Ultrasound molecular imaging of E-selectin in tumor vessels using poly n-butyl cyanoacrylate microbubbles covalently coupled to a short targeting peptide.

Abstract

OBJECTIVES:

The purposes of this study were the development and preclinical evaluation of clinically translatable E-selectin-specific ultrasound contrast agents based on a peptide ligand with the recognition sequence IELLQAR.

MATERIALS AND METHODS:

The E-selectin-specific peptide was synthesized through solid phase peptide synthesis and covalently attached to poly n-butylcyanoacrylate-stabilized microbubbles with an air core. Quantification of the microbubble surface coverage with peptides was performed through flow cytometry. Targeted adhesion of peptide-coated microbubbles was investigated in vitro using parallel plate flow chamber assays on tumor necrosis factor-α-stimulated human umbilical vein endothelial cells. In vivo imaging was performed in nude mice bearing human ovarian carcinoma xenografts (MLS), followed by ex vivo immunohistochemistry validation of E-selectin expression.

RESULTS:

Success of peptide synthesis was validated through preparative reverse phase high-pressure liquid chromatography and electronspray ionization-mass spectrometry. Results of the flow cytometry revealed approximately 4000 E-selectin-specific peptides/microbubble surface. Results of the in vitro experiments demonstrated the specificity of peptide-coated microbubbles to E-selectin (1.10 ± 0.48 vs 0.19 ± 0.09 bound microbubbles per cell, before and after competition respectively; P < 0.01). The in vivo imaging enabled specific assessment of E-selectin expression in MLS carcinoma xenografts (5.21 ± 3.41 vs 1.37 ± 0.67 contrast intensity before and after competition, respectively; P < 0.05).

CONCLUSIONS:

Clinically translatable microbubbles that were covalently coupled to the short E-selectin-specific peptide (IELLQAR) enabled specific imaging of the E-selectin expression in tumor vessels in vivo.

• Authors: Stanley Fokong, Ana Fragoso, Anne Rix, Adelina Curaj, Zhuojun Wu, Wiltrud Lederle, Olga Iranzo, Jessica Gätjens, Fabian Kiessling, Moritz Palmowski
• Journal: Investigative radiology (Invest Radiol) Vol. 48 Issue 12 Pg. 843-50 (Dec 2013) ISSN: 1536-0210 [Electronic] United States
• PMID: 23857137 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Drug Carriers
• E-Selectin
• Peptides
• Enbucrilate

Topics

• Animals
• Cell Line, Tumor
• Drug Carriers (chemistry)
• E-Selectin (metabolism)
• Enbucrilate (chemistry)
• Female
• Mice
• Mice, Nude
• Microbubbles
• Molecular Imaging (methods)
• Ovarian Neoplasms (diagnostic imaging, metabolism)
• Peptides (pharmacokinetics)
• Reproducibility of Results
• Sensitivity and Specificity
• Ultrasonography (methods)