HYDRODYNAMIC INTERACTIONS/CELL DEFORMATION IN NEUTROPHIL

许多物理和生物化学因素联合收割机控制微循环中炎性白细胞募集的过程。虽然分子介质和血液动力学对白细胞粘附和外渗的作用或多或少被单独理解，但这些因素之间复杂的非线性相互作用却不那么清楚。该项目的重点是将影响白细胞募集率的多种因素，如微尺度血流动力学，白细胞变形和粘附受体的空间分布，整合到仿生实验和最先进的计算机模拟流动下的细胞粘附。在目标1中，我们将进行人类中性粒细胞流过具有圆形横截面和选择素涂层表面的微加工分支导管的流动粘附实验，以了解 白细胞边缘化并在整个微血管网络中滚动。这些结果将进行比较，以理论预测的改进版本的多粒子粘附动力学，并最终在体内实验中的小鼠模型的炎症。在目标2中，我们将进一步扩展计算机模拟，以考虑粘弹性变形中性粒细胞和细胞扁平化的作用，稳定选择素和整合素介导的粘附内皮细胞。该理论模型将通过在各种细胞骨架修饰剂下中性粒细胞压缩的微管实验进行验证，然后用于帮助解释选择素和整合素呈递表面的流动室粘附实验，其中接触面积 通过从侧面观察相互作用来测量滚动的中性粒细胞。这些研究将解决我们的假设，即细胞扁平化的作用，以稳定滚动粘附和下调中性粒细胞或底物粘附受体可以破坏这种稳定。最后，在目标3中，我们将使用微接触印刷方法系统地研究选择素和整合素配体分子在模型内皮细胞上的相对空间分布如何控制白细胞粘附的动力学和白细胞牢固停滞的最终位置。该项目的拟议工作将使用工程方法，将目前对白细胞-内皮细胞相互作用的了解整合到体内炎症的更完整的图片中。

Many physical and biochemical factors combine to control the process of inflammatory leukocyte recruitment in the microcirculation. While the roles of molecular mediators and hemodynamics on leukocyte adhesion and extravasation are more or less understood individually, the complex, nonlinear interaction between these factors is less so. This project focuses on integrating multiple factors affecting rates of leukocyte recruitment such as microscale hemodynamics, leukocyte deformation, and spatial distributions of adhesion receptors, into biomimetic experiments and state-of-the-art computer simulations of cell adhesion under flow. In Aim 1 we will conduct flow adhesion experiments with human neutrophils flowing through microfabricated branching conduits with circular cross-section and selectin-coated surfaces, to understand the physics of leukocyte margination and rolling throughout the microvascular network. These results will be compared to theoretical predictions of an improved version of multiparticle adhesive dynamics and ultimately to in vivo experiments in mouse models of inflammation. In Aim 2 we will further extend the computer simulation to consider viscoelastically deforming neutrophils and the role of cell flattening in stabilizing selectin and integrin-mediated adhesion to the endothelium. The theoretical model will be validated with micropipette experiments of neutrophil compression under various cytoskeletal modifiers, and then used to help interpret flow chamber adhesion experiments to selectin and integrin-presenting surfaces where the contact area under rolling neutrophils is measured by viewing interactions from the side. These studies will address our hypothesis that cell flattening acts to stabilize rolling adhesion and that downregulation of either neutrophil or substrate adhesion receptors can disrupt this stabilization. Finally, in Aim 3 we will use microcontact printing methods to systematically study how relative spatial distributions of selectin and integrin ligand molecules on model endothelium act to control the dynamics of leukocyte adhesion and the ultimate location of leukocyte firm arrest. The proposed work of this project will use engineering methods to integrate current knowledge of leukocyte-endothelial interactions into a more complete picture of inflammation in vivo.