Efficient Gene Delivery Vectors Research Articles

Collagen synthesis promoting pullulan–PEI–ascorbic acid conjugate as an efficient anti-cancer gene delivery vector

Cationized pullulan (pullulan–PEI; PP) was synthesized and further modified with an anti-oxidant molecule, ascorbic acid (PPAA) at various ratios. The nanoplexes formed at an optimum ratio of 4:1 was within a size of 150nm and had a zeta potential of 9–14mV. The nanoplexes at this ratio was used for further investigations. The cell internalization and transfection efficiency of these nanoplexes were determined in presence of serum. The internalization and transfection efficiency were found to be unaffected by the presence of fetal bovine serum. Another interesting observation was that this polymer was found to have collagen synthesis promoting property. The collagen synthesis effect of these polymers was quantified and observed that PPAA3 promoted the highest. Transfection efficiency was evaluated by assessing the p53 gene expression in C6 rat glioma cells and cell death was quantified to be 96% by flow cytometry, thus establishing the high efficacy of this polymer.

A Tailor‐Made Specific Anion‐Binding Motif in the Side Chain Transforms a Tetrapeptide into an Efficient Vector for Gene Delivery

AbstractArginine‐rich cell‐penetrating peptides are widely utilized as vectors for gene delivery. However, their transfection efficacy still needs to be optimized. To accomplish this, guanidinocarbonylpyrrole groups, which are tailor‐made anion binding sites, were introduced into the side chains of tetralysine to obtain the peptide analogue 1. In contrast to the common strategy of adding a lipophilic tail to peptide vectors, this novel method most likely enhances transfection efficacy through more specific interactions between the binding motifs and DNA or the cell membrane. Tetrapeptide analogue 1 is thus the smallest peptidic transfection vector that has been reported to date. The transfection efficacy of 1, which on average has less than two positive charges under physiological conditions, is even better than that of polyethylenimine (PEI). Furthermore, 1 exhibits only negligible cytotoxicity, which makes it an interesting candidate for further development.

Development of hybrid-type modified chitosan derivative nanoparticles for the intracellular delivery of midkine-siRNA in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Most of the patients with HCC lose the surgical opportunity at the time of diagnosis. Some novel therapeutic modalities, like gene therapy, are promising for the treatment of HCC. However, the success of gene therapy depends on two aspects: efficient gene materials and gene delivery vectors. The present study was to develop new chitosan-based nanoparticles for a midkine-siRNA (anti-HCC gene drug) delivery. The novel gene delivery vector (MixNCH) was synthesized by hybrid-type modification of chitosan with 2-chloroethylamine hydrochloride and N, N-dimethyl-2-chloroethylamine hydrochloride. The chemical structure of MixNCH was characterized by FT-IR and 1HNMR. The cytotoxicity of MixNCH was determined by MTS assay. The gene condensation ability and size, zeta potential and morphology of MixNCH/MK-siRNA nanoparticles were measured. The in vitro transfection and gene knockdown efficiency of midkine by MixNCH/MK-siRNA nanoparticles was detected by qRT-PCR and Western blotting. Gene knockdown effect at the molecule level on the proliferation of HepG2 in vitro was determined by MTS assay. MixNCH was successfully acquired by aminoalkylation modification of chitosan. The MixNCH could condense MK-siRNA well above the weight ratio of 3. The average size of MixNCH/MK-siRNA nanoparticles was 100-200 nm, and the surface charge was about +5 mV. Morphologically, MixNCH/MK-siRNA nanoparticles were in regular spherical shape with no aggregation. Regarding to the in vitro transfection of nanoparticles, the MixNCH/MK-siRNA nanoparticles reduced MK mRNA level to 14.03%+/-4.03%, which were comparable to Biotrans (8.94%+/-3.77%). MixNCH/MK-siRNA effectively inhibited the proliferation of HepG2 in vitro. MixNCH/MK-siRNA nanoparticles could be effective for the treatment of hepatocellular carcinoma.

