Cationic corticosteroid for nonviral gene delivery

Dexamethasone Conjugates: Synthetic Approaches and Medical Prospects

Dexamethasone (DEX) is the most commonly prescribed glucocorticoid (GC) and has a wide spectrum of pharmacological activity. However, steroid drugs like DEX can have severe side effects on non-target organs. One strategy to reduce these side effects is to develop targeted systems with the controlled release by conjugation to polymeric carriers. This review describes the methods available for the synthesis of DEX conjugates (carbodiimide chemistry, solid-phase synthesis, reversible addition fragmentation-chain transfer [RAFT] polymerization, click reactions, and 2-iminothiolane chemistry) and perspectives for their medical application as GC drug or gene delivery systems for anti-tumor therapy. Additionally, the review focuses on the development of DEX conjugates with different physical-chemical properties as successful delivery systems in the target organs such as eye, joint, kidney, and others. Finally, polymer conjugates with improved transfection activity in which DEX is used as a vector for gene delivery in the cell nucleus have been described.

Viral vector mimicking and nucleus targeted nanoparticles based on dexamethasone polyethylenimine nanoliposomes: Preparation and evaluation of transfection efficiency

Non-viral vectors such as polymers and liposomes have been used as gene delivery systems to overcome intrinsic problems of viral vectors, but transfection efficiency of these vectors is lower than viral vectors. In the present study, we tried to design non-viral gene delivery vectors that mimic the viral vectors using the benefits of both cationic liposomes and cationic polymer vectors along with targeting glucocorticoid receptors to enhance cellular trafficking of vectors. Cationic liposomes containing DOTAP and cholesterol were prepared by thin-film hydration following extrusion method. Dexamethasone mesylate was synthesized and then conjugated to polyethylenimine through a one-step reaction. A novel gene delivery system, Lipopolyplex was developed by premixing liposome and different molecular weight of bPEI-Dexa as carriers followed by addition of plasmid at three different carrier/pDNA (C/P) weight ratios. The resulted complexes were characterized for their size, zeta potential and ability of DNA condensation. Transfection efficiency of vectors in neuro2A was determined by Luciferase reporter gene assay. Also, the toxicity of gene carriers was investigated in this cell line. Mean particle size of prepared complexes was less than 200 nm and there was no significant difference in their size by increasing the molecular weight of PEIs. All complexes had positive surface charge. Complete condensation of DNA was occurred at C/P ratio of one for all complexes. Lipopolyplexes were more efficient than polyplexes and lipoplexes alone and transfection efficiency was improved by adding dexamethasone. The complexes containing liposome, PEI 10 kDa and dexamethasone (PEI10:Lipo:Dexa(0.05)) had the highest transfection activity about 40-fold and 3.6-fold in comparison with PEI10 and PEI10:Lipo, respectively. Furthermore, the non-viral vectors described in this study showed low cytotoxicity. The results of this study confirmed that PEI in combination with liposome forms lipopolyplex with low toxicity and enhanced transfection efficiency. Moreover, using dexamethasone, in combination with lipopolyplex might be useful to increase the gene delivery potential of these lipopolyplexes.

Nanocarrier-based co-delivery of small molecules and siRNA/miRNA for treatment of cancer

Aberrant gene expression can trigger several vital molecular events that not only result in carcinogenesis but also cause chemoresistance, metastasis and relapse. Gene-based therapies using siRNA/miRNA have been suggested as new treatment method to improve the current regimen. Although these agents can restore the normal molecular cascade thereby resensitizing the cancer cells, delivering a standard regimen (either subsequently or simultaneously) is necessary to achieve the therapeutic benefit. However, co-delivery using a single carrier could give an additional advantage of similar biodistribution profile of the loaded agents. While much research has been carried out in this field in recent years, challenges involved in designing combination formulations including efficient coloading, stability, appropriate biodistribution and target specificity have hampered their clinical translation. This article highlights current aspects of nano-carriers used for co-delivery of small molecules and genes to treat cancer.

