Evaluation of PEG-transferrin-PEI nanocomplex as a gene delivery agent

Polyethylenimine (PEI) has been shown to be an efficient nonviral delivery vector. To improve its specificity and reduce its cytotoxicity, PEI should be modified. Transferrin (Tf) is a cell-binding ligand and Tf-receptors are expressed in malignant cells. Modification of cationic polymer by polyethylene glycol (PEG) can reduce the protein interaction and cell cytotoxicity of delivery vectors. We have synthesized PEG-Tf-PEI conjugate as an efficient and safe carrier of plasmid DNA (pDNA). Nanocomplexes of conjugates with pDNA were characterized by measuring the particle size and the surface charge. Transfection efficiency of nanocomplexes in Jurkat cells was improved and cytotoxicity was decreased compared with those of PEI complex. This was due to a reduction in the membrane damaging effect via shielding of the positive charge on the nanocomplex surface by PEG.     

Encapsulation of Plasmid DNA by Nanoscale Metal–Organic Frameworks for Efficient Gene Transportation and Expression

The intracellular delivery and functionalization of genetic molecules play critical roles in gene‐based theranostics. In particular, the delivery of plasmid DNA (pDNA) with safe nonviral vectors for efficient intracellular gene expression has received increasing attention; however, it still has some limitations. A facile one‐pot method is employed to encapsulate pDNA into zeolitic imidazole framework‐8 (ZIF‐8) and ZIF‐8‐polymer vectors via biomimetic mineralization and coprecipitation. The pDNA molecules are found to be well distributed inside both nanostructures and benefit from their protection against enzymatic degradation. Moreover, through the use of a polyethyleneimine (PEI) 25 kD capping agent, the nanostructures exhibit enhanced loading capacity, better pH responsive release, and stronger binding affinity to pDNA. From in vitro experiments, the cellular uptake and endosomal escape of the protected pDNA are greatly improved with the superior ZIF‐8‐PEI 25 kD vector, leading to successful gene expression with high transfection efficacy, comparable to expensive commercial agents. New cost‐effective avenues to develop metal–organic‐framework‐based nonviral vectors for efficient gene delivery and expression are provided.     

Charge shielding effects on gene delivery of polyethylenimine/DNA complexes: PEGylation and phospholipid coating

Polyethylenimine (PEI) is an efficient cationic polymer for gene delivery, but defective in biocompatibility. In this study, we developed two different strategies to shield the positively charged PEI/DNA complexes: PEGylation and lipid coating. The physicochemical properties, cytotoxicity and transfection efficiency of the two gene delivery systems were investigated. Both PEGylation and lipid coating succeeded in reducing the zeta-potential of the complexes. Lipid-coated PEI/DNA complexes (LPD complexes) and PEI/DNA complexes exhibited similar cytotoxicity, whereas PEG-PEI/DNA complexes showed lower cytotoxicity, especially at high N/P ratios. LPD complexes were less efficient in transfection compared to PEG-PEI/DNA complexes. The transfection efficiency was influenced remarkably by cytotoxicity and surface charge of the complexes. Intracellular processes studies revealed that endosomal release might be one of the rate-limiting steps in cell transfection with PEI as a gene delivery carrier.     

Cationic liposomes-polyallylamine-plasmid nanocomplexes for gene delivery

The aim of the present study was to prepare, characterise and evaluate the transfection efficiency of ternary complexes (lipopolyplexes) composed of cationic liposome, polyallylamine (PAA), plasmid DNA (pDNA). PAA was reacted with a varying amount of a linker, 6-bromohexanoic acid (6-bromo-HA), to prepare a series of modified polymers. Lipopolyplexes consisting of cationic liposome, PAA (or modified PAA), pDNA were prepared. The nanoparticles, so formed, were characterised by their size and zeta potential and were subsequently evaluated for their cytotoxicity and transfection ability on Neuro2A cells. Mean size of prepared complexes ranged from 170 to 280 nm. All lipopolylexes showed a positive zeta potential. Highest transfection efficiency was for lipopolyplex containing PAA 15 kDa-modified polymer and liposome at C/P ratio of 0.5. High molecular weight PAA was more toxic than PAA 15 kDa for Neuro2A cells especially in higher C/P ratio. The results indicate that using the hydrophobic modified PAA in the structure of lipopolyplexes is an effective strategy for improving transfection efficiency.     

