Synthesis of Copolymers Polyethyleneimine-co-Polyphenylalanine as Gene and Drug Codelivery Carrier

In this study, a series of hyperbranched copolymers polyethyleneimine-co-polyphenylalanine (PEI-co-PPhe) are synthesized by ring-opening polymerization with phenylalanine-N-carboxyanhydride as monomer and PEI-25k as initiator, using as a gene and drug codelivery carrier. Among them, PEI-co-PPhe (1:170) is selected out from transfection efficiency and cytotoxicity tests. Then, doxorubicin-cis-aconitic anhydride (CAD) and BCl2-shRNA (as a therapeutic gene) are coloaded into the PEI-co-PPhe carrier to form PEI-co-PPhe/Bcl2-shRNA/CAD complexes as a codeliver system. When the mass ratio of PEI-co-PPhe:Bcl2-shRNA:CAD is 5:1:1, the codeliver system has the most obvious synergistic therapeutic effect against B16F10 cells. Confirmed by confocal laser scanning microscope and flow cytometry, compared with drug and gene alone, the codeliver complexes can be endocytosed into B16F10 cells efficiently. As a result, the appropriate length of PPhe grafted on PEI will improve the gene transfer efficiency and decrease cytotoxicity, as well as effective codelivery of gene and drug into cancer cells to be a promising codelivery carrier for cancer therapy.

Redox-responsive polymer inhibits macrophages uptake for effective intracellular gene delivery and enhanced cancer therapy

The development of advanced gene delivery carriers with stimuli-responsive release manner for tumor therapeutics is desirable, since they can exclusively release the therapeutic gene via their structural changes in response to the specific stimuli of the target site. Moreover, interactions between macrophages and drug delivery systems (DDSs) seriously impair the treatment efficiency of DDSs, thus macrophages uptake inhibition would to some extent improve the intracellular uptake of DDSs in tumor cells. Herein, a PEGylated redox-responsive gene delivery system was developed for effective cancer therapy. PEG modified glycolipid-like polymer (P-CSSO) was electrostatic interacted with p53 to form P-CSSO/p53 complexes, which exhibited an enhanced redox sensitivity in that the disulfide bond was degraded and the rate the plasmid released from P-CSSO was 2.29-fold that of nonresponsive platform (P-CSO-SA) in 10 mM levels of glutathione (GSH). PEGylation could significantly weaken macrophages uptake, while enhance the accumulation of P-CSSO in tumor cells both in vitro and in vivo. Compared with nonresponsive complexes (P-CSO-SA/p53) (59.2%) and Lipofectamine™ 2000/p53 complexes (52.0%), the tumor inhibition rate of P-CSSO/p53 complexes (77.1%) significantly increased, which was higher than CSSO/p53 complexes (69.9%). The present study indicates that tumor microenvironment sensitive and macrophages uptake suppressive P-CSSO/p53 is a powerful in vivo gene delivery system for enhanced anticancer therapy.