The effect of dexamethasone/cell-penetrating peptide nanoparticles on gene delivery for inner ear therapy

Dexamethasone (Dex)-loaded PHEA-g-C18-Arg8 (PCA) nanoparticles (PCA/Dex) were developed for the delivery of genes to determine the synergistic effect of Dex on gene expression. The cationic PCA nanoparticles were self-assembled to create cationic micelles containing an octadecylamine (C18) core with Dex and an arginine 8 (Arg8) peptide shell for electrostatic complexation with nucleic acids (connexin 26 [Cx26] siRNA, green fluorescent protein [GFP] DNA or brain-derived neurotrophic factor [BDNF] pDNA). The PCA/Dex nanoparticles conjugated with Arg8, a cell-penetrating peptide that enhances permeability through a round window membrane in the inner ear for gene delivery, exhibited high uptake efficiency in HEI-OC1 cells. This potential carrier co-delivering Dex and the gene into inner ear cells has a diameter of 120-140 nm and a zeta potential of 20-25 mV. Different types of genes were complexed with the Dex-loaded PCA nanoparticle (PCA/Dex/gene) for gene expression to induce additional anti-inflammatory effects. PCA/Dex showed mildly increased expression of GFP and lower mRNA expression of inflammatory cytokines (IL1b, IL12, and INFr) than did Dex-free PCA nanoparticles and Lipofectamine^® reagent in HEI-OC1 cells. In addition, after loading Cx26 siRNA onto the surface of PCA/Dex, Cx26 gene expression was downregulated according to real-time polymerase chain reaction for 24 h, compared with that using Lipofectamine reagent. After loading BDNF DNA into PCA/Dex, increased expression of BDNF was observed for 30 h, and its signaling pathway resulted in an increase in phosphorylation of Akt, observed by Western blotting. Thus, Dex within PCA/Dex/gene nanoparticles created an anti-inflammatory effect and enhanced gene expression.

Glucocorticoid Cell Priming Enhances Transfection Outcomes in Adult Human Mesenchymal Stem Cells

Human mesenchymal stem cells (hMSCs) are one of the most widely researched stem cell types with broad applications from basic research to therapeutics, the majority of which require introduction of exogenous DNA. However, safety and scalability issues hinder viral delivery, while poor efficiency hinders nonviral gene delivery, particularly to hMSCs. Here, we present the use of a pharmacologic agent (glucocorticoid) to overcome barriers to hMSC DNA transfer to enhance transfection using three common nonviral vectors. Glucocorticoid priming significantly enhances transfection in hMSCs, demonstrated by a 3-fold increase in efficiency, 4-15-fold increase in transgene expression, and prolonged transgene expression when compared to transfection without glucocorticoids. These effects are dependent on glucocorticoid receptor binding and caused in part by maintenance of normal metabolic function and increased cellular (5-fold) and nuclear (6-10-fold) DNA uptake over hMSCs transfected without glucocorticoids. Results were consistent across five human donors and in cells up to passage five. Glucocorticoid cell priming is a simple and effective technique to significantly enhance nonviral transfection of hMSCs that should enhance their clinical use, accelerate new research, and decrease reliance on early passage cells.

Dexamethasone-Conjugated Polyamidoamine Dendrimer for Delivery of the Heme Oxygenase-1 Gene into the Ischemic Brain

Heme oxygenase-1 (HO-1) has anti-apoptotic and anti-inflammatory effects. In this study, the HO-1 gene was delivered into the brain using dexamethasone-conjugated polyamidoamine generation 2 (PAMAM G2-Dexa) for the treatment of ischemic stroke. PAMAM G2-Dexa formed stable complexes with plasmid DNA (pDNA). The pDNA delivery efficiency of PAMAM G2-Dexa was higher than that of polyethylenimine (PEI25k, 25 kDa), dexamethasone-conjugated PEI (PEI-Dexa), and PAMAM G2 in Neuro2A cells. Therapeutic effect of PAMAM G2-Dexa/pHO-1 complexes was evaluated in a stroke animal model. PAMAM G2-Dexa delivered pHO-1 more efficiently into the ischemic brain than PEI25k and PEI-Dexa with higher therapeutic effect. Therefore, PAMAM G2-Dexa/pHO-1 complexes may be useful for ischemic stroke gene therapy.

Synthesis and structure-activity relationships of novel cationic lipids with anti-inflammatory and antimicrobial activities

Certain membrane-active cationic steroids are known to also possess both anti-inflammatory and antimicrobial properties. This combined functionality is particularly relevant for potential therapies of infections associated with elevated tissue damage, for example, cystic fibrosis airway disease, a condition characterized by chronic bacterial infections and ongoing inflammation. In this study, six novel cationic glucocorticoids were synthesized using beclomethasone, budesonide, and flumethasone. Products were either monosubstituted or disubstituted, containing one or two steroidal groups, respectively. In vitro evaluation of biological activities demonstrated dual anti-inflammatory and antimicrobial properties with limited cytotoxicity for all synthesized compounds. Budesonide-derived compounds showed the highest degree of both glucocorticoid and antimicrobial properties within their respective mono- and disubstituted categories. Structure-activity analyses revealed that activity was generally related to the potency of the parent glucocorticoid. Taken together, these data indicate that these types of dual acting cationic lipids can be synthesized with the appropriate starting steroid to tailor activities as desired.

