Murine models of vascular remodeling

血管重塑是许多血管疾病的常见过程，描述了血管壁和邻近血管周围结构内的形态变化炎症、内皮功能障碍以及血管平滑肌细胞的迁移和增殖是触发这种重塑过程的主要因素，这可能导致新生内膜增生、中层异常增生、血管周围增厚、或纤维化和血管钙化。血管重塑也会在血管成形术和血管支架植入等介入性手术后发生。静脉经常用于冠状动脉搭桥术，短期内可能由于血栓形成导致的急性移植物失败而失败，长期则可能由于病理性血管重塑而失败，这是一个复杂的过程，尽管它与其他疾病有临床相关性，但人们对此知之甚少。对于接受这些手术的患者来说，更好地了解分子信号网络和细胞反应具有巨大的潜力。我们已经开始了一系列研究，以确定小鼠静脉移植模型中的细胞反应和局部信号通路。 项目1：AD-HIEs的临床特征和信号通路，我们确定的那些在AD-HIEs成纤维细胞中受影响的，表明血管生成缺陷是AD-HIEs病理的因素。因此，我们使用共培养的体外血管生成实验来确定AD-HIEs成纤维细胞支持血管生成的能力。我们的研究证实，AD-HIEs成纤维细胞促进HUVEC细胞形成管状细胞的能力降低。为了研究AD-HIEs成纤维细胞在体内支持血管生成的能力，我们使用了一种小鼠后肢缺血模型，在该模型中，手术结扎特定部位的股动脉导致股侧支的动脉生成和远端缺血肌肉的血管生成。42初步实验表明，将正常的成纤维细胞注入小腿肌肉可以促进血流的恢复，而注入AD-HIEs成纤维细胞则不能。这些结果表明，AD-HIEs成纤维细胞在支持体内血管生成方面存在缺陷。 项目2：移植到动脉环境中的静脉经历复杂的血管重塑。EndMT是内皮细胞失去细胞特异性标志物和形态，获得间充质细胞样表型的过程。然而，EndMT在人静脉移植物重塑过程中的作用和调节细胞表型适应的机制还知之甚少。 使用两个独立的内皮细胞谱系追踪系统，我们证明，在静脉移植后35天，填充新生内膜的细胞有一半是内皮细胞起源的。这些内皮来源的细胞已经失去了其内皮表型，并获得了平滑肌细胞样的特性，但它们未能形成完全成熟的平滑肌细胞表型。我们检测到了转化生长因子-b-Smad2/3-slug信号通路的早期激活，证实了转化生长因子-b-Smad2/3-slug信号通路介导的EndMT在调节静脉移植物重塑中起着关键作用。我们正在进一步研究BMP9/Smad1介导的内皮细胞存活及其对移植静脉急性通畅性和长期结局的影响，包括由于新生内膜增生的发展而导致的移植静脉重建，以及导致早期移植失败的血栓形成。我们推测，激活BMP9/Smad1通路可以正向调节内皮功能，从而有利于小鼠静脉移植。

Vascular remodeling, a common process in many vascular diseases, describes morphological changes within the vascular wall and adjacent perivascular structures Inflammation, endothelial dysfunction, and vascular smooth muscle cell migration and proliferation are the main factors triggering this remodeling process, which may lead to neointimal hyperplasia, medial dysplasia, perivascular thickening, or fibrosis and vascular calcification 45. Vascular remodeling also occurs after interventional procedures such as angioplasty and vascular stenting. Veins are frequently used in coronary artery bypass grafting, which may fail in the short term because of acute graft failure due to thrombosis or in the long term due to pathological vascular remodeling, a complex process that is poorly understood despite its clinical relevance for other diseases. A better understanding of the molecular signaling networks and cellular responses holds tremendous potential for patients undergoing these procedures. We have embarked on a series of investigations to determine cellular responses and local signaling pathways in a murine vein graft model. Project 1: AD-HIES clinical features and signaling pathways that we identified as those affected in AD-HIES fibroblasts point to angiogenesis defects as factors that contribute to AD-HIES pathologies. Therefore, we used co-culture in vitro angiogenesis assays to determine the ability of AD-HIES fibroblasts to support angiogenesis. Our studies confirmed that AD-HIES fibroblasts have decreased ability to promote tube formation by HUVEC cells. To investigate the ability of AD-HIES fibroblasts to support angiogenesis in vivo, we are using a murine model of hind-limb ischemia, in which surgical ligation of the femoral artery at specific site leads to arteriogenesis in femoral collaterals and angiogenesis in distal ischemic muscles.42 Preliminary experiments demonstrated that injecting normal fibroblasts into the calf muscle improves restoration of blood flow while injecting AD-HIES fibroblasts does not. These results indicate that AD-HIES fibroblasts are deficient in supporting angiogenesis in vivo. Project 2: Veins grafted into an arterial environment undergo complex vascular remodeling. EndMT is the process by which endothelial cells lose their cell-specific markers and morphology and acquire a mesenchymal cell-like phenotype. However, the role of EndMT and the mechanisms regulating cell phenotype adaptation during human vein graft remodeling are poorly understood. Using two independent endothelial lineage tracing systems, we demonstrated that, at 35 days after vein grafting, half the cells populating the neointima were of endothelial origin. These endothelial-derived cells had lost their endothelial phenotype and acquired smooth muscle cell-like properties, yet they failed to develop a fully mature smooth muscle cell phenotype. We detected early activation of the TGF-b-Smad2/3-Slug signaling pathway and confirmed that TGF-b-Smad2/3-Slug signaling pathway-mediated EndMT plays a pivotal role in regulating vein graft remodeling. We are further investigating BMP9/Smad1-mediated endothelial cell survival and its impact on acute vein graft patency and long-term outcome in vein graft remodeling due to the development of neointimal hyperplasia, but also in thrombosis formation leading to early graft failure. We hypothesize that activating the BMP9/Smad1 pathway positively regulates endothelial function to benefit murine vein grafting.