Ionizing radiation (IR) is increasingly used for diagnostics and therapy of severe brain diseases. However, IR also has adverse effects on the healthy brain tissue, particularly on the neuronal network. This is true for adults but even more pronounced in the developing brain of unborn and pediatric patients. Epidemiological studies on children receiving radiotherapy showed an increased risk for cognitive decline ranging from mild deficits in academic functioning to severe late effects in intellectual ability and language as a consequence of altered neuronal development and connectivity. To provide a comprehensive approach for the analysis of radiation-induced alterations in human neuronal functionality, we developed an in vitro assay by combining microelectrode array (MEA) analyses and human embryonic stem cell (hESC) derived three-dimensional neurospheres (NS). In our proof of principle study, we irradiated hESC with 1 Gy X-rays and let them spontaneously differentiate into neurons within NS. After the onset of neuronal activity, we recorded and analyzed the activity pattern of the developing neuronal networks. The network activity in NS derived from irradiated hESC was significantly reduced, whereas no differences in molecular endpoints such as cell proliferation and transcript or protein expression analyses were found. Thus, the combination of MEA analysis with a 3D model for neuronal functionality revealed radiation sequela that otherwise would not have been detected. We therefore strongly suggest combining traditional biomolecular methods with the new functional assay presented in this work to improve the risk assessment for IR-induced effects on the developing brain.

中文翻译：

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新型体外测定法可研究辐射诱导的人类胚胎干细胞衍生神经球功能的变化。

电离辐射（IR）越来越多地用于严重脑部疾病的诊断和治疗。但是，IR对健康的大脑组织，特别是神经元网络也有不利影响。这对于成年人是正确的，但在未出生和儿科患者的大脑发育中更为明显。对接受放射治疗的儿童进行的流行病学研究显示，认知能力下降的风险增加，从轻度的学习功能缺陷到由于神经元发育和连接性改变而导致的智力和语言严重晚期影响。为了提供一种全面的方法来分析辐射诱发的人类神经元功能的改变，我们通过结合微电极阵列（MEA）分析和人类胚胎干细胞（hESC）衍生的三维神经球（NS）开发了一种体外测定方法。在原理验证研究中，我们用1 Gy X射线照射了hESC，并使其自发分化为NS内的神经元。神经元活动开始后，我们记录并分析了发育中的神经元网络的活动模式。辐射的hESC衍生的NS中的网络活动显着降低，而在分子终点（如细胞增殖和转录本或蛋白质表达分析）方面未发现差异。因此，MEA分析与3D神经元功能模型的结合显示出放射后遗症，否则将无法检测到。