Intracellular delivery of dendrimer triamcinolone acetonide conjugates into microglial and human retinal pigment epithelial cells

Triamcinolone acetonide (TA) is a potent, intermediate-acting, steroid that has anti-inflammatory and anti-angiogenic activity. Intravitreal administration of TA has been used for diabetic macular edema, proliferative diabetic retinopathy and exudative age-related macular degeneration (AMD). However, the hydrophobicity, lack of solubility, and the side effects limit its effectiveness in the treatment of retinal diseases. In this study, we explore a PAMAM dendrimer-TA conjugate (D-TA) as a potential strategy to improve intracellular delivery and efficacy of TA to target cells. The conjugates were prepared with a high drug payload (∼ 21%) and were readily soluble in saline. Compared to free TA, D-TA demonstrated a significantly improved toxicity profile in two important target [microglial and human retinal pigment epithelium (RPE)] cells. The D-TA was ∼ 100-fold more effective than free TA in its anti-inflammatory activity (measured in microglia), and in suppressing VEGF production (in hypoxic RPE cells). Dendrimer-based delivery may improve the efficacy of TA towards both its key targets of inflammation and VEGF production, with significant clinical implications.

miRNAs in pancreatic cancer: therapeutic potential, delivery challenges and strategies

Pancreatic ductal adenocarcinoma (PDAC) is a severe pancreatic malignancy and is predicted to victimize 1.5% of men and women during their lifetime (Cancer statistics: SEER stat fact sheet, National Cancer Institute, 2014). miRNAs have emerged as a promising prognostic, diagnostic and therapeutic tool to fight against pancreatic cancer. miRNAs could modulate gene expression by imperfect base-pairing with target mRNA and hence provide means to fine-tune multiple genes simultaneously and alter various signaling pathways associated with the disease. This exceptional miRNA feature has provided a paradigm shift from the conventional one drug one target concept to one drug multiple target theory. However, in vivo miRNA delivery is not fully realized due to challenges posed by this special class of therapeutic molecules, which involves thorough understanding of the biogenesis and physicochemical properties of miRNA and delivery carriers along with the pathophysiology of the PDAC. This review highlights the delivery strategies of miRNA modulators (mimic/inhibitor) in cancer with special emphasis on PDAC since successful delivery of miRNA in vivo constitutes the major challenge in clinical translation of this promising class of therapeutics.

Dexamethasone-loaded reconstitutable charged polymeric (PLGA)n -b-bPEI micelles for enhanced nuclear delivery of gene therapeutics

This study investigates the potential of dexamethasone (Dex) to enhance the nuclear accumulation and subsequent gene expression of plasmid DNA (pDNA) delivered using a charged polymeric micelle-based gene delivery system. (PLGA)n -b-bPEI25kDa block copolymers are synthesized and used to prepare Dex-loaded cationic micelles (DexCM). After preparing DexCM/pDNA complexes, bPEI1.8kDa is coated on the complexes using a Layer-by-Layer (LbL) technique to construct DexCM/pDNA/bPEI1.8kDa complexes (i.e., LbL-DexCM polyplexes) that are 100-180 nm in diameter and have a zeta potential of 30-40 mV. In MCF7 cells, LbL-DexCM polyplexes cause 3-13-fold higher transfection efficiencies compared to LbL-CM polyplexes and show negligible cytotoxicity. LbL-DexCM3 polyplexes induce much higher nuclear delivery of pDNA compared to LbL-CM3 polyplexes. These results suggest that Dex-loaded polyplexes could be used in gene and drug delivery applications to increase nuclear accumulation of therapeutic payloads, further leading to a decrease in the dose of the drug and gene necessary to achieve equivalent therapeutic effects.

