BACKGROUND:Studies have exhibited that inhibiting apoptosis caused by endoplasmic reticulum stress can save part of nerve function.Epigallocatechin-3-gallate can inhibit endoplasmic reticulum stress,but it has poor bioavailability and is difficult to penetrate the blood-brain barrier.In combination with exosomes targeting spinal cord repair and high-potency drug loading,theoretically,the combination of the two can play a greater role in spinal cord protection. OBJECTIVE:To investigate the effects of epigallocatechin-3-gallate combined with bone marrow mesenchymal stem cell exosomes on endoplasmic reticulum stress and neurological function in rats with spinal cord ischemia/reperfusion injury. METHODS:Fifty SD male rats were randomly divided into sham surgery group,model group,epigallocatechin-3-gallate group,exosome group,and combined treatment group,with 10 rats in each group.The spinal cord ischemia/reperfusion injury model was made in the other four groups except for the sham surgery group.Local injection of physiological saline,exosomes,epigallocatechin-3-gallate,epigallocatechin-3-gallate + bone marrow mesenchymal stem cell exosomes was performed 2 hours after surgery through a caudal vein.Neurological function scores were performed on 7,14 and 28 days after spinal cord injury.14 days after spinal cord injury,hematoxylin-eosin staining,Nissl staining,and immunofluorescence staining of endoplasmic reticulum stress markers such as ATF6 and GADD153 were performed in the spinal cord tissues. RESULTS AND CONCLUSION:(1)Compared with the sham surgery group,neurological function scores of the model group,exosome group,epigallocatechin-3-gallate group and combined treatment group all decreased to different degrees.The neurological function score of combined treatment group was better than that of the epigallocatechin-3-gallate group,exosome group and model group 14 days after surgery(P<0.05).The neurological function score of the combined treatment group was better than that of the model group and epigallocatechin-3-gallate group 28 days after surgery(P<0.05).(2)Hematoxylin-eosin staining and Nissl staining displayed that the number of neurons in the model group decreased,with a large number of cavity necrosis and scar hyperplasia in the spinal cord injury area.The number of neurons and peripheral cavity necrosis improved to varying degrees in the epigallocatechin-3-gallate group,exosome group,and combined treatment group,with the most significant improvement in the combined treatment group.(3)The expression of endoplasmic reticulum stress-related proteins ATF6 and GADD153:14 days postoperatively,the expression of GADD153 in the combined treatment group was lower than that in the model group and epigallocatechin-3-gallate group(P<0.05),and the expression of ATF6 in the combined treatment group was lower than that in the model group,exosome group,and epigallocatechin-3-gallate group(P<0.05).(4)These findings confirm that epigallocatechin-3-gallate combined with bone marrow mesenchymal stem cell exosome can enhance the neurological function in rats with spinal cord ischemia/reperfusionn injury,which may be associated with the inhibition of the expression of endoplasmic reticulum stress-related proteins ATF6 and GADD153.