Detection of activated platelets in a mouse model of carotid artery thrombosis with 18 F-labeled single-chain antibodies

Katie Ardipradja; Shinn Dee Yeoh; Karen Alt; Graeme O'Keefe; Angela Rigopoulos; David W Howells; Andrew M Scott; Karlheinz Peter; Uwe Ackerman; Christoph E Hagemeyer

doi:10.1016/j.nucmedbio.2013.12.006

Detection of activated platelets in a mouse model of carotid artery thrombosis with 18 F-labeled single-chain antibodies

Nucl Med Biol. 2014 Mar;41(3):229-37. doi: 10.1016/j.nucmedbio.2013.12.006. Epub 2013 Dec 18.

Authors

Affiliations

¹ Vascular Biotechnology Laboratory, Baker IDI, Melbourne, Australia; Atherothrombosis and Vascular Biology Laboratory, Baker IDI, Melbourne, Australia; Departments of Nuclear Medicine and Centre for PET, Austin Hospital, Melbourne, Australia; Department of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, Australia.
² Departments of Nuclear Medicine and Centre for PET, Austin Hospital, Melbourne, Australia.
³ Vascular Biotechnology Laboratory, Baker IDI, Melbourne, Australia; Atherothrombosis and Vascular Biology Laboratory, Baker IDI, Melbourne, Australia.
⁴ Ludwig Institute for Cancer Research, Austin Hospital, Melbourne, Australia.
⁵ The Florey Institute of Neuroscience and Mental Health, Austin Hospital, Melbourne, Australia.
⁶ Departments of Nuclear Medicine and Centre for PET, Austin Hospital, Melbourne, Australia; Department of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, Australia; Ludwig Institute for Cancer Research, Austin Hospital, Melbourne, Australia.
⁷ Atherothrombosis and Vascular Biology Laboratory, Baker IDI, Melbourne, Australia; Central Clinical School, Monash University, Melbourne, Australia.
⁸ Vascular Biotechnology Laboratory, Baker IDI, Melbourne, Australia; Central Clinical School, Monash University, Melbourne, Australia. Electronic address: christoph.hagemeyer@gmail.com.

PMID: 24440583
DOI: 10.1016/j.nucmedbio.2013.12.006

Abstract

Introduction: Activated platelets are key players in thrombosis and inflammation. We previously generated single-chain antibodies (scFv) against ligand-induced binding sites (LIBS) on the highly abundant platelet glycoprotein integrin receptor IIb/IIIa. The aim of this study was the construction and characterisation of a novel (18)F PET radiotracer based on this antibody.

Methods: ScFv(anti-LIBS) and control antibody mut-scFv were reacted with N-succinimidyl-4-[(18)F]fluorobenzoate (S[(18)F]FB). Radiolabeled scFv was incubated with in vitro formed platelet clots and injected into mice with FeCl(3) induced thrombus in the left carotid artery. Clots were imaged in the PET scanner and amount of radioactivity measured using an ionization chamber and image analysis. Assessment of vessel injury as well as the biodistribution of the radiolabeled scFv was studied.

Results: After incubation with increasing concentrations of (18)F-scFv(anti-LIBS) clots had retained significantly higher amounts of radioactivity compared to clots incubated with radiolabeled (18)F-mut-scFv (13.3 ± 3.8 vs. 3.6 ± 1 KBq, p < 0.05, n = 9, decay corrected). In the in vivo experiments we found an high uptake of the tracer in the injured vessel compared with the non-injured vessel, with 12.6 ± 4.7% injected dose per gram (ID/g) uptake in the injured vessel and 3.7 ± 0.9% ID/g in the non-injured vessel 5 minutes after injection (p < 0.05, n = 6).

Conclusions: Our results show that the novel antibody radiotracer (18)F-scFv(anti-LIBS) is useful for the sensitive detection of activated platelets and thrombosis.

Advances in knowledge and implications for patient care: We describe the first (18)F variant of a scFv(anti-LIBS) against activated platelets. This diagnostic agent could provide a powerful tool for the assessment of acute thrombosis and inflammation in patients in the future.

Keywords: Antibodies; PET/CT; Platelets; Thrombosis.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Benzoates / chemistry
Blood Coagulation
Carotid Artery Thrombosis / diagnostic imaging
Carotid Artery Thrombosis / pathology
Carotid Artery Thrombosis / physiopathology*
Disease Models, Animal
Female
Fluorine Radioisotopes*
Image Processing, Computer-Assisted
Mice
Mice, Inbred C57BL
Platelet Activation*
Positron-Emission Tomography
Single-Chain Antibodies* / chemistry
Single-Chain Antibodies* / pharmacokinetics

Substances

Benzoates
Fluorine Radioisotopes
Single-Chain Antibodies