FIBULIN-5 & WALL STRESSES IN VASCULAR REMODELING: THEORY AND EX VIVO EXPERIMENTS

描述（由申请人提供）：血管生长和重塑（G&R）在许多生理（例如，正常血管发育和老化）和病理生理过程（例如，高血压、动脉硬化和动脉瘤），以及许多临床干预的成功（或失败）（例如，静脉移植物、合成血管移植物、支架和球囊血管成形术）。尽管从分子水平到组织和整个生物体水平，关于软组织G&R的信息爆炸，但将这些数据整合到预测模型中的尝试仍处于起步阶段。当前提案的目标是开发和测试一种创新的理论-实验范式，用于表征血管重塑的时间过程，该范式集成了新型器官培养装置、双光子激光扫描显微镜（LSM）、双轴生物力学测试和多尺度数学建模。我们的中心假设是，弹性纤维，胶原纤维和平滑肌细胞的体积分数，纤维方向和无应力状态可以通过双光子LSM与双轴生物力学数据并行量化活小鼠CCA，这些数据可以被纳入一个约束的混合物模型来描述和预测正常（自适应）和适应不良重塑材料行为的时间变化。尽管壁面切应力和周向（环向）应力在血管重塑中的作用已引起人们的极大关注，但轴向应力的作用却在很大程度上被忽视了。然而，许多临床观察结果强调了血管系统轴向重塑的重要性; AAA、乳腺动脉旁路移植物和许多高血压和老化血管中的显著迂曲只是少数几个例子。弹性纤维被认为赋予动脉其体内轴向应变，并且功能性弹性纤维的丧失（其发生动脉瘤、高血压和老化）可能与受损的轴向重塑和迂曲的发展相关。纤蛋白-5是ECM蛋白，其将原弹性蛋白和原纤维蛋白与ava 3、ava 5和a9 al整联蛋白结合（60）以桥接弹性纤维与细胞。因此，fibulin-5可能是参与调节弹性纤维的关键蛋白，因此在轴向重塑中起关键作用。本提案的目的是测量和表征野生型和fib-5-/-小鼠CCA的生物力学行为和显微结构组织，并观察和量化暴露于（a）轴向伸展增加（B）跨壁压增加或（c）器官培养中轴向伸展和压力联合增加的野生型和fib-5-/-小鼠CCA的生物力学和显微结构重塑。这些目标的成功实现将建立一个创新的方法来研究正常和病理生理条件下的血管重塑，可以用来获得对发展临床病理学和设计适当的临床干预措施的见解。血管重塑在许多生理（例如，正常血管发育和老化）和病理生理过程（例如，高血压、动脉硬化和动脉瘤），以及许多临床干预的成功（或失败）（例如，静脉移植物、合成血管移植物、支架和球囊血管成形术）。这项工作的目的是开发一种研究血管重塑的创新方法，将多尺度计算建模与组织培养和多光子显微镜相结合，可用于获得对临床病理学发展和适当临床干预措施设计的见解。

DESCRIPTION (provided by applicant): Vascular growth and remodeling (G&R) plays a key role in many physiological (e.g., normal vascular development and aging) and pathophysiological processes (e.g., hypertension, arteriosclerosis, and aneurysms), as well as the success (or failure) of many clinical interventions (e.g., vein grafts, synthetic vascular grafts, stents, and balloon angioplasty). Despite the explosion of information on soft tissue G&R, from molecular level to the tissue and whole organism level, attempts at integrating these data into a predictive model is still in its infancy. The goal of the current proposal is to develop and test an innovative theoretical- experimental paradigm for characterizing the time-course of vascular remodeling that integrates a novel organ culture device, two-photon laser scanning microscopy (LSM), biaxial biomechanical testing, and multi-scale mathematical modeling. Our central hypothesis is that volume fractions, fiber directions, and stress-free states of elastic fibers, collagen fibers, and smooth muscle cells can be quantified via two-photon LSM in parallel with biaxial biomechanical data on live mouse CCAs and these data can be incorporated into a constrained mixture model to describe and predict temporal changes in material behavior in both normal (adaptive) and maladaptive remodeling. Whereas much attention has been paid to the role of wall shear stress and circumferential (hoop) stress in vascular remodeling, the role of axial stress has been largely overlooked. Many clinical observations, however, highlight the importance of axial remodeling in the vasculature; marked tortuousity in AAAs, mammary artery by-pass grafts, and many vessels with hypertension and aging are a few but a few examples. Elastic fibers are thought to endow arteries with their in vivo axial stain and the loss of functional elastic fibers (which occurs aneurysms, hypertension, and aging) may be associated with impaired axial remodeling and development of tortuousity. Fibulin-5 is an ECM protein that binds tropoelastin and fibrillins with ava3, ava5, and a9a1 integrins(60) to bridge elastic fibers with cells. Thus, fibulin-5 is likely a key protein involved in regulation of elastic fibers and thus key in axial remodeling. The aims of this proposal are to measure and characterize the biomechanical behavior and microstructural organization of CCAs from wild-type and fib-5-/- mice and observe and quantify the biomechanical and microstructural remodeling of CCAs from wild-type and fib-5-/- mice exposed to (a) increased axial extension (b) increase transmural pressure, or (c) combined increase in axial extension and pressure in organ culture. Successful realization of these aims will establish an innovative approach for studying vascular remodeling under normal and pathophysiological conditions that can be used gain insights toward the development clinical pathologies and the design of appropriate clinical interventions. Vascular remodeling plays a key role in many physiological (e.g., normal vascular development and aging) and pathophysiological processes (e.g., hypertension, arteriosclerosis, and aneurysms), as well as the success (or failure) of many clinical interventions (e.g., vein grafts, synthetic vascular grafts, stents, and balloon angioplasty). The purpose of this work is to develop an innovative approach for studying vascular remodeling that combines multi-scale computational modeling with tissue culture and multi-photon microscopy that can be used gain insights toward the development clinical pathologies and the design of appropriate clinical interventions.