Granulocyte-Macrophage Colony-Stimulating Factor Enhances Leptomeningeal Collateral Growth Induced by Common Carotid Artery Occlusion

Background and Purpose— Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been reported to accelerate collateral growth (arteriogenesis) at the circle of Willis in rat brain. However, the effect of GM-CSF on leptomeningeal collateral growth has not been established. We examined the effect of unilateral common carotid artery (CCA) occlusion and GM-CSF treatment on leptomeningeal collateral growth in mice. Methods— Adult mice were subjected to unilateral CCA occlusion or sham surgery followed by an alternate-day regimen of GM-CSF (20 μg/kg) or saline injection. On day 7, latex perfusion was performed in 1 set of mice to visualize the leptomeningeal vessels, and the number of Mac-2+ monocytes/macrophages on the dorsal surface of the brain was counted. In another set of mice, on day 7, permanent ipsilateral middle cerebral artery (MCA) occlusion was performed, and infarct volume was measured. Results— Leptomeningeal collateral growth was observed after CCA occlusion, and that was enhanced by GM-CS...