Molecular Ultrasound Imaging of αvβ3-Integrin Expression in Carotid Arteries of Pigs After Vessel Injury.
Interventions such as balloon angioplasty can cause vascular injury leading to platelet activation, thrombus formation, and inflammatory response. This induces vascular smooth muscle cell activation and subsequent re-endothelialization with expression of αvβ3-integrin by endothelial cells and vascular smooth muscle cell. Thus, poly-N-butylcyanoacrylate microbubbles (MBs) targeted to αvβ3-integrin were evaluated for monitoring vascular healing after vessel injury in pigs using molecular ultrasound imaging.



Approval for animal experiments was obtained. The binding specificity of αvβ3-integrin-targeted MB to human umbilical vein endothelial cells was tested with fluorescence microscopy. In vivo imaging was performed using a clinical ultrasound system and an 8-MHz probe. Six mini pigs were examined after vessel injury in the left carotid artery. The right carotid served as control. Uncoated MB, cDRG-coated MB, and αvβ3-integrin-specific cRGD-coated MB were injected sequentially. Bound MBs were assessed 8 minutes after injection using ultrasound replenishment analysis. Measurements were performed 2 hours, 1 and 5 weeks, and 3 and 6 months after injury. In vivo data were validated by immunohistochemistry.



Significantly stronger binding of cRGD-MB than MB and cDRG-MB to human umbilical vein endothelial cells was found (P < 0.01). As vessel injury leads to upregulation of αvβ3-integrin, cRGD-MBs bound significantly stronger (P < 0.05) in injured carotid arteries than at the counter side 1 week after vessel injury and significant differences could also be observed after 5 weeks. After 3 months, αvβ3-integrin expression decreased to baseline and binding of cRGD-MB was comparable in both vessels. Values remained at baseline also after 6 months.



Ultrasound imaging with RGD-MB is promising for monitoring vascular healing after vessel injury. This may open new perspectives to assess vascular damage after radiological interventions.
From the *Institute for Experimental Molecular Imaging, University Clinic and Helmholtz Center for Biomedical Engineering, and †Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany.
Anne
A
Rix
Stanley
S
Fokong
Sarah
S
Heringer
Rastislav
R
Pjontek
Lisa
L
Kabelitz
Benjamin
B
Theek
Marc-Alexander
MA
Brockmann
Martin
M
Wiesmann
Fabian
F
Kiessling
D000818:Animals; D002339:Carotid Arteries / Q000000981:diagnostic imaging* / Q000378:metabolism; D020212:Carotid Artery Injuries / Q000000981:diagnostic imaging* / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D045423:Microbubbles; D057054:Molecular Imaging / Q000379:methods; D015203:Reproducibility of Results; D013552:Swine; D014463:Ultrasonography / Q000379:methods*; D014945:Wound Healing / Q000502:physiology*
D039302:Integrin alphaVbeta3