Nasal Administration Of Exosome Derived From Adipose Mesenchymal Stem Cells For The Treatment Of Alzheimer’s Disease

Alzheimer’s disease（AD）is a serious chronic neurodegenerative disease and also the most common type of dementia.The pathogenesis of AD remains to be completely explained.Abnormal deposition ofβ-amyloid protein（Aβ）,hyperphosphorylation of tau protein,oxidative stress and inflammatory reaction are universally acknowledged to exert great effect on the progress of AD that caused neuronal damage and apoptosis,synaptic dysfunction.Apparently,the repair and protection of neurons is the core link for the improvement of cognitive function and plays a key role in the intervention of AD.Therefore,to investigate novel neuroprotection strategies is of great significance for the treatment of AD.Exosomes derived from mesenchymal stem cells have been proved to transfer many bioactive molecules including cytokines,grow factors and functional mi RNA molecules for target cells to reduce inflammation.Studies have found that exosomes derived from mesenchymal stem cells promoted repairment for damaged tissues and had many mi RNA molecules such as mi R-133b which noticed that exosome had the potential of neuroprotection effect.Therefore,we firstly hypothesized that exosomes derived from mesenchymal stem cells could reduce the progress of AD which is one kind of chronic neurodegenerative diseases through neuroprotective effects.Moreover,in order to overcome blood-brain barrier（BBB）and achieve efficient brain delivery,we delivered exosome through intranasal administration to study its neuroprotective effects and verify its functions on the treatment of AD.In this research,we study on the neuroprotective effect of exosome derived from human adipose mesenchymal stem cells（ADSCs）on AD.This article is divided into four parts:In the first part,we collected exosomes from ADSCs by classical differential centrifugation and ADSCs derived exosomes（EXO）was characterized by dynamic light scattering,transmission electron microscopy,nanoparticle tracking analysis,Coomassie bright blue staining,western blot and sucrose density gradient centrifugation.In the second part,the high brain delivery efficiency was verified by using ¹²⁵I-labeled EXO via intranasal administration.Most EXO were uptaken by neurons than microglia and astrocytes confirmed by the frozen sections of brain in AD mode mice.The transport pathways of EXO from nose to brain was investigated by immunofluorescence labeling of olfactory and submucosal nerves.It indicated that EXO in the submucosa were mostly uptaken by immature olfactory sensory neurons,might transport along nerve axons to the second nerve cell-mitral cells through glomerulus and send output to higher brain sections.In the third part,we proved EXO could protect neurons and reverse the cytotoxicity induced by Aβ_1-42oligomer and glutamic acid in vitro.In the fourth part,EXO was verified to improve the spatial learning and memory ability of AD mode mice by new object recognition and Y maze experiments.Historical results showed that EXO have the ability to improve the pathological state of neuron,promote the formation of newborn neurons in the DG region of hippocampus,increase the clearance of Aβplaques in hippocampus and cortex and decrease the number of activated microglia.Moreover,it has no obvious toxicity to the peripheral major organs.The purpose of this study is to provide a neuroprotective strategy for the treatment of chronic neurodegenerative disease by verifying the effects of exosomes derived from MSCs on AD.