Department of Genetics, Harvard Medical School, Boston, MA, USA.
Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.
Methods Mol Biol. 2024;2767:115-122. doi: 10.1007/7651_2023_507.
Paraxial mesoderm in the early embryo is segmented into epithelial blocks called somites that establish the metameric organization of the vertebrate body plan. Somites are sequentially formed from head to tail in a rhythmic manner controlled by an oscillating gene regulatory network known as the segmentation clock. We know very little about this important process during human development due to limited access to human embryos and ethical concerns. To bypass these difficulties, model systems derived from human pluripotent stem cells have been established. Here, we detail three protocols modeling different aspects of human paraxial mesoderm development in vitro: a 2D cell monolayer system recapitulating dynamics of the human segmentation clock, a 3D organoid system called "somitoid" supporting the simultaneous formation of somite-like structures, and another organoid system called "segmentoid" reconstituting in vivo-like hallmarks of somitogenesis. Together, these complementary model systems provide an excellent platform to decode somitogenesis and advance human developmental biology.
早期胚胎的轴旁中胚层被分割成称为体节的上皮块，这些体节建立了脊椎动物身体模式的分节组织。体节以头部到尾部的顺序有节奏地形成，这种节奏受称为体节时钟的振荡基因调控网络控制。由于获取人类胚胎的限制和伦理问题，我们对人类发育过程中的这一重要过程知之甚少。为了克服这些困难，已经建立了源自人类多能干细胞的模型系统。在这里，我们详细介绍了三种体外模拟人类轴旁中胚层发育不同方面的方案：一种 2D 细胞单层系统重现了人类体节时钟的动力学，一种称为“体节样结构”的 3D 类器官系统支持同时形成类体节结构，另一种称为“节段样结构”的类器官系统重建了体内样体节发生的标志。这些互补的模型系统共同为解码体节发生和推进人类发育生物学提供了一个极好的平台。
