Neuromuscular junctions (NMJs), specialized synapses between motor neurons and muscle fibers, are essential for muscle activity. A simple and reproducible cell-based in vitro NMJ platform is needed to test the impact of chemicals on the neuron-muscle communication. Our platform utilizes genetically modified neurons and muscle cells, optimized culture conditions, and commercially available multielectrode array system for recording action potentials. Neuronal cells (NSC34) were optogenetically modified with channelrhodopsin chimera to allow for simultaneous, light-mediated, millisecond-precise activation of neuronal population. This signal is propagated through functional synapses to the muscle fibers. Muscle cells (C2C12) were modified by incorporating gap junction protein (Connexin-43) to improve intracellular communication without affecting muscle differentiation. This communication between muscle fibers resulted in better signal propagation and signal strength. Optimized culture medium facilitated the growth and differentiation of both cell types together. Our system was validated using vecuronium, a muscle relaxant, which abolished the muscle response. This in vitro model provides a unique tool for establishing a NMJ platform that is easy to record and analyze. Potential applications include nondestructive long-term screening of drugs affecting the NMJ.

中文翻译：

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针对电动平台优化的神经肌肉连接模型

神经肌肉接头 (NMJ) 是运动神经元和肌肉纤维之间的特殊突触，对肌肉活动至关重要。一种简单且可重复的基于细胞的体外需要 NMJ 平台来测试化学物质对神经元肌肉通讯的影响。我们的平台利用转基因神经元和肌肉细胞、优化的培养条件和商用多电极阵列系统来记录动作电位。神经元细胞 (NSC34) 用视紫红质通道嵌合体进行了光遗传学修饰，以允许同时、光介导、毫秒级精确激活神经元群。该信号通过功能性突触传播到肌肉纤维。肌肉细胞 (C2C12) 通过加入间隙连接蛋白 (Connexin-43) 进行修饰，以在不影响肌肉分化的情况下改善细胞内通讯。肌肉纤维之间的这种交流导致了更好的信号传播和信号强度。优化的培养基促进了两种细胞类型的生长和分化。我们的系统使用维库溴铵进行了验证，维库溴铵是一种肌肉松弛剂，可以消除肌肉反应。这个体外模型为建立易于记录和分析的NMJ平台提供了独特的工具。潜在应用包括对影响 NMJ 的药物进行非破坏性长期筛选。