A tailor-made specific anion-binding motif in the side chain transforms a tetrapeptide into an efficient vector for gene delivery.

Arginine-rich cell-penetrating peptides are widely utilized as vectors for gene delivery. However, their transfection efficacy still needs to be optimized. To accomplish this, guanidinocarbonylpyrrole groups, which are tailor-made anion binding sites, were introduced into the side chains of tetralysine to obtain the peptide analogue 1. In contrast to the common strategy of adding a lipophilic tail to peptide vectors, this novel method most likely enhances transfection efficacy through more specific interactions between the binding motifs and DNA or the cell membrane. Tetrapeptide analogue 1 is thus the smallest peptidic transfection vector that has been reported to date. The transfection efficacy of 1, which on average has less than two positive charges under physiological conditions, is even better than that of polyethylenimine (PEI). Furthermore, 1 exhibits only negligible cytotoxicity, which makes it an interesting candidate for further development.

Efficient gene delivery to photoreceptors using AAV2/rh10 and rescue of the Rho−/− mouse

As gene therapies for various forms of retinal degeneration progress toward human clinical trial, it will be essential to have a repertoire of safe and efficient vectors for gene delivery to the target cells. Recombinant adeno-associated virus (AAV) serotype 2/2 has been shown to be well tolerated in the human retina and has provided efficacy in human patients for some inherited retinal degenerations. In this study, the AAV2/8 and AAV2/rh10 serotypes have been compared as a means of gene delivery to mammalian photoreceptor cells using a photoreceptor specific promoter for transgene expression. Both AAV2/8 and AAV2/rh10 provided rescue of the retinal degeneration present in the rhodopsin knockout mouse, with similar levels of benefit as evaluated by molecular, histological, and functional readouts. Transgene expression levels were significantly higher (fivefold) 1 week postsubretinal injection when employing AAV2/8 for rhodopsin gene delivery compared to AAV2/rh10, and were indistinguishable by 6 weeks postadministration of vector. This study reports the use of the AAV2/rh10 serotype to provide rescue in a degenerating retina and provides a comparative evaluation of AAV2/rh10 with respect to AAV2/8, a serotype regarded as providing efficient delivery to photoreceptors.

Mixing-sequence-dependent nucleic acid complexation and gene transfer efficiency by polyethylenimine.

Polyplexes, complexed nucleic acids by cationic polymers, are the most common forms of nonviral gene delivery vectors. In contrast to a great deal of efforts in synthesizing novel cationic polymers and exploring their extracellular and intracellular delivery pathways, polyplex preparation methods of mixing nucleic acids and cationic polymers are often overlooked. In this study, the mixing sequence, that is adding nucleic acids to polymers or vice versa, was found to greatly affect complexation of both plasmid DNA and siRNA, polyplexes' size, and polyplexes' surface charge, which all collaboratively affected the transfection efficiency and cytotoxicity. Adding polyethylenimine (PEI), the most conventionally used standard in nonviral gene delivery, to plasmid DNA and siRNA resulted in larger polyplexes, higher gene expression and silencing, but higher cytotoxicity than polyplexes prepared in the reverse order. Based on the experimental results, the authors developed a model that gradual addition of cationic polymers (e.g., PEI) to nucleic acids (e.g., plasmid DNA and siRNA) incorporates more copies of nucleic acids in larger polyplexes in a smaller number, results in higher gene expression and silencing levels in transfected cells, and generates higher cytotoxicity by leaving more free polymers upon complete mixing than the other mixing sequence. The proposed model can be explored using a broad range of cationic polymers and nucleic acids, and provide insightful information about how to prepare polyplexed nonviral vectors for efficient and safe gene delivery.

Bioreducible dextran-polyethylenimine conjugates regulate transgene expression distribution in vivo.