A Highly Emissive Conjugated Polyelectrolyte Vector for Gene Delivery and Transfection

An intrinsically fluorescent cationic polyfluorene ( CCP ) has been designed, synthesized, characterized, and examined as a plasmid DNA (pDNA) delivery vector. This material facilitates nucleic acid binding, encapsulation and efficient cellular uptake. CCP can effectively protect pDNA against nuclease degradation, which is necessary for gene carriers. Green fluorescent protein (GFP) expression experiments reveal that CCP can achieve efficient delivery and transfection of pDNA encoding GFP gene with 92% efficiency, which surpasses that of commercial transfection agents, lipofectamine 2000 (Lipo) and polyethylenimine (PEI). CCP is also highly fluorescent, with 43% quantum yield in water, and exhibits excellent photostability, which allows for real‐time tracking the location of gene delivery and transfection. These features and capabilities represent a major step toward designing and applying conjugated polymers that function in both imaging and therapeutic applications.     

Insight into the role of N,N-dimethylaminoethyl methacrylate (DMAEMA) conjugation onto poly(ethylenimine): cell viability and gene transfection studies

In the present study, the effect of N,N-dimethylaminoethyl methacrylate (DMAEMA) conjugation onto branched poly(ethylenimine) (PEI) with different grafting degree was examined for gene delivery applications. The DMAEMA-grafted-PEI conjugates were characterized and complexed with plasmid DNA (pDNA) at various concentrations, and the physicochemical properties, cell viability, and in vitro transfection efficiency of the complexes were evaluated in HEK 293T cells. Computational techniques were used to analyze the interaction energies and possible binding modes between DNA and conjugates at different grafting degrees. The cytotoxicity analysis and in vitro transfection efficiency of the conjugate/pDNA complexes exhibited a beneficial effect of DMAEMA conjugation when compared to PEI alone. The computational results revealed that the DNA/vector interaction energy decreases with increasing grafting degree, which can be associated to an enhanced release of the pDNA from the carrier once inside cells. The results indicate the significance of DMAEMA conjugation onto PEI as a promising approach for gene delivery applications.     

Hybrid polymer-grafted multiwalled carbon nanotubes for in vitro gene delivery

Carbon nanotubes (CNTs) consist of carbon atoms arranged in sheets of graphene rolled up into cylindrical shapes. This class of nanomaterials has attracted attention because of their extraordinary properties, such as high electrical and thermal conductivity. In addition, development in CNT functionalization chemistry has led to an enhanced dispersibility in aqueous physiological media which indeed broadens the spectrum for their potential biological applications including gene delivery. The aim of this study is to determine the capability of different cationic polymer-grafted multiwalled carbon nanotubes (MWNTs) (polymer-g-MWNTs) to efficiently complex and transfer plasmid DNA (pCMV-βGal) in vitro without promoting cytotoxicity. Carboxylated MWNT is chemically conjugated to the cationic polymers polyethylenimine (PEI), polyallylamine (PAA), or a mixture of the two polymers. In order to explore the potential of these polymer-g-MWNTs as gene delivery systems, we first study their capacity to complex plasmid DNA (pDNA) using agarose gel electrophoresis. Gel migration studies confirm pDNA binding to polymer-g-MWNT with different affinities, highest for PEI-g-MWNT and PEI/PAA-g-CNT constructs. β-galactosidase expression is assessed in human lung epithelial (A549) cells, and the cytotoxicity is determined by modified LDH assay after 24 h incubation period. Additionally, PEI-g-MWNT and/or PEI/PAA-g-MWNT reveal an improvement in gene expression when compared to the naked pDNA or to the equivalent amounts of PEI polymer alone. Mechanistically, pDNA was delivered by the polymer-g-MWNT constructs via a different pathway compared to those used by polyplexes. In conclusion, polymer-g-MWNTs may be considered in the future as a versatile tool for efficient gene transfer in cancer cells in vitro, provided their toxicological profile is established.     

