Symmetry-breaking Technologies for Cerebral Organoid Engineering

根据全球疾病负担，神经系统疾病是导致残疾的主要原因，也是全球第二大死亡原因。这些疾病的衰弱性质可能会对个人的生活质量和从事日常生活活动的能力产生毁灭性的影响。这给家庭、照顾者、社会和医疗保健系统带来了沉重的压力，此外，脑部疾病引起的医疗成本、护理成本和生产力损失估计每年给英国经济造成超过1000亿GB的损失。为了设计预防和治疗策略，我们需要了解神经疾病是如何发生的，以及它们如何影响人类的大脑。然而，人脑作为一个活的器官相对难以获得研究，而尸检也不能用来研究脑组织的功能。与此同时，大脑解剖学上的差异意味着动物通常不适合研究人类神经学。在过去的十年里，出现了一种研究人脑的新方法：使用由3D干细胞簇产生的“脑器官”。这些有机化合物为动物研究提供了另一种选择，并已被用于模拟人类大脑发育和神经疾病，如小头症。大脑有机化合物的一个主要限制是缺乏对其形成和发育的控制，这导致有机化合物在几何和生物上是对称的。这是一个问题，因为人类大脑是一个自然不对称的结构，不同的区域由一个被称为神经管的细长细胞结构形成。因此，对称的脑器官不能用于研究大脑发育的不对称方面或许多神经疾病中存在的不对称过程。这一限制将在本奖学金中通过开发一套技术来直接解决，该技术可以打破脑器官的对称性，以产生能够研究复杂神经疾病的人脑模型。这些技术将从我之前开发的用于生长肌肉和软骨的方法中进行调整。超声波模式将被用来远程将干细胞组装成细长的神经管，这将在生物材料缓慢释放的化学梯度的影响下，可控制地发育大脑的不同区域。超声波还将被用来远程拾取、移动和融合不同的大脑器官来组装复杂的大脑结构。这些不对称的器官将被用来研究常见神经系统疾病中的不对称过程：全前脑畸形时无法形成大脑的不同区域，许多精神疾病(如精神分裂症、自闭症)中神经元的功能障碍迁移，以及阿尔茨海默病中有毒蛋白质的传播。对于每个过程，对称性破坏的有机体将被用来评估不同的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，有能力解决其他有机体(如胰腺、子宫内膜)的类似挑战。为了使广大用户受益，对称破缺技术将被改进为用户友好的工具包，同时将为对称破缺有机化合物开发高通量制造方法。将利用学术合作、行业伙伴关系和产品商业化向学术团体、生物技术行业和制药行业传播这些工具包和有机化合物。这将为来自不同领域的研究人员提供工具，培养他们自己的复杂有机化合物，用于研究发育、疾病和药物反应，从而确保产生超出本奖学金近期目标的深远影响。

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.