Experimental Study On The Effect Of Exosomes Derived From HUVECs On Ischemic Stroke

BACKGROUND: Currently,ischemic stroke is the leading cause of adult disability worldwide.To date,the main treatment method of it is hyperacute thrombolysis,but the prognosis is mostly unsatisfactory.Therefore,it is crucial of effective treatment to promote tissue repair and functional reconstruction after stroke.It was reported that human umbilical vein endothelial cells could protect damaged neurons for reducing the apoptosis of damaged neurons and promoting the proliferation and differentiation of neural stem cells.However,there were few studies on human umbilical vein endothelial cell-derived exosomes in promoting angiogenesis,neurogenesis,and synaptic remodeling after stroke.OBJECTIVE: To explore whether exosomes derived from human umbilical vein endothelial cells can reduce infarct volume,promote angiogenesis and neurogenesis,and promote synaptic plasticity in the ischemic boundary zone,improve the neurological outcome after ischemic stroke.METHODS: Human umbilical vein endothelial cells were cultured,and exosomes secreted by human umbilical vein endothelial cells were isolated.The size and concentration of exosomes were detected by NTA;the morphology was observed with transmission electron microscope,and the surface protein markers was examined using western blot.Models of transient middle cerebral artery occlusion in mice(tMCAO)were prepared.In experimental group,30 ug of total protein(dissolved in 100 ul PBS)of exosomes was injected into the tail vein within 24 hours after tMCAO model prepared successfully and control group was injected with the same amount of PBS solution.mNSS scores of mice were performed after ischemic stroke on days 1,3,7,14,and 28,respectively.The mice were sacrificed at 28 days after surgery.The infract volume was observed by cresyl-violet staining.Angiogenesis in the ischemic boundary zone was detected with CD31/BrdU immunofluorescence staining,neurogenesis was examed with DCX/ BrdU and NeuN/BrdU immunofluorescence staining,and the expression of synaptophysin and PSD-95 was assayed by Western blot to detect synaptic plasticity.RESULT: 1.NTA displayed that the particles size of exosomes derived from HUVECs ranged from 30 to 100 nm.The exosomes appeard circular under electron microscope.Western blot showed that exosome surface protein markers including CD9,CD63 and CD81 were positive.2.The infarct volume of HUVECs-exo treatment group were significantly reduced compared to the PBS group.3.Exosomes derived from HUVECs can promote angiogenesis,neurogenesis,and synaptic plasticity in the ischemic boundary zone and improve the neurological outcome.CONCLUSION: Exosomes derived from human umbilical vein endothelial cells can promote the recovery of ischemic stroke.