Abstract 049: Novel Tirofiban Conjugate for the in vivo Detection of Activated Platelets
| Autor: | Farouc A. Jaffer, Chase W. Kessinger, Xiaoxin Zheng, Jason R. McCarthy, Khanh Ha |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Arteriosclerosis, Thrombosis, and Vascular Biology. 38 |
| ISSN: | 1524-4636 1079-5642 |
| Popis: | Background: Current intracoronary imaging approaches such as intravascular ultrasound and optical coherence tomographic imaging do not specifically detect activated platelets, a key cell that drives stent thrombosis, a life-threatening condition following percutaneous coronary intervention (PCI). Glycoprotein IIb/IIIa (GPIIb/IIIa) is the key receptor involved in platelet activation and is a validated target for both therapeutic approaches and diagnostic imaging. A GPIIb/IIIa-targeted fluorescent imaging agent, used in conjunction with a catheter-based NIR fluorescence imaging system may provide powerful tool to detect thrombus prone stents. Methods: A NIRF conjugate of tirofiban (Tf), a clinical IIb/IIIa antagonist, was synthesized via the chemical modification of the sulfonamide fragment of the molecule with a benzoic acid moiety and subsequent addition of the PEG-modified fluorophore, CyAl5.5 (ex/em 675/695nm). The efficacy of the conjugate was validated in vivo in the FeCl 3 -induced model of femoral thrombosis, and compared to the free dye or blocking with the parent drug Tf. After injection, serial intravital fluorescence microscopy (IVFM) was carried out for one hour, followed by histological examination of binding. Results: A NIR fluorescent conjugate of Tf was successfully synthesized via an optimized multi-step synthesis, with the identity and purity of the agent fully characterized after the final HPLC-based purification. IVFM characterization of conjugate efficacy showed an increase in NIRF signal in the thrombus over the initial 30 minutes, followed by a slow decrease until the endpoint of the experiment (1 h). The NIRF signal was 92% ablated by preinjection of excess Tf. Free dye did not display any localization to the thrombus. Histological analysis showed significant accumulation within the thrombus that co-localized with GPIIb/IIIa expression. Conclusions: A novel NIR fluorescent Tf conjugate has been developed that specifically binds to GPIIb/IIIa, and could be used for the detection of activated platelets in experimental thrombi in vivo . This novel agent should permit assessment of GPIIb/IIIa activation in a broad range of biological processes and may also aid in the detection of thrombosis-prone stents. |
| Databáze: | OpenAIRE |
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