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

1067481/1066746 Gooch/Sieminski众所周知，外部施加的和内源性产生的机械力是许多组织（包括软骨、肌腱、韧带、皮肤、血管、肺和心脏）结构和功能的关键调节剂。除了环境的这些主动机械部件的重要作用（即，力以及由此产生的应力和应变），在过去的十年中已经越来越清楚的是，被动机械环境（即，环境的局部机械或材料特性）也影响细胞功能。根据主要研究者的？在这一领域正在进行的工作中，已经开发了一个概念模型，解释了主动和被动机械环境如何相互作用以调节细胞功能。拟议的研究将使用两种模型生物系统-内皮细胞形成微血管网络和间充质干细胞的形态学变化/分化来批判性地评估该模型。这些研究将利用由申请人开发的细胞外基质仿生物，其允许在三维细胞相容设置内独立控制主动和被动机械环境的方面。拟议工作的主要科学目标是：1）扩展这些现有细胞外基质仿生学的能力，作为严格评估细胞对主动和被动机械环境响应的概念模型的工具; 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相关的重要科学问题，3）结合研究和教育，培养下一代生物医学工程机械生物学研究人员。具体的问题要解决，这不能回答目前可用的材料，包括以下内容：什么是独立的贡献矩阵的刚度和矩阵的刚度在3D环境中的细胞功能？对于3D环境中的给定细胞类型，为什么分化细胞行为的理想刚度似乎取决于特定的生物材料？细胞-基质粘附和/或细胞产生的力是如何调节基质刚度的？什么样的分子和细胞水平的过程是由基质的机械刚度的变化，以及这些分子和细胞水平的过程如何有助于观察到的变化，在分化的多细胞结构调制。这些问题的答案将探索使用微血管网络形成的主要模型系统在拟议的研究。由于多细胞分支微血管网络的形成涉及许多协调的细胞行为（例如，粘附、延伸、迁移和细胞-细胞连接形成）在其他生理学、病理学和组织工程学环境中是重要的，从所提出的研究中获得的知识将可能转化为其他重要的系统，包括工程化组织的血管化。与间充质干细胞的其他工作将提供有关在第二相关细胞系统中细胞分化期间主动和被动机械环境之间的相互作用的信息。

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.