Vascular disease on the ASK


Overview


Optical-based in vivo imaging of blood vessels and vascular leak is an emerging modality for studying changes that occur in a variety of different cancers and inflammatory states. A number of fluorescent imaging agents that circulate with the blood, but have no target selectivity, have been used to detect tumor leakiness as an indication of abnormal tumor vasculature. Inflammation is also characterized by distinct vascular changes, including vasodilation and increased vascular permeability, which are induced by the actions of various inflammatory mediators.

PerkinElmer offers imaging agents that fluoresce in the near infrared (NIR) for detection of changes in vascular permeability.


Products


ProductAgent typeMolecular weight/sizeExcitation/emission wavelengthsBlood half-lifeTissue half-life
Superhance®BSA-targeted small molecule1540 g/mol675/692 nm1.5 h5 h
AngioSense®PEGylated large scaffold250,000 g/mol680/700 nm7 h72 h
AngioSPARK®Nanoparticle30-50 nm particles673/690 nm20 h>100 h

How to choose an agent for vascular imaging

NIR vascular agents can vary in size and physicochemical properties that affect their overall utility for particular imaging applications or affect the time window for optimal imaging. In studies, we compared three NIR fluorescent agents, Superhance (a low molecular weight agent), AngioSense (a high molecular weight agent), and AngioSPARK (30-50 nm nanoparticles). Each agent differs significantly in pharmacokinetics, biodistribution, and tissue clearance rates, offering three slightly different imaging tools for cancer and inflammation research. All three agents can detect tumor vascular leak, with AngioSense showing superior signal to background in orthotopic mouse breast cancer. In contrast, Superhance shows superior imaging capability when applied to a mouse model of acute, inflammatory paw edema. AngioSPARK, designed as a highly robust agent for intravital microscopy assessment of vessel morphometry, shows the ability to image both tumors and inflammation with long term accumulation at the imaging site (sometimes a benefit for long term studies). Images and quantification of timecourses in animal models of cancer and inflammation provide guidance regarding optimal usage of these three vascular imaging agents.

Summary for four vascular applications

SuperhanceAngioSenseAngioSPARK
Tumor imaging+++++
Tumor imaging time3 h24-48 h24-48 h
Tumor washout48 h144 h >192 h
Response to antiangiogenic agentsnd+++nd
Acute edema imaging+++++
Tissue imaging time3 h24 h24 h
Tissue washout48 h144 h>192 h
Arthritis imagingnd++++++
Tissue imaging timend24 h24 h
Tissue washoutnd144 h>192 h
Intravital microscopy++++++++
Optimal imaging time5-15 min5-60 min5 min – 3 h


Mouse model for imaging vascular disease


Imaging Tumors with Vascular Agents

To determine the optimal imaging time points for the different vascular imaging agents, we used a syngeneic mouse tumor model, orthotopic implantation of 4T1 mouse breast adenocarcima at two sites (in each upper mammary fat pad).

vasculardisease1.jpg
Figure 1. Superhance tumor imaging. FMT and planar images show the patterns of fluorescence that occur in animals bearing tumor masses on the upper mammary fat pads. A) Whole body signal by FMT imaging. B) FMT imaging showing only tumor region fluorescence over time. Inset panels represent surface fluorescence detected by planar imaging.

vasculardisease2.jpg
Figure 2. AngioSense tumor imaging. FMT and planar images show the patterns of fluorescence that occur in animals bearing tumor masses on the upper mammary fat pads. A) Whole body signal by FMT imaging. B) FMT imaging showing only tumor region fluorescence over time. Inset panels represent surface fluorescence detected by planar imaging.

vasculardisease3.jpg
Figure 3. AngioSPARK tumor imaging. FMT and planar images show the patterns of fluorescence that occur in animals bearing tumor masses on the upper mammary fat pads. A) Whole body signal by FMT imaging. B) FMT imaging showing only tumor region fluorescence over time. Inset panels represent surface fluorescence detected by planar imaging.


Imaging Acute Edema with vascular agents

We used a mouse model of acute neutrophil-driven paw edema induced by injection of carrageenan (CG) into the right hindpaws. This provided an experimental approach that permitted the comparison of FMT imaging and planar imaging in the analysis of vascular agent kinetics. Superhance was injected at t = 2 h post carrageenan, whereas AngioSense and AngioSPARK were injected at t = 3 h, to accommodate the differences in blood pharmacokinetics and to permit imaging at the peak edema response (3 h). All three agents showed increased signal in carrageenan paws, although AngioSPARK showed high background signal in control paws. Superhance cleared quickly from tissue, making this agent ideal for imaging acute edema. Both AngioSense and AngioSPARK showed continued carrageenan paw accumulation at 24 h, a time at which there is less edema and more cellular inflammation.

vasculardisease4.jpg
Figure 4. Imaging Acute Paw Edema Induced by Carrageenan Injection. FMT and planar images show the patterns of fluorescence of three different vascular imaging agents that accumulate in paws of animals with inflammatory edema induced in the right footpad. A) Paw signal by FMT imaging. Numbers indicate quantitated pmol per paw. B) Planar imaging of the same mice shows the superficial fluorescence associated with the edema response.


Application notes and posters


  • Application note: Comparison of PerkinElmer Vascular Pre-clinical Fluorescent Imaging Agents in Oncology and Inflammation Research


Citations


Search or browse the PerkinElmer Citations Library for references related to vascular disease and preclinical imaging.