Polycation/DNA complexes coated with oligonucleotides for gene delivery

4-Iodo-6-phenylpyrimidine (4-IPP) suppresses fibroblast-like synoviocyte- mediated inflammation and joint destruction associated with rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic immune-mediated inflammatory disease that significantly impacts patients' quality of life. Fibroblast-like synovial cells (FLSs) within the synovial intima exhibit "tumor-like" properties such as increased proliferation, migration, and invasion. Activation of FLSs and secretion of pro-inflammation factors result in pannus formation and cartilage destruction. As an inhibitor of the cytokine, macrophage migration inhibitory factor (MIF), 4-Iodo-6-phenylpyrimidine (4-IPP) has been shown to reduce cell proliferation, migration, invasion, and the secretion of pro-inflammatory mediators in a variety of diseases. However, the usefulness of 4-IPP for RA treatment has not been assessed and was the purpose of this study. In vitro, 4-IPP was demonstrated to inhibit proliferation, migration, and invasion of RA FLSs, as well as the expression of pro-inflammatory cytokines. 4-IPP was also shown to inhibit MIF-induced phosphorylation of ERK, JNK, and p38, as well as reduce expression of COX2 and PGE2. In order to efficiently deliver 4-IPP to anatomical RA sites, we developed lactic-co-glycolic acid (PLGA) nanospheres, which not only protected 4-IPP from degradation but also controlled the release of 4-IPP. 4-IPP/PLGA nanospheres had potent anti-inflammatory activity and a high degree of biosafety. Results showed that local 4-IPP concentration was increased by nanosphere delivery, effectively reducing the inflammatory microenvironment as well as synovial inflammation, joint swelling, and cartilage destruction in a collagen-induced rheumatoid arthritis (CIA) rat model. Therefore, 4-IPP nanospheres are a sustained-release delivery system that may be an effective therapeutic strategy for RA treatment.

Effect of nanoparticle-mediated delivery of SFRP4 siRNA for treating Dupuytren disease

Dupuytren disease (DD) is a progressive fibrous proliferative disease. It invades the palmar aponeurosis and extends to the finger fascia, eventually leading to flexion contracture of the metacarpophalangeal or interphalangeal joint. At present, surgical resection and the local injection of collagenase are the main methods for the treatment of DD, but postoperative complications and high recurrence rates often occur. Bioinformatics analysis showed that the increased expression of SFRP4 protein was closely related to the incidence of DD. Persistent and effective inhibition of SFRP4 expression may be a promising treatment for DD. We prepared SFRP4 siRNA/nanoparticle complexes (si-SFRP4) and negative siRNA/nanoparticle complexes (NC) and applied them in vitro and in vivo. Flow cytometry analysis showed that si-SFRP4 could be successfully transfected into DD cells. MTT and EdU staining assays showed that the OD values and percentage of EdU-positive cells in the si-SFRP4 group were significantly lower than those in the NC group. Scratch tests showed that the wound healing rate of the si-SFRP4 group was lower than that of the NC group, and the difference was statistically significant. The expression of SFRP4 and α-SMA protein in the si-SFRP4 group significantly decreased in both DD cells and xenografts. Compared with the NC group, the xenograft quality of the si-SFRP4 group was significantly reduced. Masson's trichrome staining showed that the collagen and fibrous cells in the si-SFRP4 group were more uniform, slender, parallel and regular. The above experimental results suggest that the proliferation and metabolism of palmar aponeurosis cells and the quality of metacarpal fascia xenografts were both significantly decreased. We speculated that nanoparticle-mediated SFRP4 siRNA can be used as a potential new method for the treatment of DD.

Inhibition of Ureteral Stricture by Pirfenidone-Loaded Nanoparticle-Coated Ureteral Stents with Slow-Release Pirfenidone

Introduction

Ureteral stricture caused by iatrogenic ureteral injury induced ureteral injury is more common and challenging to recover quickly. The effective prevention of ureteral stricture due to iatrogenic ureteral injury-induced ureteral damage is a current challenge for urologists. The purpose of this study was to evaluate the effectiveness of nanoparticle/pirfenidone complex-coated ureteral stents with slow-release pirfenidone for the prevention of ureteral stricture in rabbits. In this study, we developed a nanoparticle/pirfenidone complex-coated ureteral stent to deliver pirfenidone into the injured ureter to inhibit ureteral stricture.

