specific eselectin targeting with a superparamagnetic mri contrast agent targeting of the endothelial inflammatory adhesion molecule eselectin 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 lewisx slex a natural ligand of eselectin expressed on leukocytes on the dextran coating of ultrasmall particles of iron oxide uspio this new contrast agent called uspiogslex 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 proinflammatory cytokine tumor necrosis factor alpha tnfalpha and were then incubated with uspiogslex or ungrafted uspio in vivo hepatitis was induced on nmri mice by injection of concanavalin a con a uspiogslex and ungrafted uspio were injected intravenously in vitro results showed an extensive retention of uspiogslex on tnfalpha stimulated huvecs image intensity and r2 measurements performed on t2weighted mr images demonstrated a significantly higher binding of uspiogslex 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 t2weighted mr images unexpectedly when injected to con atreated mice uspiogslex induced a significantly lower attenuation of liver signal intensity than uspio or uspiogslex injected to healthy mice or uspio injected to con atreated mice suggesting that the specific contrast media is retained extracellularly by an interaction with eselectin overexpressed on the vascular endothelium both in vitro and in vivo results therefore indicate that uspiogslex is recognizing endothelial eselectin uspiogslex is thus well suited for the mri diagnosis of inflammation and for the in vitro evaluation of endothelial cells activation