Developing branch stress microscopy for the mechanobiology of 3D morphogenesis and invasive diseases

项目摘要/摘要 在发育过程中，分支结构对于许多器官和腺体的形成是必不可少的。此外, 许多侵袭性疾病，包括异常血管生成和集体癌症侵袭，也以 树枝。因此，了解树枝形成模式和形态发生的潜在机制是 在人类疾病的发展和治疗的基础生物学方面都具有至关重要的意义。分支 过程，包括枝条的伸长、分叉和终止，可以通过 生化信号，如成纤维细胞生长因子和激素。最近的研究还表明，机械 来自细胞外基质和邻近细胞的信号也影响分支动力学。然而， 很可能是由于缺乏量化工具来测量机械力在内部的分布 对于树枝，机械如何调节树枝的过程仍然不是很清楚。在这个项目中，我们建议 为了开发一种新的定量工具，称为分支应力显微镜(BSM)，它可以精确地绘制出 分枝过程中细胞间机械应力的时空分布。即使是在 细胞和组织力学在过去几十年中的重大发展，量化了细胞间的力学 三维空间中的压力仍然是一项具有挑战性的任务。因此，为了管理风险，建议的 该项目的设计有两个逐步风险和更有回报的目标。在目标1中，我们将开发一种相对 BSM的简单一维版本，它量化了沿形态发生分支的横截面应力。共焦 将显微镜与三维牵引应力计算相结合，得到总力和 通过力平衡方程在横截面上施加的平均应力。然后我们将验证压力 根据1D BSM与使用3D癌症集体迁移作为 生物模型。在目标2中，我们将进一步开发3D版本的BSM，以解决完整的 分支节段内细胞间应力的三维分布。我们将进行必要的测量和 关于分支材料属性和边界处的应力或位移值的假设 分支分段，并将任务转化为固体力学中的边值问题。然后，我们将计算 肿瘤侵袭分支内应力分布的有限元分析及假设验证 并通过与由当前技术状态测量的应力进行比较来确定工具的坚固性。总而言之， 该项目将结合硅学和体外工程以及生物学方法来开发一种新的 可广泛适用于体外、体外甚至体内任何分支过程的定量工具，因此 为发育和疾病中的机械生物学分支提供通用技术。

PROJECT SUMMARY/ABSTRACT Branched structures are essential for the formation of many organs and glands during development. In addition, many invasive diseases including abnormal angiogenesis and collective cancer invasion also take the form of branches. Hence, understanding the mechanism underlying the patterning and morphogenesis of branches is of critical importance in both fundamental biology of development and treatment of human diseases. Branching processes, including the elongation, bifurcation, and termination of the branches, can be regulated by biochemical signals, such as fibroblast growth factors and hormones. Recent work also suggests that mechanical signals from the extracellular matrix and from neighboring cells also influence branching dynamics. However, likely due to the lack of quantitative tools that can measure the distribution of mechanical forces within the branches, how mechanics regulates the branching process is still not well understood. In this project, we propose to develop a novel quantitative tool, termed branch stress microscopy (BSM), that can precisely map the spatiotemporal distribution of intercellular mechanical stresses during the branching process. Even with significant developments in cell and tissue mechanics over the past decades, quantifying intercellular mechanical stresses within a three-dimensional space remains a challenging task. Hence, to manage the risk, the proposed project is designed with two progressively riskier and more rewarding aims. In Aim 1, we will develop a relatively simple 1D version of BSM that quantifies the cross-sectional stress along a morphogenetic branch. Confocal microscopy will be combined with a three-dimensional traction stress calculation to obtain the total force and average stress exerted at the cross section via force balance equations. We will then validate the stress calculated from 1D BSM against that from the current state of the art using 3D cancer collective migration as a biological model. In Aim 2, we will take one step further to develop a 3D version of BSM to resolve the complete 3D distribution of intercellular stresses within a branch segment. We will make necessary measurements and assumptions regarding the branch material properties and stress or displacement values at the boundary of the branch segment and turn the task into a boundary value problem in solid mechanics. We will then calculate the stress distribution within invading cancer branches using finite element analysis and validate the assumptions and the robustness of the tool by comparing with the stresses measured by the current state of the art. In sum, this project will combine in silico and in vitro engineering and biological approaches to develop a novel quantitative tool that may be widely applicable to any branching processes in vitro, ex vivo and even in vivo, thus providing a versatile technology for branching mechanobiology in development and diseases.