Controllable gene therapy pharmaceutics of non-viral gene delivery systems

Non-Viral in Vitro Gene Delivery: It is Now Time to Set the Bar!

Transfection by means of non-viral gene delivery vectors is the cornerstone of modern gene delivery. Despite the resources poured into the development of ever more effective transfectants, improvement is still slow and limited. Of note, the performance of any gene delivery vector in vitro is strictly dependent on several experimental conditions specific to each laboratory. The lack of standard tests has thus largely contributed to the flood of inconsistent data underpinning the reproducibility crisis. A way researchers seek to address this issue is by gauging the effectiveness of newly synthesized gene delivery vectors with respect to benchmarks of seemingly well-known behavior. However, the performance of such reference molecules is also affected by the testing conditions. This survey points to non-standardized transfection settings and limited information on variables deemed relevant in this context as the major cause of such misalignments. This review provides a catalog of conditions optimized for the gold standard and internal reference, 25 kDa polyethyleneimine, that can be profitably replicated across studies for the sake of comparison. Overall, we wish to pave the way for the implementation of standardized protocols in order to make the evaluation of the effectiveness of transfectants as unbiased as possible.

Nanodelivery: An Emerging Avenue for Nutraceuticals and Drug Delivery

Aquaculture has been globally recognized as the fastest growing food production sector which plays a major role in meeting the increasing demand for animal protein requirement. A consensus is growing that a dramatic increase in aquaculture is needed to supply future aquatic food needs. However, there are sustained problems with the aquaculture like disease outbreaks, chemical pollution, the environmental destruction, and inefficient feed utilization. These altogether raise question mark on sustainability of aquaculture. In spite of the several strategy adopted on national and international level, as improved laboratory facilities, diagnostic expertise, and control and therapeutic strategies in order to handle disease outbreaks more effectively. Aquaculture industry is under uncertainty and the progress has not matched that of the rapidly developing aquaculture sector. In order to control disease prevalence and ensure better health of system and sustainable production, the sector demand more technical innovation for the drug use, disease treatment, water quality management, production of tailored fish for suiting better health, productivity drive by epigenetic and nutrigenomic interaction, better breeding success by efficient delivery of maturation and spawning inducing agent, nutraceutical delivery for rapid growth promotion and culture time reduction, successful use of autotransgenic, and effective vaccine. Nanotechnology has a tremendous potential to revolutionize agriculture and allied fields including aquaculture and fisheries. For these multiple purposes effort, importance of nanotechnology and nanodelivery of drugs, vaccine, nutraceutical, inducing hormones, and growth-promoting anabolics open tremendous opportunity. The paper has been targeted to delineate the possible future application of nanodelivery for the aquaculture development.

Synthesis and Evaluation of Poly(Ethylene Glycol)-Polylysine Block Copolymers as Carriers for Gene Delivery

Different types of poly(ethylene glycol)-poly(l-lysine) PEG-PLL block copolymers were examined for their ability to form polyelectrolyte complexes with DNA, their toxicity toward red blood cells and their in vitro transfection efficiency. The complexation of the polymers with DNA was studied using the ethidium bromide fluorescence technique. All polymers complexed DNA to form particles with sizes ranging from 80 nm to 150 nm. In most cases, smaller particles were also observed, and sometimes populations of even larger particles could be detected. In vitro toxicity toward red blood cells was low. Agglutination of red blood cells with some of the noncomplexed block copolymers was observed, but the aggregates were less dense than with polylysine. Transfection efficiency of 293 cells in vitro in the presence of chloroquine was dependent upon the charge ratio of polymer/DNA. Efficient transfection was achieved for the PEG-PLL block copolymers with linear PLL blocks. On the other hand, very low transfection efficiency was obtained from the PEG-PLL with a dendritic PLL block.

Synergistic nanomedicine by combined gene and photothermal therapy

To date, various nanomaterials with the ability for gene delivery or photothermal effect have been developed in the field of biomedicine. The therapeutic potential of these nanomaterials has raised considerable interests in their use in potential next-generation strategies for effective anticancer therapy. In particular, the advancement of novel nanomedicines utilizing both therapeutic strategies of gene delivery and photothermal effect has generated much optimism regarding the imminent development of effective and successful cancer treatments. In this review, we discuss current research progress with regard to combined gene and photothermal therapy. This review focuses on synergistic therapeutic systems combining gene regulation and photothermal ablation as well as logically designed nano-carriers aimed at enhancing the delivery efficiency of therapeutic genes using the photothermal effect. The examples detailed in this review provide insight to further our understanding of combinatorial gene and photothermal therapy, thus paving the way for the design of promising nanomedicines.

An antibody fragment functionalized dendritic PEGylated poly(2-(dimethylamino)ethyl diacrylate) as a vehicle of exogenous microRNA

The translation of interfering RNA to the clinic requires more effective delivery agents to enable safe and efficient delivery. The aim of this work was to create a multi-functional delivery agent using deactivation enhanced ATRP synthesis of poly(dimethylamino)ethyl methacrylate (pDMAEMA)-co-PEGMEA/PEGDA (pD-b-P/DA) with linear pDMAEMA as a macro-initiator. The pD-b-P/DA was characterized for its potential to bind synthetic microRNA mimics to form structures and reacted with antibody-derived fragments (Fabs) using Michael-type addition. Conjugation of antibody fragments was verified using SDS-PAGE. Functional delivery of these interfering RNA complexes was proven using a dual luciferase reporter assay. Functional silencing of a reporter gene was improved by complexation of microRNA mimics with pD-b-P/DA alone and with Fab-decorated pD-b-P/DA. The improved silencing with Fab-decorated pD-b-P/DA was evident at 48 h but disappeared at 96 h. The resultant agent enables complexation of nucleic acid (microRNA mimic) and facile conjugation of antibody fragments via a Michael-type addition. In conclusion, this platform is effective at silencing in this reporter system and has potential as an effective delivery system of interfering RNA.

