A single-cell transcriptomic map of the human developing cortex in Down syndrome

唐氏综合症人类皮质发育的单细胞转录组图

• 批准号: MR/V034529/1
• 负责人: Vincenzo De Paola
• 金额: $ 96.92万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FV034529%2F1
• 关键词: single; cell; transcriptomic; map; human

The human brain is a highly complex system comprised of billions of neurons interconnected to each other to form functional neural circuits. Normal brain function is dependent on effective communication between neurons, a process that requires the establishment of normal patterns of neural network activity. Several diseases that affect the brain result from impairments in the communication between neurons, which is why it is essential to understand how neural circuits are initially established and the mechanisms involved. We are particularly interested in understanding how the emergence of neural network activity can be controlled by the precise composition of various cell types in the immature foetal human brain and in Down syndrome (DS). DS is a common neurodevelopmental disorder and a major cause of congenital intellectual disability caused by a trisomy of Chromosome 21 (Ts21). Advances in our understanding of the underlying cellular and molecular mechanisms have been hampered by the limited availability of model systems that recapitulate this complex chromosomal condition. Cellular analyses in the immature human brain though focus on post-mortem fixed tissue samples, which cannot provide direct observation of dynamic events such the formation of electrical activity patterns. This limitation raises the question of how to study the cellular and molecular mechanisms of human neural circuit assembly and their dysfunction in DS. My team has recently developed a new approach to study in real-time the establishment of human neuronal networks using transplanted donor-derived induced pluripotent stem cells (iPSC) and longitudinal in vivo imaging. This experimental design allows the study of human neural network activity in a vascularized human graft over several weeks, overcoming several limitations of current in vitro approaches (e.g. the lack of blood vessels). We showed that neuronal activity is less synchronous in DS, which could contribute to cognitive deficits in DS. We also found a reduction in cortical volume and identified a potential molecular mechanism. With the prospect of developing strategies to correct defects in the wiring of the fetal brain in DS, we will obtain a map of all the cell types, which populate the developing DS cortex. This map will identify cortical cell populations which are either missing/reduced or whose maturation is delayed, which could explain the reduced size of the DS brain and its altered activity patterns. We will take advantage of powerful genetic tools that allow to probe the content of individual cells in the DS brain and in human cells transplanted in the brain of laboratory animals. The ultimate aim of this research proposal is therefore to gain new and fundamental insights into the cellular and molecular mechanisms that regulate the establishment of human cortical circuits, in the hope that this knowledge will, in the future, translate into new ways to rescue the network activity deficits in DS and guide the development of therapeutic strategies.

人脑是一个高度复杂的系统，由数十亿个神经元组成，这些神经元彼此互连以形成功能性神经回路。正常的大脑功能依赖于神经元之间的有效沟通，这一过程需要建立神经网络活动的正常模式。影响大脑的几种疾病是由神经元之间的通讯受损引起的，这就是为什么有必要了解神经回路最初是如何建立的以及所涉及的机制。我们特别感兴趣的是了解未成熟胎儿大脑和唐氏综合症（DS）中各种细胞类型的精确组成如何控制神经网络活动的出现。 DS 是一种常见的神经发育障碍，也是由 21 号染色体（Ts21）三体性引起的先天性智力障碍的主要原因。由于重现这种复杂染色体状况的模型系统的可用性有限，阻碍了我们对潜在细胞和分子机制的理解的进展。未成熟人脑的细胞分析虽然侧重于死后固定的组织样本，但无法直接观察动态事件，例如电活动模式的形成。这种局限性提出了如何研究 DS 中人类神经回路组装及其功能障碍的细胞和分子机制的问题。我的团队最近开发了一种新方法，利用移植的供体来源的诱导多能干细胞 (iPSC) 和纵向体内成像来实时研究人类神经元网络的建立。这种实验设计允许在几周内研究血管化人体移植物中的人类神经网络活动，克服了当前体外方法的一些限制（例如缺乏血管）。我们发现 DS 中的神经元活动不太同步，这可能导致 DS 中的认知缺陷。我们还发现皮质体积减少并确定了潜在的分子机制。为了制定纠正 DS 胎儿大脑接线缺陷的策略，我们将获得所有细胞类型的图谱，这些细胞类型分布在发育中的 DS 皮层中。该图谱将识别缺失/减少或成熟延迟的皮质细胞群，这可以解释 DS 大脑尺寸的减小及其活动模式的改变。我们将利用强大的遗传工具来探测 DS 大脑中单个细胞以及移植到实验动物大脑中的人类细胞的内容。因此，这项研究计划的最终目的是获得对调节人类皮质回路建立的细胞和分子机制的新的基本见解，希望这些知识将来能够转化为拯救 DS 网络活动缺陷的新方法并指导治疗策略的开发。