Elucidating the molecular mechanisms behind human neurodevelopmental disorders using brain organoids

项目摘要 神经发育障碍和神经精神障碍是一个全球性的健康问题，但人们对这一问题知之甚少。 它们在人类的神经基础。因此，治疗选择仍然有限。的出现 指导由人胚胎和诱导多能干细胞形成神经元的方法 （统称hPSC）提供了前所未有的机会来研究人类造血干细胞的功能如何。 神经回路被神经系统疾病破坏，并筛选新的治疗方法。朝着这些目标迈出的重要一步 这些目标已经通过类器官培养技术的发展得以实现， 定向形成空间上有组织的类似大脑的结构。到目前为止，脑类器官已经成功地 用于模拟基因突变和环境病原体的影响，这些病原体导致 大脑发育然而，在大多数神经系统疾病中，大脑的整体结构是保留的， 主要由神经活动的改变来定义。因此，在制定手段， 定义类器官内神经网络的组织和功能，并使用这种方法探索 潜在的疾病机制和治疗机会。在我们最近的工作中，我们发现， 非常复杂的神经网络活动可以通过皮层神经节隆起的产生而出现 融合类器官，其允许兴奋性和抑制性神经元的混合和功能耦合。 使用钙传感器成像和电生理方法的组合，我们确定了融合 类器官表现出持续的多频神经振荡，让人想起在神经元中看到的更高的网络功能。 完整的大脑样本和切片培养物我们进一步开发了一个融合类器官模型， 神经发育障碍Rett综合征，并发现在MECP2中携带突变的类器官 基因表现出明显异常的神经网络活动，包括超同步爆发， 低至中频振荡节律丧失，癫痫样高频异常出现 振荡总之，这些研究说明了融合类器官平台的非凡潜力， 报告正常和功能失调的神经网络功能，并概括突出的病理特征 在Rett患者中观察到的，如癫痫发作。在这里，我们试图解决三个核心问题，以阐明 与Rett综合征相关的神经网络功能障碍的潜在机制和其他 神经发育障碍首先，在Rett综合征类器官中观察到的神经网络功能障碍 与突变的性质相关吗？第二， MECP2功能中的细胞镶嵌性对神经网络活动的影响？第三，类器官模型 对于具有癫痫发作成分的不同神经系统疾病， 侧写？通过我们的研究，我们将探索如何最好地利用脑类器官来确定根源 研究一系列人类神经病理学的原因，并朝着发现新治疗方法的目标努力。

PROJECT SUMMARY Neurodevelopmental and neuropsychiatric disorders are a global health problem; yet remarkably little is known about their neurological basis in humans. Consequently, treatment options remain limited. The advent of methods to direct the formation of neurons from human embryonic and induced pluripotent stem cells (collectively hPSCs) provides unprecedented opportunities to both investigate how the function of human neural circuits is subverted by neurological disease and screen for new therapies. A major step towards these goals has been realized by the development of organoid culture techniques through which hPSC can be directed to form spatially organized, brain-like structures. Thus far, brain organoids have been successfully employed to model the impact of genetic mutations and environmental pathogens that result in overt defects in brain growth. However, overall brain structure is preserved in most neurological disorders, and defects are primarily defined by alterations in neural activities. Major challenges thus remain in developing means for defining the organization and function of neural networks within organoids and using this approach to explore underlying disease mechanisms and therapeutic opportunities. In our recent work, we discovered that remarkably complex neural network activities can emerge through the creation of cortex-ganglionic eminence fusion organoids, which permits the intermixing and functional coupling of excitatory and inhibitory neurons. Using a combination of calcium sensor imaging and electrophysiological approaches, we identified that fusion organoids exhibit sustained multifrequency neural oscillations reminiscent of higher network functions seen in intact brain samples and slice cultures. We further developed a fusion organoid model for the neurodevelopmental disorder Rett syndrome and found that organoids harboring mutations in the MECP2 gene exhibit markedly abnormal neural network activities including episodes of hypersynchronous bursting, loss of low-to-mid frequency oscillatory rhythms, and abnormal appearance of epileptiform high frequency oscillations. Together, these studies illustrate the extraordinary potential for the fusion organoid platform to report both normal and dysfunctional neural network functions and recapitulate salient pathological features seen in Rett patients such as seizures. Here, we seek to address three central questions for elucidating the mechanisms underlying neural network dysfunction associated with Rett syndrome and other neurodevelopmental disorders. First, does neural network dysfunction seen in Rett syndrome organoids generated from patients harboring different mutations correlate with the nature of the mutation? Second, what is the impact of cellular mosaicism in MECP2 function on neural network activities? Third, do organoid models for different neurological diseases with a seizure component exhibit shared or distinct network dysfunction profiles? Through our studies, we will explore how brain organoids can be best utilized to determine the root causes of a range of human neuropathologies and work towards the goal of discovering new treatments.