Polyion complex micelles as vectors in gene therapy--pharmacokinetics and in vivo gene transfer.
ABSTRACT To establish non-viral gene delivery systems for intravenous administration, complexes of DNA and block copolymer consisting of poly-L-lysine and poly(ethylene glycol) were tested in in vivo turnover studies. The polyion complex micelles have self-assembling core-shell structures, yielding spherical nano-particles with small absolute values of zeta-potential. Southern blot analysis showed that supercoiled DNA was observed for 30 min and open circular or linear DNA was seen for 3 h after intravenous administration of PIC micelles having the charge ratios of 1:4 and PLL length of 48 mer. The PIC micelles with shorter PLL length showed lower stability in the blood stream suggesting that DNA is able to persist as an intact molecule in the blood stream using this system. Though having no ligands, PIC micelles with charge ratios of 1:2 and 1:4 transfected efficiently into HepG2 cells. Preincubation with free copolymer inhibited expression of the reporter gene, suggesting that adsorption of block copolymer to the cell surface blocked the interaction site of the PIC micelles. When the PIC micelles were injected via supramesenteric vein, expression of the gene was observed only in the liver and was sustained for 3 days. It was suggested that this gene delivery system is intrinsically efficient.
Full-textDOI: · Available from: Kazunori Kataoka, Jun 21, 2014
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ABSTRACT: The applicability of small interfering RNA (siRNA) in future therapies depends on the availability of safe and efficient carrier systems. Ideally, siRNA delivery requires a system that is stable in the circulation, but upon specific uptake into target cells can rapidly release its cargo into the cytoplasm. Previously, we evaluated a novel generation of carrier systems ('decationized' polyplexes) for DNA delivery and it was shown that folate targeted decationized polyplexes had an excellent safety profile and showed intracellular triggered release upon cell specific uptake. Targeted decationized polyplexes consist of a core of disulfide crosslinked poly(hydroxypropyl methacrylamide) (pHPMA) stably entrapping nucleic acids and a shell of poly(ethylene glycol) (PEG) decorated with folate molecules. In the present study the applicability of folate targeted decationized polyplexes for siRNA delivery was investigated. This required optimization of the carrier system particularly regarding the crosslinking density of the core of the polyplexes. Stable and nanosized siRNA decationized polyplexes were successfully prepared by optimizing the crosslink density of their core. Upon incubation in human plasma, a significant portion of siRNA remained entrapped in the decationized polyplexes as determined by fluorescence correlation spectroscopy (FCS). When tested in a folate receptor overexpressing cell line stably expressing luciferase, Skov3-luc, sequence specific gene silencing was observed. As expected, neither interference on the intrinsic luciferase expression nor on the cell metabolic activity (determined by XTT) was induced by the free-polymer or the siRNA polyplexes. In conclusion, targeted decationized polyplexes are safe and stable carriers that interact with the targeted cells and rapidly disassemble upon cell entry making them promising siRNA delivery systems.Molecular Pharmaceutics 11/2014; 12(1). DOI:10.1021/mp500499x · 4.79 Impact Factor
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ABSTRACT: pH-sensitive drug delivery systems can be engineered to release their contents or change their physicochemical properties in response to variations in the acidity of the surroundings. The present work describes the preparation and characterization of novel polymeric micelles (PM) composed of amphiphilic pH-responsive poly(N-isopropylacrylamide) (PNIPAM) or poly(alkyl(meth)acrylate) derivatives. On one hand, acidification of the PNIPAM copolymers induces a coil-to-globule transition that can be exploited to destabilize the intracellular vesicle membranes. In this work, PNIPAM-based PM were loaded with either doxorubicin or aluminium chloride phthalocyanine and their cytotoxicity was assessed in murine tumoral models. On the other hand, poly(alkyl(meth)acrylate) copolymers can be designed to interact with either hydrophobic drugs or polyions and release their cargo upon an increase in pH.International Journal of Pharmaceutics 06/2004; 277(1-2):81-90. DOI:10.1016/S0378-5173(04)00138-3 · 3.79 Impact Factor
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ABSTRACT: For successful gene therapy, expansion of appropriate gene delivery systems could be one of the factors of major significance. Gene therapy provides large opportunities for treating diseases, including genetic disorders, infections, and cancer. Polymeric carriers have relatively low cytotoxicity and immunogenicity. Polymeric gene carriers are a potential substitute to using viral vectors. Overall, polymeric carriers can contain large-sized DNA, be conjugated with suitable functionalities, and be administered frequently. However, polymeric gene carriers have some restrictions, such as low gene transfection efficiencies and a moderately short period of gene expression. This study explores the current status of development of polymeric gene carriers, and presents guidelines for the prospective use of the polymer-based gene delivery systems in gene therapy.11/2014; DOI:10.3109/21691401.2014.971805