title: Low-Dose Molecular Ultrasound Imaging with E-Selectin-Targeted PBCA Microbubbles.
abstract: OBJECTIVE
  Our objective was to determine the lowest diagnostically effective dose for E-selectin-targeted poly n-butyl cyanoacrylate (PBCA)-shelled microbubbles and to apply it to monitor antiangiogenic therapy effects.
  
  
  METHODS
  PBCA-shelled microbubbles (MBs) coupled to an E-selectin-specific peptide were applied in mice carrying MLS or A431 carcinoma xenografts scaling down the MB dosage to the lowest level where binding could be examined with a 18-MHz small animal ultrasound transducer. Differences in E-selectin expression in the two carcinoma xenografts were confirmed by enzyme-linked immunosorbent assay (ELISA). In addition, MLS tumor-bearing mice under antiangiogenic therapy were monitored using E-selectin-targeted MBs at the lowest applicable dose. Therapy effects on tumor vascularization were verified by immunohistological analyses.
  
  
  RESULTS
  The minimally required dosage was 7 × 10(7) MBs/kg body weight. This dosage was sufficient to enable E-selectin detection in high E-selectin-expressing MLS tumors, while low E-selectin-expressing A431 tumors required almost 2.5-fold higher doses. At the dose of 7 × 10(7) MBs/kg body weight, a decrease in E-selectin MB binding under antiangiogenic therapy could be assessed (being significant after 3 days of treatment; p < 0.0001), which was in line with the significant drop in E-selectin-positive area fractions that was found histologically (p < 0.05).
  
  
  CONCLUSIONS
  Molecular ultrasound imaging with our E-selectin-targeted MB and therapy monitoring was possible down to a dose of 7 × 10(7) MBs/kg body weight (equates to 66 μg PBCA/kg and 4.6 mg PBCA/70 kg). Improvements in choice of targets, MB composition, and other MB detection methods may improve sensitivity and lead to reliable detection results of clinically transferrable MBs at even lower dosage levels.
authors.affiliation: Department of Experimental Molecular Imaging, Medical Faculty, RWTH Aachen University, Aachen, Germany.
authors.forename: Igor
authors.initials: I
authors.lastname: Spivak
authors.affiliation: Department of Experimental Molecular Imaging, Medical Faculty, RWTH Aachen University, Aachen, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Rix
authors.affiliation: Institute of Medical Engineering, Ruhr-University Bochum, Bochum, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Schmitz
authors.affiliation: Department of Experimental Molecular Imaging, Medical Faculty, RWTH Aachen University, Aachen, Germany.
authors.forename: Stanley
authors.initials: S
authors.lastname: Fokong
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.|Aix Marseille Université, Centrale Marseille, CNRS, iSm2 UMR 7313, 13397, Marseille, France.
authors.forename: Olga
authors.initials: O
authors.lastname: Iranzo
authors.affiliation: Department of Experimental Molecular Imaging, Medical Faculty, RWTH Aachen University, Aachen, Germany.
authors.forename: Wiltrud
authors.initials: W
authors.lastname: Lederle
authors.affiliation: Department of Experimental Molecular Imaging, Medical Faculty, RWTH Aachen University, Aachen, Germany. fkiessling@ukaachen.de.|Institute for Experimental Molecular Imaging, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany. fkiessling@ukaachen.de.
authors.forename: Fabian
authors.initials: F
authors.lastname: Kiessling
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019040:E-Selectin / Q000378:metabolism*; D004659:Enbucrilate / Q000737:chemistry*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D008819:Mice, Nude; D045423:Microbubbles; D057054:Molecular Imaging / Q000379:methods*; D009369:Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging / Q000188:drug therapy; D009389:Neovascularization, Pathologic / Q000188:drug therapy; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D011485:Protein Binding; D047368:Tumor Burden; D014463:Ultrasonography / Q000379:methods*; D023041:Xenograft Model Antitumor Assays
chemical_list: D020533:Angiogenesis Inhibitors; D019040:E-Selectin; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D004659:Enbucrilate
keywords: Angiogenesis; Contrast-enhanced ultrasound; Microbubble; Molecular imaging; PBCA