The purpose of this work is to design a well-defined cationic dextran for intravenous gene delivery into tumor and examine the effect of the dextran on transfection efficacy in vivo. To this end, disulfide-linked dextran-linear polyethylenimine (Dex-SS-LPEI) conjugates were designed as non-viral vectors for intravenous gene delivery into tumor-bearing Balb/c nude mice. By coupling different molecular weights (2 kDa or 5 kDa) of LPEI disulfide pyridine to thiolated dextran (5 kDa or 10 kDa), Dex-SS-LPEI conjugates were prepared which have dextran as the main chain and disulfide-linked LPEI as the side chain. Dex-SS-LPEI conjugates can condense gene into nanosized polyplexes with moderate surface charge. Besides, the polyplexes of the conjugates have an improved colloidal stability under physiological conditions as compared to that of 22 kDa LPEI lacking dextran and can liberate gene by disulfide cleavage in an intracellular reducing environment. In vitro transfection experiments manifest that Dex-SS-LPEI conjugates mediate efficient gene transfection in different cells. The most efficient transfection in vitro was found for the conjugate with 5 kDa dextran and 5 kDa LPEI. Besides, Dex-SS-LPEI conjugates are practical for systemic gene delivery into tumor-bearing Balb/c nude mice by intravenous injection, affording comparable or higher transgene expression in HepG2 or SKOV-3 tumor than that yielded by 22 kDa LPEI as a positive control. Further, the polyplexes of the conjugate with 10 kDa dextran and 5 kDa LPEI can induce comparable transgene expression in the tumor but lower expression in the lung when compared to those of 22 kDa LPEI. The results of this study indicate that dextran plays a critical role in regulating in vivo gene delivery properties of Dex-SS-LPEI conjugates and transfection efficacy in tumor-xenografted nude mice. Dex-SS-LPEI conjugates have low cytotoxicity in vitro and cause no death of the mice, showing great potential as safe and highly efficient gene delivery vectors towards cancer gene therapy.

Synergistic effect of amino acids modified on dendrimer surface in gene delivery

Design of an efficient gene vector based on dendrimer remains a great challenge due to the presence of multiple barriers in gene delivery. Single-functionalization on dendrimer cannot overcome all the barriers. In this study, we synthesized a list of single-, dual- and triple-functionalized dendrimers with arginine, phenylalanine and histidine for gene delivery using a one-pot approach. The three amino acids play different roles in gene delivery: arginine is essential in formation of stable complexes, phenylalanine improves cellular uptake efficacy, and histidine increases pH-buffering capacity and minimizes cytotoxicity of the cationic dendrimer. A combination of these amino acids on dendrimer generates a synergistic effect in gene delivery. The dual- and triple-functionalized dendrimers show minimal cytotoxicity on the transfected NIH 3T3 cells. Using this combination strategy, we can obtain triple-functionalized dendrimers with comparable transfection efficacy to several commercial transfection reagents. Such a combination strategy should be applicable to the design of efficient and biocompatible gene vectors for gene delivery.

Multifunctional disulfide-based cationic dextran conjugates for intravenous gene delivery targeting ovarian cancer cells.

