Increased receptor-mediated gene delivery to the liver by protamine-enhanced-asialofetuin-lipoplexes

A novel lipidic vector composed of DOTAP/Chol liposomes, asialofetuin (AF), protamine sulfate and DNA has been developed. The resulting protamine-AF-lipoplexes improved significantly the levels of gene expression in cultured cells and in the liver upon i.v. administration. Lipoplexes containing the optimal amount of AF (1 μg/μg DNA) showed a 16-fold higher transfection activity in HepG2 cells than non-targeted (plain) complexes. The uptake by cells having asialoglycoprotein receptors (ASGPr) on their plasma membrane was decreased by the addition of free AF, indicating that AF-lipoplexes were taken up specifically by cells via ASGPr-mediated endocytosis. Results from transfections performed in cells defective in ASGPr, ie HeLa cells, confirmed this mechanism. By addition of the condensing peptide, protamine sulfate, smaller complexes were obtained, which enhanced even more the uptake of AF-complexes in HepG2 cells and in the liver. The optimal amount of protamine was 0.4 μg/μg DNA, and gene expression was about 5-fold over that obtained with AF-lipoplexes in the absence of the peptide, and 75-fold higher than that with plain conventional lipoplexes. Protamine-AF-lipoplexes increased by a factor of 12 luciferase gene expression in the liver of mice administered systemically via the tail vein, compared to plain complexes. In summary, our findings extend the scope of previous studies where AF-lipoplexes were used to Introduce DNA into hepatocytes. The combination of targeting and protamine condensation obviated the need for partial hepatectomy, commonly required to obtain efficient gene delivery in this organ. Since protamine sulfate has been proven to be non-toxic in humans, the novel liver-specific vector described here may be useful for the delivery of clinically important genes to this organ

Strategies for cancer gene-delivery improvement by non-viral vectors

Lack of selectivity together with severe side effects in conventional cancer treatment have afforded the devel- opment of new strategies based on gene therapy. Nowadays, gene therapy is employed through both viral and non-viral vectors. In spite of the high transfection activity of viral vectors, some drawbacks have pointed out to non-viral vectors as a safer alternative. To overcome low efficiency as well as other issues associated with the use of non-viral vectors, complexes formed by lipids and polymers with DNA, named lipoplexes and polyplexes respectively, have been modified in order to improve its features. Suitability of cancer gene therapy also requires the capacity to distinguish between normal and tumoral cells. This requirement has been solved by the addition of specific ligands that enable receptor binding and subsequent endocytosis. In this article we review the most recent approaches in structure modification of non-viral vectors through different methods comprising conjugation, addition of helper lipids or changes in design and synthesis as well as the strategy based on exploiting receptors that are usually overexpressed in malignancies. Such improvements confer specificity, efficient gene delivery, condensation, protection of DNA and low levels of toxicity avoiding off-target effects which turn into a potential tool to treat cancer

Enhanced gene delivery in vitro and in vivo by improved transferrin-lipoplexes

AbstractCationic liposomes and the complexes they form with DNA (lipoplexes) constitute the most promising alternative to the use of viral vectors for gene therapy. One of the limitations to their application in vivo, however, is the inhibition of gene delivery by serum. In a previous study, we demonstrated that transferrin (Tf)-lipoplexes were superior to plain lipoplexes in transfecting HeLa cells in the presence of high concentrations of serum. With the goal of obtaining efficient gene expression in vivo, we evaluated the efficacy of Tf-lipoplexes (containing DOTAP and cholesterol) in transfecting primary hepatocytes and adipocytes in the presence of high serum concentrations. The association of transferrin with cationic liposomes increased luciferase expression compared to plain lipoplexes in primary cells as well as in HepG2 and 3T3-L1 differentiated adipocytes. The complexes were not cytotoxic and were highly effective in protecting DNA from attack by DNase I. An efficient and reliable method was developed to prepare lipoplexes containing both Tf and protamine sulfate, where the latter was mixed with transferrin, followed by the addition of cationic liposomes and DNA. The resulting protamine-Tf-lipoplexes increased significantly the levels of gene expression in cultured cells and in various tissues in mice following i.v. administration

