Magnetic Resonance Imaging of Neurogenesis

描述（由申请人提供）：成人大脑中没有新神经元的传统教条受到了挑战。 随着对干细胞的广泛研究和对脑中神经源性小生境的表征，现在清楚的是，新的神经元确实通过移植的干细胞或祖细胞或通过内源性神经干细胞产生。 这在基础条件下以及在损伤中是真实的。 重要的是，不仅是新的神经元被制造出来，而且在包括中风、帕金森病和ALS在内的许多疾病模型中，动物的功能也得到了改善。 对于任何这些实验性疗法，以实现临床可行性，这将是至关重要的，以开发用于检测细胞迁移，分化和功能的非侵入性方法。 对于细胞移植程序，使用基于磁共振成像（MRI）的细胞追踪已经完成了细胞的非侵入性检测。 然而，虽然对用营养因子操纵内源性细胞的研究正在加速，但在脑中内源性细胞的非侵入性检测和定量方面存在未满足的需求。 该提案的目的是开发MRI方法，用于纵向检测和定量完整生物体中的内源性细胞迁移。 首先，将优化体内细胞标记方案，同时优化MRI参数和图像分析。 然后，这些协议将在一个已知的神经增强模型中进行验证。 最后，这些协议将被用来研究一个潜在的新方法，提高天然神经源性反应中风。 传统上，神经发生研究依赖于脑组织组织切片的显微镜分析。 虽然信息量很大，但由于需要大量动物和动物间变异性，这种方法无法转化为临床，并且提供的细胞迁移率和轨迹信息有限。 在活体动物中成像神经发生的建议中采取的方法是非常不同和创新的。 这项工作将开发一个强大的协议，使用基于MRI的细胞跟踪，以监测在单细胞水平上，无论是在基础条件下，并在应对中风的天然神经母细胞的迁移。 重复研究同一动物的能力将允许在四维中研究神经发生，整合细胞迁移率，3D迁移轨迹和总细胞数。 在任何细胞追踪成像实验中，细胞数量都从未被量化到单个细胞。 基于MRI的数据将通过与常规显微镜分析的相关性进行验证。 此外，这些方法将适用于广泛的疾病模型，采用神经元重建，以及进一步研究基础神经发生和神经母细胞参与学习和可塑性。 预计数据模式的高度确证将确实证明所提出的MRI方法的稳健性，并为将这些技术转移到临床研究领域提供动力。 公共卫生相关性：非侵入性成像技术将在将基于细胞的治疗从实验室转移到床边方面发挥关键作用。 本提案中详细介绍的这项研究旨在开发磁共振成像技术，以实现在基础条件下和对损伤的反应中神经前体细胞迁移的可视化和定量。

DESCRIPTION (provided by applicant): The traditional dogma that no new neurons are made in the adult brain has been challenged. With the widespread study of stem cells and the characterization of the neurogenic niches in the brain, it is now clear that new neurons are indeed generated, either by way of transplanted stem or progenitor cells, or via endogenous neural stem cells. This is true under basal conditions as well as in injury. Importantly, not only are new neurons being made, but functional improvements have been realized in animals in a number of disease models including stroke, Parkinson's disease and ALS. For any of these experimental therapies to achieve clinical feasibility, it will be critical to develop non-invasive methods for detecting cell migration, differentiation and function. For cell transplant procedures, non-invasive detection of cells has been accomplished with the use of magnetic resonance imaging (MRI)-based cell tracking. However, while research into the manipulation of endogenous cells with trophic factors is accelerating, there are unmet needs in non-invasive detection and quantification of endogenous cells in the brain. The aim of this proposal is to develop MRI methods for longitudinal detection and quantification of endogenous cell migration in intact organisms. First, in vivo cell labeling protocols will be optimized with concurrent optimization of MRI parameters and image analysis. Then, these protocols will be validated in a known model of neurogenic enhancement. Lastly, these protocols will be used to investigate a potentially novel method of boosting the native neurogenic response to stroke. Classically, neurogenesis studies have relied on microscopic analysis of histological sections of brain tissues. While highly informative, this approach cannot be translated into the clinic and provides limited information on cell migration rates and trajectories due to the large number of animals needed and inter-animal variability. The approach taken in this proposal of imaging neurogenesis in the living animal is very different and innovative. This work will develop a robust protocol for using MRI based cell tracking to monitor the migration of native neuroblasts at the single cell level, both under basal conditions and in response to stroke. The ability to study the same animal repeatedly will allow neurogenesis to be studied in four dimensions, integrating cellular migration rates, 3D migration trajectories and overall cell numbers. Never before, in any cell tracking imaging experiment, has cell number been quantified down to individual cells. MRI based data will be validated through correlation with conventional microscopic analyses. Furthermore, these methods will be applicable for a broad range of disease models employing neuron-reconstitution, as well as furthering research into basal neurogenesis and the participation of neuroblasts in learning and plasticity. It is anticipated that the high degree of corroboration of the data modalities will indeed demonstrate the robustness of the proposed MRI methods and provide the motivation to move these techniques into the regime of clinical research. PUBLIC HEALTH RELEVANCE: Non-invasive imaging technologies will play a critical role in translating may cell based therapies from bench to bedside. This research detailed in this proposal aims to develop magnetic resonance imaging technologies to enable visualization and quantification of neural precursor cell migration, both under basal conditions and in response to injury.