Influence of Hydraulic Resistance on the Osmotic Engine Model of Cell Migration

摘要 了解细胞迁移的机制是细胞、发育和癌症的一个基本问题。 生物学。数十年的研究表明，细胞迁移的分子基础是复杂的和 推动迁徙的物理机制是多样的。我们已经证明，这取决于当地的 微环境下，细胞迁移可以由肌动蛋白聚合以及渗透梯度驱动 细胞外的水通量。这种所谓的渗透引擎模型(OEM)在细胞紧密接触时表现突出 密闭空间。在体内，细胞在不同的微环境中迁移，从密集的3D细胞外 用来缩小存在于组织中的微通道的基质，到具有各种物理的复杂的身体空间 障碍。一个悬而未决的问题是，什么是决定相对关系的重要变量 肌动蛋白聚合驱动和水基迁移机制在不同环境中的作用 微环境。最近的数据显示，单元格的限制程度和水力阻力 细胞所经历的是决定驱动细胞运动的机制的关键因素。理论上的 利用细胞质的两相模型进行的建模也预测了水力阻力 电池的经验决定了水流/OEM对观察到的电池速度的相对贡献。 越来越多的实验证据也表明，细胞可以感知水压并调节细胞 迁移机制。在这项拨款申请中，我们建议开发一种集成的建模和 确定肌动蛋白相和水相对细胞相对贡献的实验方法 作为外部水力阻力的函数的迁移。在目标1中，我们建议直接量化水力 阻力通过在添加甲基纤维素的介质中检测2D中的细胞来影响细胞迁移速度， 这增加了介质粘度，以及不同通道长度的内部限制微通道，这也 调节水力阻力。关键离子通道和转运体的作用 水通量和迁移的能量学将从实验和理论上进行探索。我们还将确定 负责传感水力阻力的关键机械敏感离子通道。在目标2中，我们将探索 高温环境下肌动蛋白聚合、膜张力变化与OEM的相互作用 水力阻力。我们还将在Include中扩展细胞迁移的两阶段理论模型 膜张力和流量。由于细胞迁移速度可能取决于细胞形状，在目标3中，我们将开发 计算任意形状单元运动的通用两相移动边界方法。我们还将 探索OEM如何影响致密与多孔3D胶原基质中的细胞迁移， 不同的水力阻力。综上所述，我们将发现反直觉背后的机制 使用多学科方法在高水力阻力环境中观察到更快的迁移， 涉及最先进的微型设备、成像、分子生物学工具以及数学建模。

Summary Understanding the mechanisms of cell migration is a fundamental question in cell, developmental and cancer biology. Decades of research has shown that the molecular underpinnings of cell migration are complex and the physical mechanisms driving migration are diverse. We have shown that depending on the local microenvironment, cell migration can be driven by actin polymerization as well as an osmotic gradient-driven water flux external to the cell. This so-called osmotic engine model (OEM) is prominent when cells are in tightly confined spaces. In vivo, cells migrate within diverse microenvironments, ranging from dense 3D extracellular matrices to narrow microchannels present in tissue, to complex somatic spaces with various kinds of physical obstacles. An open and un-addressed question is what are the important variables that dictate the relative contribution of actin polymerization-driven and water-based migratory mechanisms in diverse microenvironments. Recent data reveal that the degree of cell confinement and the hydraulic resistance experienced by cells represent key factors in determining the mechanisms driving cell movement. Theoretical modeling utilizing a two-phase model of the cell cytoplasm also predicts that the hydraulic resistance experienced by the cell dictates the relative contribution of water flow/OEM to the observed cell speed. Mounting experimental evidence also suggests that cells can sense hydraulic pressure and modulate cell migration mechanisms. In this grant application, we propose to develop an integrated modeling and experimental approach to delineate the relative contributions of the actin-phase and the water-phase to cell migration as a function of external hydraulic resistance. In Aim 1, we propose to directly quantify how hydraulic resistance influences cell migration speeds by examining cells both in 2D in media with added methylcellulose, which increases medium viscosity, and inside confining microchannels of varying channel length, which also modulate hydraulic resistance. The roles of key ion channels and transporters that are involved in setting up water flux and the energetics of migration will be explored experimentally and theoretically. We will also identify the key mechanosensitive ion channels responsible for sensing hydraulic resistance. In Aim 2, we will explore the interplay between actin polymerization, membrane tension changes and OEM in environments of elevated hydraulic resistance. We will also extend the two-phase theoretical model of cell migration in include membrane tension and flows. Since cell migration speeds may depend on cell shape, in Aim 3, we will develop a general two-phase moving boundary method to compute cell movement for arbitrary cell shapes. We will also explore how OEM influences cell migration in dense vs more porous 3D collagen matrices, which exhibit different hydraulic resistances. Taken together, we will discover the mechanisms behind the counterintuitive observation of faster migration in high hydraulic resistance environments using a multidisciplinary approach, involving state-of-the-art microdevices, imaging, molecular biology tools along with mathematical modeling.