a source of cardiomyocytes makes this system particularly appropriate for the development of gene therapy strategies for heart disease. This new cell line provides a powerful model for the study of cardiomyocytes differentiation.