Hemodynamic forces such as shear stress are intimately linked with cardiac morphogenesis. Mutations in Notch signaling components result in congenital heart defects in humans and mice. During heart development, the trabeculae form a network of branching outgrowths from the ventricular wall, and both trabeculation and compaction are essential for normal cardiac contractile function. Hemodynamic shear stress induces vascular endothelial Notch signaling, and Notch pathway mediates differentiation and proliferation of trabecular myocytes. However, the mechanotransduction mechanisms underlying endocardial shear stress (ESS) and the initiation of trabeculation remain elusive. Our multi-disciplinary approach has demonstrated that peristaltic contraction of the embryonic heart tube produces time-varying shear stress (??/?t) and pressure gradients (?P) across the atrioventricular (AV) canal in a zebrafish model of cardiac development. The advent of zebrafish genetic system has enabled the application of fli1 promoter to drive expression of enhanced green fluorescent protein (EGFP) in all vasculature throughout embryogenesis (Tg(fli1a:EGFP)y1); thereby, allowing for 3-D visualization of the moving boundary conditions (2D + time) for computational fluid dynamics (CFD) simulation. However, 4-D (3-D + time) imaging to recapitulate the endocardium throughout the cardiac cycle requires fast tissue scanning and deep axial penetration. In this context, we seek to develop fluorescent Super-Resolution Light-Sheet Microscopy (SRLSM) to capture the 4-D endocardial trabecular network. We hypothesize that spatial (??/?x) and temporal ??/?t) variations in shear stress differentially modulate endocardial Notch signaling to initiate trabeculation. To test our hypothesis, we propose the following three aims.
In Aim 1, we will develop a fast 4-D cardiac imaging technique for moving boundary conditions. Our goal is to image endocardiac morphogenesis throughout the cardiac cycle.
In Aim 2, we will establish a link between shear stress and endocardial trabeculation. Our goal is to determine the effects of temporal (??/?t) and spatial (??/?x) variations in endocadial shear stress on the initiation of trabeculation from 20 to 120 hours post fertilization.
In Aim 3, e will elucidate the mechanotransduction mechanisms underlying trabeculation via Notch signaling. Our goal is to demonstrate that the shear stress-mediated endocardial Notch signaling pathway initiates differentiation and proliferation of cardiac trabeculation. Overall, ou team approach aims to establish a fundamental direction at the interface of hemodynamic forces and cardiac development with pathophysiological significance to non- compaction cardiomopathy.

Public Health Relevance

Non-compaction (LVNC) is the third most common cardiomyopathy with an estimated prevalence from 4.5 to 26 per 10,000 adult patients referred for echocardiographic diagnosis. While most clinical studies are based on the anatomical feature of LVNC, there remains a poor genotype-phenotype association in LVNC patients, and a paucity of knowledge regarding the mechanotransduction mechanisms of trabeculation and compaction. For these reason, our multi-disciplinary team seeks to embrace hemodynamic forces and laser light-sheets to elucidate endocardiac development with clinical relevance to pediatric and adult cardiovascular diseases. .

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL129727-03
Application #
9292371
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Evans, Frank
Project Start
2015-07-09
Project End
2019-06-30
Budget Start
2017-07-01
Budget End
2018-06-30
Support Year
3
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Baek, Kyung In; Packard, René R Sevag; Hsu, Jeffrey J et al. (2018) Ultrafine Particle Exposure Reveals the Importance of FOXO1/Notch Activation Complex for Vascular Regeneration. Antioxid Redox Signal 28:1209-1223
Abiri, Arash; Ding, Yichen; Abiri, Parinaz et al. (2018) Simulating Developmental Cardiac Morphology in Virtual Reality Using a Deformable Image Registration Approach. Ann Biomed Eng 46:2177-2188
Ding, Yichen; Lee, Juhyun; Hsu, Jeffrey J et al. (2018) Light-Sheet Imaging to Elucidate Cardiovascular Injury and Repair. Curr Cardiol Rep 20:35
Ding, Yichen; Bailey, Zachary; Messerschmidt, Victoria et al. (2018) Light-sheet Fluorescence Microscopy for the Study of the Murine Heart. J Vis Exp :
Baek, Kyung In; Ding, Yichen; Chang, Chih-Chiang et al. (2018) Advanced microscopy to elucidate cardiovascular injury and regeneration: 4D light-sheet imaging. Prog Biophys Mol Biol 138:105-115
Ding, Yichen; Ma, Jianguo; Langenbacher, Adam D et al. (2018) Multiscale light-sheet for rapid imaging of cardiopulmonary system. JCI Insight 3:
Baek, Kyung In; Li, Rongsong; Jen, Nelson et al. (2018) Flow-Responsive Vascular Endothelial Growth Factor Receptor-Protein Kinase C Isoform Epsilon Signaling Mediates Glycolytic Metabolites for Vascular Repair. Antioxid Redox Signal 28:31-43
Lee, Juhyun; Chou, Tzu-Chieh; Kang, Dongyang et al. (2017) A Rapid Capillary-Pressure Driven Micro-Channel to Demonstrate Newtonian Fluid Behavior of Zebrafish Blood at High Shear Rates. Sci Rep 7:1980
Ding, Yichen; Lee, Juhyun; Ma, Jianguo et al. (2017) Light-sheet fluorescence imaging to localize cardiac lineage and protein distribution. Sci Rep 7:42209
Vedula, Vijay; Lee, Juhyun; Xu, Hao et al. (2017) A method to quantify mechanobiologic forces during zebrafish cardiac development using 4-D light sheet imaging and computational modeling. PLoS Comput Biol 13:e1005828

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