Experimental Studies Of Inhibitory Effects Of Paclitaxel Loaded Microspheres On Ovarian Tumor-Bearing Nude Mice

PART1. Preparation of paclitaxel-loaded PLGA (PTX-PLGA) microspheres and determination of their physical features in vitro.Objective:1. To prepare paclitaxel-loaded PLGA (PTX-PLGA) microspheres for contrast enhanced ultrasound imaging, with lactic acid/glycolic acid copolymer (poly (lactic-Co.-glycolic acid), PLGA) being the carrier.2. To detect physical features and drug-releasing characteristics of PTX-PLGA microspheres,and to determine their effects on ultrasound imaging for the tumor on the ovarian tumor-bearing mice and therapeutic effects.Methods:1. PLGA and PTX-PLGA microspheres were prepared by W/O/W double Emulsion/Evaporation technique and the injection of perfluoropropane gas.2. Morphology of these microspheres were observed by the scanning electron microscope (SEM). Encapsulation efficiency and concentrations of the PTX-PLGA microspheres were caculated by high-performance liquid chromatography (HPLC) analysis. 3. In vitro detection for ultrasound imaging was performed using water balloons of PLGA microspheres and PTX-PLGA microspheres, together with degassed water balloon for backscattered signals respectively.Results:1. PTX-PLGA and PLGA microspheres were successfully prepared by W/O/W double Emulsion/Evaporation technique and the injection of perfluoro propane gas.2. SEM illustrated that both PTX-PLGA and PLGA microspheres were intact uniform-shaped spheres that were sized (2.00±0.19)μm in diameter, with smooth surface and no adhesion between. And that the drug loading efficiency was about5.68%and encapsulation rate81.10%was detected by HPLC analysis.3. PTX-PLGA microspheres aquired equally enhanced ultrasound imaging in vitro, compared with the PLGA microspheres.Conclusion:Apart from its drug-loading capability, PTX-PLGA microspheres by W/O/W double Emulsion/Evaporation technique and the injection of perfluoropropane gas showed favorable contrast enhanced in vivo ultrasound imaging; extra-loading with paclitaxel had limited impact on the ultrasound imaging of PLGA microspheres. PART2In vivo ultrasound imaging of PTX-PLGA microspheres and their inhibitory effects on the tumor on the ovarian tumor-bearing mice.Objective:To observe the potential inhibitory effects of PTX-PLGA microspheres on the tumor on the ovarian tumor-bearing mice. Methods:1. Four-week-old female BALB/C-NU mice were used as tumor models for in vivo study, by subcutaneously injecting Skov3cells suspension at the back of the nude mice. Then the tumors were respectively treated with physiological saline solution, PLGA microspheres, paclitaxel, PLGA-PTX microspheres. Tumors without treatment were the controls.2. In vivo ultrasound imaging was performed immediately after injection of1ml PLGA or PTX-PLGA microspheres both with a concentration of109/ml into the tumor on the ovarian tumor-bearing mice.Results:1.6weeks after the treatments, compared to the control,tumors treated with physiological saline solution or PLGA microspheres showed no significant difference of the growth rate (P>0.05), whereas volumes of tumors after injection of paclitaxel or PLGA-PTX microspheres markedly reduced (P<0.05). Moreover, tumors treated with PLGA-PTX microspheres showed significant reduction of tumor volume, compare to other groups(P<0.01).2. Ultrasound imaging in vivo demonstrated that equally enhanced backscattered signals were detected by introducing of PTX-PLGA microspheres, compared with PLGA-microspheres.Conclusion:PTX-PLGA microspheres exhibited favorable enhanced backscattered signals for contrast enhanced ultrasound imaging, and have significant inhibitory effects on the ovarian tumors than solo application of paclitaxel, thus providing us novel insights into future clinical treatment of ovarian tumors and drug-tracing.