A folate-decorated, disulfide-based cationic dextran conjugate having dextran as the main chain and disulfide-linked 1,4-bis(3-aminopropyl)piperazine (BAP) residues as the grafts was designed and successfully prepared as a multifunctional gene delivery vector for targeted gene delivery to ovarian cancer SKOV-3 cells in vitro and in vivo. Initially, a new bioreducible cationic polyamide (denoted as pSSBAP) was prepared by polycondensation reaction of bis(p-nitrophenyl)-3,3'-dithiodipropanoate, a disulfide-containing monomer, and BAP. It was found that the pSSBAP was highly efficient for in vitro gene delivery against MCF-7 and SKOV-3 cell lines. Subsequently, two cationic dextran conjugates with different amounts of BAP residues (denoted as Dex-SSBAP6 and Dex-SSBAP30, respectively) were synthesized by coupling BAP to disulfide-linked carboxylated dextran or coupling pSSBAP-oligomer to p-nitrophenyl carbonated dextran. Both two conjugates were able to bind DNA to form nanosized polyplexes with an improved colloidal stability in physiological conditions. The polyplexes, however, were rapidly dissociated to liberate DNA in a reducing environment. In vitro transfection experiments revealed that the polyplexes of Dex-SSBAP30 efficiently transfected SKOV-3 cells, yielding transfection efficiency that is comparable to that of linear polyethylenimine or lipofectamine 2000. AlamarBlue assay showed that the conjugates had low cytotoxicity in vitro at a high concentration of 100 mg/L. Further, Dex-SSBAP30 has primary amine side groups and thus allows for folate (FA) conjugation, yielding FA-coupled Dex-SSBAP30 (Dex-SSBAP30-FA). It was found that Dex-SSBAP30-FA was efficient for targeted gene delivery to SKOV-3 tumor xenografted in a nude mouse model by intravenous injection, inducing a higher level of gene expression in the tumor as compared to Dex-SSBAP30 lacking FA and comparable gene expression to linear polyethylenimine as one of the most efficient polymeric vectors for intravenous gene delivery in vivo. Disulfide-based cationic dextran system thus has a high potential for intravenous gene delivery toward cancer gene therapy.

Dendritic polyglycerol with secondary amine shell as an efficient gene delivery vector with reduced toxicity

Dendritic polycation (PG‐BEN) using polyglycerol as a core and secondary amine shell consisting of N1,N11‐bisethylnorspermine (BEN) was synthesized. Polymers containing primary amines in the shell (PG‐Nor and PG‐NH2) were synthesized as controls to allow evaluation of the shell effect on physicochemical and transfection properties of the polymers. All studied polymers condensed DNA and formed polyplexes with sizes less than 110 nm. PG‐BEN and PG‐Nor had a similar transfection activity that was fully comparable with that of the control polyethylenimine. Amongst the studied polymers, PG‐BEN demonstrated the lowest cytotoxicity, suggesting that PG‐BEN is a promising gene delivery vector with favorable transfection/toxicity profile. Copyright © 2014 John Wiley & Sons, Ltd.

Polyamidoamine dendrimer and oleic acid-functionalized graphene as biocompatible and efficient gene delivery vectors.

Functionalized graphene has good potential in biomedical applications. To address a better and multiplex design of graphene-based gene vectors, the graphene-oleate-polyamidoamine (PAMAM) dendrimer hybrids were synthesized by the oleic acid adsorption and covalent linkage of PAMAM dendrimers. The micromorphology, electrical charge property, and amount of free amine groups of the graphene-oleate-PAMAM hybrids were characterized, and the peripheral functional groups were identified. The PAMAM dendrimers could be tethered onto graphene surface in high density. The graphene-oleate-PAMAM hybrids exhibit relatively good dispersity and stability in aqueous solutions. To evaluate the potential application of the hybrids in gene delivery vectors, cytotoxicity to HeLa and MG-63 cells and gene (plasmid DNA of enhanced green fluorescent protein) transfection capacity of the hybrids were investigated in detail. The graphene-oleate-PAMAM hybrids show mammalian cell type- and dose-dependent in vitro cytotoxicity. Under the optimal condition, the hybrids possess good biocompatibility and gene transfection capacity. The surface modification of graphene with oleic acid and PAMAM improves the gene transfection efficiency 13 times in contrast to the ultrasonicated graphene. Moreover, the hybrids show better transfection efficiency than the graphene oxide-PAMAM without the oleic acid modification.

Poly(2-hydroxyethyl methacrylate)-b-poly(L-Lysine) cationic hybrid materials for non-viral gene delivery in NIH 3T3 mouse embryonic fibroblasts.