Methods

Twelve New Zealand rabbits were divided into four groups: Sham, US, US+ Unmodified ureteral stent, and US+NP/PFD ureteral stent; we constructed an irreversible electroporation model of ureteral injury in rabbits and placed unmodified ureteral stents and nanoparticle/pirfenidone complex-coated ureteral stents into the ureter. Two weeks later, we euthanized the rabbits and removed their bilateral kidneys and ureters. We evaluated the effect of ureteral stent prophylaxis by gross specimen observation, section staining, and Western Blot.

Results

We found that the nanoparticle/pirfenidone complexes could adhere uniformly to the surface of the ureteral stent. After placement into the ureter, the nanoparticle/pirfenidone complexes were able to remain on the surface of the ureteral stent. We found nanoparticle/pirfenidone complexes could diffuse in the ureteral epithelial tissue two weeks after the order. The study showed that nanoparticle/pirfenidone complex-coated ureteral stents placed into the ureter showed significantly less stenosis due to fibrosis than in US control rabbits and rabbits treated with unmodified ureteral stents.

Conclusion

We used a novel platform based on nanoparticle/pirfenidone complex-coated ureteral stents for local and sustained delivery of pirfenidone, which can effectively deliver pirfenidone to the tissue and can slowly control the release of pirfenidone. Therefore, combining ureteral stents with nanoparticle/pirfenidone complexes was an effective measure to prevent ureteral stricture.

Identification of nanoparticle-mediated siRNA-ASPN as a key gene target in the treatment of keloids

Background: Keloid, also known as connective tissue hyperplasia, is a benign proliferative disorder with a global distribution. The available therapeutic interventions are steroid injections, surgical removal of keloids, radiotherapy, compression therapy, the application of cryosurgery, and many other methods.

Objectives: Existing treatments or approaches for keloids may lead to similar or even larger lesions at the site of keloid excision, leading to a high recurrence rate. Therefore, this study aims at identifying a new gene-based therapy for the treatment of keloids.

Methods: An ASPN-siRNA/nanoparticle combination (si-ASPN) and a negative siRNA/nanoparticle complex (NC) was developed on the basis of bioinformatics studies and used in vitro and in vivo experiments.

Results: The results showed a strong correlation between the development of keloids and high expression of ASPN protein. With the expression of ASPN protein greatly reduced in keloid fibroblasts and nude mice allografts after treatment with si-ASPN, the collagen and fibroblasts were also uniform, thinner, parallel and regular.

Conclusion: All the above experimental results suggest that keloid and ASPN are closely related and both fibroblast growth and metabolism of keloid are inhibited after silencing ASPN. Therefore, ASPN-siRNA delivered via nanoparticles can serve as a novel intervention therapy for the treatment of keloids.

An overview of polyallylamine applications in gene delivery

A chief objective of gene transportation studies is to manipulate clinically accepted carriers that can be utilized to combat incurable diseases. Despite various strategies, efficiency and application of these vectors have been hindered, owing to different obstacles. Polyallylamine (PAA) is a synthetic water-soluble, weak base cationic polymer with different properties that could be administrated as an ideal candidate for biomedical applications such as gene delivery, drug delivery, or even tissue engineering. However, some intrinsic properties of this polymer limit its application. The two associated problems with the use of PAA in gene delivery are low transfection efficiency (because of low buffering capacity) and cytotoxic effects attributed to intense cationic character. Most of the strategies for structural modification of the PAA structure have focused on introducing hydrophobic groups to the polymeric backbone that target both cytotoxicity and transfection. In this perspective, we concentrate on PAA as a gene delivery vehicle and the existing approaches for modification of this cationic polymer to give insight to researchers for exploitation of PAA as an efficient carrier in biomedical applications.

