Adipose-derived stem cell exosomes ameliorate traumatic brain injury through the NLRP3 signaling pathway

The exosomes of mesenchymal stem cells have immunoregulatory properties and can effectively mitigate secondary neuroinflammation due to traumatic brain injury (TBI). In this study, we found that adipose-derived stem cell exosomes (ADSCs-Exo) could reduce the inflammatory response after traumatic brain injury by reducing NLRP3 inflammasome secretion by microglial. ADSCs-Exo were monitored by Western blot and electron microscopy. An in-vitro lipopolysaccharide (LPS)-caused primary microglia model and a TBI rat model were constructed. Functional recovery was examined using the modified neurological severity score and foot fault tests. Inflammasome inactivation in LPS-stimulated microglial, ADSCs-Exo can reduce the secretion of interleukin (IL)-1β, IL-6 and tumor necrosis factor α. Compared with PBS-processed controls, the sensorimotor functional recovery was significantly improved by exosome treatment after injury at 14-35 days. Additionally, NLRP3 inflammasome was stimulated within 24 h after TBI. ADSCs-Exo application led to remarkable down-expression of NLRP3 and caspase-1. ADSCs-Exo can ameliorate LPS-induced inflammatory activation by reducing microglial pro-inflammatory cytokines. Moreover, the neuroprotective effect of ADSCs-Exo may be partially attributed to the inhibition thereof on the formation of NLRP3-mediated inflammasome. Such findings imply a potential function of ADSCs-Exo in treating TBI.