Design of novel polysaccharidic nanostructures for gene delivery

The goal of the present work was to develop a new synthetic nanosystem for gene delivery. For this purpose, we chose two polysaccharides, hyaluronic acid (HA) and chitosan (CS), as the main components of the nanocarrier. Nanoparticles with different hyaluronate:chitosan (HA:CS) mass ratios (0.5:1 and 1:1) and different polymer molecular weights (hyaluronate 170 (HA) or <10?kDa (HAO) and chitosan 125 (CS) or 10-12?(CSO)?kDa) could be obtained using an ionic crosslinking method. These nanoparticles were loaded with pDNA and characterized for their size, zeta potential and pDNA association efficiency. Moreover, their toxicity and ability to transfect the model plasmid pEGFP-C1 were evaluated in the cell line HEK 293, as well as their intracellular fate. The results showed that HA:CS nanoparticles have a small size in the range of 110-230?nm, a positive zeta potential of +10 to +32?mV and a very high pDNA association efficiency of 87-99% (w/w). On the other hand, nanoparticles exhibited low cell toxicity and transfection levels up to 25% GFP expressing HEK?293 cells, lasting for the whole observation period of 10 days. We also provide basic information about the role of both polymers, HA and CS, and the effect of their molecular weight on the effectiveness of the resulting DNA nanocarrier, being the highest transfection levels observed with HAO:CSO 1:1 nanoparticles. In?conclusion, HA:CS nanoparticles are promising carriers for gene delivery.     

Nano‐Sized Sunflower Polycations As Effective Gene Transfer Vehicles

The architecture of polycations plays an important role in both gene transfection efficiency and cytotoxicity. In this work, a new polymer, sunflower poly(2‐dimethyl amino)ethyl methacrylate) (pDMAEMA), is prepared by atom transfer radical polymerization and employed as nucleic acid carriers compared to linear pDMAEMA homopolymer and comb pDMAEMA. The sunflower pDMAEMAs show higher IC₅₀, greater buffering capacity, and stronger binding capacity toward plasmid DNA than their linear and comb counterparts. In vitro transfection studies demonstrate that sunflower pDMAEMAs exhibit high transfection efficiency as well as relatively low cytotoxicity in complete growth medium. In vivo gene delivery by intraventricular injection to the brain shows that sunflower polymer delivers plasmid DNA more effectively than comb polymer. This study provides a new insight into the relationship between polymeric architecture and gene delivery capability, and as well as a useful means to design potent vectors for successful gene delivery.     

A novel dendrimer based on poly (L-glutamic acid) derivatives as an efficient and biocompatible gene delivery vector

Non-viral gene delivery systems based on cationic polymers have faced limitations related to their relative low gene transfer efficiency, cytotoxicity and system instability in vivo. In this paper, a flexible and pompon-like dendrimer composed of poly (amidoamine) (PAMAM) G4.0 as the inner core and poly (L-glutamic acid) grafted low-molecular-weight polyethylenimine (PLGE) as the surrounding multiple arms was synthesized (MGI dendrimer). The novel MGI dendrimer was designed to combine the merits of size-controlled PAMAM G4.0 and the low toxicity and flexible chains of PLGE. In phosphate-buffered saline dispersions the well-defined DNA/MGI complex above a N/P ratio of 30 showed good stability with particle sizes of approximately 200 nm and a comparatively low polydispersity index. However, the particle size of the DNA/25 kDa polyethylenimine (DNA/PEI 25K) complex was larger than 700 nm under the same salt conditions. The shielding of the compact amino groups at the periphery of flexible PAMAM and biocompatible PLGE chains in MGI resulted in a dramatic decrease of the cytotoxicity compared to native PAMAM G4.0 dendrimer. The in vitro transfection efficiency of DNA/MGI dendrimer complex was higher than that of PAMAM G4.0 dendrimer. Importantly, in serum-containing medium, DNA/MGI complexes at their optimal N/P ratio maintained the same high levels of transfection efficiency as in serum-free medium, while the transfection efficiency of native PAMAM G4.0, PEI 25K and Lipofectamine 2000 were sharply decreased. In vivo gene delivery of pVEGF165/MGI complex into balloon-injured rabbit carotid arteries resulted in significant inhibition of restenosis by increasing VEGF165 expression in local vessels. Therefore, the pompon-like MGI dendrimer may be a promising vector candidate for efficient gene delivery in vivo.     

