Constitutive and Agent-Based Multiscale Models to Improve Vein Graft Survival

描述（由申请人提供）：心脏病、中风和肢体丧失仍然是美国死亡率和发病率的主要原因。尽管这些疾病的外科治疗取得了进展，但这些干预措施的长期成功仍然有限。先前旨在提高静脉移植物耐久性的策略主要集中在还原论策略上，并使用线性模型来描述血管疾病进展的物理和生物成分。为了促进我们对这种复杂现象的理解，有必要整合不同类型的数据并使用定量模型来预测行为和结果。总体假设：一组特定的、有限的剪切调节基因对控制病理性静脉移植物适应至关重要。利用多尺度建模和实验技术的结合，这些基因可以在体内被识别和操纵，以提高静脉移植物的耐久性。具体目的1：确定那些对静脉移植物腔加速损失最关键的模型参数。方法：采用随机优化算法来评估我们的静脉移植物适应的计算机模型，通过大规模模拟来定义最小参数集，以及相应的核心生物过程，从而减少内膜增厚和增强外重构。具体目标2：创建一个动态的基因调控网络，当与基于agent的血管适应模型相结合时，确定对减少内膜增生和保留静脉移植物管腔有最显著影响的基因子集。方法：利用静脉移植样本的转录谱来创建基因调控网络。通过对该网络的系统评估，鉴定出高度互联的基因，特别是鉴定出那些被删除后导致整体基因表达发生实质性变化的基因。使用基于agent的静脉移植物适应模型来探索这一基因子集，以确定一组关键的中心基因，当删除这些基因时，会显著改善管腔保存。具体目标3：验证模型预测并探索对病理性静脉移植物适应的核心生物过程提供最关键影响的关键枢纽基因的组合。方法：采用高通量细胞培养系统和siRNA抑制策略，评估关键枢纽基因缺失对细胞增殖、凋亡、基质产生、蛋白酶激活和细胞运动的影响。最有希望的基因，无论是单独的还是组合的，将进入Aim 4进行体内测试。具体目标4：确定基因的最佳组合，将进入大型动物验证模型，并转化为提高静脉移植物存活率的治疗工具。方法：用siRNA结构包装慢病毒递送载体，我们将利用兔静脉旁路移植模式来评估通过Aim 1至3审查的最有希望的基因集的体内性能，评估它们对减少内膜增生和保留静脉移植管腔的影响。

DESCRIPTION (provided by applicant): Heart disease, stroke, and limb loss continue to be a leading cause of U.S. mortality and morbidity. Despite advances in the surgical treatments for these pathologies, the long-term success of these interventions remains limited. Prior strategies aimed at improving the durability of vein grafts have focused largely on reductionist strategies and used linear models to describe the physical and biologic components of vascular disease progression. In order to advance our understanding of such complex phenomena, it is necessary to integrate different types of data and use quantitative models to predict behavior and outcomes. OVERALL HYPOTHESIS: A specific, finite set of shear-regulated genes are critical to controlling pathologic vein graft adaptation. Using the integration of multiscale modeling and experimental techniques, these genes can be identified and manipulated in vivo to improve vein graft durability. SPECIFIC AIM 1: Identify those model parameters that are most critical for accelerated loss of the vein graft lumen. Approach: Using a stochastic optimization algorithm to evaluate our in silico model of vein graft adaptation, a large-scale simulation is use to define the minimum parameter set, and correspondingly the core biologic processes, that lead to reduced intimal thickening and enhanced outward remodeling. SPECIFIC AIM 2: Create a dynamic gene regulatory network, which when integrated with an agent-based model of vascular adaptation, identifies the subset of genes that have the most significant impact on reducing intimal hyperplasia and preserving vein graft lumen. Approach: Transcriptional profiling of vein graft samples is used to create a gene regulatory network. Through a systematic evaluation of this network, highly interconnected genes are identified, specifically identifying those genes that when deleted lead to substantial changes in global gene expression. This subset of genes is explored using an agent-based model of vein graft adaptation to identify a set of key hub genes that when deleted result in significant improvements in lumen preservation. SPECIFIC AIM 3: Validate the model prediction and explore combinations of key hub genes that provide the most critical impact on the biologic processes that are central to pathologic vein graft adaptation. Approach: Employing a high throughput, cell culture system and an siRNA inhibition strategy, the effect of key hub gene deletion on cell proliferation, apoptosis, matrix production, protease activation and cell motility will be evaluated. The most promising genes, either alone or in combination, will move into Aim 4 for in vivo testing. SPECIFIC AIM 4: Identify the optimum combination of genes that will move forward into a large animal validation model and translated into a therapeutic tool to improve vein graft survival. Approach: Packaging a lentivirus delivery vehicle with a siRNA construct, we will utilize a rabbit vein bypass graft mode to evaluate the in vivo performance of the most promising gene sets that have been vetted through Aim 1 through 3, assessing their impact on reducing intimal hyperplasia and preserving vein graft lumen.