Molecular Imaging and Biology

, Volume 8, Issue 6, pp 315–323

In Vivo Near-Infrared Fluorescence Imaging of Integrin αvβ3 in an Orthotopic Glioblastoma Model

  • Andrew R. Hsu
  • Lewis C. Hou
  • Anand Veeravagu
  • Joan M. Greve
  • Hannes Vogel
  • Victor Tse
  • Xiaoyuan Chen
Research Article

Abstract

Purpose

Expression of cell adhesion molecule integrin αvβ3 is significantly up-regulated during tumor growth, and sprouting of tumor vessels and correlates well with tumor aggressiveness. The purpose of this study was to visualize tumor integrin αvβ3 expression in vivo by using near-infrared fluorescence (NIRF) imaging of Cy5.5-linked cyclic arginine–glycine–aspartic acid (RGD) peptide in an orthotopic brain tumor model.

Procedures

U87MG glioma cells transfected with the firefly luciferase gene were stereotactically injected into nude mice in the right frontal lobe. Bioluminescence imaging (BLI) using d-luciferin substrate and small animal magnetic resonance imaging (MRI) using gadolinium contrast enhancement were conducted weekly after tumor cell inoculation to monitor intracranial tumor growth. Integrin αvβ3 expression was assessed by using a three-dimensional optical imaging system (IVIS 200) 0–24 hours after administration of 1.5 nmol monomeric Cy5.5-RGD via the tail vein. Animals were injected intravenously with both Texas Red–tomato lectin and Cy5.5-RGD prior to sacrifice to visualize peptide localization to tumor vasculature using histology.

Results

Fluorescence microscopy demonstrated specific Cy5.5-RGD binding to both U87MG tumor vessels and tumor cells with no normal tissue binding. NIRF imaging showed highest tumor uptake and tumor to normal brain tissue ratio two hours postinjection (2.64 ± 0.20). Tumor uptake of Cy5.5-RGD was effectively blocked by using unlabeled c(RGDyK), and injection of Cy5.5 dye alone showed nonspecific binding.

Conclusions

Optical imaging via BLI and NIRF offer a simple, effective, and rapid technique for noninvasive in vivo monitoring and semiquantitative analysis of intracranial tumor growth and integrin αvβ3 expression. This study suggests that NIRF via fluorescently labeled RGD peptides may provide enhanced surveillance of tumor angiogenesis and anti-integrin treatment efficacy in orthotopic brain tumor models.

Key words

Near-infrared fluorescence (NIRF) Bioluminescence imaging (BLI) Optical imaging Integrin RGD Cy5.5 Orthotopic glioblastoma 

Copyright information

© Academy of Molecular Imaging 2006

Authors and Affiliations

  • Andrew R. Hsu
    • 1
  • Lewis C. Hou
    • 1
  • Anand Veeravagu
    • 1
  • Joan M. Greve
    • 2
  • Hannes Vogel
    • 3
  • Victor Tse
    • 1
  • Xiaoyuan Chen
    • 4
  1. 1.Department of NeurosurgeryStanford University School of MedicineStanfordUSA
  2. 2.Department of RadiologyStanford University School of MedicineStanfordUSA
  3. 3.Department of PathologyStanford University School of MedicineStanfordUSA
  4. 4.Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X ProgramStanford University School of MedicineStanfordUSA

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