Schilling Matthias, Besselmann Michael, Leonhard Christine, Mueller Marcus, Ringelstein E Bernd, Kiefer Reinhard
Department of Neurology, Universitätsklinikum Münster, Münster, Germany.
Exp Neurol. 2003 Sep;183(1):25-33. doi: 10.1016/s0014-4886(03)00082-7.
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.
常驻小胶质细胞和血源性巨噬细胞在脑缺血后的发病机制级联反应中发挥着关键作用，但在神经保护和细胞毒性特性方面可能存在功能差异。由于缺乏区分性的细胞标志物，无法区分这些细胞。我们通过将绿色荧光蛋白（GFP）转基因小鼠的骨髓移植到经照射的野生型受体中，构建了骨髓嵌合小鼠。通过短暂大脑中动脉闭塞（MCAO）30分钟诱导短暂性局灶性脑缺血。在1 - 28天后，通过免疫组织化学和GFP荧光鉴定常驻小胶质细胞和浸润性巨噬细胞。在第1天可见第一批浸润梗死区域的血源性细胞，被鉴定为粒细胞。血源性GFP（+）巨噬细胞在第2天很少观察到，在第7天达到峰值，此后减少。相比之下，常驻GFP（-）小胶质细胞在MCAO后第1天就迅速被激活。即使在第4天和第7天，大多数巨噬细胞样细胞仍为GFP（-），表明它们源自常驻小胶质细胞。血源性巨噬细胞能够获得与常驻小胶质细胞难以区分的分支形态，而小胶质细胞能够发展成与浸润性巨噬细胞难以区分的吞噬表型。梗死区域的绝大多数巨噬细胞源自局部小胶质细胞，这表明局部防御机制相对于来自血液的免疫细胞具有显著优势。GFP骨髓嵌合小鼠是进一步区分脑缺血后常驻小胶质细胞和血源性巨噬细胞功能的有力工具。
