In vivo imaging
The permeability of blood-brain barrier (BBB) was assessed with bovine serum albumin coupled with Cy5.5 (BSA-Cy5.5) as described before(Schmitz et al., 2014). The BSA-Cy5.5 (50 mg/kg) was injected by tail vein, and imaging was performed 6 h after injection. The images were acquired using a IVIS Spectrum CT Imaging System (PerkinElmer, Inc. USA) with Ex/Em=680/720 nm. Myelin imaging was performed with a near-infrared dye, 3,3-diethylthiatricarbocyanine iodide (DBT), that binds to myelin and can be used to evaluated demyelination(Wang et al., 2011). DBT dye (0.3 mg/kg) were administered to mice by intravenous injections in the tail vein. The fluorescence signals of the mouse myelin were acquired using a IVIS Spectrum CT Imaging System (PerkinElmer, Inc. USA) 5 min post-injection of DBT with Ex/Em=745/800 nm.