'Click' synthesized sterol-based cationic lipids as gene carriers, and the effect of skeletons and headgroups on gene delivery

In this work, we have successfully prepared a series of new sterol-based cationic lipids (1-4) via an efficient 'Click' chemistry approach. The pDNA binding affinity of these lipids was examined by EB displacement and agarose-gel retardant assay. The average particle sizes and surface charges of the sterol-based cationic lipids/pDNA lipoplexes were analyzed by dynamic laser light scattering instrument (DLS), and the morphologies of the lipoplexes were observed by atomic force microscopy (AFM). The cytotoxicity of the lipids were examined by MTT and LDH assay, and the gene transfection efficiencies of these lipid carriers were investigated by luciferase gene transfection assay in various cell lines. In addition, the intracellular uptake and trafficking/localization behavior of the Cy3-DNA loaded lipoplexes were preliminarily studied by fluorescence microscopy. The results demonstrated that the pDNA loading capacity, lipoplex particle size, zeta potential and morphology of the sterol lipids/pDNA lipoplexes depended largely on the molecular structure factors including sterol-skeletons and headgroups. Furthermore, the sterol-based lipids showed quite different cytotoxicity and gene transfection efficacy in A549 and HeLa cells. Interestingly, it was found that the cholesterol-bearing lipids 1 and 2 showed 7-10(4) times higher transfection capability than their lithocholate-bearing counterparts 3 and 4 in A549 and HeLa cell lines, suggested that the gene transfection capacity strongly relied on the structure of sterol skeletons. Moreover, the study on the structure-activity relationships of these sterol-based cationic lipid gene carriers provided a possible approach for developing low cytotoxic and high efficient lipid gene carriers by selecting suitable sterol hydrophobes and cationic headgroups.

Dexamethasone conjugation to polyamidoamine dendrimers G1 and G2 for enhanced transfection efficiency with an anti-inflammatory effect

Polyamidoamine (PAM) dendrimers with low generation such as PAM generation 1 (PAMG1) and PAM generation 2 (PAMG2) have been widely used as a gene carrier due to low toxicity, albeit their low transfection efficiency. In this study, dexamethasone was conjugated to PAMG1 and PAMG2 in order to increase the transfection efficiency. In a gel retardation assay, the dexamethasone conjugated PAMG1 and PAMG2 (PAMG1-Dexa and PAMG2-Dexa) retarded plasmid DNA (pDNA) completely at 5:1 and 3:1 weight ratios (polymer:pDNA), respectively. In transfection assays, PAMG1-Dexa and PAMG2-Dexa had the highest transfection efficiency at 20:1 and 10:1 weight ratios, respectively. In addition, PAMG1-Dexa and PAMG2-Dexa had higher transfection efficiencies than PAMG1, PAMG2, PEI25k, and lipofectamine. In a MTT assay, PAMG1-Dexa and PAMG2-Dexa were less cytotoxic than lipofectamine. In addition, PAMG1-Dexa and PAMG2-Dexa decreased the TNF-α level more efficiently than dexamethasone only in the lipopolysaccharide (LPS)-induced Raw264.7 cells. Therefore, PAMG1-Dexa and PAMG2-Dexa may prove to be useful as gene delivery carriers with an anti-inflammatory effect.

Polymeric nucleic acid carriers: current issues and novel design approaches

To deliver nucleic acids including plasmid DNA (pDNA) and short interfering RNA (siRNA), polymeric gene carriers equipped with various functionalities have been extensively investigated. The functionalities of these polymeric vectors have been designed to overcome various extracellular and intracellular hurdles that nucleic acids and their carriers encounter during their journey from injection site to intracellular target site. This review briefly introduces known extracellular and intracellular issues of nucleic acid delivery and their solution strategies. We examine significant yet overlooked factors affecting nucleic acid delivery (e.g., microenvironmental pH, polymer/siRNA complexation, and pharmaceutical formulation) and highlight our reported approaches to solve these problems.

Development of a successive targeting liposome with multi-ligand for efficient targeting gene delivery

BACKGROUND

A successful gene delivery system needs to breakthrough several barriers to allow efficient transgenic expression. In the present study, successive targeting liposomes (STL) were constructed by integrating various targeting groups into a nanoparticle to address this issue.

METHODS

Polyethylenimine (PEI) 1800-triamcinolone acetonide (TA) with nuclear targeting capability was synthesized by a two-step reaction. Lactobionic acid was connected with cholesterol to obtain a compound of [(2-lactoylamido) ethylamino]formic acid cholesterol ester (CHEDLA) with hepatocyte-targeting capability. The liposome was modified with PEI 1800-TA and CHEDLA to prepare successive targeting liposome (STL). Its physicochemical properties and transfection efficiency were investigated both in vitro and in vivo.