聚乙烯亚胺改性的双介孔氧化硅基因载体构建

为了开发一种新型的非病毒无机基因载体,采用3-氨丙基三乙氧基硅烷(APTMS)和聚乙烯亚胺(PEI)对嵌入型双介孔氧化硅球(EDMSNs)进行改性,分别得到EDMSNs-NH₂和EDMSNs-PEI,并比较了两种载体结合和保护pCMV-EGFP-N1质粒(pDNA)的能力及细胞转染性能。利用透射电镜、动态光散射及氮气吸附-脱附实验对材料的颗粒形态,动力学粒径,Zeta电位及孔结构参数进行表征。结果显示,EDMSNs-NH₂和EDMSNs-PEI均表现出明显的双介孔结构,形貌为规整的球形且平均动力学粒径分别为343.2和338.9 nm,表面电位分别为+18和+43 mV。琼脂糖凝胶电泳、CCK-8法及荧光显微镜结果表明,EDMSNs-PEI对pDNA的担载量为8%,远高于EDMSNs-NH₂(1%)。与PEI和lipofectamine2000相比,EDMSNs-PEI载体展示出更低的细胞毒性。EDMSNs-PEI/pDNA质量比为33:1时,EDMSNs-PEI/pDNA对293T细胞的转染效率在72h达到最大值。因此...     

Galactosylation of chitosan-graft-spermine as a gene carrier for hepatocyte targeting in vitro and in vivo

Polyethyleneimine (PEI) has been described as a highly efficient gene carrier due to its efficient proton sponge effect within endosomes. However, many studies have demonstrated that PEI is toxic and associated with a lack of cell specificity despite high transfection efficiency. In order to minimize the toxicity of PEI, we prepared chitosan-graft-spermine (CHI-g-SPE) in a previous study. CHI-g-SPE showed low toxicity and high transfection efficiency. However, this compound also had limited target cell specificity. In the present study, we synthesized galactosylated CHI-g-SPE (GCS) because this modified GCS could be delivered specifically into the liver due to hepatocyte-specific galactose receptors. The DNA-binding properties of GCS at various copolymer/DNA weight ratios were evaluated by a gel retardation assay. The GCS copolymer exhibited significant DNA-binding ability and efficiently protected DNA from nuclease attack. Using energy-filtered transmission electron microscopy (EF-TEM), we observed dense spherical, nano-sized GCS/DNA complexes with a homogenous distribution. Most importantly, GCS was associated with remarkably low cytotoxicity compared to PEI in HepG2, HeLa, and A549 cells. Moreover, GCS carriers specifically delivered the gene-of-interest into hepatocytes in vitro as well as in vivo. Our results suggest that the novel GCS described here is a safe and highly efficient carrier for hepatocyte-targeted gene delivery.     

Self-assembled micellar aggregates based monomethoxyl poly(ethylene glycol)-<Emphasis Type="Italic">b</Emphasis>-poly(ε-caprolactone)-<Emphasis Type="Italic">b</Emphasis>-poly(aminoethyl methacrylate) triblock copolymers as efficient gene delivery vectors

Amphiphilic triblock copolymers monomethoxyl poly(ethylene glycol) (mPEG)-b-poly(ε-caprolactone) (PCL)-b-poly(aminoethyl methacrylate)s (PAMAs) (mPECAs) were synthesized as gene delivery vectors. They exhibited lower cytotoxicity and higher transfection efficiency in COS-7 cells in presence of serum compared to 25 kDa bPEI. The influence of mPEG and PCL segments in mPECAs was evaluated by comparing with corresponding diblock copolymers. The studies showed the incorporation of the hydrophobic PCL segment in triblock copolymers affected the binding capability to pDNA and surface charges of complexes due to the formation of micelles increasing the local charges. The presence of mPEG segment in gene vector decreased the surface charges of the complexes and increased the stability of the complexes in serum because of the steric hindrance effect. It was also found that the combination of PEG and PCL segments into one macromolecule might lead to synergistic effect for better transfection efficiency in serum.     

