Dynamic changes in the chick developing heart in response to altered hemodynamics

雏鸡发育中的心脏因血流动力学改变而发生动态变化

• 批准号: 8055060
• 负责人: Sandra Rugonyi
• 金额: $ 38.05万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8055060
• 关键词: Affect; Animal Model; Animals; Biological; Biomechanics; Blood Flow Velocity; Blood Pressure; Blood Volume; Blood flow; Cardiac; Cause of Death; Cells; Chick Embryo; Chickens; Clip; Collagen; Collagen Type VI; Congenital Heart Defects; Data; Defect; Development; Disease; Elements; Embryo; Gene Expression; Gene Expression Regulation; Genes; Genetic; Goals; Growth; Health; Heart; Heart failure; Human; Image; Immunohistochemistry; In Situ Hybridization; Infant; Integrins; Lead; Life; Ligation; Measurable; Measures; Methods; Modeling; Molecular; Morphology; Motion; Newborn Infant; Optical Coherence Tomography; Other Genetics; Physiological; Polymerase Chain Reaction; Prevention; Procedures; Staging; Stimulus; Structure; Structure of omphalomesenteric vein; Surgical sutures; System; Three-Dimensional Image; Time; Tissues; Tube; Variant; base; cardiogenesis; congenital heart disorder; hemodynamics; in vivo; pressure; response; shear stress; simulation; time use

DESCRIPTION (provided by applicant): About 1% of newborn babies in the US have congenital heart disease (CHD), the leading cause of death among infants. Hemodynamic forces, which are wall shear stresses and pressures generated by the flow of blood, are key factors that regulate heart development and, if abnormal, can lead to CHD. Even when CHD has a genetic cause, altered blood-flow conditions produced by heart defects may lead to additional abnormalities. However, the extent to which alterations in hemodynamics affect cardiac cells and ultimately heart formation is not yet clear. A detailed study of the effects of hemodynamics on heart development requires quantification of hemodynamic forces and of changes in heart growth, morphology and gene expression in an intact, in vivo animal model. The objective of this project is to elucidate the relationship among hemodynamic forces, cardiac growth, heart morphology and expression of selected genes during early developmental stages; with the ultimate goal of understanding the biological mechanisms by which hemodynamics affect heart development. This project will use chick embryos at 2 early stages of development (3 and 3.5 days of a 21-day incubation period - HH18 and HH21), and will focus on the heart outflow tract (OFT), which acts like a primitive valve. Normal blood-flow dynamics will be altered by outflow tract banding, a procedure in which a suture is placed around the OFT, constraining the motion of the OFT wall; and by vitelline-vein ligation, in which a vitelline vein is clipped to obstruct blood flow. The hypothesis is that alterations of hemodynamic forces due to outflow tract banding and vitelline-vein ligation at HH18 lead to measurable, correlated changes in OFT wall morphology, growth and gene expression at HH21. The aims of the project are: Aim 1: Determine in vivo changes in the motion, morphology, and growth of the OFT wall in response to altered hemodynamics. To measure wall motion and geometrical changes in the OFT of chick embryos, the OFT will be imaged using optical coherence tomography. Aim 2: Determine dynamic variations of hemodynamic forces in the OFT and associated expression of selected genes under normal and altered hemodynamic conditions over the cardiac cycle. Blood pressure will be measured using a servo null system. Wall shear stress will be quantified from simulations of finite element models of the OFT. Gene expression levels of integrins and collagen VI (up-regulated after OTB) will be quantified by real time polymerase chain reaction, and localization determined from in situ hybridization and immunohistochemistry. PUBLIC HEALTH RELEVANCE: Although hemodynamic forces have long been recognized as key factors in heart development, the mechanisms by which these forces affect heart development and lead to congenital heart disease (CHD) are not well understood. This project seeks to better understand the relationship between alterations in hemodynamic conditions and changes in heart development - changes that could lead to CHD or even predispose the heart for failure later in life. A better understanding of the relationship between blood flow and heart formation could eventually be used in the prevention and treatment of CHD and other heart-related diseases.

描述(申请人提供)：在美国，大约1%的新生儿患有先天性心脏病(CHD)，这是导致婴儿死亡的主要原因。血流动力，即壁面切应力和血液流动产生的压力，是调节心脏发育的关键因素，如果异常，可能会导致冠心病。即使CHD有遗传原因，心脏缺陷引起的血液流动状况改变也可能导致额外的异常。然而，血流动力学的改变对心脏细胞和最终心脏形成的影响程度尚不清楚。要详细研究血流动力学对心脏发育的影响，需要在一个完整的活体动物模型中量化血液动力以及心脏生长、形态和基因表达的变化。本项目的目的是阐明血流动力、心脏生长、心脏形态和选定基因在早期发育阶段的表达之间的关系，最终目的是了解血流动力学影响心脏发育的生物学机制。该项目将使用两个早期发育阶段的鸡胚胎(21天潜伏期中的3天和3.5天--HH18和HH21)，并将重点放在心脏流出道(OFT)上，它的作用类似于原始瓣膜。正常的血流动力学将通过流出道束带和卵黄静脉结扎来改变，前者是在OFT周围放置缝线，限制OFT壁的运动；后者是通过夹闭卵黄静脉来阻止血流。假设HH18的流出道束带和卵黄静脉结扎引起的血流动力的改变导致HH21的OFT壁形态、生长和基因表达的可测量的、相关的变化。该项目的目标是：目标1：确定OFT壁的运动、形态和生长在体内的变化，以响应血流动力学的改变。为了测量鸡胚OFT的室壁运动和几何变化，将使用光学相干断层成像技术对OFT进行成像。目的2：测定心脏周期内正常和异常血流动力学条件下OFT血流动力的动态变化及相关基因的表达。血压将使用伺服零位系统进行测量。壁面剪应力将通过对OFT的有限元模型的模拟来量化。整合素和VI型胶原的基因表达水平(OTB后上调)将通过实时聚合酶链式反应进行定量，并通过原位杂交和免疫组织化学确定定位。公共卫生相关性：尽管血液动力学力量长期以来一直被认为是心脏发育的关键因素，但这些力量影响心脏发育并导致先天性心脏病(CHD)的机制尚不清楚。这个项目试图更好地了解血液动力学条件的变化和心脏发育变化之间的关系-这些变化可能导致CHD，甚至使心脏在以后的生活中容易衰竭。更好地了解血流和心脏形成之间的关系最终可能被用于预防和治疗冠心病和其他心脏相关疾病。