PH-sensitive Peptide Modified Exosomes For Tumor Targeted Drug Delivery

Exosomes are vesicles with a diameter of 30-100 nm secreted by cells,and they are important vesicles for interaction between cells.Exosomes are biocompatibility,biosafety and high stability,and can be used as drug delivery vesicles for disease treatment.GALA peptide is a pH-responsive polypeptide composed of 30 amino acids.When the pH of the environment drops from neutral to weakly acidic,GALA peptides will change from random coils to alpha helixes,forming a transmembrane peptide pore on the cell membrane surface to promote membrane fusion.Hypoxic tumor cells are abnormally active in glycolysis,producing a large amount of lactic acid and carbonic acid metabolites and excreting,forming an acidic microenvironment(pH≤6.8).We constructed Exo-SAV which expressing streptavidin(SAV)outside to exosomes,considering the specific binding of SAV with biotin,biotin-modified GALA peptide will bind to form Exo-GALA.Exo-GALA can not only respond to hypoxic tumor microenvironment,but can also be loaded with chemotherapeutic drugs to achieve drug delivery.Method:We first designed and synthesized the recombinant DNA sequence of SAV,cloned it into an expression vector,and packaged it into a lentivirus to infect bone marrow mesenchyme stem cells(BMSC).Next,the expression of SAV in BMSC and its exosomes was identified by confocal microscopy,transmission electron microscope(TEM),Western blot,and nanoparticle size analyzer.Then,the chemotherapeutic drug paclitaxel(PTX)was loaded into Exo-SAV by ultrasound.We quantified PTX by high performance liquid chromatography(HPLC),the PTX release curve was determined,and the pharmacokinetics in mice was determined.Finally,hypoxic SCC-Ⅶ cells and hypoxic SCC-Ⅶ xenograft nude mouse models were used to verify the hypoxic targeting of Exo-GALA.The H&E staining assessed safety of Exo-GALA.Result and Conclusion:We successfully constructed BMSC-SAV and Exo-SAV.Exo-SAV expressed SAV and exosomal marker proteins CD63,Alix,HSP70,and the size is 30-100 nm.Exo-SAV was successfully loaded with PTX and quantified by HPLC.The pharmacokinetic parameters showed that exosomes as the carrier of PTX can reduce the clearance rate in the body and prolong the drug in Time in the body.In vitro an vivo results showed that compared with normoxia,hypoxic SCC-Ⅶ cells take up more Exo-GALA.In the nude mouse model of SCC-Ⅶ xenograft tumor,the targeting effect of Exo-GALA is better than that of the control group GALA,Exo/GALA,the main organ of H&E staining results showed that Exo-GALA is safe.In summary,the Exo-GALA can be used as a drug carrier targeting hypoxic tumor microenvironment.This is not only a structural upgrade after exosomal modification,but also a new targeted therapy for hypoxic tumor microenvironment.