Suivi par IRM de macrophages marqués et étude de la biotransformation cellulaire de l’agent de contraste

Abstract

Objectives To monitor by magnetic resonance imaging (MRI) intra-carotid injection of labeled macrophages in an animal model of stroke, and to characterize the cellular biotransformation of iron nanoparticles using transmission electron microscopy (TEM). Materials and methods Male Sprague-Dawley rats were subjected to one hour transient occlusion of middle cerebral artery (MCAO). Immediately after reperfusion, four million macrophages magnetically labeled with iron oxide nanoparticles (USPIO) were administered into the (ipsilateral) carotid artery and MRI monitoring was performed on D0 and D1. Finally, to study iron oxide nanoparticles biotransformation, a TEM study combining conventional and electron diffraction approaches was performed on spleen sections of mice injected with contrast agent. Results and discussion Animals injected with labeled cells show a large number of hypointense spots in the ischemic lesion with a widespread and persistent distribution. The TEM results on D0 and D40 show the same maghemite structure of iron oxide nanoparticles heart. Conclusion MRI combined with in vitro cell labeling allows noninvasive and longitudinal cell monitoring. The intra-arterial administration provides a large number of cells to the lesion site. Finally, TEM study shows untransformed iron oxide particles on D40.