Mechanisms of hemodynamic-force-regulated vascular smooth muscle cell recruitment and attachment

项目总结 在未来的医疗中，重要的一步将是用 在体外生长的工程化器官。然而，实现这一目标的一个主要障碍是 组织工程师培养复杂的、有功能的血管，为这些血管提供氧气和营养 外部生长的器官。缺少的一块拼图是如何知道血液厚度的差异 管壁在整个血管系统中形成。出于这个原因，研究人员必须了解 直径较大的血管(位于心脏附近)形成由多层血管组成的厚管壁。 平滑肌细胞(VSMC)，以及小直径血管(远离心脏)是如何形成细的或 缺少VSMC层。这些血管壁厚的差异是形成的关键要求 功能血管系统，但不清楚壁厚是如何调节的。因此，长期目标是 这项建议是为了阐明血管壁厚形成的机制。从我们的 在以前的研究中，我们根据血管形成厚壁的程度确定发育中的血管形成厚壁。 暴露在血液流动的力量中。因此，高流量的血管比低流量的血管招募和附着更多的VSMC 船只。目前尚不清楚的是解释血液流动力量的具体机制 (血流动力)调节vSMC的募集和附着。利用小鼠胚胎模型，一个团队 本科生、硕士生和首席调查员将探索两大机制 关于如何获得血管壁厚。在目标1中，我们将测试血液动力学 调节几种Semaphorin3信号蛋白(Sema3F/G和Sema3A)的表达以控制vSMC 在高流量船舶上进行招募。这一目标将通过破坏这些Sema3蛋白来研究，以确定 如果这阻碍了血管系统的vSMC募集，并通过挽救所展示的vSMC募集缺陷 在血流量减少时，通过重新引入Sema3蛋白梯度。在目标2中，我们将测试 血流动力调节血管的粘附性，促进VSMC与血管的附着。这一目标 将通过确定血流量减少是否会降低VSMC附着到 通过减弱黏附分子的表达，如细胞外基质基因(或抑制物 细胞外基质降解酶)，并通过上调细胞外基质降解酶的表达 基因(基质金属蛋白酶[MMP]抑制物)。为了达到这个目的，我们还将确定是否使用基质金属蛋白酶抑制剂 将促进细胞外基质的形成，从而增强血管与血管平滑肌细胞的黏附。由 确定血管壁与血管平滑肌细胞投资的机制，这将使研究人员能够识别 一套合适的分子工具，将被用来设计功能血管以及修复 成年人的血管受损。此外，这些研究将有助于支持本科生和 生物医学研究硕士研究生。

Project summary In the future, an important step in medical treatment will be the replacement of diseased or injured organs with engineered organs grown outside the body. However, one major impediment towards this goal is the ability for tissue engineers to grow complex and functional blood vessels that supply oxygen and nutrients to these externally grown organs. A missing piece of the puzzle is in knowing how differences in thickness of the blood vessel wall forms throughout the vasculature. For this reason, researchers must understand how large- diameter blood vessels (located close to the heart) form thick vessel walls composed of layers of vascular smooth muscle cells (vSMCs), and how small-diameter vessels (located far away from the heart) form thin or absent layers of vSMCs. These differences in vessel wall thickness are critical requirements for the formation of a functional vasculature, but it is unclear how wall thickness is regulated. Thus, the long-term objective of this proposal is to elucidate the mechanisms governing the formation of blood vessel wall thickness. From our previous studies, we determined that developing blood vessels form thick vessel walls based on extent of exposure to blood flow forces. Thus, high-flow vessels recruit and attach to more vSMCs than low-flow vessels. What remains unknown are the specific mechanisms explaining how the force of blood flow (hemodynamic force) regulates vSMC recruitment and attachment. Using the mouse embryonic model, a team of undergraduate students, master’s students and the principal investigator will explore two major mechanisms regarding how vessel wall thickness is attained. In aim 1, we will test the whether hemodynamic force regulates expression of several Semaphorin3 signaling proteins (Sema3F/G and Sema3A) to control vSMC recruitment to high-flow vessels. This aim will be investigated by disrupting these Sema3 proteins to determine if this impedes vSMC recruitment to the vasculature, and by rescuing the vSMC recruitment defects exhibited upon reduction of blood flow, by reintroducing the Sema3 protein gradients. In aim 2, we will test whether hemodynamic force regulates the adhesiveness of vessels to promote vSMC attachment to vessels. This aim will be investigated by determining whether reduction of blood flow reduces the ability for vSMCs to attach to vessels by attenuating expression of adhesive molecules, such as extracellular matrix genes (or inhibitors to extracellular matrix-degrading enzymes), and by upregulating expression of extracellular matrix-degrading genes (Matrix metalloproteinase [Mmp] inhibitors). In this aim, we will also determine if use of Mmp inhibitors will enhance extracellular matrix formation, and as a result enhance the adhesion of vessels to vSMCs. By the determining the mechanisms of vessel wall investment with vSMCs, this will allow researchers to identify an appropriate set of molecular tools that will be used to engineer functional blood vessels, as well as repair damaged blood vessels in adults. Further, these studies will help support the training of undergraduate and master’s students in biomedical research.