Effects of nanoparticle-mediated Co-delivery of bFGF and VEGFA genes to deep burn wounds: An in vivo study

Deep burns are a common form of trauma worldwide, and they are hard to be cured in a short time and enhance psychological pressure of the patients. How to effectively promote the healing of wounds after burns is a continuing challenge currently faced by burn physicians. Various strategies of promoting wound healing of deep burns have been developed, including gene therapy and growth factor therapy. In this study, we developed a combined therapy using PLGA nanoparticles as carriers to deliver bFGF and VEGFA genes to promote healing of burn wounds. We first inserted the bFGF and VEGFA genes into pEGFP-N1 vectors and loaded the mixed generated plasmids into PLGA nanoparticles. Next, we injected the nanoparticle/plasmid complexes into the rats intracutaneously and found that the complexes were successfully transfected in vivo one week later. Finally, we injected the nanoparticle/plasmid complexes containing bFGF and VEGFA around burn wounds. We found that the percentage of wound healing of rats treated with nanoparticles/bFGF+ VEGFA plasmid complexes was higher than that of rats in the scald control group, and the early percentage of wound complete epithelialization was also higher. Therefore, combining gene therapy with nanoparticles may be an effective biological strategy for wound repair.

Polarity control of DNA adsorption enabling the surface functionalization of CuO nanozymes for targeted tumor therapy

Nanomaterials with intrinsic catalytic activities (nanozyme) have drawn broad attention for various biomedical applications, with peroxidase-mimic nanozymes particularly attractive for cancer therapy due to their capability to catalyze the conversion of tumor-abundant H₂O₂ into more toxic hydroxyl radicals (˙OH) for effective tumor ablation. However, the facile surface modification of nanozymes for tumor-targeted delivery while retaining their catalytic activity remains a challenge. Here, we report an approach to functionalize the CuO nanozyme with DNA to enable targeted delivery and selective tumor destruction. We systematically studied the adsorption of DNA on the CuO surface, with special attention paid to the catalytic activity and DNA adsorption stability in the presence of various biological ligands. After gaining a fundamental understanding, a di-block DNA sequence was designed for adsorption on to the CuO surface, which allowed stable adsorption during in vivo circulation, passive accumulation into the tumor tissue, and the specific recognition of tumor cells, resulting in significant nanocatalytic tumor suppression in tumor xenograft mice models with no noticeable cytotoxicity. This work paves a way for the rational design of DNA-modified nanozymes for catalytic tumor therapy, and fundamentally, provides a new insight into the biointerface chemistry of CuO with DNA.

Carbon dioxide-modified polyethylenimine as a novel gene delivery vector and its in vitro validation

In this work, the CO₂-modified polyethylenimine, as a novel delivery vector, has been validated by combining with the plasmid DNA to form plasmid DNA/CO₂-modified polyethylenimine complexes. We have modified polyethylenimine using CO₂ to partially convert amine groups to carbamic acid groups. The buffering capacity and the plasmid DNA binding ability of the CO₂-modified polyethylenimine and PEI-25 (polyethylenimine with Mw = 25 kDa) were characterized by acid-base titration and agarose gel electrophoresis, respectively. The particle size and zeta potential of the complexes were determined using a Zetasizer Nano ZS. Resistance to nuclease digestion was determined via DNase I protection assay. The cytotoxicity was measured by the MTT assay. The transfection efficiency of the complexes has been evaluated by flow cytometry. It is observed that the condensation capacity of CO₂-modified polyethylenimine is still comparable to polyethylenimine and the CO₂-modified polyethylenimine can protect plasmid DNA from degradation by DNase I. The diameter of the plasmid DNA/CO₂-modified polyethylenimine complex is around 140 nm and the zeta potential decreases. MTT assays confirm that the cytotoxicity is much lower for plasmid DNA/CO₂-modified polyethylenimine than for plasmid DNA/PEI-25. The flow cytometry found that in serum-free medium the transfection efficiency can reach a value of ∼60% for plasmid DNA/CO₂-modified polyethylenimine, and in 10% fetal bovine serum medium, the transfection efficiency is still as high as ∼40%, which is much higher than that of plasmid DNA/PEI-25. CO₂-modified polyethylenimine could be a novel and promising nonviral gene vector for gene therapy.

