Versace Amelia, Hitchens T Kevin, Wallace Callen T, Watkins Simon C, D'Aiuto Leonardo
University of Pittsburgh Department of Psychiatry, Pittsburgh, Pennsylvania.
University of Pittsburgh Magnetic Resonance Research Center, Pittsburgh, Pennsylvania.
Biol Psychiatry Glob Open Sci. 2024 Jun 7;4(5):100344. doi: 10.1016/j.bpsgos.2024.100344. eCollection 2024 Sep.
Human brain organoids are 3-dimensional cellular models that mimic architectural features of a developing brain. Generated from human induced pluripotent stem cells, these organoids offer an unparalleled physiologically relevant in vitro system for disease modeling and drug screening. In the current study, we sought to establish a foundation for a magnetic resonance imaging (MRI)-based, label-free imaging system that offers high-resolution capabilities for deep tissue imaging of whole organoids.
An 11.7T Bruker/89 mm microimaging system was used to collect high-resolution multishell 3-dimensional diffusion images of 2 induced pluripotent stem cell-derived human hippocampal brain organoids. The MRI features identified in the study were interpreted on the basis of similarities with immunofluorescence microscopy.
MRI microscopy at ≤40 μm isotropic resolution provided a 3-dimensional view of organoid microstructure. T2-weighted contrast showed a rosette-like internal structure and a protruding spherical structure that correlated with immunofluorescence staining for the choroid plexus. Diffusion tractography methods can be used to model tissue microstructural features and possibly map neuronal organization. This approach complements traditional immunohistochemistry imaging methods without the need for tissue clearing.
This proof-of-concept study shows, for the first time, the application of high-resolution diffusion MRI microscopy to image 2-mm diameter spherical human brain organoids. Application of ultrahigh-field MRI and diffusion tractography is a powerful modality for whole organoid imaging and has the potential to make a significant impact for probing microstructural changes in brain organoids used to model psychiatric disorders, neurodegenerative diseases, and viral infections of the human brain, as well as for assessing neurotoxicity in drug screening.
人脑类器官是模拟发育中大脑结构特征的三维细胞模型。这些类器官由人诱导多能干细胞生成，为疾病建模和药物筛选提供了无与伦比的生理相关体外系统。在本研究中，我们试图为基于磁共振成像（MRI）的无标记成像系统奠定基础，该系统可为整个类器官的深部组织成像提供高分辨率能力。
使用11.7T布鲁克/89mm显微成像系统收集2个人诱导多能干细胞衍生的人海马脑类器官的高分辨率多壳三维扩散图像。根据与免疫荧光显微镜的相似性对研究中确定的MRI特征进行解释。
各向同性分辨率≤40μm的MRI显微镜提供了类器官微观结构的三维视图。T2加权对比度显示出与脉络丛免疫荧光染色相关的玫瑰花结样内部结构和突出的球形结构。扩散束描记法可用于模拟组织微观结构特征并可能绘制神经元组织图谱。这种方法补充了传统的免疫组织化学成像方法，无需组织透明化处理。
这项概念验证研究首次展示了高分辨率扩散MRI显微镜在对直径2mm的球形人脑类器官成像中的应用。超高场MRI和扩散束描记法的应用是一种用于整个类器官成像的强大方式，有可能对探究用于模拟精神疾病、神经退行性疾病和人脑病毒感染的脑类器官中的微观结构变化以及评估药物筛选中的神经毒性产生重大影响。
