title: A strategy to improve serum-tolerant transfection activity of polycation vectors by surface hydroxylation.
abstract: The aim of this contribution is to develop a universal method to promote the serum-tolerant capability of polycation-based gene delivery system. A "hydroxylation camouflage" strategy was put forward by coating the polycation vectors with hydroxyl-enriched "skin". Branched polyethyleneimine (PEI) was herein used as the polycation model and modified via the catalyst-free aminolysis reaction with 5-ethyl-5-(hydroxymethyl)-1,3-dioxan-2-oxo (EHDO). PEI-g-EHDO, PEI and alkylated PEI derivative termed as PEI-g-DPA were comparatively explored with respect to the transfection efficiency in the serum-free and serum-conditioned medium. The resultant data indicate that the serum-tolerant capability largely depended on the surface composition and substitution degree. In addition to the reduced surface charge, the introduced function caused by hydroxyl coating is believed to play a crucial role for the improved properties of PEI-g-EHDOs. The EHDO modification can effectively inhibit the adsorption of BSA proteins onto polyplexes surface. And the polyplexes stability was remarkably enhanced in the presence of DNase and heparin after EHDO modification. Note that the transfection activity of PEI-g-EHDO(34.5%) in the serum-conditioned medium was even higher than that without serum addition. In contrast, serum addition led to appreciable reduction in the transfection efficiency mediated by PEI and PEI-g-DPAs. Specifically, as far as the transfection activity in the presence of serum is concerned, PEI-g-EHDO could be up to 30-fold higher than unmodified PEI25k. PEI-g-EHDO(34.5%) displayed little to no hemolytic effect and high cell-biocompatibility with nearly no cytotoxicity detected in 293T cells and HeLa cells. Taking into account the high biocompatibility and serum-tolerant transfection activity, PEI-g-EHDO(34.5%) holds great potential for the use as efficient gene vector. More importantly, it is expected that such "hydroxylation camouflage" strategy may be universally applicable for a majority of existing polycation vectors.
authors.affiliation: Key Laboratory of Biomedical Polymers (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, PR China.
authors.forename: Xiao-hua
authors.initials: XH
authors.lastname: Luo
authors.forename: Fu-wei
authors.initials: FW
authors.lastname: Huang
authors.forename: Si-yong
authors.initials: SY
authors.lastname: Qin
authors.forename: Hua-fen
authors.initials: HF
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Feng
authors.forename: Xian-zheng
authors.initials: XZ
authors.lastname: Zhang
authors.forename: Ren-xi
authors.initials: RX
authors.lastname: Zhuo
mesh_terms: D000327:Adsorption / Q000187:drug effects; D000818:Animals; D002417:Cattle; D016923:Cell Death / Q000187:drug effects; D003851:Deoxyribonucleases / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D024202:Electrophoretic Mobility Shift Assay; D005822:Genetic Vectors / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006461:Hemolysis / Q000187:drug effects; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D006900:Hydroxylation / Q000187:drug effects; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D018613:Microscopy, Confocal; D010316:Particle Size; D011073:Polyamines / Q000378:metabolism*; D000071228:Polyelectrolytes; D011094:Polyethyleneimine / Q000138:chemical synthesis / Q000737:chemistry; D011817:Rabbits; D044967:Serum / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013055:Spectrophotometry, Infrared; D013499:Surface Properties / Q000187:drug effects; D014162:Transfection / Q000379:methods*
chemical_list: D003851:Deoxyribonucleases; D006493:Heparin; D011073:Polyamines; D000071228:Polyelectrolytes; D011094:Polyethyleneimine; D012710:Serum Albumin, Bovine