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Updated: Jun 10, 2026
Intravital Microscopy of Tumor-associated Vasculature Using Advanced Dorsal Skinfold Window Chambers on Transgenic Fluorescent Mice
Published on: January 19, 2018
Targeting of alpha(nu)beta(3)-integrins expressed on tumor tissue and neovasculature using fluorescent small
Walter J Akers1, Zongren Zhang, Mikhail Berezin
1Department of Radiology, Washington University School of Medicine, 4525 Scott Avenue, St. Louis, MO 63110, USA.
Aim:
Receptor-specific small molecules and nanoparticles are widely used in molecular imaging of tumors. Although some studies have described the relative strengths and weaknesses of the two approaches, reports of a direct comparison and analysis of the two strategies are lacking. Herein, we compared the tumor-targeting characteristics of a small near-infrared fluorescent compound (cypate-peptide conjugate) and relatively large perfluorocarbon-based nanoparticles (250 nm diameter) for imaging alpha(nu)beta(3)-integrin receptor expression in tumors.
Materials & Methods:
Near-infrared fluorescent small molecules and nanoparticles were administered to living mice bearing subcutaneous or intradermal syngeneic tumors and imaged with whole-body and high-resolution optical imaging systems.
Results:
The nanoparticles, designed for vascular constraint, remained within the tumor vasculature while the small integrin-avid ligands diffused into the tissue to target integrin expression on tumor and endothelial cells. Targeted small-molecule and nanoparticle contrast agents preferentially accumulated in tumor tissue with tumor-to-muscle ratios of 8 and 7, respectively, compared with 3 for nontargeted nanoparticles.
Conclusion:
Fluorescent small molecular probes demonstrate greater overall early tumor contrast and rapid visualization of tumors, but the vascular-constrained nanoparticles are more selective for detecting cancer-induced angiogenesis. A combination of both imaging agents provides a strategy to image and quantify integrin expression in tumor tissue and tumor-induced neovascular systems.
Insights
Small molecule imaging probes offer rapid tumor visualization, while nanoparticles target tumor vasculature. Combining both provides a comprehensive strategy for imaging integrin expression in tumors and their associated neovascular systems.
Area of Science:
- Molecular imaging
- Nanotechnology
- Oncology
Background:
- Receptor-specific small molecules and nanoparticles are key tools in molecular tumor imaging.
- Direct comparative analyses of these two strategies are limited.
- This study addresses the need for a direct comparison of small molecules and nanoparticles for tumor targeting.
Purpose of the Study:
- To directly compare the tumor-targeting characteristics of small molecules and nanoparticles for imaging alpha(nu)beta(3)-integrin receptor expression.
- To evaluate the efficacy of a cypate-peptide conjugate (small molecule) versus perfluorocarbon-based nanoparticles (250 nm) for tumor imaging.
Main Methods:
- Administered near-infrared fluorescent small molecules and nanoparticles to mice with syngeneic tumors.
- Utilized whole-body and high-resolution optical imaging systems for tumor visualization.
- Assessed tumor-to-muscle ratios for targeted and non-targeted agents.
Main Results:
- Nanoparticles localized within tumor vasculature, while small molecules diffused into tumor tissue.
- Both targeted small molecules and nanoparticles showed preferential accumulation in tumor tissue.
- Targeted agents achieved higher tumor-to-muscle ratios (8 and 7) compared to non-targeted nanoparticles (3).
Conclusions:
- Small molecular probes provide superior early tumor contrast and rapid visualization.
- Vascular-constrained nanoparticles are more selective for detecting cancer-induced angiogenesis.
- Combining both agents allows for comprehensive imaging and quantification of integrin expression in tumors and neovascular systems.
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