MacGreen mice: a novel tool to investigate inflammation following experimental stroke

Siyi Chen, Laura Bennet and Ailsa L. McGregor

Background and Purpose: CSF-1R-EGFP (‘MacGreen’) transgenic mice carry an enhanced green fluorescent protein (EGFP) reporter gene in monocyte and macrophage populations. MacGreen mice have been used as a model system to investigate macrophage development and function. The current study investigated brain inflammation following experimental stroke.
Methods: MacGreen mice were subjected to transient middle cerebral artery occlusion and neurological deficit and ischemic damage compared to C57Bl/6j mice. EGFP expression was also characterized at 24h and 7 and 35 days post stroke in MacGreen mice.
Results: MacGreen mice show a comparable response to ischemia and progression of damage to C57Bl/6j mice. Inflammation was related to stroke severity at both acute (24h) time points and several weeks (35 days) after experimental stroke. The increased EGFP signal in the ipsilateral hemisphere post stroke was attributed to both increased cell density and increased cell size. EGFP positive cells co-labelled with the microglia/macrophage marker Iba1 and changes in the morphology of these cells from 24h to 7 and 35 days suggest temporal changes in the function of microglia/macrophages within ischemic regions.
Conclusion: MacGreen provide a clinically relevant platform in which to investigate the role of inflammation in the pathogenesis and recovery from stroke.