A new macromolecular paramagnetic MR contrast agent binds to activated human platelets

Fréderic Chaubet, Isabelle Bertholon, Jean Michel Serfaty, Ramin Bazeli, Hasan Alsaid, Martine Jandrot-Perrus, Charaf Zahir, Pascale Even, Laure Bachelet, Ziad Touat, Eric Lancelot, Claire Corot, Emmanuelle Canet-Soulas, Didier Letourneur

Research output: Contribution to journalArticlepeer-review

Abstract

A new functionalized macromolecular magnetic resonance (MR) contrast agent has been developed from a carboxymethyldextran-Gd(DOTA) devoid of biospecificity. The functionalized contrast agent was synthesized in order to mimic PSGL-1, the main ligand of P-selectin, a glycoprotein mainly expressed on the surface of activated platelets. The starting compound, CM1, was first carboxymethylated by monochloroacetic acid leading to a series of 10 derivatives varying in their carboxymethyl content. CM8 derivative, with a degree of substitution in carboxymethyl of 0.84, was chosen for subsequent fluorolabeling and sulfation to give CM8FS. CM8FS has an average number molecular weight of 27 000 ± 500 g/ mol, a hydrodynamic radius of 5.7 ± 0.2 nm and a high relaxivity (r1 = 11.2/mM (Gd)/s at 60 MHz). Flow cytometry experiments on whole human blood or on isolated platelets evidenced in vitro a preferential binding of CM8FS on TRAP-activated human platelets. Interestingly, CMSFS did not bind to other blood cells or to resting platelets. Pellets of TRAP-activated human platelets have also been imaged in tubes with a 1.5 T MR imager. A MR signal was observed for activated platelets incubated with CMSFS. Altogether, these in vitro results evidenced the recognition of activated human platelets by a fluorescent paramagnetic contrast agent grafted with carboxyl and sulfate groups. This biomimetic approach associated with the versatile macromolecular platform appears promising for the development of new contrast agents for molecular imaging of activated platelets in cardiovascular diseases such as atherosclerosis and aneurysms.

Original languageEnglish (US)
Pages (from-to)178-188
Number of pages11
JournalContrast Media and Molecular Imaging
Volume2
Issue number4
DOIs
StatePublished - Jul 2007
Externally publishedYes

Keywords

  • Activated platelets
  • Atherosclerosis
  • Contrast agent
  • Flow cytometry
  • Gadolinium
  • Magnetic resonance imaging

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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