Understanding brain regeneration in a zebrafish larval model of intracerebral haemorrhage

脑出血是最严重的中风类型，患者往往因脑损伤而致残。我们目前对出血后脑组织如何适应还不太了解。目前，对出血后脑再生的研究主要使用侵入性的、动物诱导的啮齿动物模型，这些模型不能准确地再现人类状况的自发性质。在实验中，干细胞和合成支架被注射到大脑中以促进再生，然而一旦被输送到体内，反应就很难准确测量。斑马鱼可以从损伤中再生，包括中枢神经系统的损伤。我们之前已经证明，斑马鱼幼虫，一个小的，透明的，不成熟的生物体，可以像人类一样表现出自发性脑出血，然后迅速从损伤中恢复，成长为健康的成年人。我认为我们可以从出血后的斑马鱼大脑恢复中了解更多，并利用它们独特的透明度，非侵入性地可视化活体恢复反应，这在啮齿动物模型中是不可能的。这项工作将减少此类实验所需的受保护动物数量，因为一对繁殖斑马鱼可以产生约200个胚胎。我项目的第一步将是成像大脑内对出血做出反应的细胞，以回答以下问题：免疫细胞清除血液的速度有多快？是什么填补了血肿留下的空间？是新的脑细胞在空间中形成，还是现有的脑细胞在差距中扩散？我的项目的第二部分将需要从斑马鱼中提取这些脑干细胞，并研究影响其行为的遗传和蛋白质组因素。在我的项目的最后阶段，我将把我所学到的知识应用于培养皿中的人脑干细胞培养物，并确定是否打开相同的基因，或将它们暴露于相同的蛋白质，会鼓励我们在斑马鱼中观察到的相同的再生行为。这项工作的最终目的是使科学家能够开发更好的脑再生模型，以研究患者的再生疗法，这些疗法可能会预防脑出血后的长期残疾，并减少对动物模型的长期需求。

Brain haemorrhages are the most severe type of stroke, and patients are often left with disabilities due to brain damage. We currently do not know much about how the brain tissue adapts after the bleed. Presently, the research into brain regeneration following haemorrhage mostly uses invasive, surgically-induced rodent models that do not accurately recreate the spontaneous nature of the human condition. Experimentally, stem cells and synthetic scaffolds are injected into the brain to encourage regrowth, however once delivered into the body, the response is very difficult to measure accurately. Zebrafish can regenerate from injuries, including damage to the central nervous system. We have previously shown that zebrafish larvae, a small, transparent, immature organism can exhibit spontaneous brain bleeds like humans and then quickly recover from injury, growing into healthy adults. I think that we can learn more from the zebrafish brain recovery after a haemorrhage, and utilise their unique transparency, to non-invasively visualise the live recovery response, something that is impossible in rodent models. This work would lead to a reduction in the number of protected animals required for such experiments, as a single pair of breeding zebrafish can produce ~200 embryos.The first step of my project will be to image the cells inside the brain responding to the bleed, to answer the following questions: How quickly do immune cells clear the blood? What fills the space left by the haematoma? Do new brain cells form in the space, or do existing ones spread across the gap? The second part of my project will require extracting these brain stem cells from the zebrafish and investigating the genetic and proteomic factors that influence their behaviour. In the final stage of my project I will apply what I have learnt to human brain stem cell cultures in a dish and determine if turning on the same genes, or exposing them to the same proteins, encourages the same regenerative behaviours we observe in the zebrafish. The ultimate aim of this work is to enable scientists to develop better models of brain regeneration in which to investigate regenerative therapies for patients that could potentially prevent long-term disability after a brain haemorrhage, and reduce the need for animal models in the long term.