NOS2 and neuropathy: BMSCs-EXOs can also regulate the polarization of microglia/macrophages by down-regulating inducible nitric oxide synthase (iNOS) and up-regulating a cluster of differentiation (CD) 206 and arginase-1 to alleviate the early inflammatory response in TBI, reduce neuropathy, and improve neurobehavioral performance, such as the modified neurological severity score and rotary-rod test.