Recent progress in gene therapy to deliver nucleic acids with multivalent cationic vectors

Due to the potential use as transfecting agents of nucleic acids (DNA or RNA), multivalent cationic non-viral vectors have received special attention in the last decade. Much effort has been addressed to synthesize more efficient and biocompatible gene vectors able to transport nucleic acids into the cells without provoking an immune response. Among them, the mostly explored to compact and transfect nucleic acids are: (a) gemini and multivalent cationic lipids, mixed with a helper lipid, by forming lipoplexes; and (b) cationic polymers, polycations, and polyrotaxanes, by forming polyplexes. This review is focused on the progress and recent advances experimented in this area, mainly during the present decade, devoting special attention to the lipoplexes and polyplexes, as follows: (a) to its biophysical characterization (mainly electrostatics, structure, size and morphology) using a wide variety of experimental methods; and (b) to its biological activity (transfection efficacy and cytotoxicity) addressed to confirm the optimum formulations and viability of these complexes as very promising gene vectors of nucleic acids in nanomedicine.

An Oligonucleotide Transfection Vector Based on HSA and PDMAEMA Conjugation: Effect of Polymer Molecular Weight on Cell Proliferation and on Multicellular Tumor Spheroids

A novel gene transfection vector was fabricated based on the conjugation of human serum albumin (HSA) and maleimide end functionalized poly[(N,N-dimethylamino) ethyl methacrylate] (PDMAEMA). The bioconjugation was achieved in a site-specific manner to yield well-defined polymer-protein conjugates. The biohybrid was able to bind DNA with high affinity resulting in nanoparticles with a HSA shell. This paper mainly focuses on the influence of polymeric chain length on the particle properties and their drug-carrying ability to deliver oligonucleotides into breast cancer cells. The cytotoxic agent of interest, ISIS5132, is an oligonucleotide which disrupts DNA function within the cell. There was no evidence that the polymeric chain length had any effects on the conjugation efficiency and the subsequent condensation ability of the conjugates to oligonucleotide. However, the polymeric chain length had an obvious effect on the size of the complex micelles. Low molecular weights only led to loosely compacted complexes with the oligonucleotide, while large molecular weight led to well-defined nanoparticle structures. More importantly, it was found that the variation in the length of the PDMAEMA block resulted in a change in cytotoxicity of the drug loaded complex micelle. That is, the concentration of 50% inhibition (IC50 ) of the complex micelle on MDA-MB-231 and MCF-7 cells reached the lowest value at a chain length of around 21 000 g mol(-1) . The IC50 value increased when the polymeric chain length was shorter (8000 g mol(-1) and 10 000 g mol(-1) ) while it increased again when PDMAMEA of M¯n = 47 000 g mol(-1) , probably due to insufficient release of the drug. These result were reflected when investigating the performance of the polyplex using MCF-7 multicellular tumor spheroids, where again the medium PDMAEMA chain length led to the best delivery vehicle for ISIS5132.

Drug and gene co-delivery systems for cancer treatment

Cancer remains a major killer and a leading cause of death in the world; thus, a growing number of new treatments have been focused on cancer therapy over the past few decades. Chemotherapy, which is thought to be a powerful strategy for cancer treatment, has been widely used in clinical therapy in recent years. However, due to the complexity of cancer, a single therapeutic approach is insufficient for the suppression of cancer growth and migration. Therefore, increasing attention has been paid to the use of smart multifunctional carriers and combinatorially delivers chemotherapeutic drugs and functional genes in order to maximize therapeutic efficiency. Combination therapy using selected drugs and genes can not only overcome multidrug resistance and inhibit the cellular anti-apoptotic process but also achieve a synergistic therapeutic effect. Because multifunctional nanocarriers are important for achieving these goals, this review will illustrate and discuss some advanced biomaterial nanocarriers for co-delivering therapeutic genes and drugs, including multifunctional micelles, liposomes, polymeric conjugates and inorganic nanoparticles. In addition, the challenges and future perspectives for co-delivery systems, containing therapeutic drugs and genes to achieve better therapeutic effects for cancer treatment will be discussed.

Imprinting of metal receptors into multilayer polyelectrolyte films: fabrication and applications in marine antifouling