Recent In Vivo Evidences of Particle-Based Delivery of Small-Interfering RNA (siRNA) into Solid Tumors

Small-interfering RNA (siRNA) is both a powerful tool in research and a promising therapeutic platform to modulate expression of disease-related genes. Malignant tumors are attractive disease targets for nucleic acid-based therapies. siRNA directed against oncogenes, and genes driving metastases or angiogenesis have been evaluated in animal models and in some cases, in humans. The outcomes of these studies indicate that drug delivery is a significant limiting factor. This review provides perspectives on in vivo validated nanoparticle-based siRNA delivery systems. Results of recent advances in liposomes and polymeric and inorganic formulations illustrate the need for mutually optimized attributes for performance in systemic circulation, tumor interstitial space, plasma membrane, and endosomes. Physiochemical properties conducive to efficient siRNA delivery are summarized and directions for future research are discussed.

Growth factor-delivery systems for tissue engineering: a materials perspective

The transplantation of organs, their surgical reconstruction or implantation of synthetic devices that can perform the function of organs, are the currently available methods for treating loss of tissue/organs in humans. However, the limitations associated with these techniques have led to the development of tissue engineering. One of the primary goals of tissue engineering is to provide growth factor delivery systems that can induce desired cell responses both in vitro and in vivo, in order to cause accelerated tissue regeneration. To make growth factors a more therapeutically viable alternative for the treatment of chronic degenerative diseases, a wide range of natural and synthetic materials have been employed as vehicles for their controlled delivery. The choice of material and design of the carrier device influence the mode of immobilization of growth factors on the scaffolds and their local/systemic administration. From a tissue engineer's perspective, materials could be used for designing scaffolds as well as for delivering single or multiple growth factors. Therefore, this review discusses growth factor delivery systems, with particular reference to carrier-based growth factor delivery systems with a focus on materials.

Chemical oxidation of a redox-active, ferrocene-containing cationic lipid: influence on interactions with DNA and characterization in the context of cell transfection

We report an approach to the chemical oxidation of a ferrocene-containing cationic lipid [bis(11-ferrocenylundecyl)dimethylammonium bromide, BFDMA] that provides redox-based control over the delivery of DNA to cells. We demonstrate that BFDMA can be oxidized rapidly and quantitatively by treatment with Fe(III)sulfate. This chemical approach, while offering practical advantages compared to electrochemical methods used in past studies, was found to yield BFDMA/DNA lipoplexes that behave differently in the context of cell transfection from lipoplexes formed using electrochemically oxidized BFDMA. Specifically, while lipoplexes of the latter do not transfect cells efficiently, lipoplexes of chemically oxidized BFDMA promoted high levels of transgene expression (similar to levels promoted by reduced BFDMA). Characterization by SANS and cryo-TEM revealed lipoplexes of chemically and electrochemically oxidized BFDMA to both have amorphous nanostructures, but these lipoplexes differed significantly in size and zeta potential. Our results suggest that differences in zeta potential arise from the presence of residual Fe(2+) and Fe(3+) ions in samples of chemically oxidized BFDMA. Addition of the iron chelating agent EDTA to solutions of chemically oxidized BFDMA produced samples functionally similar to electrochemically oxidized BFDMA. These EDTA-treated samples could also be chemically reduced by treatment with ascorbic acid to produce samples of reduced BFDMA that do promote transfection. Our results demonstrate that entirely chemical approaches to oxidation and reduction can be used to achieve redox-based 'on/off' control of cell transfection similar to that achieved using electrochemical methods.

Addition of ascorbic acid to the extracellular environment activates lipoplexes of a ferrocenyl lipid and promotes cell transfection

The level of cell transfection mediated by lipoplexes formed using the ferrocenyl lipid bis(11-ferrocenylundecyl)dimethylammonium bromide (BFDMA) depends strongly on the oxidation state of the two ferrocenyl groups of the lipid (reduced BFDMA generally mediates high levels of transfection, but oxidized BFDMA mediates very low levels of transfection). Here, we report that it is possible to chemically transform inactive lipoplexes (formed using oxidized BFMDA) to "active" lipoplexes that mediate high levels of transfection by treatment with the small-molecule reducing agent ascorbic acid (vitamin C). Our results demonstrate that this transformation can be conducted in cell culture media and in the presence of cells by addition of ascorbic acid to lipoplex-containing media in which cells are growing. Treatment of lipoplexes of oxidized BFDMA with ascorbic acid resulted in lipoplexes composed of reduced BFDMA, as characterized by UV/vis spectrophotometry, and lead to activated lipoplexes that mediated high levels of transgene expression in the COS-7, HEK 293T/17, HeLa, and NIH 3T3 cell lines. Characterization of internalization of DNA by confocal microscopy and measurements of the zeta potentials of lipoplexes suggested that these large differences in cell transfection result from (i) differences in the extents to which these lipoplexes are internalized by cells and (ii) changes in the oxidation state of BFDMA that occur in the extracellular environment (i.e., prior to internalization of lipoplexes by cells). Characterization of lipoplexes by small-angle neutron scattering (SANS) and by cryogenic transmission electron microscopy (cryo-TEM) revealed changes in the nanostructures of lipoplexes upon the addition of ascorbic acid, from aggregates that were generally amorphous, to aggregates with a more extensive multilamellar nanostructure. The results of this study provide guidance for the design of redox-active lipids that could lead to methods that enable spatial and/or temporal control of cell transfection.

RNA interference therapy via functionalized scaffolds

Tissue engineering aims to provide structural and biomolecular cues to compromised tissues through scaffolds. An emerging biomolecular cue is that of RNA interference by which the expression of genes can be silenced through a potent endogenous pathway. Recombinant viral-based approaches in RNAi delivery exist; however non-viral strategies offer many opportunities to exploit this mechanism of regulation in a safer way. Current RNAi therapies in clinical trials are without a vector (naked) or have slightly modified structures. Modification of these molecules with efficient backbone moieties for improved stability and potency, protecting and buffering them with delivery vehicles, and using scaffolds as reservoirs of delivery is at the frontier of current research. However, to enable an efficient sustained therapeutic effect scaffolds have a potentially significant role to play. This review presents non-viral delivery of RNAi that have been attempted via tissue engineered scaffolds. For RNAi to have a clinical impact, it is imperative to evaluate optimal delivery systems to ensure that the efficacy of this promising technology can be maximized.

