Induction of inverted morphology in brain organoids by vertical-mixing bioreactors. Induction of inverted morphology in brain organoids by vertical-mixing bioreactors

Organoid technology provides an opportunity to generate brain-like structures by recapitulating developmental steps in the manner of self-organization. We examined the vertical-mixing effect on brain organoid structures using bioreactors and established inverted brain organoids. The organoids generated by vertical mixing showed neurons that migrated from the outer periphery to the inner core of organoids, in contrast to orbital mixing. To uncover the mechanisms of the inverted structure, we investigated the direction of primary cilia, a cellular mechanosensor. Primary cilia of neural progenitors by vertical mixing were aligned in a multidirectional manner, and those by orbital mixing in a bidirectional manner. Single-cell RNA sequencing revealed that neurons of inverted brain organoids presented a GABAergic character of the ventral forebrain. Overall design: We conducted single-cell RNA-sequencing to dissect transcriptional traits of the cells in brain organoids.

类器官（Organoid）技术可通过模拟发育进程、以自组织方式构建类脑结构，为相关研究提供了全新契机。本研究借助生物反应器（bioreactor）探究了垂直搅拌对脑类器官结构的影响，并成功构建了倒置型脑类器官。与轨道搅拌制备的类器官相比，垂直搅拌制备的类器官中，神经元可从类器官外周迁移至内部核心区域。为揭示倒置结构的形成机制，本研究针对作为细胞力学感受器的初级纤毛（primary cilia）的朝向展开了探究：垂直搅拌组的神经祖细胞初级纤毛呈多方向排列，而轨道搅拌组则呈双向排列。单细胞RNA测序（single-cell RNA sequencing）结果显示，倒置型脑类器官的神经元呈现出腹侧前脑的GABA能神经元特征。实验整体设计：本研究通过单细胞RNA测序解析脑类器官内细胞的转录组特征。