Prepreation Of RGD-Plga Contrast Agents And Targeting Study In Vitro And In Vivo

PART I PREPREATION OF RGD-PLGA ULTRASOUNDCONTRAST AGENTS AND TARGETINGSTUDY IN VITROObjective To synthesize RGD-PLGA and further explore its targetedability in vitro.Methods The high molecular polymer PLGA-COOH were preparedby the double emulsion technique， Targeted high molecular polymerultrasound contrast agents RGD-PLGA was synthesized by combiningPLGA-COOH ultrasound contrast agents with RGD peptides using covalentbinding. The conjugation of FITC-RGD and PLGA was detected by laserscanning confocal microscope, the affinity of RGD-PLGA and PLGA forSKOV-3cells was investigated by light microscope and fluorescencemicroscope. And then the targeted ability between RGD-PLGA and controlPLGA was compared by flow cytometry technique.Results FITC-RGD-PLGA showed a clear green light by laserscanning confocal microscope. It was showed that many RGD-PLGA attached to SKOV-3tightly in vitro experiment by light microscope andfluorescence microscope. It was also showed that RGD-PLGA has strongertargeted ability to SKOV-3cells by flow cytometry technique.Conclusion RGD-PLGA was successfully synthesized, and it hasstronger targeted ability to SKOV-3cells expressed integrin αvβ3, whichmay pave a way for molecular imaging of tumor. PART II ULTRASOUND MOLECULAR IMAGING OFTUMOR ANGIOGENISIS WITH PLGA CONTRASTAGENTS TARGETED TO INTEGRINObjective To evaluate contrast enhanced ultrasound(CEUS) withPLGA targeted to integrin αvβ3for imaging tumor angiogenesis in nudemice.Methods Targeted high molecular polymer agents RGD-PLGA weresynthesized by combining PLGA-COOH ultrasound contrast agents withRGD peptides using covalent binding, and the conjugation of FITC-RGDand PLGA was detected by laser scanning confocal microscope. SKOV-3tumor models in nude-mice were established and underwent CEUS with RGD-PLGA and control PLGA． Sonograms were analyzed by DFYquantometer， and time-intensity curve(TIC) and statistical table weredepicted according to the results of analyzing．The sonograms were digitalsubtracted and color coded, which to observe directivly the differencebetween the two kinds of sonograms.Results RGD-PLGA was successfully synthesized.TIC and statisticalanalysis showed that peak echogenicity was higher，and the time to wash outwas longer in RGD-PLGA group compared with that in contrast PLGAgroup. The sonograms directly showed that the RGD-PLGA group enhancedmore apparently than PLGA group.Conclusion RGD-PLGA targeted agents were better than PLGAcontrast agents to evaluate the tumor angiogenesis, which would realizeultrasound molecular imaging of tumor angiogenesis.