RESULTS

The diameter of STL was approximately 100 nm with 20 mV of potential. The confocal microscopy observation and potential assay verified that lipid bilayer of STL was decorated with PEI 1800-TA. Cytotoxicity of STL was significantly lower than that of PEI 1800-TA and PEI 25K. The transfection efficiency of 10% CHEDLA STL in HepG2 cells was the higher than of the latter two with serum. Its transfection efficiency was greatly reduced with excessive free galactose, indicating that STL was absorbed via galactose receptor-mediated endocytosis. The in vivo study in mice showed that 10% CHEDLA STL had better transgenic expression in liver than the other carriers.

CONCLUSIONS

STL with multi-ligand was able to overcome the various barriers to target nucleus and special cells and present distinctive transgenic expression. Therefore, it has a great potential for gene therapy as a nonviral carrier.

Combinational therapy of ischemic brain stroke by delivery of heme oxygenase-1 gene and dexamethasone

Combinational therapies using genes and drugs are promising therapeutic strategies for various diseases. In this research, a co-delivery carrier of dexamethasone and plasmid DNA (pDNA) was developed by conjugation of dexamethasone to polyethylenimine (2 kDa, PEI2k) for combinational therapy of ischemic brain. Dynamic light scattering, atomic force microscopy and flow cytometry studies showed that the pDNA/dexamethasone-conjugated PEI2k (PEI2k-Dexa) complex was 150 nm in size and was taken up by cells more easily than PEI2k-Dexa only. The tumor necrosis factor-α (TNF-α) level was decreased more efficiently by pDNA/PEI2k-Dexa complex than dexamethasone only in hypoxia activated Raw 264.7 macrophage cells, suggesting that pDNA/PEI2k-Dexa complex increased the delivery efficiency and therapeutic effect of dexamethasone. In in vitro transfection assay, PEI2k-Dexa had higher transfection efficiency than PEI2k and lipofectamine. However, the simple mixture of PEI2k and dexamethasone did not show this effect, suggesting that the conjugation of dexamethasone to polyethylenimine increased DNA delivery efficiency of PEI2k. To evaluate the effects of combinational therapy in vivo, pDNA/PEI2k-Dexa complex was applied to a transient focal ischemia animal model. At 24 h after the injection, mean infarction volume and the TNF-α level were reduced more efficiently in the pDNA/PEI2k-Dexa injection group, compared with the control, pDNA/PEI2k, or dexamethasone injection group. The infarction volume and inflammatory cytokines were further decreased by delivery of pSV-HO-1 using PEI2k-Dexa. Magnetic resonance imaging and microPET studies confirmed the therapeutic effect of pSV-HO-1/PEI2k-Dexa complex at 10 days after the injection. Therefore, pSV-HO-1/PEI2k-Dexa complexes may be useful in combinational therapy for ischemic diseases such as stroke.

Investigation of polyethylenimine-grafted-triamcinolone acetonide as nucleus-targeting gene delivery systems

BACKGROUND

Nuclear membrane is one of the main barriers in polymer mediated intracellular gene delivery. To improve the transgenic activity and safety of nonviral vector, triamcinolone acetonide (TA) as a nuclear localization signal was conjugated with different molecular weight polyethylenimine (PEI).

METHODS

Different molecular weight PEI [600, 1800, 25,000 (25k)] was conjugated with TA to synthesize PEI-TA by two-step reaction. Their physicochemical characteristics, in vitro cytotoxicity and transfection efficiency were evaluated. To investigate the difference of transfection efficiency of various molecular weight PEI-TA, their transfection mechanism was further investigated by confocal microscopy and competition assay. Transgenic expression in vivo was evaluated by injection into hepatic portal vein of mice.

RESULTS

All PEI-TA could form nanosize polyplexes with DNA and their physicochemical properties resemble each other. Their cytotoxicities were negligible compared to PEI 25k. The order of transfection efficiency was PEI 1800-TA > PEI 600-TA > PEI 25k-TA. A transfection mechanism study displayed that TA could inhibit considerably the transgenic activity of PEI 1800-TA and PEI 600-TA, but that of PEI 25k-TA was not inhibited. It was suggested that PEI 1800-TA and PEI 600-TA might translocate into the nucleus. Confocal microscopy investigation verified this suggestion. The data strongly suggested that the transfection efficiency of PEI 1800-TA in vivo was much higher than that of PEI 25k, which was consistent with the results obtained in vitro.

CONCLUSIONS

Low molecular weight PEI-TA could translocate into the nucleus efficiently. PEI 1800-TA presented higher transgenic activity and it has a great potential for gene therapy as a nonviral carrier.

