Dynamic Imaging of VEGF Relative to the ECM and its Effects on Endocardial Cell Behavior During Cardiovascular Morphogenesis

Abstract

Vascular endothelial growth factor (VEGF) interacts with extracellular matrix (ECM) constituents; setting up morphogenetic gradients and regulating ligand presentation to cells. We are investigating the behavior of ECM-interacting VEGF165 and soluble VEGF121 during endocardial assembly in quail. We use fluorescent anti-VEGF antibodies and VEGF receptor bodies to visualize VEGF. ECM constituents are visualized by microinjection of fluorescent antibodies against fibronectin and fibrillin-2. All experiments are performed in Tie1::H2B-YFP quail embryos (nuclear labeling of endocardial cells). Endocardial cell, ECM, and VEGF tissue components are recorded using time lapse imaging, with their relative movements analyzed using tracing and image analysis techniques. During formation of the endocardium, ECM components move in a coordinated manner with endocardial precursors (tissue motion). However, neither VEGF over-activation (hypervascularization) or inactivation (blocking of endocardial differentiation) halts the tissue movement that results in formation (albeit abnormal) of a midline heart tube. Our results further the current understanding of the coordinated behavior of VEGF and ECM constituents of embryonic tissues and their collective role in cardiovascular morphogenesis. HL085694 (BJR); HL087136 (AC); Mathers Foundation (BJR, AC, CDL); AHA predoctoral award (AA).

Additional details