Paramagnetic Phospholipid-Based Micelles Targeting VCAM-1 Receptors for MRI Visualization of Inflammation.
Inflammation is signaled by the overexpression of epitopes on the vascular endothelium that primarily aim at recruiting immune cells into the inflamed area. The intravascular localization of these biomarkers makes them suitable targets for the MRI visualization of inflammation. Phospholipid-based nanosystems appear excellent candidates in virtue of their good biocompatibility, ability to deliver a high number of imaging units at the target site, and for the easy functionalization with targeting vectors. In this work, phospholipid-based micelles (hydrodynamic diameter of 20 nm) loaded with the amphiphilic Gd(III)-complex Gd-DOTAMA(C18)2 were vectorized with a small peptide able to specifically bind VCAM-1 receptors. The micelles displayed a high longitudinal relaxivity (36.4 s(-1)mmolGd(-1) at 25 °C and 0.7 T). A (1)H- and (17)O-water relaxometry study indicated that the paramagnetic complex embedded in the nanoparticles adopted two isomeric conformations, likely reflecting the well-known square antiprismatic (SAP) and twisted square antiprismatic (TSAP) configurations typically observed in DOTA-like lanthanide complexes. Interestingly, the TSAP structure, showing a much faster exchange rate for the water molecule coordinated to the metal ion, was the most abundant, thus explaining the high relaxivity of the micellar agent. The systemic administration of the micelles into a lipopolysaccharide-induced murine model of acute inflammation successfully demonstrated the ability of the targeting agents to detect the diseased area by T1 contrast enhanced MRI.
Molecular & Preclinical Imaging Centers, Department of Molecular Biotechnology and Health Sciences, University of Torino , Via Nizza 52, 10126-Torino, Italy.
Amerigo
A
Pagoto
Molecular & Preclinical Imaging Centers, Department of Molecular Biotechnology and Health Sciences, University of Torino , Via Nizza 52, 10126-Torino, Italy.
Rachele
R
Stefania
Molecular & Preclinical Imaging Centers, Department of Molecular Biotechnology and Health Sciences, University of Torino , Via Nizza 52, 10126-Torino, Italy.
Francesca
F
Garello
Molecular & Preclinical Imaging Centers, Department of Molecular Biotechnology and Health Sciences, University of Torino , Via Nizza 52, 10126-Torino, Italy.
Francesca
F
Arena
DISIT, Università del Piemonte Orientale "A. Avogadro", Via T. Michel 11, 15121 Alessandria, Italy.
Giuseppe
G
Digilio
Molecular & Preclinical Imaging Centers, Department of Molecular Biotechnology and Health Sciences, University of Torino , Via Nizza 52, 10126-Torino, Italy.
Silvio
S
Aime
Molecular & Preclinical Imaging Centers, Department of Molecular Biotechnology and Health Sciences, University of Torino , Via Nizza 52, 10126-Torino, Italy.
Enzo
E
Terreno
D000818:Animals; D007249:Inflammation / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D059346:Magnets / Q000737:chemistry*; D051379:Mice; D008823:Micelles; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000737:chemistry; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism*
D008070:Lipopolysaccharides; D008823:Micelles; D010743:Phospholipids; D019010:Vascular Cell Adhesion Molecule-1; D011092:Polyethylene Glycols; C000595210:polyethylene glycol 2000