PEARL® IMAGER

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Vascular and Lymphatic Imaging

VASCULAR AND LYMPHATIC IMAGING

Application Overview

IMPORTANT: IRDye 680LT dye products should not be used for small animal in vivo imaging.

Imaging of targeting agents in the vascular and lymphatic systems is a specialized type of biodistribution study.

Tumor vasculature commonly displays enhanced permeability and retention. The vascular endothelium in the tumor microenvironment is often discontinuous, allowing molecules to diffuse into surrounding tissue.^1,2 Lymphatic drainage in these regions is also poor.³

These properties cause larger molecules to accumulate in tumors
Can be exploited for molecular imaging of cancer

Figure 1 [ABOVE] Dorsal view of athymic male nu/nu mouse, with A431 subcutaneous tumor on the right flank. IV injection of IRDye 800CW PEG was administered ~1 hr prior to image capture with the Pearl Imager. Increased vasculature is seen in the tumor region.

¹ Vasey, PA, et al. 1999. Clin. Cancer Res. 5:83-94.

² Matsumura, Y and H Maeda. 1986. Cancer Res 46:6387-6392.

³ Seymour, LW. 1992. Crit. Rev. Ther. Drug Carrier Syst. 9(2):135-187.

Vascular Imaging

IRDye 800CW PEG Contrast Agent exploits the unique vascular properties of tumors for molecular imaging of cancer.

IRDye 800CW is conjugated to polyethylene glycol (PEG; a soluble synthetic polymer) to create a non-specific contrast agent for vascular imaging.

Agent is administered by intravenous (IV) injection
Highlights surface vasculature for ~0.5 hour after intravenous injection (Figure 1; requires appropriate mouse model* )
Retention of agent is visible in the tumor ~4 hr post-injection (Figure 2)
By 9 hours post-injection, the tumor is well defined (Figure 3)

Use of IRDye 800CW near-infrared fluorophore minimizes interfering autofluorescence, to improve image quality and resolution.

* Success of vascular imaging depends on the mouse model used. Vessels may be less visible in mice that are obese or have hair.

Images were captured with the Pearl® Imaging System.

Figure 1. Athymic male nu/nu mouse (~5-6 wks old), 0.5 hr after injection of IRDye 800CW PEG (1 nmole). Surface blood vessels are visible. Note: ability to visualize vasculature is dependent on mouse model used.

Figure 2a. Athymic male nu/nu mouse, ~4 hr after injection of IRDye 800CW PEG (1 nmole). Large blood vessels and tumor are visible.
Figure 2b. High resolution (85 µm) image of the tumor region shows large blood vessels recruited to feed the tumor. Sequestration of contrast agent in tumor is likely due to enhanced permeability and retention.

Figure 3. Athymic male nu/nu mouse, ~ 9 hr after injection of IRDye 800CW PEG (1 nmole). Tumor is clearly defined.

Lymphatic Imaging

IRDye 800CW PEG is an effective lymph tracking agent (Figure 4).

Administer by intradermal injection
Other contrast agents labeled with IRDye 800CW have been used for intraoperative identification of lymphatic branches and small sentinel lymph nodes, and outperformed NIR quantum dots.¹
The new Pearl Imager Impulse permits rapid time-lapse imaging of vasculature and lymphatics. Watch a two-minute video about Impulse here.

Image captured with the Pearl® Imaging System.

Figure 4. Athymic male nu/nu mouse, minutes after receiving IRDye 800CW PEG (~0.1 nmole) intradermally on the tail (right side). Image highlights use of IRDye PEG as a lymph imaging agent.

^1. Tanaka, E et al. 2006. Ann Surg Oncol. 13(12):1672-81.