Formulation and characterization of naked DNA and complexed DNA loaded polymer films

Sustained release of DNA from polymeric films is of considerable interest for enhanced and prolonged gene therapy. This report describes the detailed studies of the formulation of naked plasmid DNA (pDNA) and complexed DNA-incorporated polymer films and in vitro release of the DNA. The effect of hydrophilic polymers (PEG, HA) also studied to modulate the release of pDNA and complexed DNA (lipoplex) from slow biodegradable polymer (PCL) films. The polymer system consists of a biodegradable semi-crystalline polymer (PCL) blended with a hydrophilic polymer such as poly (ethylene glycol) (PEG) or hyaluronic acid (HA). For the release of pDNA (naked DNA), a burst effect was always seen, and the addition of HA and PEG did not suppress the burst release of pDNA from PCL films. For complexed pDNA (lipoplex), the release was slow, but it could be accelerated using additives such as PEG or HA. The transfection efficiency of the complexed DNA and the naked pDNA was determined in vitro using COS 7 cells to evaluate the bioactivity of the released DNA. Transfection was observed from released lipoplexes samples from PCL/HA film. Overall, this work suggested that these polymeric DNA delivery systems are promising for the local sustained release of DNA from implanted films.     

Novel redox nanomedicine improves gene expression of polyion complex vector

Abstract

Gene therapy has generated worldwide attention as a new medical technology. While non-viral gene vectors are promising candidates as gene carriers, they have several issues such as toxicity and low transfection efficiency. We have hypothesized that the generation of reactive oxygen species (ROS) affects gene expression in polyplex supported gene delivery systems. The effect of ROS on the gene expression of polyplex was evaluated using a nitroxide radical-containing nanoparticle (RNP) as an ROS scavenger. When polyethyleneimine (PEI)/pGL3 or PEI alone was added to the HeLa cells, ROS levels increased significantly. In contrast, when (PEI)/pGL3 or PEI was added with RNP, the ROS levels were suppressed. The luciferase expression was increased by the treatment with RNP in a dose-dependent manner and the cellular uptake of pDNA was also increased. Inflammatory cytokines play an important role in ROS generation in vivo. In particular, tumor necrosis factor (TNF)-α caused intracellular ROS generation in HeLa cells and decreased gene expression. RNP treatment suppressed ROS production even in the presence of TNF-α and increased gene expression. This anti-inflammatory property of RNP suggests that it may be used as an effective adjuvant for non-viral gene delivery systems.     

An E3‐14.7K Peptide that Promotes Microtubules‐Mediated Transport of Plasmid DNA Increases Polyplexes Transfection Efficiency

Chemical vectors as cationic polymers and cationic lipids are promising alternatives to viral vectors for gene therapy. Beside endosome escape and nuclear import, plasmid DNA (pDNA) migration in the cytosol toward the nuclear envelope is also regarded as a limiting step for efficient DNA transfection with non‐viral vectors. Here, the interaction between E3‐14.7K and FIP‐1 to favor migration of pDNA along microtubules is exploited. E3‐14.7K is an early protein of human adenoviruses that interacts via FIP‐1 (Fourteen.7K Interacting Protein 1) protein with the light‐chain components of the human microtubule motor protein dynein (TCTEL1). This peptide is conjugated with pDNA and mediates interaction of pDNA in vitro with isolated microtubules as well as with microtubules in cellulo. Videomicroscopy and tracking treatment of images clearly demonstrate that P79‐98/pDNA conjugate exhibits a linear transport with large amplitude along microtubules upon 2 h transfection with polyplexes whereas control pDNA conjugate exhibits small non‐directional movements in the cytoplasm. Remarkably, P79‐98/peGFP polyplexes enhance by a factor 2.5 (up to 76%) the number of transfected cells. The results demonstrate, for the first time, that the transfection efficiency of polyplexes can be drastically increased when the microtubules migration of pDNA is facilitated by a peptide allowing pDNA docking to TCTEL1. This is a real breakthrough in the non viral gene delivery field that opens hope to build artificial viruses.     

