发表机构
Graduate School of Information Science and Technology The University of Tokyo（东京大学信息理工学研究科）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过实验观察和理论分析，揭示了三重连通区域内障碍物尺寸调控细胞群-1/2缺陷稳定构型对称性的规律，为生物力学研究提供了新见解。
AI 中文摘要
受限细胞群的向列序在决定细胞排列和拓扑缺陷的稳定构型中发挥重要作用，这些缺陷与多种生物力学现象相关。拓扑缺陷的拓扑电荷（或环绕数）严格依赖于受限区域的欧拉特征，在聚焦于无内部障碍物的区域的研究中，欧拉特征通常为非负值。然而，生物组织常环绕两个或更多内部障碍物或孔洞，这会固有地产生带负电荷的缺陷。为理解细胞组织与障碍物之间的力学相互作用，有必要阐明障碍物的几何结构对细胞排列和负电荷缺陷的影响。本研究探究细胞群如何在三重连通区域内实现两个-1/2缺陷的稳定构型。首先，我们对被不同直径的两个圆形障碍物限制的C2C12成肌细胞进行实验观察，结果表明当障碍物足够大时，两个-1/2缺陷是最常见的构型。其次，为从理论上验证这些实验观察，我们利用细胞排列的显式表达式和Frank弹性能的数值最小化对缺陷构型进行系统稳定性分析。我们的数值计算显示，随着障碍物尺寸增大，最稳定的构型会从水平构型连续过渡到离轴构型，再变为垂直构型。此外，实验观察到的缺陷位置与这些理论预测的偏差在60μm以内。这些发现表明，障碍物尺寸可控制细胞排列的对称性，为理解形态发生或器官运动过程中几何与拓扑约束如何产生复杂力模式提供了见解。
英文摘要
Nematic order of confined cell populations plays an important role in determining cell alignment and stable configurations of topological defects, which are related to various biomechanical phenomena. Topological charges (or winding numbers) of topological defects strictly depend on the Euler characteristic of the confining domain, which has typically been non-negative in studies focused on domains without internal obstacles. However, biological tissues often surround two or more internal obstacles or holes, which inherently generate defects with negative charges. To understand the mechanical interaction between cellular tissue and obstacles, it is necessary to elucidate the geometrical effects of obstacles on cell alignment and defects with negative charges. Here, we investigate how cell populations achieve stable defect configurations of two -1/2 defects in a triply connected domain. First, we present experimental observations of C2C12 myoblasts confined by two circular obstacles of varying diameter, demonstrating that two $-1/2$ defects are the most frequent configuration when the obstacles are sufficiently large. Second, to theoretically validate these experimental observations, we perform systematic stability analyses of defect configurations using an explicit expression of cell alignment and numerical minimization of the Frank elastic energy. Our numerical calculations reveal that the most stable configuration shifts continuously from a horizontal, through off-axis, to a vertical configuration as the obstacle size increases. In addition, the experimentally observed defect positions agreed with these theoretical predictions to within 60 $μ$m. These findings suggest that obstacle sizes control the symmetry of cell alignment, providing insights into how geometric and topological constraints can generate complex force patterns during morphogenesis or organ movements.
