Developmental basis for vascular smooth muscle cell dysfunction in Marfan syndrome aortic aneurysm

项目总结/摘要 马凡氏综合征（MFS），由突变引起的在BFN-1（FBN 1）基因，是最常见的遗传性 结缔组织疾病，影响1/5，000的个体。主动脉根部动脉瘤导致预期寿命缩短 由于动脉瘤夹层或破裂，除非进行预防性主动脉手术。一般来说，血管 平滑肌细胞（SMC）通过动态收缩/舒张维持主动脉内的稳态， 细胞外基质的产生，然而，这些细胞保留了显着的可塑性，以改变其表型， 对损伤、生长因子或其他刺激的反应。已知功能失调的SMC表型调节 有助于MFS中的动脉瘤发展。转化生长因子-β（TGF-β）信号转导失调 也会导致主动脉瘤，尽管该途径的确切作用仍然存在争议。此外，委员会认为， 驱动主动脉根（最接近主动脉瓣的节段）发展趋势的机制 局灶性动脉瘤尽管FBN 1突变的全身效应知之甚少。不同的胚胎起源 主动脉根部（来自第二心脏野，SHF）和升主动脉段（来自神经节）的SMC crest，NC）被假设为导致主动脉根部特异性病理学，然而，尚不清楚这些 胚胎起源影响动脉瘤发展的倾向。最近，单细胞RNA测序（scRNA- seq）已经允许对个体SMC基因表达进行高分辨率分析。我的初步工作是 针对MFS小鼠模型的scRNA-seq已经鉴定了具有严重调节的病理性、非特异性和非特异性SMCs亚组。 表型这项研究将促进我们目前对SMC发育和功能障碍的理解 在MFS主动脉瘤中使用两个互补的目标。在目标1中，我将定义胸肺动脉瘤的不同表型。 应用单细胞RNA从第二心野和神经嵴谱系中分离主动脉平滑肌细胞 胚胎谱系追踪小鼠模型的测序及TGF-β在SHF中调控异常的体外研究 和NC衍生的SMC表型。在目标2中，我将描述调制的 小鼠MFS主动脉根部动脉瘤中平滑肌细胞的谱系追踪及应用 计算转录组学分析工具，以scRNAseq数据，以确定分子机制，推动他们的 表型变化表型调节的SMC与健康主动脉SMC的共培养实验将 体外主动脉瘤病理模型。这些研究将产生重要的数据， MFS和其他遗传性动脉瘤疾病中驱动主动脉病理学向新的 治疗发展。拟议的研究培训计划的特点是由一个委员会直接指导， 有成就的临床科学家和获得最先进的设施和技术。该计划还 结合专业发展和职业规划战略，采用独特的协作精神， 在斯坦福大学的心血管外科和医学之间进行了一次旨在最大限度地发挥培训潜力的培训。

Project Summary/Abstract Marfan syndrome (MFS), caused by mutations in the fibrillin-1 (FBN1) gene, is the most common inherited connective tissue disorder, affecting 1 in 5,000 individuals. Aortic root aneurysm leads to reduced life expectancy due to dissection or rupture of the aneurysm unless preventative aortic surgery is performed. Normally, vascular smooth muscle cells (SMCs) maintain homeostasis within the aorta via dynamic contraction/relaxation and extracellular matrix production, however these cells retain significant plasticity to alter their phenotype in response to injury, growth factors, or other stimuli. Dysfunctional SMC phenotype modulation is known to contribute to aneurysm development in MFS. Dysregulated transforming growth factor-beta (TGF-b) signaling also contributes to aortic aneurysm, though the precise role of this pathway remains controversial. Furthermore, mechanisms driving the tendency of the aortic root (the segment most proximal to the aortic valve) to develop focal aneurysm despite systemic effects of FBN1 mutations are poorly understood. Distinct embryonic origins of SMCs populating the aortic root (from the second heart field, SHF) and ascending aortic segments (from neural crest, NC) is hypothesized to contribute to aortic root-specific pathology, however it remains unclear how these embryonic origins affect propensity for aneurysm development. Recently, single-cell RNA sequencing (scRNA- seq) has permitted high-resolution analysis of individual SMC gene expression. My preliminary work applying scRNA-seq to a mouse model of MFS has identified a subset of SMCs with a severely modulated, pathologic phenotype. The proposed study will advance our current understanding of SMC development and dysfunction in MFS aortic aneurysm using two complementary aims. In Aim 1 I will define the distinct phenotypes of thoracic aortic SMCs derived from the second heart field and neural crest lineages by applying single-cell RNA sequencing to an embryonic lineage-tracing mouse model and in vitro studies of TGF-b dysregulation on SHF and NC-derived SMC phenotype. In Aim 2 I will characterize the source and pathologic effects of modulated SMCs in MFS aortic root aneurysm by lineage-tracing early SMCs in a murine MFS model and applying computational transcriptomic analysis tools to scRNAseq data to determine molecular mechanisms driving their phenotype changes. Co-culture experiments of phenotypically modulated SMCs with healthy aortic SMCs will model aortic aneurysm pathology in vitro. These studies will generate important data that will help pinpoint molecular mechanisms driving aortic pathology in MFS and other hereditary aneurysm disorders toward new therapy development. The proposed research training plan features direct mentorship from a committee of accomplished clinician-scientists and access to state-of-the art facilities and techniques. This plan also incorporates professional development and career planning strategies, employing the unique collaborative spirit between Cardiovascular Surgery and Medicine at Stanford University intended to maximize training potential.