These results indicate that large amounts of blood-derived CCR2(+) monocytes infiltrate the brain parenchyma at 6 h and day 1 following the blood–brain barrier disruption caused by ischemic stroke, and then the reparative process is initiated by locally secreted cytokine IL-4 and IL-13 in the ischemic milieu, thereby reprogramming the CCR2(+) monocytes to CX3CR1-overexpressing macrophages during days 3 and 7 after ischemic stroke. The gene discussed is CCR2; the disease is ischemic stroke.