Collaborative Proposal: Active and Passive Mechanical Environments Interact to Regulate Cellular Structure and Function

1067481/1066746古奇/西敏斯基众所周知，外加和内生的机械力是许多组织结构和功能的重要调节因素，包括软骨、肌腱、韧带、皮肤、血管、肺和心脏。在过去的十年里，除了环境的这些主动机械组件(即力以及由此产生的应力和应变)的重要作用外，越来越明显的是，被动的机械环境(即环境的局部机械或材料特性)也影响细胞功能。根据首席调查员？在这一领域正在进行的工作中，已经开发出一个概念模型，解释主动和被动机械环境如何相互作用来调节细胞功能。拟议的研究将使用两个模型生物学系统--内皮细胞形成微血管网络和间充质干细胞的形态变化/分化--对这一模型进行批判性评估。这些研究将利用申请人开发的细胞外基质仿生剂，允许在三维细胞兼容环境中独立控制主动和被动机械环境的各个方面。拟议工作的主要科学目标是：1)扩展这些现有的细胞外基质仿生学的能力，作为一种工具来严格评估细胞对主动和被动机械环境的响应的概念模型；2)使用细胞外基质仿生学来回答与细胞如何响应其机械环境有关的重要科学问题；以及3)将研究与教育相结合，以培养机械生物学方面的下一代生物医学工程研究人员。目前可用的材料无法回答的具体问题包括：在3D环境中，基质硬度和基质粘附性对细胞功能的独立贡献是什么？对于3D环境中给定的细胞类型，为什么分化细胞行为的理想硬度似乎取决于特定的生物材料？细胞-基质黏附和/或细胞产生的力是如何调节基质硬度的？哪些分子和细胞水平的过程受基质机械硬度的变化调节，以及这些分子和细胞水平的过程如何有助于观察到分化的多细胞结构的变化。在拟议的研究中，将使用微血管网络形成作为主要的模型系统来探索这些问题的答案。由于多细胞、分支微血管网络的形成涉及许多在其他生理、病理和组织工程环境中非常重要的协调细胞行为(例如，黏附、延长、迁移和细胞-细胞连接的形成)，因此从拟议的研究中获得的知识可能会转化为其他重要的系统，包括工程组织的血管形成。对间充质干细胞的额外研究将提供有关第二个相关细胞系统中细胞分化过程中主动和被动机械环境之间相互作用的信息。

1067481/1066746Gooch/SieminskiIt is well-established that externally applied and endogenously generated mechanical forces are crucial regulators of the structure and function of numerous tissues including cartilage, tendons, ligaments, skin, blood vessels, lungs and the heart. In addition to the important role for these active mechanical components of the environment (i.e., forces and the resulting stresses and strains), it has become increasingly clear over the past decade that the passive mechanical environment (i.e., the local mechanical or material properties of the environment) also impacts cellular function. Based on the Principal Investigators? ongoing work in this area, a conceptual model explaining how the active and passive mechanical environments interact to regulate cellular function has been developed. The proposed studies will critically evaluate this model using two model biological systems - microvascular network formation by endothelial cells and morphological changes / differentiation of mesenchymal stem cells. These studies will utilize an extracellular matrix biomimetic developed by the applicants that allows for independent control of aspects of the active and passive mechanical environments within a three-dimensional cell-compatible setting. The major scientific goals of the proposed work are 1) to expand the capabilities of these existing extracellular matrix biomimetics as a tool to rigorously evaluate the conceptual model of cellular responses to active and passive mechanical environments and 2) to use the extracellular matrix biomimetics to answer important scientific questions related to how cells respond to their mechanical environments, and 3) to integrate research and education to train the next generation of biomedical engineering researchers in mechanobiology. Specific questions to be addressed, which cannot be answered with currently available materials, include the following: What are the independent contributions of matrix stiffness and matrix adhesiveness to cellular function in a 3D environment? For a given cell type in a 3D environment, why does the ideal stiffness for differentiated cell behavior appear to depend on the specific biomaterial? How are the effects of matrix stiffness modulated by cell-matrix adhesion and/or force generation by the cells? What molecular and cellular level processes are modulated by changes in the mechanical stiffness of the matrix and how do these molecular and cellular level processes contribute to observed changes in differentiated multi-cellular structures. The answers to these questions will be explored using microvascular network formation as the primary model system in the proposed studies. Since the formation of multi-cellular, branched microvascular networks involves many coordinated cellular behaviors (e.g., adhesion, elongation, migration, and cell-cell junction formation) important in other physiological, pathological, and tissue engineering settings, the knowledge gained from the proposed studies will likely translate to other important systems including the vascularization of engineered tissues. Additional work with mesenchymal stem cells will provide information about the interplay between the active and passive mechanical environments during cell differentiation in a second relevant cell system.