title: Specific E-selectin targeting with a superparamagnetic MRI contrast agent.
abstract: Targeting of the endothelial inflammatory adhesion molecule E-selectin by magnetic resonance imaging (MRI) was performed with a superparamagnetic contrast agent in the context of in vitro and in vivo models of inflammation. The specific contrast agent was obtained by grafting a synthetic mimetic of sialyl Lewis(x) (sLe(x)), a natural ligand of E-selectin expressed on leukocytes, on the dextran coating of ultrasmall particles of iron oxide (USPIO). This new contrast agent, called USPIO-g-sLe(x), was tested, in vitro, on cultured human umbilical vein endothelial cells (HUVECs) stimulated to express inflammatory adhesion molecules, and in vivo, on a mouse model of hepatitis. In vitro, HUVECs were stimulated with the pro-inflammatory cytokine tumor necrosis factor alpha (TNF-alpha) and were then incubated with USPIO-g-sLe(x) or ungrafted USPIO. In vivo, hepatitis was induced on NMRI mice by injection of concanavalin A (Con A). USPIO-g-sLe(x) and ungrafted USPIO were injected intravenously. In vitro results showed an extensive retention of USPIO-g-sLe(x) on TNF-alpha stimulated HUVECs. Image intensity and R(2) measurements performed on T(2)-weighted MR images demonstrated a significantly higher binding of USPIO-g-sLe(x) on stimulated HUVECs. In vivo, USPIO are known to pass through the fenestrae of the liver and to be captured by Kupffer cells, inducing a loss of signal intensity on T(2)-weighted MR images. Unexpectedly, when injected to Con A-treated mice, USPIO-g-sLe(x) induced a significantly lower attenuation of liver signal intensity than USPIO or USPIO-g-sLe(x) injected to healthy mice, or USPIO injected to Con A-treated mice, suggesting that the specific contrast media is retained extracellularly by an interaction with E-selectin overexpressed on the vascular endothelium. Both in vitro and in vivo results therefore indicate that USPIO-g-sLe(x) is recognizing endothelial E-selectin. USPIO-g-sLe(x) is thus well suited for the MRI diagnosis of inflammation and for the in vitro evaluation of endothelial cells activation.
authors.affiliation: Department of General, Organic and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons-Hainaut, B-7000 Mons, Belgium.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Boutry
authors.forename: Sophie
authors.initials: S
authors.lastname: Laurent
authors.forename: Luce Vander
authors.initials: LV
authors.lastname: Elst
authors.forename: Robert N
authors.initials: RN
authors.lastname: Muller
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003287:Contrast Media / Q000737:chemistry; D019040:E-Selectin / Q000097:blood / Q000378:metabolism*; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D006505:Hepatitis / Q000175:diagnosis; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D053768:Metal Nanoparticles / Q000737:chemistry; D051379:Mice; D008815:Mice, Inbred Strains; D008954:Models, Biological; D009844:Oligosaccharides / Q000737:chemistry; D000080506:Sialyl Lewis X Antigen
chemical_list: D003287:Contrast Media; D019040:E-Selectin; D009844:Oligosaccharides; D000080506:Sialyl Lewis X Antigen; C427127:superparamagnetic blood pool agent; D052203:Ferrosoferric Oxide