title: Magnetic resonance imaging of inducible E-selectin expression in human endothelial cell culture.
abstract: Covalent conjugates of the cross-linked iron oxide nanoparticles (CLIO) and high-affinity (K(d)(app) = 8.5 nM) anti-human E-selectin (CD62E) F(ab')(2) fragments were prepared and tested in vitro to establish feasibility of endothelial proinflammatory marker magnetic resonance (MR) imaging. The conjugates were obtained by using thiol-disulfide exchange reaction between 3-(2-pyridyl)propionyl-CLIO and S-acetylthioacetate-modified F(ab')(2) fragments. The purified CLIO-F(ab')(2) conjugates (average hydrodynamic diameter 40.6 nm) were used in experiments with the live human endothelial umbilical vein cells (HUVEC). Cells treated with IL-1 beta expressed E-selectin and showed a 100-200 times higher binding of CLIO particles (83-104 ng iron/million cells) than control cells. The binding resulted in a high superparamagnetism of HUVEC with the transverse water proton relaxation time (T2) decrease to 30-40 ms in cell precipitates. Cells did not bind/internalize CLIO-F(ab')(2) conjugates prepared using a control fragment or nonconjugated iron oxide particles before or after treatment with IL-1 beta. MR imaging of cells showed a highly specific T2-weighted signal darkening associated with cells treated with IL-1 beta and incubated with anti-E selectin. Demonstration of MR imaging of E-selectin expression justifies further development of MR-targeted agents for monitoring tumor vascular endothelial proliferation, angiogenesis, and atherosclerosis.
authors.affiliation: Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Building 149, 13th Street, Charlestown, Massachusetts 02129, USA.
authors.forename: Hye Won
authors.initials: HW
authors.lastname: Kang
authors.forename: Lee
authors.initials: L
authors.lastname: Josephson
authors.forename: Alexander
authors.initials: A
authors.lastname: Petrovsky
authors.forename: Ralph
authors.initials: R
authors.lastname: Weissleder
authors.forename: Alexei
authors.initials: A
authors.lastname: Bogdanov
mesh_terms: D002478:Cells, Cultured; D003432:Cross-Linking Reagents; D019040:E-Selectin / Q000096:biosynthesis* / Q000235:genetics; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005290:Ferric Compounds; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry; D007202:Indicators and Reagents; D007375:Interleukin-1 / Q000494:pharmacology; D008279:Magnetic Resonance Imaging; D010316:Particle Size
chemical_list: D003432:Cross-Linking Reagents; D019040:E-Selectin; D005290:Ferric Compounds; D007140:Immunoglobulin Fab Fragments; D007202:Indicators and Reagents; D007375:Interleukin-1; C000499:ferric oxide