Determining the role of tissue stiffness in the development of Alzheimer's disease pathology

项目摘要 阿尔茨海默氏病是痴呆症最常见的形式，并施加了一个数不清的负担， 患者、家庭和护理人员以及美国医疗保健系统。老年痴呆症是一种渐进性的 由淀粉样蛋白斑和神经纤维缠结的积累引起的神经变性疾病 （NFT）在大脑中，阿尔茨海默病的两个神经病理学标志。了很大努力 致力于了解淀粉样蛋白和NFT积累的分子机制， 迄今为止的治疗方法都针对这些途径。然而，该领域尚未产生 一种有效的治疗阿尔茨海默病的方法，可以令人信服地减缓，停止或逆转这种情况， 毁灭性的疾病最近，脑组织的生物力学特性已经成为一种潜在的 有用的生物标志物，因为阿尔茨海默病患者的大脑一直被证明具有 相对于健康受试者的机械刚度降低。这些生物力学变化是 可能是由于神经变性和组成变化的组合作用， 脑细胞外基质（BECM）结构。重要的是，神经变性与临床 阿尔茨海默病的症状，而BECM的变化发生在阿尔茨海默病之前的几年到几十年。 认知能力下降，这表明它们与疾病的发病机制有着错综复杂的联系。在此我们 建议系统地评估BECM生物力学特性对发展的贡献， 阿尔茨海默病神经病理学的研究不幸的是，体内模型提供非常有限的能力， 调节脑组织的机械硬度。因此，我们开发了新颖的三维 (3D)具有可调机械性能的脱细胞BECM模型，并已证明， 我们可以在正常和阿尔茨海默病人脑组织的范围内改变模型刚度。 我们还使用人类诱导多能干细胞开发了3D脑类器官（CO）模型 在一个实施方案中，本发明提供了来源于阿尔茨海默病患者或健康对照（HC）的hiPSC。我们发现，相对 与HC CO相比，阿尔茨海默病CO的机械刚度降低， 淀粉样斑块和NFT以及神经变性。在此，我们建议在3D BECM中嵌入CO 模型，使高通量实验的组织生物力学和 阿尔茨海默病的病理生理学。我们将检验阿尔茨海默病的假设 CO内的神经病理学与BECM的机械特性错综复杂地联系在一起，并且增加 BECM的机械刚度将降低阿尔茨海默病的表型。这些实验将 建立3D BECM-CO作为研究组织生物力学交叉点的新工具， 疾病病理生物学，旨在确定一个新的机制途径，有助于阿尔茨海默病 有可能通过治疗手段改变疾病的轨迹。

PROJECT SUMMARY Alzheimer's disease is the most common form of dementia, and exerts an untold burden on patients, families and caregivers, and the U.S. healthcare system. Alzheimer's disease is a progressive neurodegenerative disorder caused by the accumulation of amyloid plaques and neurofibrillary tangles (NFTs) in the brain, the two neuropathological hallmarks of Alzheimer's disease. Much effort has been devoted to understanding the molecular mechanisms of amyloid and NFT accumulation, and the majority of therapeutic approaches thus far have targeted these pathways. However, the field has yet to produce an effective therapeutic for Alzheimer's disease that can convincingly slow, halt or reverse this devastating illness. Recently, the biomechanical properties of brain tissues have emerged as a potentially useful biomarker, as the brains of Alzheimer's disease patients have been consistently shown to have decreased mechanical stiffness relative to those of healthy subjects. These biomechanical changes are likely due to a combination of the effects of neurodegeneration and changes to the composition and structure of brain extracellular matrix (BECM). Importantly, neurodegeneration correlates well with clinical symptoms of Alzheimer's disease, whereas changes in the BECM occur years to decades prior to cognitive decline, suggesting that they are intricately connected with disease pathogenesis. Herein, we propose to systematically evaluate the contribution of BECM biomechanical properties to the development of Alzheimer's disease neuropathology. Unfortunately, in vivo models offer very limited capacity to regulate the mechanical stiffness of brain tissue. Therefore, we have developed novel three-dimensional (3D) decellularized BECM-based models with tunable mechanical properties, and have demonstrated that we can vary the model stiffness within the range of normal and Alzheimer's disease human brain tissue. We have also developed 3D cerebral organoid (CO) models using human induced pluripotent stem cells (hiPSCs) derived from Alzheimer's disease patients or from healthy controls (HC). We found that, relative to HC COs, Alzheimer's disease COs have decreased mechanical stiffness and develop progressive amyloid plaques and NFTs and neurodegeneration. Herein, we propose to embed COs within 3D BECM models, enabling high-throughput experimentation of the relationship between tissue biomechanics and Alzheimer's disease pathophysiology. We will test the hypothesis that the Alzheimer's disease neuropathology within the CO is intricately linked with BECM mechanical properties, and that increasing the BECM mechanical stiffness will reduced Alzheimer's disease phenotypes. These experiments will establish 3D BECM-CO as a new tool for investigation at the intersection of tissue biomechanics and disease pathobiology, and aims to identify a new mechanistic pathway contributing to Alzheimer's disease that has the potential to be modified therapeutically to alter disease trajectory.