A microglia e os macrófagos hematogênicos exercem um papel crucial na cascata patogenética que acompanha a isquemia cerebral, mas podem diferir funcionalmente considerando suas propriedades neuroprotetoras e citotóxicas. A distinção entre esses dois tipos celulares não era possível com a escassez de marcadores celulares .
Pesquisadores do Instituto de Pesquisa Neurológica Max-Planck, na Alemanha, fabricaram camundongos com medula óssea quimérica, transplantando medula óssea de um camundongo transgênico com proteína fluorescente verde (PFV) em recipientes irradiados. A isquemia cerebral focal transitória foi induzida com oclusão da artéria cerebral média (OACM) transitória por 30 minutos.
A microglia residente e os macrófagos infiltrados foram identificados por imuno-histoquímica e fluorescência da PFV após 1-28 dias.. Os macrófagos hematogênicos com PFV-positiva foram observados raramente no dia 2, alcançando picos no dia 7 e decaindo após isso. Em contraste, a microglia residente com PFV-negativa rapidamente foram ativadas no dia 1 após a OACM.
A grande maioria dos macrófagos na área infartada eram derivados da microglia local, revelando uma predominância remarcada dos mecanismos de defesa locais sobre as células imunes derivadas do sangue. Os pesquisadores concluíram que a PFV da medula óssea quimérica de camundongos é uma arma poderosa para futuras diferenciações da função da microglia local e dos macrófagos hematogênicos após a isquemia cerebral.
Microglial activation precedes and predominates over macrophage infiltration in transient focal cerebral ischemia: a study in green fluorescent protein transgenic bone marrow chimeric mice - Experimental Neurology
Experimental Neurology
Volume 183, Issue 1 , September 2003, Pages 25-33
doi:10.1016/S0014-4886(03)00082-7 
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Copyright © 2003 Elsevier Science (USA). All rights reserved.
Regular article
Microglial activation precedes and predominates over macrophage infiltration in transient focal cerebral ischemia: a study in green fluorescent protein transgenic bone marrow chimeric mice
Matthias Schillingb, Michael Besselmanna, Christine Leonhardb, Marcus Muellerb, E. Bernd Ringelsteinb and Reinhard Kiefer
, 
, b
a Max-Planck-Institut für Neurologische Forschung, Köln, Germany
b Department of Neurology, Universitätsklinikum Münster, Münster, Germany
Received 28 October 2002; revised 23 December 2002; accepted 21 January 2003. ; Available online 9 July 2003.
Abstract
Resident microglia and hematogenous macrophages play crucial roles in the pathogenetic cascade following cerebral ischemia but may functionally differ regarding neuroprotective and cytotoxic properties. Distinction between these cells has not been possible due to a lack of discriminating cellular markers. We generated bone marrow chimeric mice by transplanting bone marrow from green fluorescent protein (GFP) transgenic mice into irradiated wild-type recipients. Transient focal cerebral ischemia was induced by transient middle cerebral artery occlusion (MCAO) for 30 min. Resident microglia and infiltrating macrophages were identified by immunohistochemistry and GFP fluorescence after 1–28 days. The first blood-derived cells infiltrating the infarct area were seen on Day 1 and identified as granulocytes. Hematogenous GFP+ macrophages were rarely observed on Day 2, reached peak numbers on Day 7, and decreased thereafter. In contrast, resident GFP- microglial cells rapidly became activated already on Day 1 after MCAO. Even on Days 4 and 7, most macrophage-like cells remained GFP-, indicating their derivation from resident microglia. Hematogenous macrophages were able to acquire a ramified morphology indistinguishable from resident microglia while microglial cells could develop into a phagocytic phenotype indistinguishable from infiltrating macrophages. The vast majority of macrophages in the infarct area are derived from local microglia, revealing a remarkable predominance of local defense mechanisms over immune cells arriving from the blood. GFP bone marrow chimeric mice are a powerful tool to further differentiate the function of resident microglia and hematogenous macrophages following cerebral ischemia.
Author Keywords: Microglia; Macrophage; Cerebral ischemia; Inflammation; Bone marrow; Transplantation; Green fluorescent protein
Corresponding author. Dept. of Neurology, Universitätsklinikum Münster, Albert-Schweitzer-Str. 33, D-48129 , Münster, , Germany. Fax: +49-251-83-48181.
