title: Certain types of iron oxide nanoparticles are not suited to passively target inflammatory cells that infiltrate the brain in response to stroke.
abstract: Intravenous administration of iron oxide nanoparticles during the acute stage of experimental stroke can produce signal intensity changes in the ischemic region. This has been attributed, albeit controversially, to the infiltration of iron-laden blood-borne macrophages. The properties of nanoparticles that render them most suitable for phagocytosis is a matter of debate, as is the most relevant timepoint for administration. Both of these questions are examined in the present study. Imaging experiments were performed in mice with 30 minutes of middle cerebral artery occlusion (MCAO). Iron oxide nanoparticles with different charges and sizes were used, and mice received 300 μmol Fe/kg intravenously: either superparamagnetic iron oxide nanoparticles (SPIOs), ultrasmall SPIOs, or very small SPIOs. The particles were administered 7 days before MCAO, at the time of reperfusion, or 72 hours after MCAO. Interestingly, there was no observable signal change in the ischemic brains that could be attributed to iron. Furthermore, no Prussian blue-positive cells were found in the brains or blood leukocytes, despite intense staining in the livers and spleens. This implies that the nanoparticles selected for this study are not phagocytosed by blood-borne leukocytes and do not enter the ischemic mouse brain.
authors: Department of Experimental Neurology, Center for Stroke Research Berlin, Charité University Medicine, Berlin, Germany.
authors: Christoph
authors: C
authors: Harms
authors: Anna Lena
authors: AL
authors: Datwyler
authors: Frank
authors: F
authors: Wiekhorst
authors: Lutz
authors: L
authors: Trahms
authors: Randall
authors: R
authors: Lindquist
authors: Eyk
authors: E
authors: Schellenberger
authors: Susanne
authors: S
authors: Mueller
authors: Gunnar
authors: G
authors: Schütz
authors: Farnoosh
authors: F
authors: Roohi
authors: Andreas
authors: A
authors: Ide
authors: Martina
authors: M
authors: Füchtemeier
authors: Karen
authors: K
authors: Gertz
authors: Golo
authors: G
authors: Kronenberg
authors: Ulrike
authors: U
authors: Harms
authors: Matthias
authors: M
authors: Endres
authors: Ulrich
authors: U
authors: Dirnagl
authors: Tracy D
authors: TD
authors: Farr
mesh_terms: D000818:Animals; D001921:Brain / Q000098:blood supply* / Q000473:pathology*; D003287:Contrast Media / Q000737:chemistry; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology*; D007962:Leukocytes / Q000166:cytology / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000737:chemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010316:Particle Size; D010587:Phagocytosis
chemical_list: D003287:Contrast Media; D058185:Magnetite Nanoparticles