In order to develop efficient and nontoxic gene delivery vectors, a series of biocompatible block copolymers, poly[(2-hydroxyethyl methacrylate)40 -block-(L-lysine)n ] (n = 40, 80, 120, 150), are prepared by combining an atom transfer radical polymerization of 2-hydroxyethyl methacrylate with a ring-opening polymerization of N(ϵ) -(carbobenzoxy)-L-lysine N-carboxyanhydride. The block copolymers are successfully condensed with plasmid DNA (pDNA) into nanosized (<200 nm) polyplexes. As a representative sample, p(HEMA)40 -b-p(lys)150 is utilized to confirm the effective cellular and nuclear uptake of pDNA. The polymer/pDNA polyplexes exhibit very low cytotoxicity and enhanced transfection activity by being easily taken up into mouse embryonic fibroblast cell line (NIH 3T3). Thus, the chimeric block copolymers provide a means for developing versatile nonviral gene vectors harboring the ideal requirements of low cytotoxicity, good stability, and high transfection efficiency for gene therapy.

A sight on the current nanoparticle-based gene delivery vectors.

Nowadays, gene delivery for therapeutic objects is considered one of the most promising strategies to cure both the genetic and acquired diseases of human. The design of efficient gene delivery vectors possessing the high transfection efficiencies and low cytotoxicity is considered the major challenge for delivering a target gene to specific tissues or cells. On this base, the investigations on non-viral gene vectors with the ability to overcome physiological barriers are increasing. Among the non-viral vectors, nanoparticles showed remarkable properties regarding gene delivery such as the ability to target the specific tissue or cells, protect target gene against nuclease degradation, improve DNA stability, and increase the transformation efficiency or safety. This review attempts to represent a current nanoparticle based on its lipid, polymer, hybrid, and inorganic properties. Among them, hybrids, as efficient vectors, are utilized in gene delivery in terms of materials (synthetic or natural), design, and in vitro/in vivo transformation efficiency.

In vivo image analysis of BoHV-4-based vector in mice.

Due to its biological characteristics bovine herpesvirus 4 (BoHV-4) has been considered as an appropriate gene delivery vector. Its genomic clone, modified as a bacterial artificial chromosome (BAC), is better genetically manipulable and can be used as an efficient gene delivery and vaccine vector. Although a large amount of data have been accumulated in vitro on this specific aspect, the same cannot be asserted for the in vivo condition. Therefore, here we investigated the fate of a recombinant BoHV-4 strain expressing luciferase (BoHV-4-A-CMVlucΔTK) after intraperitoneal or intravenous inoculation in mice, by generating a novel recombinant BoHV-4 expressing luciferase (BoHV-4-A-CMVlucΔTK) and by following the virus replication through in vivo imaging analysis. BoHV-4-A-CMVlucΔTK was first characterized in vitro where it was shown, on one hand that its replication properties are identical to those of the parental virus, and on the other that the transduced/infected cells strongly express luciferase. When BoHV-4-A-CMVlucΔTK was inoculated in mice, either intraperitoneally or intravenously, BoHV-4-A-CMVlucΔTK infection/transduction was exclusively localized to the liver, as detected by in vivo image analysis, and in particular almost exclusively in the hepatocytes, as determined by immuno-histochemistry. These data, that add a new insight on the biology of BoHV-4 in vivo, provide the first indication for the potential use of a BoHV-4-based vector in gene-transfer in the liver.

Circumventing Antivector Immunity: Potential Use of Nonhuman Adenoviral Vectors

Adenoviruses are efficient gene delivery vectors based on their ability to transduce a wide variety of cell types and drive high-level transient transgene expression. While there have been advances in modifying human adenoviral (HAdV) vectors to increase their safety profile, there are still pitfalls that need to be further addressed. Preexisting humoral and cellular immunity against common HAdV serotypes limits the efficacy of gene transfer and duration of transgene expression. As an alternative, nonhuman AdV (NHAdV) vectors can circumvent neutralizing antibodies against HAdVs in immunized mice and monkeys and in human sera, suggesting that NHAdV vectors could circumvent preexisting humoral immunity against HAdVs in a clinical setting. Consequently, there has been an increased interest in developing NHAdV vectors for gene delivery in humans. In this review, we outline the recent advances and limitations of HAdV vectors for gene therapy and describe examples of NHAdV vectors focusing on their immunogenicity, tropism, and potential as effective gene therapy vehicles.

