Imaging to Detect Abnormalities in the Innervation and Microvasculature of the Developing Heart

Abstract

The developing heart is a challenge to image because of its small size, rapid morphogenesis, and complex 3‐D structure. Capturing function is even more challenging because the heart begins beating at an early stage. Our group has developed a suite of biophotonic tools to capture structure and function in a quail model of fetal alcohol syndrome, induced by a single administration of ethanol to the fertilized egg to mimic a first trimester binge drinking episode. The quail is a useful model because it develops a 4‐chambered heart, it is economical, and the embryos are more easily accessible than mouse embryos to biophotonic interrogation for longitudinal structure and function analysis. Ethanol exposure reduces survival and increases the prevalence of congenital malformations, including congenital heart defects. We have previously reported on structural heart defects in the outflow tract, great vessels, septation, and in cardiac valves, and we have discovered that certain compounds (e.g. betaine) can alleviate these negative effects.Prenatal ethanol is thought to induce cardiac abnormalities by damaging neural crest cells, which may cause abnormalities in their derivatives. Many studies, including ours, have focused on the consequences of neural crest cell disruption in the formation of abnormalities of the cardiac outflow tract. In our current studies we explore how ethanol exposure may disrupt cardiac innervation, coronary vasculature, and other important derivatives of the neural crest cells.Eggs were injected with an ethanol at gastrulation and incubated until the embryos form four chambered hearts. The heart were dissected and immunofluorescently stained as whole mounts with neuron‐specific tubulin (TUJ1) to label the autonomic innervation. Our preliminary findings demonstrate that ethanol‐treated embryos have fewer innervation branching points and ganglia on the ventral ventricular base than controls. We also found more splitting of the major nerve, the thoracic sympathetic cardiac branch of the vagus that runs along the ventral surface of the pulmonary artery. Filling the microvasculature with SLIME (Scattering Labeled Imaging of Microvascular in Excised tissues) revealed that ethanol exposure results in coronary microvascular misalignment and uneven vessel distribution. In summary, both innervation and coronary microvasculature of the heart are altered by ethanol exposure. These findings may have implications for the cardiac health risks of individuals exposed to ethanol prenatally.Support or Funding InformationNIH R01 HL126747, NIH R01 HL083048, NIH T32 HD060537This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.