Self-assembled and nanostructured siRNA delivery systems

A wide range of organic and inorganic materials have been used in the development of nano-scale self-assembling gene delivery systems to improve the therapeutic efficacy of nucleic acid drugs. Small interfering RNA (siRNA) has recently been recognized as a promising and potent nucleic acid medicine for the treatment of incurable genetic disorders including cancer; however, siRNA-based therapeutics suffer from the same delivery problems as conventional nucleic acid drugs such as plasmid DNA and antisense oligonucleotides. Many of the delivery strategies developed for nucleic acid drugs have been applied to siRNA therapeutics, but they have not produced satisfactory in vivo gene silencing efficiencies to warrant clinical trials. This review discusses recent progress in the development of self-assembled and nanostructured delivery systems for efficient siRNA-induced gene silencing and their potential application in clinical settings.

Spatial and temporal control of surfactant systems

This paper reviews some recent progress on approaches leading to spatial and temporal control of surfactant systems. The approaches revolve around the use of redox-active and light-sensitive surfactants. Perspectives are presented on experiments that have realized approaches for active control of interfacial properties of aqueous surfactant systems, reversible control of microstructures and nanostructures formed within bulk solutions, and in situ manipulation of the interactions of surfactants with polymers, DNA and proteins. A particular focus of this review is devoted to studies of amphiphiles that contain the redox-active group ferrocene - reversible control of the oxidation state of ferrocene leads to changes in the charge/hydrophobicity of these amphiphiles, resulting in substantial changes in their self-assembly. Light-sensitive surfactants containing azobenzene, which undergo changes in shape/polarity upon illumination with light, are a second focus of this review. Examples of both redox-active and light-sensitive surfactants that lead to large (>20mN/m) and spatially localized ( approximately mm) changes in surface tensions on a time scale of seconds are presented. Systems that permit reversible transformations of bulk solution nanostructures - such as micelle-to-vesicle transitions or monomer-to-micelle transitions - are also described. The broad potential utility of these emerging classes of amphiphiles are illustrated by the ability to drive changes in functional properties of surfactant systems, such as rheological properties and reversible solubilization of oils, as well as the ability to control interactions of surfactants with biomolecules to modulate their transport into cells.

Chemical activation of lipoplexes formed from DNA and a redox-active, ferrocene-containing cationic lipid

We recently reported that the ferrocene-containing cationic lipid BFDMA [bis(11-ferrocenylundecyl)dimethylammonium bromide] can be used to mediate cell transfection, and that levels of transfection depend critically upon the oxidation state of the ferrocenyl groups of the lipid. Here, we report that the redox activity of BFDMA can be exploited to transform lipoplexes formed from oxidized BFDMA (which do not transfect cells) to lipoplexes that are "active" (and thus mediate high levels of transgene expression) by treatment with the chemical reducing agent glutathione (GSH). We demonstrate that GSH can be used to reduce the ferrocenium groups of oxidized BFDMA rapidly both (i) in solution and (ii) in lipoplexes formed by mixing oxidized BFDMA and DNA. Lipoplexes transformed in this manner mediate levels of cell transfection in vitro that are comparable to levels of transfection mediated by lipoplexes prepared by mixing DNA and reduced BFDMA. We demonstrate further that the chemical reduction of oxidized BFDMA leads to changes in the zeta potentials of these lipoplexes (e.g., from negative to positive). Characterization of lipoplex internalization using confocal microscopy demonstrated that these changes in zeta potential correlate to differences in the extents to which these lipoplexes are internalized by cells. These results provide a framework from which to interpret differences in cell transfection mediated by reduced and oxidized BFDMA. When combined, the results of this study suggest the basis of an approach that could be used to transform lipoplexes actively or "on-demand" and provide spatial and/or temporal control over the transfection of cells in a range of different fundamental and applied contexts.

A matrix reservoir for improved control of non-viral gene delivery

Non-viral gene delivery suffers from a number of limitations including short transgene expression times and low transfection efficiency. Collagen scaffolds have previously been investigated as in vitro DNA reservoirs, which allow sustained release of genetic information. Efficient viral gene-transfer from these scaffolds has previously been demonstrated. However, due to concerns about the safety of viral gene therapy, the use of non-viral vectors may be preferable. In this study a DNA-dendrimer complex embedded in a cross-linked collagen scaffold was investigated as a reservoir for non-viral delivery. Elution from the scaffolds and transfection of seeded rat mesenchymal stem cells were used to evaluate the scaffold's ability to act as a reservoir for the complexes. Elution from the scaffolds was minimal after 2 days with a total of 25% of the complexes released after 7 days. Extended transgene expression after DNA-dendrimer complex delivery from the scaffolds in comparison to direct delivery to cells was observed. The elongated transfection period and relatively high levels of reporter gene expression are significant advantages over other non-viral gene therapy techniques. This platform has the potential to be an effective method of scaffold-mediated gene delivery suitable for in vitro and in vivo applications.

DNA nanoparticles encapsulated in 3D tissue-engineered scaffolds enhance osteogenic differentiation of mesenchymal stem cells

In this study, we enhanced the expression of a plasmid DNA in mesenchymal stem cells (MSC) by the combination of three-dimensional (3D) tissue-engineered scaffold and nonviral gene carrier. To function as an enhanced delivery of plasmid DNA, acetic anhydride was reacted with polyethylenimine (PEI) to acetylate 80% of the primary and 20% of the secondary amines (PEI-Ac(80)). This acetylated PEI has been demonstrated to show enhanced gene-delivery efficiency over unmodified PEI. Collagen sponges reinforced by incorporating of poly(glycolic acid) (PGA) fibers were used as the scaffold material. DNA nanoparticles formed through simple mixing of plasmid DNA encoding bone morphogenetic protein-2 (BMP-2) and PEI-Ac(80) solutions were encapsulated within these scaffolds. MSC were seeded into each scaffold and cultured for several weeks. Within these scaffolds, the level of BMP-2 expression by transfected MSC was significantly enhanced compared to MSC transfected by DNA nanoparticles in solution (in 2D tissue culture plates). Homogeneous bone formation was histologically observed throughout the sponges seeded with transfected MSC by using DNA nanoparticles after subcutaneous implantation into the back of rats. The level of alkaline phosphatase activity and osteocalcin content at the implanted sites of sponges seeded with transfected MSC by using DNA nanoparticles were significantly higher when compared with those seeded with other agents.

