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

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

来源：Nuclear Medicine and Biology, 2014, 41(3): 229-237.

DOI：10.1016/j.nucmedbio.2013.12.006

• Antibodies
• Thrombosis
• Platelets
• PET/CT

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 F-18 PET radiotracer based on this antibody.
Methods: ScFv(anti-LIBS) and control antibody mut-scEv were reacted with N-succinimidyl-4-[F-18]fluorobenzoate (S[F-18]FB). Radiolabeled scEv was incubated with in vitro formed platelet clots and injected into mice with FeCl3 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 scEv was studied.
Results: After incubation with increasing concentrations of F-18-scFv(anti-LIBS) clots had retained significantly higher amounts of radioactivity compared to clots incubated with radiolabeled F-18-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 F-18-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 F-18 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.

• 出版日期2014-3