Application of different methods to formulate PEG-liposomes of oxaliplatin: Evaluation in vitro and in vivo

In this work the film method (FM), reverse-phase evaporation (REV) and the heating method (HM) were applied to prepare PEG-coated liposomes of oxaliplatin with natural neutral and cationic lipids, respectively. The formulations developed with the three methods, showed similar physicochemical characteristics, except in the loading of oxaliplatin, which was statistically lower (P<0.05) using the HM. The incorporation of a semi-synthetic lipid in the formulation developed by FM, provided liposomes with a particle size of 115 nm associated to the lowest polydispersity index and the highest drug loading, 35%, compared to the other two lipids, suggesting an increase of the membrane stability. That stability was also evaluated according to the presence of cholesterol, the impact of the temperature, and the application of different cryoprotectans during the lyophilization. The results indicated long-term stability of the developed formulation, because after its intravenous in-vivo administration to HT-29 tumor bearing mice was able to induce an inhibition of tumor growth statistically higher (P < 0.05) than the inhibition caused by the free drug. In conclusion, the FM was the simplest method in comparison with REV and HM to develop in vivo stable and efficient PEG-coated liposomes of oxaliplatin with a loading higher than those reported for REV

A gemini cationic lipid with histidine residues as a novel lipid-based gene nanocarrier: a biophysical and biochemical study

This work reports the synthesis of a novel gemini cationic lipid that incorporates two histidine-type head groups (C3(C16His)2). Mixed with a helper lipid 1,2-dioleoyl-sn-glycero3-phosphatidyl ethanol amine (DOPE), it was used to transfect three different types of plasmid DNA: one encoding the green fluorescence protein (pEGFP-C3), one encoding a luciferase (pCMV-Luc), and a therapeutic anti-tumoral agent encoding interleukin-12 (pCMV-IL12). Complementary biophysical experiments (zeta potential, gel electrophoresis, small-angle X-ray scattering (SAXS), and fluorescence anisotropy) and biological studies (FACS, luminometry, and cytotoxicity) of these C3(C16His)2/DOPE-pDNA lipoplexes provided vast insight into their outcomes as gene carriers. They were found to efficiently compact and protect pDNA against DNase I degradation by forming nanoaggregates of 120–290 nm in size, which were further characterized as very fluidic lamellar structures based in a sandwich-type phase, with alternating layers of mixed lipids and an aqueous monolayer where the pDNA and counterions are located. The optimum formulations of these nanoaggregates were able to transfect the pDNAs into COS-7 and HeLa cells with high cell viability, comparable or superior to that of the standard Lipo2000*. The vast amount of information collected from the in vitro studies points to this histidine-based lipid nanocarrier as a potentially interesting candidate for future in vivo studies investigating specific gene therapies

A Non-Viral Plasmid DNA Delivery System Consisting on a Lysine-Derived Cationic Lipid Mixed with a Fusogenic Lipid

The insertion of biocompatible amino acid moieties in non-viral gene nanocarriers is an attractive approach that has been recently gaining interest. In this work, a cationic lipid, consisting of a lysine-derived moiety linked to a C12 chain (LYCl) was combined with a common fusogenic helper lipid (DOPE) and evaluated as a potential vehicle to transfect two plasmid DNAs (encoding green fluorescent protein GFP and luciferase) into COS-7 cells. A multidisciplinary approach has been followed: (i) biophysical characterization based on zeta potential, gel electrophoresis, small-angle X-ray scattering (SAXS), and cryo-transmission electronic microscopy (cryo-TEM); (ii) biological studies by fluorescence assisted cell sorting (FACS), luminometry, and cytotoxicity experiments; and (iii) a computational study of the formation of lipid bilayers and their subsequent stabilization with DNA. The results indicate that LYCl/DOPE nanocarriers are capable of compacting the pDNAs and protecting them efficiently against DNase I degradation, by forming Lα lyotropic liquid crystal phases, with an average size of ~200 nm and low polydispersity that facilitate the cellular uptake process. The computational results confirmed that the LYCl/DOPE lipid bilayers are stable and also capable of stabilizing DNA fragments via lipoplex formation, with dimensions consistent with experimental values. The optimum formulations (found at 20% of LYCl content) were able to complete the transfection process efficiently and with high cell viabilities, even improving the outcomes of the positive control Lipo2000*

