title: Non-invasive near-infrared fluorescence imaging of the neutrophil response in a mouse model of transient cerebral ischaemia.
abstract: Near-infrared fluorescence (NIRF) imaging enables non-invasive monitoring of molecular and cellular processes in live animals. Here we demonstrate the suitability of NIRF imaging to investigate the neutrophil response in the brain after transient middle cerebral artery occlusion (tMCAO). We established procedures for ex vivo fluorescent labelling of neutrophils without affecting their activation status. Adoptive transfer of labelled neutrophils in C57BL/6 mice before surgery resulted in higher fluorescence intensities over the ischaemic hemisphere in tMCAO mice with NIRF imaging when compared with controls, corroborated by ex vivo detection of labelled neutrophils using fluorescence microscopy. NIRF imaging showed that neutrophils started to accumulate immediately after tMCAO, peaking at 18 h, and were still visible until 48 h after reperfusion. Our data revealed accumulation of neutrophils also in extracranial tissue, indicating damage in the external carotid artery territory in the tMCAO model. Antibody-mediated inhibition of α4-integrins did reduce fluorescence signals at 18 and 24, but not at 48 h after reperfusion, compared with control treatment animals. Antibody treatment reduced cerebral lesion volumes by 19%. In conclusion, the non-invasive nature of NIRF imaging allows studying the dynamics of neutrophil recruitment and its modulation by targeted interventions in the mouse brain after transient experimental cerebral ischaemia.
authors: 1 Institute for Biomedical Engineering, ETH & University of Zurich, Zurich, Switzerland.|2 Neuroscience Center Zurich, University of Zurich and ETH Zurich, Switzerland.
authors: Markus
authors: M
authors: Vaas
authors: 3 Theodor Kocher Institute, University of Bern, Bern, Switzerland.
authors: Gaby
authors: G
authors: Enzmann
authors: 3 Theodor Kocher Institute, University of Bern, Bern, Switzerland.
authors: Therese
authors: T
authors: Perinat
authors: 4 Division of Immunology, University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland.
authors: Ulrich
authors: U
authors: Siler
authors: 4 Division of Immunology, University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland.
authors: Janine
authors: J
authors: Reichenbach
authors: 5 Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.
authors: Kai
authors: K
authors: Licha
authors: 6 Institute of Veterinary Pathology, University of Zurich, Zürich, Switzerland.
authors: Anja
authors: A
authors: Kipar
authors: 1 Institute for Biomedical Engineering, ETH & University of Zurich, Zurich, Switzerland.|2 Neuroscience Center Zurich, University of Zurich and ETH Zurich, Switzerland.|7 Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
authors: Markus
authors: M
authors: Rudin
authors: 3 Theodor Kocher Institute, University of Bern, Bern, Switzerland.
authors: Britta
authors: B
authors: Engelhardt
authors: 1 Institute for Biomedical Engineering, ETH & University of Zurich, Zurich, Switzerland.|2 Neuroscience Center Zurich, University of Zurich and ETH Zurich, Switzerland.
authors: Jan
authors: J
authors: Klohs
mesh_terms: D000818:Animals; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000276:immunology; D002342:Carotid Artery, External / Q000000981:diagnostic imaging* / Q000276:immunology; D004195:Disease Models, Animal; D002546:Ischemic Attack, Transient / Q000000981:diagnostic imaging* / Q000276:immunology; D008297:Male; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D008991:Monitoring, Physiologic / Q000379:methods*; D020556:Neutrophil Infiltration; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
keywords: Cerebral ischaemia; external carotid artery; middle cerebral artery occlusion; mouse; near-infrared fluorescence imaging; neutrophils