Advancing nonviral gene delivery: lipid- and surfactant-based nanoparticle design strategies

Gene therapy is a technique utilized to treat diseases caused by missing, defective or overexpressing genes. Although viral vectors transfect cells efficiently, risks associated with their use limit their clinical applications. Nonviral delivery systems are safer, easier to manufacture, more versatile and cost effective. However, their transfection efficiency lags behind that of viral vectors. Many groups have dedicated considerable effort to improve the efficiency of nonviral gene delivery systems and are investigating complexes composed of DNA and soft materials such as lipids, polymers, peptides, dendrimers and gemini surfactants. The bottom-up approach in the design of these nanoparticles combines components essential for high levels of transfection, biocompatibility and tissue-targeting ability. This article provides an overview of the strategies employed to improve in vitro and in vivo transfection, focusing on the use of cationic lipids and surfactants as building blocks for nonviral gene delivery systems.

Novel cationic lipids with enhanced gene delivery and antimicrobial activity

Cationic lipids facilitate plasmid delivery, and some cationic sterol-based compounds have antimicrobial activity because of their amphiphilic character. These dual functions are relevant in the context of local ongoing infection during intrapulmonary gene transfer for cystic fibrosis. The transfection activities of two cationic lipids, dexamethasone spermine (DS) and disubstituted spermine (D(2)S), were tested as individual components and mixtures in bovine aortic endothelial cells and A549 cells. The results showed a 3- to 7-fold improvement in transgene expression for mixtures of DS with 20 to 40 mol% D(2)S. D(2)S and coformulations with DS, dioleoyl phosphatidylethanolamine, and DNA exhibited potent bactericidal activity against Escherichia coli MG1655, Bacillus subtilis, and Pseudomonas aeruginosa PAO1, which was maintained in bronchoalveolar lavage fluid. Complete bacterial killing was demonstrated at approximately 5 microM, including gene delivery formulations, with 2 orders of magnitude higher tolerance before eukaryotic membrane disruption (erythrocyte hemolysis). D(2)S also exhibited lipopolysaccharide (LPS) scavenging activity resulting in significant inhibition of LPS-mediated activation of human neutrophils with 85 and 65% lower interleukin-8 released at 12 and 24 h, respectively. Mixtures of DS and D(2)S can improve transfection activity over common lipofection reagents, and D(2)S has strong antimicrobial action suited for the suppression of bacterial-mediated inflammation.

Combined antibacterial and anti-inflammatory activity of a cationic disubstituted dexamethasone-spermine conjugate

The rising number of antibiotic-resistant bacterial strains represents an emerging health problem that has motivated efforts to develop new antibacterial agents. Endogenous cationic antibacterial peptides (CAPs) that are produced in tissues exposed to the external environment are one model for the design of novel antibacterial compounds. Here, we report evidence that disubstituted dexamethasone-spermine (D2S), a cationic corticosteroid derivative initially identified as a by-product of synthesis of dexamethasone-spermine (DS) for the purpose of improving cellular gene delivery, functions as an antibacterial peptide-mimicking molecule. This moiety exhibits bacterial killing activity against clinical isolates of Staphylococcus aureus, Pseudomonas aeruginosa present in cystic fibrosis (CF) sputa, and Pseudomonas aeruginosa biofilm. Although compromised in the presence of plasma, D2S antibacterial activity resists the proteolytic activity of pepsin and is maintained in ascites, cerebrospinal fluid, saliva, and bronchoalveolar lavage (BAL) fluid. D2S also enhances S. aureus susceptibility to antibiotics, such as amoxicillin (AMC), tetracycline (T), and amikacin (AN). Inhibition of interleukin-6 (IL-6) and IL-8 release from lipopolysaccharide (LPS)- or lipoteichoic acid (LTA)-treated neutrophils in the presence of D2S suggests that this molecule might also prevent systemic inflammation caused by bacterial wall products. D2S-mediated translocation of green fluorescent protein (GFP)-labeled glucocorticoid receptor (GR) in bovine aorta endothelial cells (BAECs) suggests that some of its anti-inflammatory activities involve engagement of glucocorticoid receptors. The combined antibacterial and anti-inflammatory activities of D2S suggest its potential as an alternative to natural CAPs in the prevention and treatment of some bacterial infections.

