Transmission electron microscopy, qNano® particles analyzer, and Western blotting were employed to determine the morphology and CCR2 expression of ExoCtrl or ExoCCR2. 
Transmission electron microscopy
Transmission electron microscopy, qNano® particles analyzer, and Western blotting were employed to determine the morphology and CCR2 expression of ExoCtrl or ExoCCR2.  Remyelination and oligodendrogenesis were analyzed by Western blotting and immunofluorescence microscopy.  The infiltration and activation of hematogenous macrophages were analyzed by Western blotting and transwell migration analysis.



Western blotting
ELISA was used to study the binding capacity of exosomes to CC chemokine ligand 2 (CCL2) in vivo. 
ELISA
After the intravenous injection of ExoCtrl or ExoCCR2 into experimental rats, the effect of ExoCtrl and ExoCCR2 on PSCI was assessed by Morris water maze. 
Morris water maze
Remyelination and oligodendrogenesis were analyzed by Western blotting and immunofluorescence microscopy.  Although both ExoCCR2 and ExoCtrl showed beneficial effects on PSCI, oligodendrogenesis, remyelination, and microglia/macrophage polarization, ExoCCR2 exhibited a significantly superior beneficial effect.  CCR2 over-expression enhanced the therapeutic effects of exosomes on the experimental PSCI by promoting M2 microglia/macrophage polarization, enhancing oligodendrogenesis and remyelination. 
Remyelination
Remyelination and oligodendrogenesis were analyzed by Western blotting and immunofluorescence microscopy.  Although both ExoCCR2 and ExoCtrl showed beneficial effects on PSCI, oligodendrogenesis, remyelination, and microglia/macrophage polarization, ExoCCR2 exhibited a significantly superior beneficial effect.  CCR2 over-expression enhanced the therapeutic effects of exosomes on the experimental PSCI by promoting M2 microglia/macrophage polarization, enhancing oligodendrogenesis and remyelination. 
oligodendrogenesis
QRT-PCR and immunofluorescence microscopy were conducted to compare the microglia/macrophage polarization. 
QRT-PCR
Remyelination and oligodendrogenesis were analyzed by Western blotting and immunofluorescence microscopy.  QRT-PCR and immunofluorescence microscopy were conducted to compare the microglia/macrophage polarization. 
immunofluorescence microscopy
The infiltration and activation of hematogenous macrophages were analyzed by Western blotting and transwell migration analysis.



transwell migration analysis