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Rychak JJ, Li B, Acton ST, Leppänen A, Cummings RD, Ley K, Klibanov AL. Selectin Ligands Promote Ultrasound Contrast Agent Adhesion under Shear Flow. Mol Pharm 2006; 3:516-24. [PMID: 17009850 DOI: 10.1021/mp0600541] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Contrast-enhanced ultrasound imaging has shown promise in the field of molecular imaging. This technique relies upon the adhesion of ultrasound contrast agent (UCA) to targeted molecular markers of disease. This is accomplished by coating the surface of the contrast agent with a ligand that specifically binds to the intended molecular marker. Most UCA particles remain in the blood space, and their retention is influenced by the forces imposed by blood flow. For a UCA bound to a molecular target on the vascular endothelium, blood flow imposes a dislodging force that counteracts retention. Additionally, contrast agent adhesion to the molecular marker requires rapid binding kinetics, especially in rapid blood flow. The ability of a ligand:target bond complex to mediate fast adhesion and withstand dislodging force is necessary for efficient ultrasound-based molecular imaging. In the current study, we describe a flow-based adhesion assay which, combined with a novel automated tracking algorithm, enables quick determination of the ability of a targeting ligand to mediate effective contrast agent adhesion. This system was used to explore the adhesion of UCA targeted to the proinflammatory endothelial protein P-selectin via four targeting ligands, which revealed several interesting adhesive behaviors. Contrast agents targeted with glycoconjugate ligands modeled on P-selectin glycoprotein ligand 1 exhibited primarily unstable or transient adhesion, while UCA targeted with an anti-P-selectin monoclonal antibody exhibited primarily firm adhesion, although the efficiency with which these agents were recruited to the target surface was relatively low.
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Affiliation(s)
- J J Rychak
- University of Virginia Department of Biomedical Engineering, Charlottesville, Virginia 22908-0158, USA
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Klibanov AL, Rychak JJ, Yang WC, Alikhani S, Li B, Acton S, Lindner JR, Ley K, Kaul S. Targeted ultrasound contrast agent for molecular imaging of inflammation in high-shear flow. Contrast Media Mol Imaging 2006; 1:259-66. [PMID: 17191766 DOI: 10.1002/cmmi.113] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Targeted ultrasound contrast materials (gas-filled microbubbles carrying ligands to endothelial selectins or integrins) have been investigated as potential molecular imaging agents. Such microbubbles normally exhibit good targeting capability at the slower flow conditions. However, in the conditions of vigorous flow, binding may be limited. Here, we describe a microbubble capable of efficient binding to targets both in slow and fast flow (exceeding 4 dyne/cm(2) wall shear stress) using a clustered polymeric form of the fast-binding selectin ligand sialyl Lewis(X). Microbubbles were prepared from decafluorobutane gas and stabilized with a monolayer of phosphatidylcholine, PEG stearate and biotin-PEG-lipid. Biotinylated PSLe(x) (sialyl Lewis(X) polyacrylamide) or biotinylated anti-P-selectin antibody (RB40.34) was attached to microbubbles via a streptavidin bridge. In a parallel plate flow chamber targeted adhesion model, PSLe(x) bubbles demonstrated specific adhesion, retention and slow rolling on P-selectin-coated plates. Efficiency of firm targeted adhesion to a P-selectin surface (140 molecules/microm(2)) was comparable for antibody-carrying bubbles and PSLe(x)-targeted bubbles at 0.68 dyne/cm(2) shear stress. At fast flow (4.45 dyne/cm(2)), PSLe(x)-targeted bubbles maintained their ability to bind, while antibody-mediated targeting dropped more than 20-fold. At lower surface density of P-selectin (7 molecules/microm(2)), targeting via PSLe(x) was more efficient than via antibody under all the flow conditions tested. Negative control casein-coated plates did not retain bubbles in the range of flow conditions studied. To confirm echogenicity, targeted PSLe(x)-bubbles were visualized on P-selectin-coated polystyrene plates by ultrasound imaging with a clinical scanner operated in pulse inversion mode; control plates lacking targeted bubbles did not show significant acoustic backscatter. In vivo, in a murine model of inflammation in the femoral vein setting, targeting efficacy of intravenously administered PSLe(x)-microbubbles was comparable with targeting mediated by anti-P-selectin antibody, and significantly exceeded the accumulation of non-targeted control bubbles. In the inflamed femoral artery setting, PSLe(x)-mediated microbubble targeting was superior to antibody-mediated targeting.
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Affiliation(s)
- A L Klibanov
- University of Virginia, Charlottesville, VA 22908-0158, USA.
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Lahoutte T, Vanhove C, Caveliers V, Defrise M, Everaert H, Bossuyt A, Franken PR, Schäfers KP, Kriens M, Barnard C, Schober O, Schäfers M, Kopka K, Wagner S, Law MP, Riemann B, Pike VW, Herrero P, Dence CS, Kisrieva-Ware Z, Eisenbeis P, Welch MJ, Gropler RJ, Bucerius J, Joe AY, Schmaliohann J, Gündisch D, Reinhardt MJ, Biersack HJ, Wüllner U, Ranney DF, Peshock RM, McDonald GG, Slomka PJ, deKemp RA, Beanlands RSB, Nishina H, Abidov A, Berman DS, Germano G, Riou LM, Goode AR, Hatada K, Ruiz M, Lima R, Harris TD, Beller GA, Glover DK, Kim H, Miceli MH, Delbeke D, Bhargava P, Jackson LBJ, Walker RC, Anaissie E, Alavi A, Hanrahan SM, Janabi M, Taylor SE, Rychak JJ, Klibanov AL, Leppanen A, Cummings RD, Ley K, Rychak JJ, Klibanov AL, Hossack J, Dence CS, Herrero P, Gropler RJ, Welch MJ, Veress AI, Feng B, Yang Y, Weiss JA, Huesman RH, Gullberg GT, Sharp TL, Herrero P, Englebach JA, Fettig NM, Gropler RJ, Welch MJ, Dobrucki LW, Hua J, Bourke BN, Sadeghi MM, Cavaliere P, Mendizabal M, VanRoyen N, Buschmann IR, Sinusas AJ, Sadeghi MM, Zhang J, Fassaei HR, Krassilnikova S, Esmailzadeh L, Gharaei AA, Kooshkabadi A, Edwards DS, Harris TD, Yalamanchili P, Sinusas AJ, Zaret BL, Bender JR, Epstein FH, Gilson WD, Sureau FC, Yang Z, French BA, Lewis S, Lu XE, Tom EM, Felix MM, Gretton JE, Varghese RP, Wagner WR, Villanueva FS. Abstracts of Original Contributions Cardiovascular Molecular Imaging Symposium May 3–4, 2004 Bethesda, Maryland. J Nucl Cardiol 2004. [DOI: 10.1007/bf02972758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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