Peptide-based cationic molecules for the production of positive charged liposomes and micelles

This paper describes the synthesis and the physico-chemical characterization of cationic peptides (CPs) for possible application as non-viral gene delivery systems. Particularly, the production of cationic liposomes and micelle solutions was considered. Liposomes were prepared by REV-phase and extrusion presenting an average diameter reflecting the pore size of the membrane used for the extrusion. After DNA complexation the mean diameter of complexes decreased by increasing the number of positive charges. The non-complexed liposome preparations showed a net positive zeta potential comprised between 17.8-30 mV. After adding Defibrotide (DFT) to liposomes (at a 1:4 +/- molar ratio) the zeta potential fell down to a net negative value indicating the formation of the ionic complex. Concerning micelles, before complexation it was not possible to measure their size by PCS. However, after DFT complexation the size of complexes highly increased. In addition, as previously seen for liposomes, before complexation, the five CPs solutions showed a positive zeta potential ranging from 10-17.8 mV, while after addition of DFT the zeta potential fell to negative values. Concerning toxicity studies, in general CP-liposomes displayed a lower toxicity towards K562 cells as compared to the corresponding CP-solution. Taking into account these results, the studied CPs could be efficiently used to obtain both cationic liposomes and micelles. Moreover they are able to complex DNA with different interaction strength, depending on the type of peptide-based cationic molecule used.

Ex vivo magnetofection with magnetic nanoparticles: a novel platform for nonviral tissue engineering

Several methods have been described to introduce DNA expression vectors into mammalian cells both in vitro and in vivo. Each system has benefits and limitations, and to date there is still no ideal method for gene transfer. In this study, we introduced a novel method of gene transfer by using Fe3O4 nanoparticles. The magnetic nanoparticles composed of Fe3O4, and the transfected genes used are Lac Z and enhanced green fluorescence protein gene (EGFG). Four different groups of preparations included in this study were homemade liposome-enveloped EGFP-DNA/Fe3O4, homemade liposome EGFP-DNA gene without magnetic Fe3O4 nanoparticles, lipofectamine 2000-enveloped EGFP-DNA, and EGFP-DNA gene only. Mice osteoblast and He99 lung cancer cell line were used as host cells for gene transfection. The time-dependent EGFP gene expression was monitored and analyzed. The results showed that the diameter of the complex was less than 100 nm. There was no cytotoxicity observed at any of the magnetic Fe3O4 nanoparticle concentrations tested. In the presence of magnetic field, the liposome-enveloped EGFP-DNA/Fe3O4 complex exhibited a much higher efficiency for transfecting EGFP-DNA into osteoblast cells under external magnetic fields. The gene can be transfected into cells with an aid of magnetic vectors and magnetic force. Under a gradient magnetic field, the efficiency of magnetofection is enhanced as compared to that without magnetic field.

Lipoplexes formed by DNA and ferrocenyl lipids: effect of lipid oxidation state on size, internal dynamics, and zeta-potential

The effect of lipid oxidation state on the physical properties of complexes formed by plasmid DNA and the redox-active lipid bis-(11-ferrocenylundecyl)dimethylammonium bromide (BFDMA) is reported. With increasing concentration of BFDMA, the hydrodynamic sizes of complexes formed by BFDMA and DNA (in the presence of 1 mM Li(2)SO(4)) pass through a maximum and the zeta-potential changes monotonically from -40 mV to +40 mV. In contrast, complexes formed by oxidized BFDMA and DNA exhibit a minimum in size and maintain a negative zeta-potential with increasing concentration of BFDMA. Angle-dependent dynamic light scattering measurements also reveal the presence of relaxation processes within complexes formed by DNA and oxidized BFDMA that are absent for complexes formed by DNA and reduced BFDMA. These results, when combined, reveal that the amphiphilic nature of reduced BFDMA leads to lipoplexes with physical properties resembling those formed by classical cationic lipids, whereas the interaction of oxidized BFDMA with DNA is similar to that of nonamphiphilic cationic molecules bearing multiple charges (e.g., spermidine). In particular, the negative zeta-potential and measurable presence of DNA chain dynamics within complexes formed by oxidized BFDMA and DNA indicate that these complexes are loosely packed with excess charge due to DNA in their outer regions. These results, when combined with additional measurements performed in OptiMEM reduced-serum cell culture medium, lead to the proposition that the strong dependence of transfection efficiency on the oxidation state of BFDMA, as reported previously, is largely a reflection of the substantial change in the zeta-potentials of these complexes with changes in the oxidation state of BFDMA.

Polymer-based siRNA delivery: Perspectives on the fundamental and phenomenological distinctions from polymer-based DNA delivery

Gene therapy holds tremendous promise in the treatment of many genetic and acquired diseases. The future of gene therapy in humans, however, is contingent upon the discovery of safe and effective carriers of genetic material. Polymers represent a class of materials that can be extensively modified to meet the needs of a particular gene delivery system. A variety of polymer formulations have been proposed in the literature as potential carriers, most of which facilitate gene delivery by encapsulating, and in some cases, condensing nucleic acids into nano-sized particles which can then be taken up by cells. Crucial to successful delivery of the gene to a cell is the polymer's ability to protect its contents from degradation in the extracellular environment. A well-designed carrier will also promote cellular uptake and intracellular release of the nucleic acid. In the past, a common approach to gene therapy has been to transfect cells with a polymer-encapsulated DNA plasmid designed to replace a defective gene in the target-cell genome. Within the last few years, however, RNA interference (RNAi) has emerged as a novel therapeutic pathway by which harmful genes can be "silenced" by delivering complementary short interfering RNA (siRNA) to target cells. siRNA delivery facilitated by polymers, although very promising, suffers from many of the same limitations as DNA delivery. This review will (1) highlight the similarities and differences between these two methods of gene therapy and (2) discuss how some of the remaining challenges in siRNA delivery facilitated by polymers can be addressed by applying knowledge from the longer-studied problem of DNA delivery.

