Mesenchymal stem cells (MSCs) derived exosomes have been shown to have 
protective effects on the kidney in ischemia/reperfusion-induced renal injury. 
However, the key components in the exosomes and their potential mechanisms for 
the kidney protective effects are not well understood. In our current study, we 
focused on the abundant proteins in exosomes derived from MSCs (MSC-exo) and 
found that the C-C motif chemokine receptor-2 (CCR2) was expressed on MSC-exo 
with a high ability to bind to its ligand CCL2. We also proved that CCR2 
high-expressed MSC-exo could reduce the concentration of free CCL2 and suppress 
its functions to recruit or activate macrophage. Further, knockdown of CCR2 
expression on the MSC-exo greatly abolished these effects. Finally, we also 
found that CCR2 knockdown impaired the protective effects of MSC-exo for the 
renal ischemia/reperfusion injury in mouse. The results indicate that CCR2 
expressed on MSC-exo may play a key role in inflammation regulation and renal 
injury repair by acting as a decoy to suppress CCL2 activity. Our study may cast 
new light on understanding the functions of the MSC-exo and these receptor 
proteins expressed on exosomes.