Introducing primary and tertiary amino groups into a neutral polymer: A simple way to fabricating highly efficient nonviral vectors for gene delivery

AbstractIn this work, a brushed polycationic polymer with primary and tertiary amino groups was designed and synthesized for gene delivery. The backbone polymer was poly(N‐hydroxyethylacrylamide) (PHEAA) by the atom transfer radical polymerization (ATRP), and then 3,3′‐diaminodipropylamine (DPA) was grafted onto the PHEAA by the reaction between hydroxyl and the secondary amine. A brushed PHEAA‐DPA cationic polymer was achieved with primary and tertiary amino groups and the ratio was 2 : 1. The PHEAA100‐DPA and PHEAA200‐DPA could effectively condense plasmid DNA (pDNA) at the weight ratio of vector/DNA of 0.6 and 0.4, respectively. The cytotoxicity of PHEAA‐DPA/pDNA to COS‐7 cells and HepG‐2 cells within the weight ratio of vector/DNA of 16 : 1 was lower than that of PEI25k, and cell viability decreased with the increment of the weight ratio. Although the cytotoxicity of PHEAA100‐DPA/pDNA was lower than PHEAA200‐DPA/pDNA, the latter possessed higher transfection efficiency at the same weight ratio both in COS‐7 cells and HepG‐2 cells, compared with PEI25k, the transfection efficiency of PHEAA200‐DPA/pDNA was better in COS‐7 cells and HepG‐2 cells with the weight ratio of 12 : 1 and 10 : 1, respectively. These results showed that the PHEAA‐DPA with less cytotoxicity and higher gene transfection efficiency has a broad perspective in gene therapy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40468.

Improving transfection efficiency of ultrapure oligochitosan/DNA polyplexes by medium acidification

Context: Ultrapure oligochitosans (UOCs) have recently been reported as efficient nonviral vectors for corneal and retinal gene delivery. However, the influence of some physicochemical factors on the transfection efficiency, such as the pH, remains unclear. Deeper in vitro research of these factors could provide valuable information for future clinical applications.Objective: The aim of this study is to determine the influence of the pH decrease on the transfection efficiency of UOC/pDNA polyplexes in HEK293 and ARPE19 cells.Materials and methods: We elaborated self-assembled UOC/pCMS-EGFP polyplexes. The influence of the most important factors on the particle size and the zeta potential was studied by an orthogonal experimental design. We evaluated, in vitro, the cellular uptake and the transfection efficiency by flow cytometry, and the cytotoxicity of the vectors by CCK-8 assay.Results and discussion: The pH of the medium strongly influences the physicochemical properties of the polyplexes, and by its modulation we are able to control their superficial charge. A significant increase on the cellular uptake and transfection efficiency of UOCs was obtained when the pH was acidified. Neither of our UOC/pCMS-EGFP polyplexes caused cytotoxicity; however, cells treated with Lipofectamine 2000™ showed decreased cell viability.Conclusion: This kind of UOC vectors could be useful to transfect cells that are in an acidic environment, such as tumor cells. However, additional in vivo studies may be required in order to obtain an effective and safe medicine for nonviral gene therapy purpose.