Enhancement of an electroporation system for gene delivery using electrophoresis with a planar electrode

In this paper a new electroporation (EP) system is developed, which includes an EP microchip and a logic circuit, which combined with electrophoresis (ES), can provide site-specific enhancement of gene concentration. In this ES-EP microchip, an arc planar electrode provides the ES function for DNA attraction, and interdigitated array electrodes provide appropriate electric fields for the EP on the chip surface. In addition, the adherent cells can be manipulated in situ without detachment of the ES-EP microchip, which performs the "Lab on a chip". Experimental results have shown that the efficiency of gene transfection with an attracting-electric field (35.89%) becomes much higher than that without an attracting-electric field (16.62%). Cell numbers as low as 10(4) cells, and DNA as little as 4 microg are sufficient for evaluating the phenotypic effects following the over-expression of the introduced genes on the ES-EP microchip. The proposed system has the advantages of portability, cost-effectiveness, a high transfection rate and ease of operation.

Chitosan–thioglycolic acid conjugate: An alternative carrier for oral nonviral gene delivery?

Regarding safety concerns, nonviral gene delivery vehicles that have the required efficiency and safety for use in human gene therapy are being widely investigated. The aim of this study was to synthesize and evaluate a thiolated chitosan to improve the efficacy of oral gene delivery systems. Thiolated chitosan was synthesized by introducing thioglycolic acid (TGA) to chitosan via amide bond formation mediated by a carbodiimide. Based on this conjugate, nanoparticles with pDNA were generated at pH 4.0 and 5.0. Cytotoxicity of the thiolated chitosan/pDNA nanoparticles on Caco-2 cells was evaluated. The diameter of thiolated chitosan/pDNA nanoparticles was in the range of 100-200 nm. The zeta potential was determined to be 5-6 mV. Due to stability toward nucleases, the transfection rate of thiolated chitosan/pDNA nanoparticles was fivefold higher than that of unmodified chitosan/pDNA nanoparticles. Lactate dehydrogenase tests for thiolated chitosan/pDNA (pH 4.0 and 5.0) showed that (3.79 +/- 0.23)% and (2.9 +/- 0.13)% cell damage. According to these results, thiolated chitosan represents promising excipients for preparation DNA nanoparticles in nonviral gene delivery system.

Synthesis and characterization of guanidinylated poly(propylene imine) dendrimers as gene transfection agents

Fourth generation poly(propylene imine) dendrimer has been completely or partially functionalized with guanidinium groups. In the second case, the remaining toxic primary amino groups of the dendrimers were reacted with propylene oxide affording the corresponding hydroxylated derivatives. Five derivatives have been prepared bearing 0, 6, 12, 24 or 32 guanidinium groups. These guanidinylated dendrimers were interacted with plasmid DNA affording the corresponding dendriplexes. The complexes were physicochemically characterized by dynamic light scattering, zeta-potential measurements and AFM, while the extent of complexation was evaluated by agarose gel electrophoresis. Furthermore, their transfection efficiency was assessed employing HEK 293 and COS-7 cell lines, while the serum effect was studied in HEK 293 cells. It was found that complete replacement of primary amino groups with the hydroxylated moieties resulted in complete loss of transfection efficiency. On the contrary, guanidinylation of the parent dendrimer resulted to significant enhancement of its transfection efficiency, this enhancement being dependent on the number of guanidinium groups per dendrimer, the cell line used and the presence or absence of FBS. The fully guanidinylated dendrimer exhibited the best transfection efficiency under all the conditions studied. This efficiency has been attributed to the enhanced penetrating ability of the guanidinylated dendrimers due to the accumulation of the guanidinium group at the dendrimeric surface. It was also found that the derivative with 12 guanidinium groups exhibited the lowest toxicity. The reduction of toxicity was apparently attributed to the decrease of the external primary amino groups coupled with the presence of hydroxylated moieties located at the dendrimeric surface. The functionalization strategy employed leads to dendrimeric derivatives that combine satisfactory transfection efficiency and cytotoxicity.

Cationic liposomes for gene delivery

Cationic liposome-DNA complexes (lipoplexes) constitute a potentially viable alternative to viral vectors for the delivery of therapeutic genes. This review will focus on various parameters governing lipoplex biological activity, from their mode of formation to in vivo behaviour. Particular emphasis is given to the mechanism of interaction of lipoplexes with cells, in an attempt to dissect the different barriers that need to be surpassed for efficient gene expression to occur. Aspects related to new trends in the formulation of lipid-based gene delivery systems aiming at overcoming some of their limitations will be covered. Finally, examples illustrating the potential of cationic liposomes in clinical applications will be provided.

Combination of 3D tissue engineered scaffold and non-viral gene carrier enhance in vitro DNA expression of mesenchymal stem cells

The objective of this study is to enhance the expression of a plasmid DNA for mesenchymal stem cells (MSC) by combination of 3-dimensional (3D) tissue engineered scaffolds and non-viral gene carrier. As a carrier of plasmid DNA, dextran-spermine cationic polysaccharide was prepared by means of reductive-amination between oxidized dextran and the natural oligoamine, spermine. As the MSC scaffold, collagen sponges reinforced by incorporation of poly(glycolic acid) (PGA) fibers were used. A complex of the cationized dextran and plasmid DNA of BMP-2 was impregnated into the scaffolds. MCS were seeded into each scaffold and cultured by a 3D culture method. When MSC were cultured in the PGA-reinforced sponge, the level of BMP-2 expression was significantly enhanced by the cationized dextran-plasmid DNA complex impregnated into the scaffold than by the cationized dextran-plasmid DNA complex in 2-dimensional (2D) (tissue culture plate) culture method. The alkaline phosphatase activity and osteocalcin content of transfected MSC cultured in the PGA-reinforced sponge were significantly higher compared with 2D culture method. We conclude that combination of cationized dextran plasmid DNA complex and 3D tissue engineered scaffold was promising to promote the in vitro gene expression for MSC.

Gene therapy of the ischemic lower limb--Therapeutic angiogenesis

The limitations of surgical revascularisation and pharmacological treatment in peripheral arterial occlusive disease (PAOD) are well recognized. Therapeutic options for critical leg ischemia are consequently limited to percutaneous transluminal angioplasty (PTA) or surgical revascularisation. Unfortunately, many patients with critical leg ischemia are poor candidates for either procedure. Therapeutic angiogenesis is a novel promising tool to treat these patients. Experimental and clinical and trials of gene transfer for therapeutic angiogenesis have already shown some clinical efficacy. This review is focused on gene transfer techniques in preclinical and clinical therapeutic angiogenesis, angiogenic growth factors, vectors, delivery methods and routes. The results of clinical and experimental studies, safety and side effects of gene therapy, and the perspectives of future research are also discussed.