TLR9 and IRF3 cooperate to induce a systemic inflammatory response in mice injected with liposome:DNA

Liposome:DNA is a promising gene therapy vector. However, this vector can elicit a systemic inflammatory response syndrome (SIRS). Prior reports indicate that liposome:DNA vectors activate Toll-like receptor (TLR)9. We hypothesized that liposome:DNA vectors also activate the cytosolic DNA-sensing pathway, which signals via interferon (IFN) regulatory factor (IRF)3. To test this, we treated dendritic cells (DCs) with liposome:DNA in vitro and found that IRF3 was phosphorylated independent of TLR9. To test the contribution of this pathway in vivo, we injected a liposome:DNA vector into wild-type (WT), TLR9-knockout (KO), IRF3-KO, and TLR9-IRF3-double-KO (DKO) mice. WT mice exhibited a systemic inflammatory response, evidenced by elevations in serum cytokines, serum enzyme changes indicating organ damage, hypothermia, and mortality. The cytokine response was reduced in TLR9-KO, IRF3-KO, and TLR9-IRF3-DKO mice and all three groups survived. We found that IFN-gamma-KO mice that receive liposome:DNA had a reduced cytokine response and 100% survival. CD11c(+) and NK1.1(+) cells produced IFN-gamma and depleting CD11c(+) cells reduced the cytokine response in mice injected with liposome:DNA. These findings may facilitate the development of immunologically inert gene therapy vectors and may provide general insight into the mechanisms of SIRS.

PAMAM-triamcinolone acetonide conjugate as a nucleus-targeting gene carrier for enhanced transfer activity

The excellent transfection efficiency and viability are essential for successful gene therapy. It suggested that when bound to its glucocorticoid receptor, glucocorticoid steroid can dilate the nuclear pore complexes and facilitated the transport of pDNA into the nucleus. In this research, the two different degrees of substitution of PAMAM-triamcinolone acetonide (PAMAM-TA) conjugates were synthesised for efficient translocation of pDNA into the nucleus. The physicochemical properties of the polyplexes were investigated by agarose gel electrophoresis, Zeta-sizer and TEM. They both could form nano-size polyplexes with pDNA. The polyplexes were very stable and showed excellent buffering capacities, facilitating endosomal escape, and no obvious difference was found between them. The TA-conjugated PAMAM-mediated transfection of luciferase and EGFP genes showed better transfer activity than native PAMAM and was comparable to the PEI 25K (polyethylenimine), and lower cytotoxicity in HEK 293 and HepG 2 cells. Even with 10% serum, their transfer activity was still high relatively. In addition, confocal microscopy examination confirmed that the enhancing mechanism for enhanced gene transfer activity of PAMAM-TA conjugate may involve the nuclear translocation of the polyplex. The low substituted degree of TA to 0.22 did not interrupt its nuclear localization potency. These findings demonstrated that the TA-grafted PAMAM dendrimer is a potential candidate as a safe and efficient gene delivery carrier for gene therapy.

Cationic lipid formulations alter the in vivo tropism of AAV2/9 vector in lung

Physicochemical properties of gene transfer vectors play an important role in both transduction efficiency and biodistribution following airway delivery. Adeno-associated virus (AAV) vectors are currently used in many gene transfer applications; however, the respiratory epithelium remains a challenging target. We synthesized two cationic sterol-based lipids, dexamethasone-spermine (DS) and disubstituted spermine (D(2)S) for pulmonary gene targeting. Scanning and transmission electron micrographs (TEM) confirmed that AAV/lipid formulations produced submicron-sized clusters. When AAV2/9 or AAV2/6.2 were formulated with these cationic lipids, the complexes had positive zeta potential (zeta) and the transduction efficiency in cultured A549 cells increased by sevenfold and sixfold, respectively. Transduction of cultured human airway epithelium with AAV2/6.2-lipid formulations also showed approximately twofold increase in green fluorescence protein (GFP) positive cells as quantified by flow cytometry. Intranasal administration of 10(11) genome copies (GC) of AAV2/9 and AAV2/6.2 coformulated with lipid formulations resulted in an average fourfold increase in transgene expression for both vectors. Formulation of AAV2/9 with DS changed the tropism of this vector for the alveolar epithelium, resulting in successful transduction of conducting airway epithelium. Our results suggest that formulating AAV2/9 and AAV2/6.2 with DS and D(2)S can lead to improved physicochemical characteristics for in vivo gene delivery to lung.

