Polylysine-modified Polyethylenimines as siRNA Carriers for Effective Tumor Treatment

Polyethylenimine-poly（L-lysine） （PEI-PLL） copolymer was synthesized via ring-opening polymerization of L-lysine N-carboxyanhydride （Lys（Z）-NCA） initiated by PEI. The complexation of PEI-PLL with siRNA was studied by particle size and zeta potential measurements. The flow cytometric analysis and confocal imaging showed its excellent intracellular trafficking ability. PEI-PLL displayed higher gene silencing efficiency and lower cytotoxicity than commercial PEI-25k in vitro. In the antitumor study, PEI-PLL was further combined with siVEGF and showed obviously tumor inhibition effect for the treatment of CT26 tumor model. Therefore, PEI-PLL is a promising siRNA carrier candidate for further antitumor treatment in vivo.

PLG-g-mPEG Mediated Multifunctional Nanoparticles for Photoacoustic Imaging Guided Combined Chemo/Photothermal Antitumor Therapy

Under laser irradiation,photothermal therapy(PTT)effectively ablates tumors above 50℃.However,hyperthermia can cause additional damage due to the inevitable heat spread to surrounding healthy tissue.Herein,nanoparticles named as GI@P NPs were designed for enhanced PTT with heat shock protein 90(HSP90)inhibition at temperatures below 50℃to achieve optimal cancer therapy and avoid surrounding damage.GI@P NPs were done by co-loading Garcinia cambogia acid(GA)and photosensitizer IR783 in polymer PLG-g-mPEG to form a nanomedicine,where IR783 with excellent photoacoustic(PA)signal acted as an excellent photothermal therapeutic agent that converted the laser energy into heat to kill tumor cells,GA was used as antitumor drug for chemotherapy and an inhibitor of HSP90 to overcome the heat resistance of tumors for efficient cryo-photothermal therapy,and PLG-g-mPEG can encapsulate IR783 and GA to increase biocompatibility and accumulate effectively in the tumor.After GI@P NPs were injected into the mice,we could observe that the PA signals gradually increased in the tumor region and showed the strongest PA signals at 12 h.Under laser irradiation,the tumor temperature of the mice could raise to about 43.5℃,and the tumor was significantly inhibited after long-term monitoring by PA imaging.As a result,gentle PTT produced by GI@P NPs exhibited good antitumor effects at relatively low temperature and minimized nonspecific thermal damage to normal tissues.The GI@P NPs as nanomedicine enriched our understanding of various applications of polymeric carriers,especially in the biomedical field.

Polyglutamic Acid Based Polyanionic Shielding System for Polycationic Gene Carriers

For the purpose of increasing the in vivo stability of polycation gene carriers, we prepared a kind of p H-sensitive poly（ethylene glycol）-poly（γ-benzyl-L-glutamate-co-glutamic acid）（PEG-PGA（65）, 65 denotes the molar ratio of glutamic acid in poly（γ-benzyl-L-glutamate-co-glutamic acid））. PEG-PGA（65） showed low cytotoxicity and could shield the positive charge of DNA/PEI（1：1） polyplexes efficiently. The transfection was enhanced due to the partially charge shielding in He La cell line at pH of 7.4. There was almost no transfection efficiency when the surface charge of the ternary particles turned to negative at p H of 7.4. However, the transfection efficiency recovered a lot by culturing at p H of 6.0 at the beginning of transfection. Confocal microscopic observation and flow cytometry results showed DNA/PEI polyplexes should be efficiently released and endocytosized at p H 6.0, because of the p H triggered deshielding action of PEG-PGA（65）. Due to the good biocompatibility and suitable p H triggered shielding/deshielding property, PEG-PGA（65） could be a potential shielding system for polycationic gene carriers used in vivo.

Anti-tumor effects of combined doxorubicin and siRNA for pulmonary delivery

Direct administration of drugs and genes to the lungs by pulmonary delivery offers a potential effective therapy for lung cancers.In this study,combined doxorubicin（DOX） and Bcl2 siRNA was employed for cancer therapy using polyethylenimine（PEI） as the carrier of Bcl2 siRNA.Most of the DOX and siRNA possessed high cellular uptake efficiency in B16F10 cells,which was proved by FCM and CLSM analysis.Real-time PCR showed that PEI/Bcl2 siRNA exhibited high gene silencing efficiency with 70%Bcl2 mRNA being knocked down.The combination of DOX and siRNA could enhance the cell proliferation inhibition and the cell apoptosis against B16F10 cells compared to free DOX or PEI/Bcl2 siRNA.Furthermore,the biodistribution of DOX and siRNA via pulmonary administration was studied in mice with B16F10 metastatic lung cancer.The results showed that most of the DOX and siRNA were accumulated in lungs and lasted at least for 3 days,which suggested that combined DOX and siRNA by pulmonary administration may have high anti-tumor effects for metastatic lung cancer treatment in vivo.