| BackgroundSpinal cord injury is a series of diseases caused by trauma,infection,tumor,metabolic abnormality,spinal stenosis,vascular injury and other causes of nerve cell death and scarring,resulting in neuronal dysfunction or loss.It can cause exercise,sensation,sphincter and autonomic dysfunction,and even lifelong disability and even death.Globally,the estimated number of SCI patients is approximately 2.5 million,and more than 130,000 new injuries are reported each year.In SCI cases,trauma-related injuries are most common,especially among young people between the ages of 15 and 29.Road traffic accidents and accidental falls in the elderly(> 65 years old).SCI severely degrades the quality of life of patients,and brings a heavy mental and economic negative to families and society.Although after years of research,the mechanism of spinal cord injury has been further explored,and a variety of treatment methods have been tried,but the effects of these treatments are not satisfactory,and the prognosis of patients with spinal cord injury is still poor.To this end,it is of great significance to study a new type of clinical treatment with good effects.In recent years,a large number of laboratory basic studies have shown that transplantation of bone marrow mesenchymal stem cells(BMSC)can be used as a potential treatment for traumatic spinal cord injury(SCI),however,bone marrow mesenchyme There are still many problems in stem cell transplantation therapy,such as the low rate of bone marrow mesenchymal stem cells moving to the core of spinal cord injury and the possibility of stem cell tumor formation,which limits the further clinical application of bone marrow mesenchymal stem cell transplantation.Recent studies have shown that the therapeutic effects of bone marrow mesenchymal stem cell transplantation are mainly dependent on its paracrine factors,and extracellular vesicles are considered to be the most valuable paracrine molecules.Therefore,this experiment aims to study the therapeutic effect and potential mechanism of extracellular vesicles of bone marrow mesenchymal stem cells on motor dysfunction after spinal cord injury.The blood-spinal cord barrier is one of the important structures in the nervous system.It can effectively reduce or even prevent harmful tissues from entering the central nervous system in the circulatory system,and is conducive to maintaining the stability of the internal environment.When the spinal cord injury of the spinal cord injury is destroyed,the endogenous immune inflammatory factor,the exogenous pathogen’s blood-spinal barrier pass rate increases,leading to exposure of the spinal cord tissue to a variety of harmful factors,aggravating spinal cord injury,therefore,the blood spinal cord barrier(Blood Spinal Cord Barrier,BSCB)abnormality is a key factor affecting the recovery of motor function after spinal cord injury.Pericytes are an important component of the blood-spinal cord barrier and play a key role in maintaining the structural integrity and normal physiological functions of the blood-spinal barrier.Objectives1.Using behavioral analysis to explore whether extracellular vesicles derived from bone marrow mesenchymal stem cells can promote motor function recovery after spinal cord injury.2.Further explore whether extracellular vesicles derived from bone marrow mesenchymal stem cells can improve the prognosis of the spinal cord barrier after spinal cord injury.Methods1.The morphology of BMSC-EV was observed by transmission electron microscopy.The BMSC-EV labeled protein was identified by Western Blot(WB).2.Immunofluorescence technique was used to trace PSK-26-labeled BMSC-EV to observe whether BMSC-EV could reach the lesion and was taken up by the pericytes.3.BBB score was used to analyze the behavior of rats.TUNEL staining and Nissl staining were used to analyze the death and survival of neurons.The scar hyperplasia of fibers was observed by tissue immunofluorescence double labeling technique.4.Evans blue staining and tissue immunofluorescence double labeling technique were used to observe the permeability and integrity of blood-spinal cord barrier.Results1.BMSC-EV into a double concave disc-like structure under transmission electron microscope,WB structure indicates that BMSC-EV expresses EV-specific protein: CD9,CD63,CD81.2.BMSC-EV tracer results show that BMSC-EV can successfully reach the damaged spinal cord and be taken up by the pericytes.3.In the behavioral analysis,from the 14 th day,the BBB scores of the hind limbs of the EV group were higher than those of the SCI group(P <0.05);TUNEL staining and Nissl staining showed that the EV group was compared with the SCI group.Cell death rate decreased(P <0.05)and the number of Nissl bodies increased(P <0.05).4.The results of Evans blue staining showed that the amount of dye exudation in EV group was significantly lower than that in SCI group(P <0.05).The double immunofluorescence of COL-1 and NF200 showed that the coverage of pericytes was significantly increased(P <0.05).ConclusionsBMSC-EV can significantly reduce brain cell death,promote neuronal survival and regeneration,and improve motor function of both hind limbs.Furthermore,our studies find that BMSC-EV can reduce blood-spinal barrier permeability and improve the rate of pericytes coverage of endothelial cells. |
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