标题： 血管生成过程中内皮单层中的解堵和向列性 flock 的理论与实验分析 显示英文标题

标题： Unjamming and nematic flocks in endothelial monolayers during angiogenesis : theoretical and experimental analysis

摘要： 血管生成是一个复杂的进程，通过该进程，新的血管从现有的血管系统中发展出来，以向组织供应营养物质和/或代谢物，在许多生理和病理条件下起着基础性作用，如胚胎发生和组织修复或肿瘤生长。 在这里，我们从单层的角度分析了\textit{体外}血管生成过程，以了解周围内皮单层、出芽和力学之间的相互作用的作用。 首先，我们注意到VEGF（血管内皮生长因子）促进了一种致密/非致密转变，通过测量形状指数因子，使单层流体化。 接下来，我们测量了单层上的密度场，并意识到细胞的流动与疏散过程有很强的相似性，其中细胞群可以流动或堵塞，形成一个收敛通道。 基于这些新观察结果，我们提出一个数学模型来描述细胞群从单层流向早期毛细血管结构时的非致密化和重新定向效应。 该模型是在连续介质力学的框架中开发的，在此我们考虑内皮单层作为一个活性生物聚合物薄膜，其中在VEGF激活促进的非致密相中出现向列序。 为了测试所提出的观点，我们将开发的耦合方程实现到有限元代码中，并用简化的几何形状描述从单层到毛细血管的流动效应和细胞取向。 在这项工作中，我们基于实验观察和理论论证，从内皮单层的顶部提出一种对血管生成的解释。 显示英文摘要

摘要： Angiogenesis is the complex process by which new blood vessels develop from an existing vasculature in order to supply nutrients and/or metabolites to tissues, playing a fundamental role in many physiological and pathological conditions such as embryogenesis and tissue repair or tumour growth. Here we analysed the \textit{in-vitro} angiogenic process from the perspective of the monolayer to understand the role of the interaction between the surrounding endothelial monolayer, the sprouting and the mechanics. First we noticed that the VEGF (Vascular Endothelial Growth Factor) promotes a jamming/unjamming transition that allows the fluidisation of the monolayer by measuring the shape index factor. Next, we measured the density field over the monolayer and realised that the flow of cells manifests strong similarities with the evacuation process where the flock of cells can flow or stuck, defining a convergent channel. Based on these novel observations we propose a mathematical model to describe the effects of unjamming and reorientation of a flock of cells which flow from the monolayer towards the early capillary structure. This model is developed into the framework of the continuum mechanics in which we consider the endothelial monolayer as an active biopolymer film where the nematic order emerges in the unjammed phase promoted by the VEGF activation. To test the proposed ideas we implement the developed coupled equations into a finite element code and describe, with a simplified geometry, the flow effect and cells orientation from the monolayer to the capillary. In this work, we propose an interpretation, from the top of the endothelial monolayer, based on experimental observations and theoretical arguments to think the angiogenesis.