Research On CRGD Modified MPEG-PLGA-PLL Targeted Nanoparticle Drug Delivery System For Breast Cancer Therapy

Recent years, targeted therapy for tumor has become the new favourite in clinical studies. It can not only enhance the therapeutic efficiency, but also lower the side effects of drug for patient. Therefore, among the various tactics in curing cancer, the targeted therapy for tumor is the most promising approach. Delivery carrier has always been the focus concern in targeted therapy. In order to enhance the drug concentration of tumor and specificly kill tumor cells, we should find the delivery carrier which is specific to tumor cells and construct the targeted delivery system to deliver drug.The polymer material (mPEG-PLGA-PLL-cRGD) had been designed and synthesized in this paper. The targeted nanoparticle delivery system was prepared using the polymer material as the carrier. The biocompatibility of delivery system was assessed. Subsequently, its targeted efficiency and therapeutic effects to breast cancer-bearing animal models were studied.The major research results of this paper were listed as follows:The mPEG-PLGA-PLL-cRGD had been synthesized, and characterized by FTIR and NMR. Blank nanoparticles (mPEG-PLGA-PLL and mPEG-PLGA-PLL-cRGD NPs) and DHAQ-loaded nanoparticles (DHAQ-mPEG-PLGA-PLL and DHAQ-mPEG-PLGA-PLL-cRGD NPs) were prepared by the emulsion-evaporation method using the polymer material as the carrier and DHAQ as the model drug. Subsequently, detailed studies were conducted in the preparing process of nanoparticles. The optimized conditions were:material concentration-20 mg/mL, F68 concentration-0.5%, ultrasonic intensity-400 W, Vinner/Vouter-1:10. The average particle size of the prepared nanoparticles was about 180 nm, and the encapsulated efficieny was 85.3 %.Cell viability of blank nanoparticles and DHAQ-loaded nanopartilces were tested by MTT method. The experimental results demonstrated that the blank nanoparticles had a limited influence to MDA-MB-231 breast cancer cells viability and showed the neglectable cytotoxicity. DHAQ-loaded nanoparticles could effectively influence the cell viability. The hemolysis test result of blank nanoparticles showed the rate of hemolysis was less than 5% which suggested the naoparticles had a good compatibility.The distribution of the uptaked nanoparticles in the cells was observed by laser confocal microscope. The experimental results indicated that the nanoparticles were mainly located in the cytoplasm. A few of the NPs were located in the nucleolus.The drug concentration in MDA-MB-231 breast cancer cells was quantitated. The experimental results showed that DHAQ-mPEG-PLGA-PLL-cRGD NPs could better uptaked by the cells so as to significantly enhance the drug concentration comparing with DHAQ-mPEG-PLGA-PLL NPs.Rhodamine B (Rb) as a fluorescence probe was encapsulated in nanoparticles to research the nanoparticles uptaked access. The experimental results demonstrated that Rb-mPEG-PLGA-PLL-cRGD NPs were much easier in binding to MDA-MB-231 breast cancer cells than Rb-mPEG-PLGA-PLL NPs. Rb-mPEG-PLGA-PLL-cRGD NPs could effectively bind to MDA-MB-231 breast cancer cells by cRGD-mediated approach. Subsequently, Rb-mPEG-PLGA-PLL-cRGD NPs were internalized into the cells by caveolat-madiated endocytosis. The Rb-mPEG-PLGA-PLL NPs were directly internalized into the cells by caveolat-madiated endocytosis and clathrin-mediated endocytosis.At 2,12,24,48 h of post-injection, the targeted efficiency of Rb-mPEG-PLGA-PLL and Rb-mPEG-PLGA-PLL-cRGD NPs in MDA-MB-231 breast cancer-bearing mice were studied by in-vivo targeted fluorescence imaging system. The experimental results demonstrated that Rb-mPEG-PLGA-PLL-cRGD NPs had a more ideal circulating time and targeted efficiency in MDA-MB-231 breast cancer-bearing mice.At 2,12,24,48 h of post-injection, the biodistributon of drug were tested by high performance liquid chromatograph. By the prcise measurement for drug concentration, it was used to further quantify and testify the experimental results of in-vivo targeted fluorescence imaging. The experimental results indicated that the DHAQ-mPEG-PLGA-PLL-cRGD NPs could effectively up-regulate the drug concentration of tumor in MDA-MB-231 breast cancer-bearing mice comparing with DHAQ-mPEG-PLGA-PLL NPs. It was suggested the DHAQ-mPEG-PLGA-PLL-cRGD NPs had a more ideal targeted efficiency for tumor. The 36 days anti-tumor experimental results of the MDA-MB-231 breast cancer-bearing mice showed that DHAQ-mPEG-PLGA-PLL-cRGD NPs had a more ideal anti-tumor effects comparing with the DHAQ-mPEG-PLGA-PLL NPs. The tumor inhibitory rate of DHAQ, DHAQ-mPEG-PLGA-PLL and DHAQ-mPEG-PLGA-PLL-cRGD NPs were 9.09%,40.46% and 69.77%, respectively.The above research results demonstrated that the mPEG-PLGA-PLL-cRGD NPs delivery system is a potentially promising targeted delivery system.