In vitro characterization and transfection of IL-2 gene complexes

BACKGROUND

Interleukin-2 used in the treatment of malignant tumors has an anti-tumor efficacy. In this study, we have studied in vitro characterization and transfection efficiency of a plasmid encoding hIL-2, pCXWN-hIL-2, complexed to chitosan, polyethylenimine or DOTAP with varying ratios.

METHODS

Plasmid DNA was amplified in Escherichia coli DH5alpha and isolated by alkali lysis method. The pDNA/chitosan, pDNA/PEI or pDNA/DOTAP complexes were analyzed by agarose gel electrophoresis for complex formation and by ESEM image analysis system for the morphology and DNA/medium relationship of complexes. DNase stability, the particle size and zeta potential values of complexes were determined. Transfection efficiencies of resulting complexes in two different cell lines were assayed by ELISA method.

RESULTS

Conclusively, a transfection activity was observed in both cell lines (HeLa and Swiss3T3) with the order of pDNA/DOTAP>pDNA/PEI>pDNA/chitosan complexes. We have observed that the transfection efficiency was higher in HeLa cell line compared to Swiss3T3 cell line.

CONCLUSION

The physicochemical studies like stability, particle size and zeta potential, showed a relationship between the properties of a complex and its transfection efficiency.

Lipid bilayer disruption by polycationic polymers: the roles of size and chemical functional group

Polycationic polymers are used extensively in biology to disrupt cell membranes and thus enhance the transport of materials into the cell. The highly polydisperse nature of many of these materials makes obtaining a mechanistic understanding of the disruption processes difficult. To design an effective mechanistic study, a monodisperse class of polycationic polymers, poly(amidoamine) (PAMAM) dendrimers, has been studied in the context of supported dimyristoylphosphatidylcholine (DMPC) lipid bilayers using atomic force microscopy (AFM). Aqueous solutions of amine-terminated generation 7 (G7) PAMAM dendrimers caused the formation of 15-40-nm-diameter holes in lipid bilayers. This effect was significantly reduced for smaller G5 dendrimers. For G3, no hole formation was observed. In addition to dendrimer size, surface chemistry had a strong influence on dendrimer-lipid bilayer interactions. In particular, acetamide-terminated G5 did not cause hole formation in bilayers. In all instances, the edges of bilayer defects proved to be points of highest dendrimer activity. A proposed mechanism for the removal of lipids by dendrimers involves the formation of dendrimer-filled lipid vesicles. By considering the thermodynamics, interaction free energy, and geometry of these self-assembled vesicles, a model that explains the influence of polymer particle size and surface chemistry on the interactions with lipid membranes was developed. These results are of general significance for understanding the physical and chemical properties of polycationic polymer interactions with membranes that lead to the transport of materials across cell membranes.

Synthetic and natural polycationic polymer nanoparticles interact selectively with fluid-phase domains of DMPC lipid bilayers

Polycationic polymers are known to disrupt lipid bilayers. In this letter, we report the dependence of this disruption on the lipid structural phase. DMPC bilayers are exposed to two polycationic polymeric nanoparticles, PAMAM dendrimers and MSI-78. We find that regions of the bilayer that are in the gel phase are unaffected by the presence of polymers, whereas the liquid phase is disrupted.

Impregnation of Plasmid DNA into Three-Dimensional Scaffolds and Medium Perfusion Enhancein VitroDNA Expression of Mesenchymal Stem Cells

This article describes the development of an in vitro culture system to enhance the expression of a plasmid DNA for mesenchymal stem cells (MSCs) by a combination of plasmid DNA impregnation into three-dimensional cell scaffolds and culture methods. Gelatin was cationized by introducing spermine to the carboxyl groups for complexation with the plasmid DNA. As the MSC scaffold, poly(glycolic acid) (PGA) fiber fabrics, collagen sponges, and collagen sponges reinforced by incorporation of PGA fibers were used. A complex of cationized gelatin and plasmid DNA encoding bone morphogenetic protein 2 (BMP-2) was impregnated into the scaffolds. Plasmid DNA was released from PGA-reinforced collagen sponge for longer than from the other scaffolds. MCS were seeded into each type of scaffold and cultured by static, stirring, and perfusion methods. When MSCs were cultured in PGA-reinforced sponge, the level of BMP-2 expression was significantly enhanced by perfusion culture compared with the other culture methods, and the time of expression was prolonged. Irrespective of the culture method, the expression level was significantly higher from plasmid DNA impregnated in scaffold than by plasmid DNA in medium. The alkaline phosphatase activity and osteocalcin content of MSCs cultured in PGA-reinforced sponge by the perfusion method were significantly higher compared with those of other methods, and a significantly higher amount of plasmid DNA internalized into MSCs was observed. We conclude that a combination of plasmid DNA-impregnated PGA-reinforced sponge and the perfusion method was promising to promote in vitro gene expression for MSCs.

Metalloproteinase and cytokine production by THP-1 macrophages following exposure to chitosan-DNA nanoparticles

The use of nanoparticles for gene therapy is gaining more and more interest for medical applications. Chitosan is among the candidate polymers that have a potential application as a gene delivery system. Before using chitosan-DNA nanoparticles in vivo, one must study their interaction and cell's behavior. Since macrophages play an important role in inflammatory processes, this study was performed to investigate the effects of chitosan-DNA nanoparticles on human THP-1 cell line. Cytokine (TNF-alpha, IL-1beta, IL-6 and IL-10) and metalloproteinase (MMP-2 and MMP-9) release as well as their inhibitors (TIMP-1 and TIMP-2) were assessed after time course incubation with different amount of nanoparticles. Their secretion was quantified by enzyme-linked immunosorbent assay. Gelatinolytic activity of MMP-2 and MMP-9 was determined by zymography in cell supernatants and lysates. Cytokine secretion was not detected even in the presence of high amount of nanoparticles. On the contrary, the secretion of MMP-9 in cell supernatants increased significantly after 24 and 48 h in comparison with non-treated cells. MMP-2 secretion was augmented only after 48 h for the highest concentrations of nanoparticles (10 and 20 microg/ml DNA content). However, zymography studies showed that the secreted MMPs were in the proactive forms, while the active form of MMP-9, but not MMP-2, was detected in cell lysates when 10 and 20 microg/ml DNA containing nanoparticles were used. In conclusion, exposure of THP-1 macrophages to Ch-DNA nanoparticles did not induce release of proinflammatory cytokines. The presence of active MMP-9 within the macrophages could possibly be related to nanoparticle phagocytosis and degradation rather than to inflammatory reactions.

