Abstract:

Understanding how a fertilized egg develops from a single cell into complex tissues and organs remains a central question in developmental biology. However, in mammals, especially in humans, technical and ethical constraints limit in utero investigation of post-implantation development and restrict ex utero culture beyond organogenesis. As a result, the molecular and cellular mechanisms underpinning spatiotemporal regulation during these stages remain poorly understood. This knowledge gap underscores the urgent need for high-fidelity in vitro models that not only recapitulate in vivo developmental processes but also allow for precise experimental perturbations. Recent advances in stem cell-based embryo models and organoids leverage the developmental potential and intrinsic self-organizing capabilities of pluripotent stem cells to mimic aspects of early embryonic and organ development, offering new platforms for studying those complex processes. Concurrently, synthetic biology provides powerful tools, such as programmable gene circuits, optogenetics, and engineered signaling pathways, to control gene expression, cell differentiation, intercellular communications, and tissue patterning with unprecedented precision. This review highlights recent progress in integrating synthetic biology with in vitro models to dissect and reconstitute fundamental mechanisms of embryonic development. By harnessing synthetic biology tools, researchers can now modulate specific pathways with temporal and spatial precision, enabling a deeper understanding of processes such as signal transduction dynamics, cellular adhesion networks, symmetry breaking, and the establishment of polarity. This bottom-up "build-to-learn" approach shifts the paradigm from observational to predictive developmental biology. Such innovations have collectively given rise to the emerging field of synthetic developmental biology. This field not only provides mechanistic insights into developmental events that were previously inaccessible but also opens new avenues for building artificial tissues and structures with tailored functions. We also discuss current limitations in mimicking the morphology and function of natural embryonic structures, emphasizing the need for robust evaluation systems and refined strategies to precisely control cell behavior. Finally, we explore how synthetic developmental biology can elucidate key principles of embryogenesis and accelerate future applications in regenerative medicine.

Key words: embryonic development, embryo model and organoid, cell fate decision, morphogenesis, synthetic biology parts

摘要：

早期胚胎发育过程中如何从单细胞合子逐步形成复杂组织与器官，是发育生物学长期关注的核心问题。然而，哺乳动物尤其是人类胚胎着床后的发育因技术和伦理限制而难以直接观测，导致对关键时空调控机制的认识仍然不足。近年来，多能性干细胞衍生的类胚胎和类器官模型迅速发展，为体外模拟早期胚胎发育和器官发生提供了新途径。与此同时，合成生物学借助工程化思维与可编程基因线路，为精确调控细胞分化、信号传递及细胞命运模式化提供了前所未有的技术支持。本文探讨基于干细胞的类胚胎和类器官模型如何融合合成生物学与定量生物学方法，从自下而上的“建物致知”角度探讨关键发育事件的机制。我们还针对目前模型与真实胚胎及器官在形态与功能层面的差距，探讨建立标准化评价体系及发展精准细胞行为调控策略的必要性，并展望了合成发育生物学在干细胞类胚胎与类器官模型中潜在的应用前景。

关键词: 胚胎发育, 类胚胎与类器官, 细胞命运决定, 形态发生, 合成生物元件