Polymeric films constructed using the layer-by-layer (LbL) fabrication process were employed as a platform for metal ion immobilization and applied as a marine antifouling coating. The novel Cu2+ ion imprinting process described is based on the use of metal ion templates and LbL multilayer covalent cross-linking. Custom synthesized, peptide mimicking polycations composed of histidine grafted poly(allylamine) (PAH) to bind metal ions, and methyl ester containing polyanions for convenient cross-linking were used in the fabrication process. Two methods of LbL film formation have been investigated using alternate polyelectrolyte deposition namely non-imprinted LbLA, and imprinted LbLB. Both LbL films were cross linked at mild temperature to yield covalent bridging of the layers for improved stability in a sea water environment. A comparative study of the non-imprinted LbLA films and imprinted LbLB films for Cu2+ ion binding capacity, leaching rate and stability of the films was performed. The results reveal that the imprinted films possess enhanced affinity to retain metal ions due to the preorganization of imidazole bearing histidine receptors. As a result the binding capacity of the films for Cu2+ could be improved by seven fold. Antifouling properties of the resulting materials in a marine environment have been demonstrated against the settlement of barnacle larvae, indicating that controlled release of Cu ions was achieved.

Structural impact of graft and block copolymers based on poly(N-vinylpyrrolidone) and poly(2-dimethylaminoethyl methacrylate) in gene delivery

The characteristics of graft and block copolymers based on PVP and PDMAEMA in pDNA compaction, cytotoxicity, transfection efficiency, internalization and intracellular distribution were systematically investigated.

Gene delivery efficiency and intracellular trafficking of novel poly(allylamine) derivatives

Non-viral gene carriers for safe and efficient gene transfection have become of particular interest among researchers of different disciplines ranging from physical chemistry to biotechnology. Recently polymeric vectors have been extensively studied as potentially new gene transfer agents. Until now most of the research efforts were made to optimize the gene-to-polymer weight ratio of polyplexes for safe and efficient gene transfection. In this work, we report on the development of novel poly(allylamine) derivatives with different balance of the primary, secondary, tertiary, and quaternary amino groups. All derivatives were able to complex pDNA into polyplexes at low gene-to-polymer weight ratios i.e., 1:1 or 1:2. Moreover, the examined polyplexes were less cytotoxic and showed better transfection efficiency when compared to linear poly(ethyleneimine). These results indicate that the presence of quaternary ammonium groups is important in the formation of stable polyplexes. Polymers with all types of amino groups showed large potential for gene delivery. Furthermore, polyplexes with such derivatives were well internalized by cells and ended up into acidic late endosomes.

Polyion complex micelle based on albumin-polymer conjugates: multifunctional oligonucleotide transfection vectors for anticancer chemotherapeutics

Novel biocompatible polyion complex micelles, containing bovine serum albumin (BSA), polymer, and oligonucleotide, were synthesized as a generation of vectors for the gene transfection. Maleimide-terminated poly((N,N-dimethyl amino) ethyl methacrylate) (PDMAEMA) was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization and subsequently deprotected. Precise one to one albumin-PDMAEMA bioconjugates have been achieved via 1,4-addition with the free thiol group on Cys34 on the BSA protein. SDS-PAGE and GPC (water) confirmed and quantified the successful conjugation. The conjugation efficiency was found to be independent of the molecular weight of PDMAEMA. After careful pH adjustment, the conjugate could efficiently condense anticancer oligonucleotide, ISIS 5132, which resulted in particles of 15-35 nm with a negative zeta-potential. The size was easily controlled by the polymer chain length. The albumin corona provides complete protection of the cationic polymer and genetic drug, which gave rise to lower potential toxicity from the polymer and higher gene transfection efficiency. Although a control experiment with a traditional PEG-based polyion complex micelle could deliver the drug just as effectively, if not more so, to the ovarian cancer cell line OVCAR-3, this carrier had no selectivity toward cancerous cells and proved just as toxic to HS27 (fibroblast) cell line. In contrast, the albumin-coated particles demonstrated desirable selectivity toward cancerous cells and have been shown to have outstanding performance in the cytotoxicity tests of several carcinoma monolayer cell models. In addition, the complex micelles were able to destroy pancreatic multicellular tumor spheroids, while free ISIS 5132 could not penetrate the spheroid at all. Hence, albumin-coated/oligonucleotide complex micelles are far more promising than the most classical gene delivery vectors.