Hydrophobized dextran-spermine conjugate as potential vector for in vitro gene transfection

Dextran polysaccharide was grafted by reductive-amination with mixtures of spermine and other natural/synthetic oligoamines of two to four amine groups. The transfection efficiencies of the polycations thus obtained were assessed in various cell lines, and found to depend on the spermine contents. Higher spermine ratios of grafted oligoamines resulted in high gene expression, whereas low to negligible expressions were obtained with lower spermine contents. The effect was explained by spermine residues which exhibit altered buffering capacity in comparison to other substituted oligoamines. Hydrophobization of dextran-spermine (D-SPM) was achieved by treating the polymer with N-hydroxysuccinimide derivatives of cholesterol and fatty acids in a mixture of water/THF. The degree of hydrophobization was in the range of 1-30% mol/mol (hydrophobic moieties/primary amine) and the coupling yields were >95% as determined by (1)H-NMR. The oleate-modified D-SPM remarkably enhanced the gene expression in serum rich media, in marked contrast to unmodified D-SPM which resulted with a drastic decrease in the transfection yields. Modified D-SPM derivatives of other fatty acids and cholesterol showed improved transfection yields in comparison to unmodified D-SPM, but to a lower extent when compared to oleate modification. The improvement in cell transfection was attributed to oleate residues which probably play a role in increasing stability and uptake of polycation-DNA complexes.

Synthesis, characterization and transfection activity of new saturated and unsaturated cationic lipids

We synthesized new cationic lipids, analogue to N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) and 1,2-dimyristyloxypropyl-3-dimethyl-hydroxyethylammonium bromide (DMRIE), in order to compare those containing a dodecyl chain with those having a relatively long chain with two or five double bonds, such as squalenyl and dihydrofarnesyl derivatives, or complex saturated structures, such as squalane derivatives. The fusogenic helper lipid dioleoylphosphatidylethanolamine (DOPE) was added to cationic lipids to form a stable complex. Liposomes composed of 50:50 w/w cationic lipid/DOPE were prepared and incubated with plasmidic DNA at various charge ratios and the diameter and zeta potential of the complexes were measured. The surface charge of the DNA/lipid complexes can be controlled by adjusting the cationic lipid/DNA ratio. Finally, we tested the in vitro transfection efficiency of the cationic lipid/DNA complexes using different cell lines. The transfection efficiency was highest for the dodecyloxy derivative containing a single hydroxyethyl group in the head, followed by the dodecyloxy and the farnesyloxy trimethylammonium derivatives. Instead the C27 squalenyl and C27 squalanyl derivatives resulted inactive.

Phase structures of a hydrated anionic phospholipid composition containing cationic dendrimers and pegylated lipids

The effect of 4th generation poly(amidoamine) dendrimer (4G PAMAM) present in an anionic phospholipid composition, consisting of hydrogenated soyphosphatidylcholine (HSPC), cholesterol (CH), dicetyl phosphate (DCP), and poly(ethylene glycol) (Mw approximately 2000) derivatized phosphatidylethanolamine (PEG2000-PE), on the hydration and liquid crystalline structure formation was investigated. The optical and polarized light microscopies of the liposomal dispersion obtained from the hydrated lipid composition show two types of birefringent structures (mesophases): plastic, wormlike microstructures and conventional, over-elongated lamellae. Differential scanning calorimetry (DSC) shows an increase in the liquid crystalline phase transition (Tg) of the lipid composition from 60 to 94 degrees C with increasing 4G PAMAM concentrations from 0 to 0.011 mM, respectively. The Tg values of the two microstructures were 68 and 84 degrees C, respectively, indicating that the plastic microstructures were 4G PAMAM/DCP-complexes-rich (alpha mesophases) and the conventional and elongated lamellae were dendrimer-doped HSPC/CH-rich microstructures (beta mesophases). Optical microscopy shows that the alpha mesophases convert into various other types of vesicular structures such as giant unilamellar vesicles and biliquid foams, upon heating above the phase transition temperature of the lipid composition (approximately 60-65 degrees C). The microstructure transformation is a result of an osmotic influx of water and the detergent action of PEG2000-PE present in the lipid composition. The transmission electron microscopy (TEM) images of the liposomal dispersion show particles embedding circular transparent domains that exactly correlate to the theoretical 4G PAMAM/DCP complex sizes, thus, providing evidence of 4G PAMAM interspersed within the two mesophases. Small-angle X-ray scattering (SAXS) measurements indicate that the alpha mesophases are a dendrimer-interlinked, symmetrically undulated lamellar phase and the beta mesophases are dendrimer-doped, occasionally kinked lamellae. An increase in dendrimer concentration in the lipid composition was found to decrease interlamellar spacing. On the basis of optical microscopy, DSC, TEM, and SAXS data, a model of dendrimer-doped mesophase structure and lamellae fusion is proposed. This investigation provides new self-assembled materials for drug/gene delivery and supplements the understanding of mechanisms involved in various biological processes such as membrane fusion, transmembrane permeation, and endocytosis.

