Combined Chemical And Photodynamic Antiglioma Therapy Based On Peptides-mediated Targeting Pro-drug Micelle

Malignant glioma is one of the most aggressive and lethal brain tumors.Although various treatments were used in the clinical trials,such as surgery,radiotherapy,chemotherapy or combination therapy,the prognosis is still not optimistic.The existence of blood-brain barrier?BBB?and blood-?brain tumor?barrier?BBTB?impede chemotherapeutic drugs effectively delivered to glioma.It is one of the vital reasons that glioma is an incurable disease.At present,nano-scale drug delivery system is becoming an effective drug delivery method of glioma treatment.Though the tumor neovasculature presents large pores and high permeability,but the new blood vessels in brain tumor are not as leaky as other cancer.The barriers cannot be crossed simply relying on high permeability and retention effect?EPR?.Meanwhile,tumor cells are in oxidized environment and the concentration of glutathione?GSH?is usually several thousand times higher than those in normal cells,which provides convenience for the design of responsive drug delivery system.Therefore,it is essentially important to exploit novel nano-scale drug delivery system with precise targeting and deep tissue penetration properties for barin tumor therapy.To resolve the problem,we designed and constructed a redox responsive drug delivery system?CPT-PEG-iRGD?which use camptothecin?CPT?prodrug grafted with disulfide bond as the hydrophobic section,OH-PEG-N₃ as the hydrophilic section and iRGD cyclic peptide with a sequence of CendR?R/KXXR/K?as the targeted unit.The results of transmittance electron microscopy?TEM?,Fourier transform infrared spectroscopy?FTIR?,dynamic light scattering?DLS?,Zeta potential measurements,mass spectrometry,NMR spectrum,UV/Vis and fluorescence emission spectra analysis demonstrate that we successfully synthesized prodrugs polymer CPT-PEG-iRGD,and the polymer can self-assembly to form micelles with dimension of about 100nm in aqueous solution.Photosensitizer IR780 was loaded into micelles during the formation process,namely CPT-PEG-iRGD@IR780 drug delivery system.The results of in vitro drug release experiments showed that CPT-PEG-iRGD micelles could be triggered to release drugs in response to redox stimuli,and the amount of drug reached to 60%in high GSH concentration environment.CPT-PEG-iRGD@IR780 drug release system could effectively produce ROS in vitro.Theinvitroexperimentssuggestedthatgliomacellactivitywas time-dependent/dose-dependent/laser treatment dependent.The combined chemical and photodynamic therapy of CPT-PEG-iRGD@IR780 prodrug micelles had significant cancer-killing effect.Flow cytometry analysis and confocal laser scanning microscopy?CLSM?observations suggested that the CPT-PEG-iRGD@IR780 system could be endocytosed by U87 cells via targeting recognition,and subsequently release drugs to kill tumor cells.With laser treatment,CPT-PEG-iRGD@IR780 prodrug micelles produced a large amount of ROS to induce cell apoptosis efficiently.In vitro BBB,BBTB model and glioma spheroid penetration experiments demonstrated that the CPT-PEG-iRGD@IR780 micelles efficiently penetrated the BBB and BBTB model and be endocytosed by U87 in lower chamber.The CPT-PEG-iRGD@IR780 micelles could effectively penetrate into glioma spheroid and release drug.All above results indicated that the grating of cyclic peptides iRGD to prodrug micelles could significantly improve their penetration BBB and tumor targeting.