Multifunctional non-viral gene vectors with enhanced stability, improved cellular and nuclear uptake capability, and increased transfection efficiency

We have developed a new multifunctional, non-viral gene delivery platform consisting of cationic poly(amine-co-ester) (PPMS) for DNA condensation, PEG shell for nanoparticle stabilization, poly(γ-glutamic acid) (γ-PGA) and mTAT (a cell-penetrating peptide) for accelerated cellular uptake, and a nuclear localization signal peptide (NLS) for enhanced intracellular transport of DNA to the nucleus. In vitro study showed that coating of the binary PPMS/DNA polyplex with γ-PGA promotes cellular uptake of the polyplex particles, particularly by γ-glutamyl transpeptidase (GGT)-positive cells through the GGT-mediated endocytosis pathway. Conjugating PEG to the γ-PGA led to the formation of a ternary PPMS/DNA/PGA-g-PEG polyplex with decreased positive charges on the surface of the polyplex particles and substantially higher stability in serum-containing aqueous medium. The cellular uptake rate was further improved by incorporating mTAT into the ternary polyplex system. Addition of the NLS peptide was designed to facilitate intracellular delivery of the plasmid to the nucleus--a rate-limiting step in the gene transfection process. As a result, compared with the binary PPMS/LucDNA polyplex, the new mTAT-quaternary PPMS/LucDNA/NLS/PGA-g-PEG-mTAT system exhibited reduced cytotoxicity, remarkably faster cellular uptake rate, and enhanced transport of DNA to the nucleus. All these advantageous functionalities contribute to the remarkable gene transfection efficiency of the mTAT-quaternary polyplex both in vitro and in vivo, which exceeds that of the binary polyplex and commercial Lipofectamine™ 2000/DNA lipoplex. The multifunctional mTAT-quaternary polyplex system with improved efficiency and reduced cytotoxicity represents a new type of promising non-viral vectors for the delivery of therapeutic genes to treat tumors.

Serum-resistant complex nanoparticles functionalized with imidazole-rich polypeptide for gene delivery to pulmonary metastatic melanoma

To enhance serum-resistance and overcome the lysosomal barrier are effective and feasible strategies to increase the transfection efficiency of non-viral gene delivery system. For the systemic delivery of therapeutic gene, we previously developed self-assemble carboxymethyl poly(l-histidine) (CM-PLH)/poly(β-amino ester) (PbAE)/pDNA ternary complex nanoparticles based on electrostatic coating as an effective pDNA carrier. Recharging cationic PbAE/pDNA polyplexes with CM-PLH was a promising method to reduce the cytotoxicity and enhance the stability in vivo of positive charged polyplexes. In the present study, the transfection activities of ternary complex nanoparticles were further evaluated in vitro and in vivo. The transfection efficiency of ternary complex nanoparticles showed significant serum-resistance (CM-PLH-containing (51.9±4.35)% in 50% FBS>CM-PLH-free (14.7±5.66)% in 50% FBS), cell line dependent (HEK293>MCF-7>COS7>B16F10>A549>Hela>SPC-A1>CHO>SKOV3) and incubation period dependent (24 h, 20 h, 16 h>12 h>8 h>4 h>2 h>1 h>0.5 h). After transfected with ternary complex nanoparticles loading pGV240-MDA-7/IL-24, the B16F10 cells exhibited significant apoptosis and proliferation inhibition due to the expression of IL-24. Moreover, in the pulmonary metastatic melanoma model, ternary complex nanoparticles loading pGV240-MDA-7/IL-24 showed significant antitumor therapeutic efficacy in vivo. These results suggested that CM-PLH/PbAE/pDNA ternary complex nanoparticles were promising and challenging gene vector for practical application.

A photo-degradable gene delivery system for enhanced nuclear gene transcription

There currently exists a significant gap in our understanding of how the detailed chemical characteristics of polycation gene carriers influence their delivery performances in overcoming an important cellular-level transport barrier, i.e., intranuclear gene transcription. In this study, a UV-degradable gene carrier material (ENE4-1) was synthesized by crosslinking low molecular weight branched polyethylenimine (bPEI-2k) molecules using UV-cleavable o-nitrobenzyl urethane (NBU) as the linker molecule. NBU degrades upon exposure to mild UV irradiation. Therefore, this UV-degradable carrier allows us to control the chemical characteristics of the polymer/DNA complex (polyplex) particles at desired locations within the intracellular environment. By using this photolytic DNA carrier, we found that the exact timing of the UV degradation significantly influences the gene transfection efficiencies of ENE4-1/DNA(pGL2) polyplexes in HeLa cells. Interestingly, even if the polyplexes were UV-degraded at different intracellular locations/times, their nuclear entry efficiency was not influenced by the location/timing of UV degradation. The UV treatment did not influence the size or binding strength of the polyplexes. However, we confirmed that the degradation of the carrier molecules impacts the chemical characteristics of the polyplexes (it produces carbamic acid and nitrosobenzyl aldehyde groups on ENE4-1). We believe that these anionic acid groups enhance the interaction of the polyplexes with nuclear transcription proteins and thus the final gene expression levels; this effect was found to occur, even though UV irradiation itself has a general effect of reducing transfection efficiencies. Excess (uncomplexed) ENE4-1 polymers appear to not play any role in the UV-enhanced gene transcription phenomenon.