Expression of luciferase in selected organs following delivery of naked and formulated DNA to rainbow trout (Oncorhynchus mykiss) by different routes of administration

In the present work, the expression of luciferase in selected organs following administration of DNA delivered as naked, liposome-formulated or chitosan-formulated by different routes of administration (intramuscular, intraperitoneal and intravenous injection, immersion and anal intubation) was studied in rainbow trout (Oncorhynchus mykiss). The different formulations and routes of administration both influenced in which organs luciferase was expressed and the magnitude of expression. The highest expression levels of luciferase in the head kidney and liver were found after an intraperitoneal injection of lipoplex 2. In the spleen, the highest levels were detected after injection of naked DNA (intraperitonal or intramuscular) and lipoplex 2 (intraperitoneal). Following intravenous injection, naked DNA gave higher expression levels in the organs than the formulated plasmids and immersion and anal intubation were not effective routes of delivery as no expression of luciferase could be detected in any of the organs tested. Additionally, PCR using a primer specific for a 600 bp region of the luciferase gene pcDNA3-luc was used to assess the distribution of the plasmid itself after intramuscular and intraperitoneal injection. Positive amplification was obtained in spleen, head kidney, liver and muscle at the injection site following injection of formulated plasmids, while only muscle tissue from the injection site was positive when naked DNA was used.

Dextran–spermine polycation: an efficient nonviral vector for in vitro and in vivo gene transfection

Dextran-spermine cationic polysaccharide was prepared by means of reductive amination between oxidized dextran and the natural oligoamine spermine. The formed Schiff-base imine-based conjugate was reduced with borohydride to obtain the stable amine-based conjugate. The transfection efficiency of the synthetic dextran-spermine was assessed in vitro on HEK293 and NIH3T3 cell lines and found to be as high as the DOTAP/Chol 1/1 lipid-based transfection reagent. Modification of the dextran-spermine polycation with polyethylene glycol resulted in high transfection yield in serum-rich medium. Intramuscular injection in mice of dextran-spermine-pSV-LacZ complex induced high local gene expression compared to low expression of the naked DNA. Intravenous injection of a dispersion of the dextran-spermine-pSV-LacZ complex resulted with no expression in all examined organs. When the partially PEGylated dextran-spermine-pSV-LacZ complex was intravenously applied, a high gene expression was detected mainly in the liver. Preliminary targeting studies indicated that the PEGylated dextran-spermine-pSV-LacZ complex bound to galactose receptor of liver parenchymal cells rather than the mannose receptor of liver nonparenchymal cells. This work offers a new biodegradable polycation based on natural components, which is capable of transfecting cells and tissues in vitro and in vivo.

Photon correlation spectroscopy investigations of proteins

Physical principles of photon correlation spectroscopy (PCS), mathematical treatment of the PCS data (converting autocorrelation functions to distribution functions or average characteristics), and PCS applications to study proteins and other biomacromolecules in aqueous media are described and analysed. The PCS investigations of conformational changes in protein molecules, their aggregation itself or in consequence of interaction with other molecules or organic (polymers) and inorganic (e.g. fumed silica) fine particles as well as the influence of low molecular compounds (surfactants, drugs, salts, metal ions, etc.) reveal unique capability of the PCS techniques for elucidation of important native functions of proteins and other biomacromolecules (DNA, RNA, etc.) or microorganisms (Escherichia coli, Pseudomonas putida, Dunaliella viridis, etc.). Special attention is paid to the interaction of proteins with fumed oxides and the impact of polymers and fine oxide particles on the motion of living flagellar microorganisms analysed by means of PCS.

Phosphatidylethanolamine mediated destabilization of lipid-based pDNA delivery systems

We have previously reported the development of lipid-DNA particles (LDPs) formed, via a hydrophobic cationic lipid-DNA complex intermediate, when detergent-solubilized cationic lipids are mixed with DNA. This study investigates the influence of zwitterionic co-lipid headgroups on the formation and stability of this intermediate and the subsequent DNA protection and transfection properties afforded by the resultant LDPs. We report that inclusion of diacylphosphatidylethanolamines (diacylPE), but not diacylphosphatidylcholines (diacylPC), as co-lipids destabilizes and prevents the formation of the cationic lipid-DNA intermediate to an extent dependent on the concentration of diacylPE and its acyl chain characteristics. DNA formulated in LDPs containing cationic:zwitterionic lipids at a 1:1 ratio is not readily accessible to the intercalating fluorescent dye, TO-PRO-1. At a lipid ratio 1:4, diacylPC LDPs are associated with significantly greater TO-PRO-1 fluorescence than equivalent diacylPE formulations, a result believed to reflect lipid-dependent penetration of TO-PRO-1 through the supramolecular LDP assembly, rather than condensation and protection of the DNA per se. Transfection studies utilizing the in vitro murine B16/BL6 melanoma cell line and the in vivo intraperitoneal B16/BL6 mouse tumor model demonstrated that only diacylPE LDPs mediated gene transfer. This was found not to be a consequence of differences in DNA delivery or cell toxicity.

In vitro cytotoxicity testing of polycations: influence of polymer structure on cell viability and hemolysis

A comparative in vitro cytotoxicity study with different water-soluble, cationic macromolecules which have been described as gene delivery systems was performed. Cytotoxicity in L929 mouse fibroblasts was monitored using the MTT assay and the release of the cytosolic enzyme lactate dehydrogenase (LDH). Microscopic observations were carried out as indicators for cell viability. Furthermore, hemolysis of erythrocytes was quantified spectrophotometrically. To determine the nature of cell death induced by the polycations, the nuclear morphology after DAPI staining and the inhibition of the toxic effects by the caspase inhibitor zVAD.fmk were investigated. All assays yielded comparable results and allowed the following ranking of the polymers with regard to cytotoxicity: Poly(ethylenimine)=poly(L-lysine)>poly(diallyl-dimethyl-ammonium chloride)>diethylaminoethyl-dextran>poly(vinyl pyridinium bromide)>Starburst dendrimer>cationized albumin>native albumin. The magnitude of the cytotoxic effects of all polymers were found to be time- and concentration dependent. The molecular weight as well as the cationic charge density of the polycations were confirmed as key parameters for the interaction with the cell membranes and consequently, the cell damage. Evaluating the nature of cell death induced by poly(ethylenimine), we did not detect any indication for apoptosis suggesting that the polymer induced a necrotic cell reaction. Cell nuclei retained their size, chromatin was homogenously distributed and cell membranes lost their integrity very rapidly at an early stage. Furthermore, the broad spectrum caspase inhibitor zVAD.fmk did not inhibit poly(ethylenimine)-induced cell damage. Insights into the structure-toxicity relationship are necessary to optimize the cytotoxicity and biocompatibility of non-viral gene delivery systems.