Study On Functional Short Peptide Modified Exosomes For The Treatment Of Glioma

The existence of the Blood Brain Barrier(BBB)is one of the difficulties in the treatment of glioma.As a new type of carrier,Exosomes(EXOs)are natural,stable,and can pass through physiological and pathological barriers.Features have become a hot spot in the research of new drug delivery systems.However,during the transportation of drug-loaded exosomes in the body,due to the concentration difference,the drug is released in advance,which has become one of the main obstacles to clinical transformation.To solve this problem,this research originally designed a functional short peptide with cross-linking behavior,embedded in the exosomal phospholipid bilayer,to improve the stability of the encapsulated drug in the body,and the short peptide responsively breaks after reaching the tumor,Release drugs and exert therapeutic effects.details as follows:Different cell-derived exosomes have different functions.We first screened lung cancer cells(LLC,A549),microglia(BV2)and glioma cells(U87-MG)from lung cancer cells(LLC,A549),using their ability to span BBB as evaluation indicators.Exosomes,the results showed that the ability of exosomes to pass the brain was better than liposomes;at 240 min,the amount of BV2-EXOs passing through the BBB model was 2.2 times that of liposomes,and the efficiency of BV2-EXOs passing the brain was higher.In vivo imaging was further used to verify its in vivo transport behavior and brain targeting,and BV2 cell-derived exosomes were selected for follow-up research.Using Dynasore inhibitors to inhibit the endocytosis of brain endothelial cells to study the brain-passing mechanism of BV2-EXOs,the results showed that the exosomes passing rate decreased from 80%to 42%at 240 min,indicating that endothelial cells exert endocytosis is exosomes One of the main mechanisms through the BBB.Next,sulfhydryl was selected as the cross-linking group,and a series of amphiphilic short peptides containing cysteine(Cys,C)were designed.The solid phase synthesis method is used to synthesize and confirm the molecular weight and purity.BV2-EXOs was loaded with DOX and short peptide sequence through a mild co-incubation method,and then oxidized to form disulfide bonds.The iodide ion fluorescence quenching method was used to determine the positional relationship between the short peptide and the exosomal membrane,which proved that the short peptide was successfully embedded in the exosomal lipid membrane;the in vitro release experiment screened out the best functional short peptide Pep2,and investigated the relationship between the short peptide and the exosomal membrane.The best fusion ratio of exosomes.In addition,the reducing agent glutathione(GSH)was used to destroy the disulfide bond in advance before investigating the drug release behavior;the control peptide and exosomal fusion group was designed in the same way,and the in vitro release results of the two groups showed that the GSH treatment group and the control peptide group did not Slow down the effect of DOX release.The study on the in vivo transport behavior of short peptide fusion carrying adriamycin-containing exosomes(Pep2-EXOs-DOX)found that compared with the DOX group and EXOs-DOX group,the blood circulation time of the Pep2-EXOs-DOX group was longer and increased respectively 2.53 times and 1.56 times.At the same time,the distribution of Pep2-EXOs-DOX in the brain tissue was significantly better than that of the short peptide fusion doxorubicin liposome(Pep2-Lp-DOX)group.The targeting efficiency was 4.27 times that of the Pep2-Lp-DOX group,which reduced the amount of Pep2-EXOs-DOX in the heart and kidney tissues.Distribution,reducing toxic side effects.Finally,using BALB/c nude mice in situ inoculated with U87-MG-luc cells as a model,the tumor volume changes after different treatments were monitored by a small animal in vivo imager to evaluate the anti-tumor activity of Pep2-EXOs-DOX.The study found that the tumor volume was significantly reduced after Pep2-EXOs-DOX treatment,the survival time of tumor-bearing mice was significantly higher than that of other treatment groups,the body weight of mice did not change significantly,and no other obvious toxicity-related effects were observed,indicating that Pep2-EXOs-DOX has a certain degree of safety.In summary,the research explores a new strategy of functional short peptide modified drug-loaded exosomes for the treatment of in situ glioma,compares and analyzes the brain-passing ability of exosomes from different cell sources,and designs an innovative new delivery system that can reduce early drug leakage and achieve precise drug release,provides new research directions for the treatment of glioma.