Bioengineered Exosomes Bearing Adenosine A2a Receptor for the Treatment of Neuroinflammation

Abstract

Brain injury is a very common but severe complication in preterm birth, and neuroinflammation caused by activated microglial cells is the main contributor. The interaction between extracellular adenosine and the adenosine A2a receptor (ADORA2A) is of great significance in microglial cell activation. Here we designed and generated ADORA2A-loaded exosomes and investigated their inhibitory effect on microglial activation in vitro. A construct expressing ADORA2A fused to an exosome marker CD9 was designed and expressed in rat NRK cells. Purified ADORA2A-CD9 exosomes were first characterized and then their ability on inhibition of microglial cell activation was investigated on an in vitro ibotenate-induced microglial cell activation model. The cytotoxicity of ADORA2A-CD9 exosomes was determined by LDH assay. Our data showed that ADORA2A was actively loaded onto exosomes by fusing it to the exosome marker CD9. ADROA2A-CD9 exosomes inhibited ibotenate-induced microglial cell activation, as evidenced by the reduction of inflammatory cytokines including TNF-α, IL-6 and IL-1β. Furthermore, ADORA2A-CD9 exosomes inhibited microglial cell activation through competitively binding to extracellular adenosine. Very low cytotoxicity of ADORA2A-CD9 exosomes was observed. Collectively, our findings reveal that ADORA2A-CD9 exosomes inhibit microglial cell activation and subsequent neuroinflammation, representing a promising treatment for preterm brain injury.