Preparation And Characterization Of Hydrophilic Cationic Polymer For Gene Delivery

Gene therapy has been confirmed as a promising strategy to cure various inheritedor acquired diseases, such as cancers, heart cerebrovascular disease, nervous systemdisease and viral infection. Development of safe and efficient gene delivery system iscrucial for successful gene therapy. Viral vectors are widely applied in gene deliverystudies because of their evolutionarily high transfection efficiency in clinic trials.However, safety concerns on the random recombination immunogenicity, limitednucleic acid loading capacity and high cost hamper their wide clinical application.Therefore, much attention has been shifted to non-viral vectors for their potentialadvantages such as low immunogenic response, easy structure modification,capability to carry large inserts and facile manufacturing. In this paper, we havedesigned and synthesized hydrophilic cationic polymers based on poly (vinylpyrrolidone)(PVP), polyester and poly (2-dimethylaminoethyl methacrylate)(PDMAEMA), and investigated their properties as DNA delivery vectors.PVP-Br was prepared by a bromination reaction between pendant allylic groups ofPVP and NBS, The graft copolymer, poly(vinylpyrrolidone)-graft-poly(2-dimethylaminoethyl methacrylate)(PPD), was synthesizedby ATRP of DMAEMA monomer using PVP-Br as the macroinitiator. Thetransfection results show that PPD/DNA complexes exhibited high transfectionefficiency both under serum free and10%serum conditions, but concomitant withcertain cytotoxicity.In order to increase the biocompatibility, negative charged bovine serum albumin(BSA) was used to dissimulate the positive charges of polyplexes formed byelectrostatic interactions between PPD and DNA. PPD-1/DNA complex (N/P=15:1)was chosen to assembly with BSA. BSA was effectively adsorbed onto the surface ofthe PPD/DNA complexes via electrostatic interaction and the introduction of BSA didnot affect the shape of PPD/DNA complexes. The ternary complexes ofBSA/PPD/DNA demonstrated no cytotoxicity as the gene delivery vector. Especially,BSA/PPD/DNA complexes show the similar transfection efficiency in10%serumcompared with that in serum-free conditions, demonstrating the ternary complexescan effectively avoid aggregation under serum-containing conditions. Particularly, the BSA/PPD/pDNA complex with5.0μg/mL BSA in this case shows slightly highertransfection efficiency compared with PEI/pDNA complex.