Targeting Endothelin Receptors in a Murine Model of Myocardial Infarction Using a Small Molecular Fluorescent Probe

Mol Pharm. 2020 Jan 6;17(1):109-117. doi: 10.1021/acs.molpharmaceut.9b00810. Epub 2019 Dec 18.

Abstract

The endothelin (ET) axis plays a pivotal role in cardiovascular diseases. Enhanced levels of circulating ET-1 have been correlated with an inferior clinical outcome after myocardial infarction (MI) in humans. Thus, the evaluation of endothelin-A receptor (ETAR) expression over time in the course of myocardial injury and healing may offer valuable information toward the understanding of the ET axis involvement in MI. We developed an approach to track the expression of ETAR with a customized molecular imaging probe in a murine model of MI. The small molecular probe based on the ETAR-selective antagonist 3-(1,3-benzodioxol-5-yl)-5-hydroxy-5-(4-methoxyphenyl)-4-[(3,4,5-trimethoxyphenyl)methyl]-2(5H)-furanone (PD156707) was labeled with fluorescent dye, IRDye800cw. Mice undergoing permanent ligation of the left anterior descending artery (LAD) were investigated at day 1, 7, and 21 post surgery after receiving an intravenous injection of the ETAR probe. Cryosections of explanted hearts were analyzed by cryotome-based CCD, and fluorescence reflectance imaging (FRI) and fluorescence signal intensities (SI) were extracted. Fluorescence-mediated tomography (FMT) imaging was performed to visualize probe distribution in the target region in vivo. An enhanced fluorescence signal intensity in the infarct area was detected in cryoCCD images as early as day 1 after surgery and intensified up to 21 days post MI. FRI was capable of detecting significantly enhanced SI in infarcted regions of hearts 7 days after surgery. In vivo imaging by FMT localized enhanced SI in the apex region of infarcted mouse hearts. We verified the localization of the probe and ETAR within the infarct area by immunohistochemistry (IHC). In addition, neovascularized areas were found in the affected myocardium by CD31 staining. Our study demonstrates that the applied fluorescent probe is capable of delineating ETAR expression over time in affected murine myocardium after MI in vivo and ex vivo.

Keywords: endothelin axis; molecular imaging; myocardial infarction; optical imaging.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cryoultramicrotomy
  • Dioxoles / chemistry
  • Dioxoles / metabolism*
  • Disease Models, Animal
  • Endothelin Receptor Antagonists / administration & dosage*
  • Endothelin Receptor Antagonists / analysis
  • Endothelin Receptor Antagonists / chemistry
  • Female
  • Fluorescent Dyes / administration & dosage*
  • Fluorescent Dyes / analysis
  • Immunohistochemistry
  • Indoles / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Myocardial Infarction / diagnostic imaging
  • Myocardial Infarction / metabolism*
  • Neovascularization, Physiologic
  • Optical Imaging
  • Platelet Endothelial Cell Adhesion Molecule-1 / metabolism
  • Receptors, Endothelin / metabolism*

Substances

  • Dioxoles
  • Endothelin Receptor Antagonists
  • Fluorescent Dyes
  • IRDye800
  • Indoles
  • PD 156707
  • Pecam1 protein, mouse
  • Platelet Endothelial Cell Adhesion Molecule-1
  • Receptors, Endothelin