Kidney-specific peptide-conjugated poly(ester amine) for the treatment of kidney fibrosis

Kidney gene therapy using the hepatocyte growth factor (HGF) gene may offer new strategies for the treatment of chronic renal disease such as kidney fibrosis, because HGF has the potential to promote tubular repair and to inhibit tissue fibrosis. As a non-viral vector for gene delivery, polyethylenimine (PEI) exhibits high gene expression due to its buffering capacity with cytotoxicity, although its cytotoxicity depends on its molecular weight. In this study, to minimize the cytotoxicity of PEI with a high transfection efficiency, biodegradable poly(ester amine) (PEA) based on glycerol dimethacrylate (GDM) and low molecular weight PEI (LMW PEI) was synthesized and kidney targeting peptide was conjugated to the PEA (PEP-PEA) to give it kidney cell specificity. The PEP-PEA showed good physicochemical properties as a gene delivery carrier, such as DNA condensation ability, protection of the DNA in the complexes from enzyme degradation, and formation of nanosized complexes with spherical shapes. Higher transfection efficiency in 293T cells was achieved with the PEP-PEA than with the PEA and the PEI 25 kDa with lower cytotoxicity. Also, the HGF gene that was complexed with the PEP-PEA was specifically delivered to the obstructed kidney in the unilateral ureteral obstruction (UUO) model rats. The delivered HGF gene exhibited potency in recovering renal functions, which indicates the potential of the PEP-PEA as a safe and efficient carrier for the treatment of kidney fibrosis.     

Ultra-small graphene oxide functionalized with polyethylenimine (PEI) for very efficient gene delivery in cell and zebrafish embryos

Efficient DNA delivery is essential for introducing new genes into living cells. However, effective virus-based systems carry risks and efficient synthetic systems that are non-toxic remain to be discovered. The bottle-neck in synthetic systems is cytotoxicity, caused by the high concentration of DNA-condensing compounds required for efficient uptake of DNA. Here we report a polyethyleneimine (PEI) grafted ultra-small graphene oxide (PEI-g-USGO) for transfection. By removing the free PEI and ensuring a high PEI density on small sized graphene, we obtained very high transfection efficiencies combined with very low cytotoxicity. Plasmid DNA could be transfected into mammalian cell lines with up to 95% efficiency and 90% viability. Transfection in zebrafish embryos was 90%, with high viability, compared to efficiencies of 30% or lower for established transfection technologies. This result suggests a novel approach to the design of synthetic gene delivery vehicles for research and therapy.      

Synthesis and characterization of three novel amphiphilic dextran self-assembled micelles as potential drug delivery system

Three types of amphiphilic dextran derivatives were synthesized via the connection of different diamine compounds between the carboxyl group of stearic acid (SA) and aldehyde group of oxidized dextran. These three amphiphilic dextran derivatives self-assemble to form polymer micelles in aqueous medium. The critical micelle concentration depended on the graft ratio of SA, which ranged from 0.0700 to 0.158 mg mL^?1. These three amphiphilic dextran micelles can form typical core–shell structures of various sizes. Curcumin (Cur) was used as a model drug, and all amphiphilic micelle dextran derivatives had excellent drug loading capacity and drug encapsulation efficiency. The in vitro drug release from amphiphilic dextran derivatives/Cur micelles could be prolonged by adjusting the type of diamine compounds and composition of Cur content. These results show the superior properties of polymer micelles and suggest that these micelles are promising carriers for drug delivery systems.