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，正常血管发育和衰老）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（例如，静脉移植，合成血管移植，支架和球囊血管成形术）的成功（或失败）中起着关键作用。尽管从分子水平到组织和整个生物体水平的软组织G&R信息爆炸式增长，但将这些数据整合到预测模型中的尝试仍处于起步阶段。目前的建议的目标是开发和测试一个创新的理论-实验范式来表征血管重构的时间过程，该范式集成了一个新的器官培养装置，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模型。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与活体小鼠cca的双轴生物力学数据并行进行量化，这些数据可以纳入约束混合模型，以描述和预测正常（适应）和不适应重构中材料行为的时间变化。尽管人们对血管壁剪切应力和周向（环向）应力在血管重构中的作用关注甚多，但轴向应力的作用在很大程度上被忽视了。然而，许多临床观察强调了轴向重构在脉管系统中的重要性；在AAAs中有明显的扭曲，乳腺动脉旁路移植，许多血管伴高血压和衰老是少数例子。弹性纤维被认为赋予动脉体内轴向染色，而功能性弹性纤维的丧失（发生动脉瘤、高血压和衰老）可能与轴向重塑受损和扭曲的发生有关。纤维蛋白-5是一种ECM蛋白，可将弹力蛋白和纤维蛋白与ava3、ava5和a9a1整合素结合（60），在弹性纤维与细胞之间架起桥梁。因此，纤维蛋白-5可能是参与弹性纤维调节的关键蛋白，因此在轴向重塑中起关键作用。本提议的目的是测量和表征野生型和fib-5-/-小鼠cca的生物力学行为和微观结构组织，并观察和量化野生型和fib-5-/-小鼠cca暴露于(a)轴向延伸增加(b)跨壁压力增加，或(c)器官培养中轴向延伸和压力联合增加的cca的生物力学和微观结构重塑。这些目标的成功实现将为研究正常和病理生理条件下的血管重构建立一种创新的方法，可以用于了解发展临床病理学和设计适当的临床干预措施。血管重构在许多生理过程（如正常血管发育和衰老）和病理生理过程（如高血压、动脉硬化和动脉瘤）以及许多临床干预（如静脉移植、合成血管移植、支架和球囊血管成形术）的成功（或失败）中起着关键作用。这项工作的目的是开发一种创新的方法来研究血管重塑，将多尺度计算模型与组织培养和多光子显微镜相结合，可以用来深入了解发展临床病理和设计适当的临床干预措施。

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.