Nanoparticles for gene delivery

Nanocarriers are a new type of nonviral gene carriers, many of which have demonstrated a broad range of pharmacological and biological properties, such as being biodegradable in the body, stimulus-responsive towards the surrounding environment, and an ability to specifically targeting certain disease sites. By summarizing some main types of nanocarriers, this Concept considers the current status and possible future directions of the potential clinical applications of multifunctional nanocarriers, with primary attention on the combination of such properties as biodegradability, targetability, transfection ability, and stimuli sensitivity.

Gene delivery of PEI incorporating with functional block copolymer via non-covalent assembly strategy

A novel functional diblock polymer P(PEGMA-b-MAH) is prepared and incorporated to improve the gene delivery efficiency of poly(ethyleneimine) PEI via non-covalent assembly strategy. First, P(PEGMA-b-MAH) is prepared from l-methacrylamidohistidine methyl ester (MAH) by reversible addition fragmentation chain transfer polymerization, with poly[poly(ethylene glycol) methyl ether methacrylate] (P(PEGMA)) as the macroinitiator. Then P(PEGMA-b-MAH) is assembled with plasmid DNA (pDNA) and PEI (M(w)=10kDa) to form PEI/P(PEGMA-b-MAH)/pDNA ternary complexes. The agarose gel retardation assay shows that the presence of P(PEGMA-b-MAH) does not interfere with DNA condensation by the PEI. Dynamic light scattering tests show that PEI/P(PEGMA-b-MAH)/pDNA ternary complexes have excellent serum stability. In vitro transfection indicates that, compared to the P(PEGMA-b-MAH) free PEI-25k/pDNA binary complexes, PEI-10k/P(PEGMA-b-MAH)/pDNA ternary complexes have lower cytotoxicity and higher gene transfection efficiency, especially under serum conditions. The ternary complexes proposed here can inspire a new strategy for the development of gene and drug delivery vectors.

Arginine functionalized peptide dendrimers as potential gene delivery vehicles

The quest for highly efficient and safe gene delivery systems has become the key factor for successful application of gene therapy. Peptide dendrimers are currently investigated as excellent candidates for non-viral gene delivery vectors. In this study, we report the synthesis and characterization of arginine functionalized peptide dendrimer-based vectors ranging from 5th generation (G5A) to 6th generation (G6A) via click chemistry, and their use for gene transfection in vitro and in vivo. The dendrimers can condense plasmid DNA (pDNA) and protect pDNAs from nuclease digestion. Both atomic force microscopy (AFM) and dynamic light scattering (DLS) revealed that the sizes of dendrimer/DNA particles were within 180-250 nm range. In vitro studies showed that the functionalized peptide dendrimers provided serum independent and high transfection efficiency on all studied cells, as over 2 fold higher than that of branched polyetherimide (PEI) in the presence of serum. Dendrimer G5A with molecular weight of 17 kDa demonstrated 6-fold transfection activity than PEI in breast tumor models, as well as good biosafety proved by in vitro and in vivo toxicity evaluation. However, G6A with molecular weight of 46 kDa showed much higher cytotoxicity. The functionalized dendrimer G5A with optimal generation may be therefore a potential candidate for gene delivery vehicle.