Oligopeptide-terminated poly(β-amino ester)s for highly efficient gene delivery and intracellular localization

The main limitation of gene therapy towards clinics is the lack of robust, safe and efficient gene delivery vectors. This paper describes new polycations for gene delivery based on poly(β-amino ester)s (pBAE) containing terminal oligopeptides. The authors developed oligopeptide-modified pBAE–pDNA nanoparticles that achieve better cellular viability and higher transfection efficacy than other end-modified pBAE and commercial transfection agents. Gene expression in highly permissive cell lines was remarkably high, but transfection efficiency in less-permissive cell lines was highly dependent on oligopeptide composition and nanoparticle formulation. Moreover, the use of selected oligopeptides in the pBAE formulation led to preferential intracellular localization of the particles. Particle analysis of highly efficient pBAE formulations revealed different particle sizes and charge features, which indicates chemical pseudotyping of the particle surface, related to the oligopeptide chemical nature. In conclusion, chemical modification at the termini of pBAE with amine-rich oligopeptides is a powerful strategy for developing delivery systems for future gene therapy applications.

Chitosan-Graft-Polyethylenimine/DNA Nanoparticles as Novel Non-Viral Gene Delivery Vectors Targeting Osteoarthritis

The development of safe and efficient gene carriers is the key to the clinical success of gene therapy. The present study was designed to develop and evaluate the chitosan-graft-polyethylenimine (CP)/DNA nanoparticles as novel non-viral gene vectors for gene therapy of osteoarthritis. The CP/DNA nanoparticles were produced through a complex coacervation of the cationic polymers with pEGFP after grafting chitosan (CS) with a low molecular weight (Mw) PEI (Mw = 1.8 kDa). Particle size and zeta potential were related to the weight ratio of CP:DNA, where decreases in nanoparticle size and increases in surface charge were observed as CP content increased. The buffering capacity of CP was significantly greater than that of CS. The transfection efficiency of CP/DNA nanoparticles was similar with that of the Lipofectamine™ 2000, and significantly higher than that of CS/DNA and PEI (25 kDa)/DNA nanoparticles. The transfection efficiency of the CP/DNA nanoparticles was dependent on the weight ratio of CP:DNA (w/w). The average cell viability after the treatment with CP/DNA nanoparticles was over 90% in both chondrocytes and synoviocytes, which was much higher than that of PEI (25 kDa)/DNA nanoparticles. The CP copolymers efficiently carried the pDNA inside chondrocytes and synoviocytes, and the pDNA was detected entering into nucleus. These results suggest that CP/DNA nanoparticles with improved transfection efficiency and low cytotoxicity might be a safe and efficient non-viral vector for gene delivery to both chondrocytes and synoviocytes.

Synthesis and evaluation of tetramethylguanidinium-polyethylenimine polymers as efficient gene delivery vectors.

Previously, we demonstrated that 6-(N,N,N′,N′-tetramethylguanidinium chloride)-hexanoyl-polyethylenimine (THP) polymers exhibited significantly enhanced transfection efficiency and cell viability. Here, in the present study, we have synthesized a series of N,N,N′,N′-tetramethylguanidinium-polyethylenimine (TP1-TP5) polymers via a single-step reaction involving peripheral primary amines of bPEI and varying amounts of 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU). These polymers were found to interact efficiently with negatively charged pDNA and formed stable complexes in the size range of ~240–450 nm. Acid-base titration profiles revealed improved buffering capacity of TP polymers as compared to bPEI. Transfection and cytotoxicity assays performed with TP/pDNA complexes on HEK293, CHO, and HeLa cells showed significantly higher transfection efficiency and cell viability with one of the complexes, TP2/pDNA complex, exhibited the highest transfection efficiency (~1.4–2.3-fold) outcompeting native bPEI and the commercially available transfection reagent, Lipofectamine 2000. Compared to previously reported THP polymers, the transfection efficiency of TP/pDNA complexes was found to be lower, as examined by flow cytometry. These results highlight the importance of the hydrophobic C-6 linker in THP polymers in forming compact nanostructures with pDNA, which might lead to efficient uptake and internalization of the complexes; however, the projected TP polymers offer an advantage of their rapid and economical one-step synthesis.