Symmetry-breaking Technologies for Cerebral Organoid Engineering

根据全球疾病负担，神经系统疾病是全球残疾的主要原因和第二大死亡原因。这些疾病的衰弱性质可能对个人的生活质量及其进行日常生活活动的能力产生破坏性影响。这给家庭、看护者、社会和医疗系统带来了沉重的压力，此外，由大脑疾病引起的医疗费用、护理费用和生产力损失估计每年使英国经济损失超过1000亿英镑。为了设计预防和治疗策略，我们需要了解神经系统疾病是如何产生的，以及它们如何影响人类大脑。然而，人类大脑作为一个活体器官相对难以研究，而死后活检不能用于研究脑组织的功能。与此同时，大脑解剖结构的差异意味着动物通常不适合研究人类神经学。在过去的十年中，出现了一种研究人类大脑的新方法：使用由3D干细胞簇生成的“大脑类器官”。这些类器官为动物研究提供了一种替代方案，并已用于模拟人类大脑发育和神经系统疾病，例如microcephaly.Brain类器官的一个主要限制是缺乏对其形成和发育的控制，这导致类器官在几何和生物学上对称。这是一个问题，因为人类大脑是一个自然的不对称结构，不同的区域由一个细长的细胞结构形成，称为神经管。因此，对称的大脑类器官不能用于研究大脑发育的不对称方面或许多神经系统疾病中存在的不对称过程。本奖学金将通过开发一套技术来直接解决这一限制，该技术可以打破大脑类器官的对称性，以产生人类大脑模型，从而能够研究复杂的神经系统疾病。这些技术将适应于我以前开发的用于生长肌肉和软骨的方法。超声波模式将被用于远程组装干细胞到细长的神经管，这将可控地开发大脑的不同区域的影响下，从生物材料缓慢释放的化学梯度。超声波还将用于远程拾取、移动和融合不同的大脑类器官，以组装复杂的大脑结构。这些不对称的类器官将用于研究常见神经系统疾病中的不对称过程：前脑无裂畸形中大脑不同区域的形成失败，许多精神疾病中神经元的功能障碍迁移（例如，精神分裂症，自闭症）和阿尔茨海默病中有毒蛋白的传播。对于这些过程中的每一个过程，破坏的类器官将用于评估不同环境和遗传风险因素的贡献，提供新的知识，为未来的预防或治疗策略提供信息。此外，这些研究成果的范围远远超出神经科学，有能力解决其他类器官中的类似挑战（例如，胰腺的、子宫内膜的）。为了使广泛的用户受益，这些破胶技术将被改进成用户友好的工具包，同时将为破胶类器官开发高通量的制造方法。学术合作，行业伙伴关系和产品商业化将用于向学术团体，生物技术行业和制药行业传播这些工具包和类器官。这将确保超越本奖学金的直接目标的深远影响，为来自不同领域的研究人员提供工具，以培养他们自己的复杂类器官，用于研究发育，疾病和药物反应。

According to the Global Burden of Disease, neurological conditions are the leading cause of disability and the second-leading cause of death worldwide. The debilitating nature of these conditions can have a devastating effect on an individual's quality-of-life and their ability to undertake activities of daily living. This exerts a heavy strain on families, carers, society and healthcare systems, moreover, the medical costs, care costs and loss of productivity arising from disorders of the brain have been estimated to cost the UK economy over £100 billion per year.In order to design preventative and therapeutic strategies, we need to understand how neurological conditions arise and how they affect the human brain. However, the human brain is relatively inaccessible to study as a living organ, while post-mortem biopsies cannot be used to study the function of brain tissue. Meanwhile, differences in brain anatomy mean that animals are often unsuitable for studying human neurology. Over the last decade, a new approach to studying the human brain has emerged: the use of "brain organoids" generated from 3D clusters of stem cells. These organoids provide an alternative to animal studies and have been used to model human brain development and neurological conditions, such as microcephaly.A major limitation of brain organoids is the lack of control exerted over their formation and development, which leads to organoids that are geometrically and biologically symmetric. This is a problem because the human brain is a naturally asymmetric structure with different regions formed from an elongated cell structure, known as the neural tube. As a result, symmetric brain organoids cannot be used to study the asymmetric aspects of brain development or the asymmetric processes present in many neurological conditions.This limitation will be directly addressed in this Fellowship by developing a suite of technologies that can break the symmetry of brain organoids to produce models of the human brain that enable the study of complex neurological conditions. These technologies will be adapted from previous methods that I have developed for growing muscle and cartilage. Ultrasound patterning will be used to remotely assemble stem cells into elongated neural tubes, which will controllably develop different regions of the brain under the influence of chemical gradients slowly released from a biomaterial. Ultrasound will also be used to remotely pick up, move and fuse different brain organoids to assembly complex cerebral structures.These asymmetric organoids will be used to study asymmetric processes in common neurological conditions: the failure to form different regions of the brain in holoprosencephaly, the dysfunctional migration of neurons in many psychiatric disorders (e.g., schizophrenia, autism) and the spread of toxic proteins in Alzheimer's disease. For each of these processes, the symmetry-broken organoids will be used to assess the contribution of different environmental and genetic risk factors, providing new knowledge that will inform future preventative or therapeutic strategies.Moreover, these research outputs have a scope that extends far beyond neuroscience, with the capacity to address similar challenges in other organoids (e.g., pancreatic, endometrial). To benefit a wide range of users, the symmetry-breaking technologies will be refined into user-friendly toolkits, while high-throughput manufacturing methods will be developed for the symmetry-broken organoids. Academic collaboration, industry partnerships and product commercialisation will be used to disseminate these toolkits and organoids to academic groups, biotechnology industry and pharmaceutical industry. This will ensure far-reaching impact beyond the immediate goals of this Fellowship by providing researchers from different fields with the tools to grow their own complex organoids for the study of development, disease and drug response.