Ternary complexes of amphiphilic polycaprolactone-graft-poly (N,N-dimethylaminoethyl methacrylate), DNA and polyglutamic acid-graft-poly(ethylene glycol) for gene delivery

Binary complexes of cationic polymers and DNA were used commonly for DNA delivery, whereas, the excess cationic charge of the binary complexes mainly leads to high toxicity and unstability in vivo. In this paper, ternary complexes by coating polyglutamic acid-graft-poly(ethylene glycol)(PGA-g-mPEG) onto binary complexes of polycaprolactone-graft-poly(N,N-dimethylaminoethyl methacrylate) (PCL-g-PDMAEMA) nanoparticles (NPs)/DNA were firstly developed for effective and targeted gene delivery. The coating of PGA-g-mPEG was able to decrease the zeta potential of the nano-sized DNA complexes nearly to electroneutrality without interferring with DNA condensation ability. As a result, the stability, the escape ability from endosomes and the transfection efficiency of the complexes were enhanced. The ternary complexes of PCL-g-PDMAEMA NPs/DNA/PGA-g-mPEG demonstrated lower cytotoxicity in CCK-8 measurements and higher gene transfection efficiency than the binary complexes in vitro. In addition, Lactate dehydrogenase (LDH) assay was performed to quantify the membrane-damaging effects of the complexes, which is consistent with the conclusion of CCK-8 measurement for cytotoxicity assay. The in vivo imaging measurement and histochemical analysis of tumor sessions confirmed that the intravenous administration of the ternary complexes with red fluorescent protein (RFP) as payload led to protein expression in tumor, which was further enhanced by the targeted coating of PGA-g-PEG-folate.

The role of adenosine receptor and caveolae-mediated endocytosis in oligonucleotide-mediated gene transfer

We previously reported the preparation and characterization of ternary nanoparticles with the negative surface charge, which comprises histidine-conjugated polyallylamine (PAA-HIS)/DNA core complex and a single-stranded oligonucleotide outer layer, to transfect various cell lines. As a continued effort, here the investigations on the endocytotic mechanisms involved in the uptake of the oligonucleotide-coated PAA-HIS/DNA complexes are reported. Interestingly, these complexes showed enhanced transfection efficiency only when deoxyadenosine-containing oligonucleotides were deposited on the PAA-HIS/DNA complex surface. The addition of uncomplexed oligonucleotide, free adenosine and adenosine receptor antagonist significantly inhibited the transfection efficiency of oligonucleotide-coated PAA-HIS/DNA complexes. These results indicated that the oligonucleotide-coated PAA-HIS/DNA complexes could specifically recognize adenosine receptors on the cell surface and were taken up by adenosine receptor-mediated process. Uptake and transfection experiments with various endocytic inhibitors suggested that, after receptor/ligand binding, oligonucleotide-coated PAA-HIS/DNA/complexes were mainly internalized via caveolae-mediated pathway to result in effective intracellular processing for gene expression. In conclusion, both adenosine receptor and caveolae-mediated endocytosis play important roles in oligonucleotide-mediated gene transfer.

In vitro and in vivo anticancer activity of a novel nano-sized formulation based on self-assembling polymers against pancreatic cancer

PURPOSE

To evaluate the in vitro and in vivo pancreatic anticancer activity of a nano-sized formulation based on novel polyallylamine grafted with 5% mole cholesteryl pendant groups (CH(5)-PAA).

METHODS

Insoluble novel anticancer drug, Bisnaphthalimidopropyldiaaminooctane (BNIPDaoct), was loaded into CH(5)-PAA polymeric self-assemblies by probe sonication. Hydrodynamic diameters and polydispersity index measurements were determined by photon correlation spectroscopy. The in vitro cytotoxicity evaluation of the formulation was carried out by the sulforhodamine B dye assay with human pancreatic adenocarcinoma BxPC-3 cells, while for the in vivo study, Xenograff mice were used. In vitro apoptotic cell death from the drug formulation was confirmed by flow cytometric analysis.

RESULTS

The aqueous polymer-drug formulation had a mean hydrodynamic size of 183 nm. The drug aqueous solubility was increased from negligible concentration to 0.3 mg mL(-1). CH(5)-PAA polymer alone did not exhibit cytotoxicity, but the new polymer-drug formulation showed potent in vitro and in vivo anticancer activity. The mode of cell death in the in vitro study was confirmed to be apoptotic. The in vivo results revealed that the CH(5)-PAA alone did not have any anti-proliferative effect, but the CH(5)-PAA-drug formulation exhibited similar tumour reduction efficacy as the commercial drug, gemcitabine.

CONCLUSIONS

The proposed formulation shows potential as pancreatic cancer therapeutics.