Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, United States of America.
PLoS One. 2012;7(7):e40154. doi: 10.1371/journal.pone.0040154. Epub 2012 Jul 3.
Our understanding of motor neuron biology in humans is derived mainly from investigation of human postmortem tissue and more indirectly from live animal models such as rodents. Thus generation of motor neurons from human embryonic stem cells and human induced pluripotent stem cells is an important new approach to model motor neuron function. To be useful models of human motor neuron function, cells generated in vitro should develop mature properties that are the hallmarks of motor neurons in vivo such as elaborated neuronal processes and mature electrophysiological characteristics. Here we have investigated changes in morphological and electrophysiological properties associated with maturation of neurons differentiated from human embryonic stem cells expressing GFP driven by a motor neuron specific reporter (Hb9::GFP) in culture. We observed maturation in cellular morphology seen as more complex neurite outgrowth and increased soma area over time. Electrophysiological changes included decreasing input resistance and increasing action potential firing frequency over 13 days in vitro. Furthermore, these human embryonic stem cell derived motor neurons acquired two physiological characteristics that are thought to underpin motor neuron integrated function in motor circuits; spike frequency adaptation and rebound action potential firing. These findings show that human embryonic stem cell derived motor neurons develop functional characteristics typical of spinal motor neurons in vivo and suggest that they are a relevant and useful platform for studying motor neuron development and function and for modeling motor neuron diseases.
我们对人类运动神经元生物学的理解主要来自对人类死后组织的研究，更间接地来自活体动物模型，如啮齿动物。因此，从人类胚胎干细胞和人类诱导多能干细胞中产生运动神经元是一种重要的新方法，可以模拟运动神经元的功能。为了成为人类运动神经元功能的有用模型，体外产生的细胞应该发育出成熟的特性，这些特性是体内运动神经元的标志，如精细的神经元过程和成熟的电生理特征。在这里，我们研究了在培养过程中，由运动神经元特异性报告基因（Hb9::GFP）驱动的 GFP 表达的人类胚胎干细胞分化的神经元的形态和电生理特性与成熟相关的变化。我们观察到细胞形态的成熟，表现为随着时间的推移，更复杂的突起生长和增加的胞体面积。电生理变化包括在体外 13 天内，输入电阻降低和动作电位放电频率增加。此外，这些源自人类胚胎干细胞的运动神经元获得了两个被认为是运动神经元在运动回路中整合功能的基础的生理特征；峰频率适应和反弹动作电位放电。这些发现表明，源自人类胚胎干细胞的运动神经元发育出了体内脊髓运动神经元的典型功能特征，这表明它们是研究运动神经元发育和功能以及模拟运动神经元疾病的一个相关且有用的平台。