P-glycoprotein silencing with siRNA delivered by DOPEmodified PEI overcomes doxorubicin resistance in breast cancer cells

AIMS: Multidrug resistance (MDR) mediated by overexpression of drug efflux transporters such as P-glycoprotein (P-gp), is a major problem, limiting successful chemotherapy of breast cancer. The use of siRNA to inhibit P-gp expression in MDR tumors is an attractive strategy to improve the effectiveness of anticancer drugs. METHOD: We have synthesized a novel conjugate between a phospholipid (dioleoylphosphatidylethanolamine) and polyethylenimine (PEI) for siRNA delivery, for the purpose of silencing P-gp to overcome doxorubicin resistance in MCF-7 human breast cancer cells. RESULTS: The dioleoylphosphatidylethanolamine-PEI conjugate enhanced the transfection efficacy of low-molecular-weight PEI, which was otherwise totally ineffective. In addition, the polyethylene glycol/lipid coating of the new complexes gave rise to small micelle-like nanoparticles with improved biocompatibility properties. Both coated and noncoated formulations delivered P-gp-specific siRNA to MDR cells. DISCUSSION: The combination of doxorubicin and P-gp silencing formulations led to a twofold increase of doxorubicin uptake and a significant improvement of the therapeutic effect of doxorubicin in resistant cells

Trehalose-based siamese twin amphiphiles with tunable self-assembling, DNA nanocomplexing and gene delivery properties

An original family of multivalent vectors encompassing gemini and facial amphiphilicity, namely cationic Siamese twin surfactants, has been prepared fromthe disaccharide trehalose; molecular engineering lets us modulate the self-assembling properties and the topology of the nanocomplexes with plasmid DNA for efficient gene delivery in vitro and in vivo

Trifaceted Mickey Mouse Amphiphiles for Programmable Self-Assembly, DNA Complexation and Organ-Selective Gene Delivery

Instilling segregated cationic and lipophilic domains with an angular disposition in a trehalose-based trifaceted macrocyclic scaffold allows engineering patchy molecular nanoparticles leveraging directional interactions that emulate those controlling self-assembling processes in viral capsids. The resulting trilobular amphiphilic derivatives, featuring a Mickey Mouse architecture, can electrostatically interact with plasmid DNA (pDNA) and further engage in hydrophobic contacts to promote condensation into transfectious nanocomplexes. Notably, the topology and internal structure of the cyclooligosaccharide/pDNA co-assemblies can be molded by fine-tuning the valency and characteristics of the cationic and lipophilic patches, which strongly impacts the transfection efficacy in vitro and in vivo. Outstanding organ selectivities can then be programmed with no need of incorporating a biorecognizable motif in the formulation. The results provide a versatile strategy for the construction of fully synthetic and perfectly monodisperse nonviral gene delivery systems uniquely suited for optimization schemes by making cyclooligosaccharide patchiness the focus.Peer reviewe

Evading innate immunity in nonviral mRNA delivery : don't shoot the messenger

In de field of non-viral gene therapy, in vitro transcribed (IVT) mRNA has emerged as a promising tool for the delivery of genetic information. Over the past few years it has become widely known the introduction of IVT mRNA into mammalian cells elicits an innate immune response which has favored mRNA use towards immunotherapeutic vaccination strategies. However, for non-immunotherapy related applications this intrinsic immune-stimulatory activity directly interferes with the aimed therapeutic outcome, as it can seriously compromise the expression of the desired protein. This review presents an overview of the immune-related obstacles that limit mRNA advance for non-immunotherapy related applications