Delivery Of Drug Targeting To Tumor In Vivo By Exosomes Derived From Reticulocyte

In this thesis, exosomes derived from reticulocyte were investigated as a carrierfor delivery of hydrophobic drug targeting to tumor in vivo. Exosomes were separatedfrom serum of rats with transferrin coupled superparamagnetic nanoparticles MNPs.The obtained MNPs-Tf-exosome complexes were used to loading and sustainedrelease hydrophobic chemotherapeutant doxorubin （DOX）, and the biologicalbehavior of drug-loaded MNPs-Tf-exosome was studied in vitro and in vivo. Theresearch solves two problems the difficulty in separation of exosomes and thetargeting delivery of hrdrophobic drug by exosome.First, Fe₃O₄MNPs decorated with transferrin were incubated with serum of ratsand the exosomes secreted by reticulocyte were separated and purified by magneticseparation based on the expression of transferrin receptor on these exosomes. Themorphologies of MNPs-Tf-exosome complexes were characterizated by DynamicLight Scattering （DLS） and Transmission Electron Microscopy （TEM）, and theresults showed that the Tf-MNPs conjugated with exosomes and the complexespossess sizes from70⁸0nm, which is suitable for the delivery drug in vivo.Second, the existence of hydrophobic domain in exosomes was demonstrated byfluorescence analysis using Nile Red as fluorescence probes. Then DOX wereencapsulated through incubation with MNPs-Tf-exosome complexes, and thereleasing behavior of DOX was studied on pH5.0and7.2respectively. A sustainedrelease profile were found for the DOX release, and the release rate increased whenthe pH value of medium decreased from7.2to5.0, suggesting MNPs-Tf-exosomescould be an suitable carrier for delivery of DOX to tumor.Third, the uptake of MNPs-Tf-exosome complexes by tumor cells was studied byconfocal imaging and flow cytometry, and the biodistribution of MNPs-Tf-exosomecomplexes after intravenous injection was investigated via optical in vivo imaging andthe observation of tissue section by confocal microscopy. The results indicated thatMNPs-Tf-exosomes could efficiently be phagocytosed by cells by means ofendocytosis mediated by clathrin. Naked exosomes didn’t have the ability of tumortargeting, but MNPs-Tf-exosomes could accumulate on tumor site under magneticfield.