Structure-transfection activity relationships with glucocorticoid-polyethyl-enimine conjugate nuclear gene delivery systems

Efficient nuclear gene delivery is essential for successful gene therapy. It was previously reported that the transport of DNA into nucleus may be facilitated by glucocorticoid (GC). In this study, five glucocorticoids with different structures and potencies were conjugated with low molecular weight PEI 1800, and the degree of substitution of glucocorticoids was controlled to be close to each other. The glucocorticoid-polyethylenimine (GC-PEI)/pDNA complexes were prepared and their physico-chemical properties and transfection efficiency were investigated. The results showed that the complexes had similar physico-chemical properties, but their transfection activities were different statistically. In order to explore the reason of this difference, the affinity of GC-PEI polymer with GC receptor was analyzed by the application of molecular docking, and the correlation between transfection activity and the potency of five GC was investigated. The result showed that receptor binding of five GC was different and transgene expression enhanced linearly with the increasing GC potency, but logP. In addition, confocal microscopy examination confirmed that GC-PEI/DNA complexes were more effectively translocated in the nucleus than PEI 25K or PEI 1800 complexes and the cytotoxicities of the GC-PEI polymers were lower than that of PEI 25K. These results demonstrated that transfection activity of GC-PEI polymer correlated with its GC potency, and this regularity might be useful for the development of more efficient GC substituted polymer as promising nuclear-targeting carrier.

DNA vector augments inflammation in epithelial cells via EGFR-dependent regulation of TLR4 and TLR2

Gene delivery applications to treat lung diseases are, in some instances, suboptimal due to deleterious host inflammatory reactions. Current DNA plasmids (pDNA) exert toxicity in part via unmethylated CpG motifs that stimulate Toll-like receptor (TLR)9-expressing leukocytes; however, the airway epithelial response has not been well defined. Bronchial epithelial cells (BEAS-2B) were exposed to pDNA complexes and inflammatory mediators were measured. As patients with inflammatory lung disease are susceptible to infectious exacerbations, we also evaluated the reciprocal inflammatory response to pDNA and bacterial components lipopolysaccharide (LPS) and lipoteichoic acid (LTA), recognized by TLR4 and TLR2, respectively. Cells primed with pDNA synergistically expressed IL-8 mRNA and protein in response to LPS and LTA (3- to 5-fold). A similar induction was also observed for IL-1beta, IL-6, colony-stimulating factor (CSF)-1, and granulocyte macrophage-CSF. Their synergistic elevation was associated with an increase in TLR4 and TLR2 levels. Methylation of pDNA only partially reduced (25-30%) IL-8 release; hence, signaling occurs via CpG/TLR9-dependent and -independent modules. As epidermal growth factor receptor (EGFR) signaling has been implicated in bronchial IL-8 expression, we assessed whether pDNA priming events were coordinated via EGFR. AG1478 (EGFR inhibitor) restored normal TLR4/2 levels and also suppressed synergistic release of IL-8. The extracellular signal-regulated kinase (Erk) mitogen-activated protein kinase inhibitor also blocked IL-8 release, implicating Erk as a key mediator of EGFR signaling. Our findings identify a novel EGFR-dependent mechanism for regulating TLR, and show that targeted disruption of EGFR signaling ameliorates the airway epithelial inflammatory response to pDNA. Targeting the EGFR system may improve the efficiency, tolerability, and safety of gene therapy strategies.

Cationic liposomes as non-viral carriers of gene medicines: resolved issues, open questions, and future promises

The clinical success of gene therapy is critically dependent on the development of efficient and safe gene delivery reagents, popularly known as "transfection vectors." The transfection vectors commonly used in gene therapy are mainly of two types: viral and non-viral. The efficiencies of viral transfection vectors are, in general, superior to their non-viral counterparts. However, the myriads of potentially adverse immunogenic aftermaths associated with the use of viral vectors are increasingly making the non-viral gene delivery reagents as the vectors of choice. Among the existing arsenal of non-viral gene delivery reagents, the distinct advantages associated with the use of cationic transfection lipids include their: (a) robust manufacture; (b) ease in handling and preparation techniques; (c) ability to inject large lipid:DNA complexes; and (d) low immunogenic response. The present review highlights the major achievements in the area of designing efficacious cationic transfection lipids, some of the more recent advances in the field of cationic liposomes-mediated gene transfer and targeted gene delivery, some unresolved issues and challenges in liposomal gene delivery, and future promises of cationic liposomes as gene-carriers in non-viral gene therapy.

Pulmonary delivery of adenovirus vector formulated with dexamethasone–spermine facilitates homologous vector re-administration

Gene transfer to lung has been hindered by inflammatory and immunological responses activated to the gene-transfer agent or transgene products. In prior work, adenovirus vector delivered to the lung with the cationic glucocorticoid, dexamethasone-spermine (DS) had improved targeting to conducting airway epithelium and reduced cellular infiltration. In this study, the effect of formulation on homologous adenovirus vector re-administration was studied in C57Bl/6 mice. Formulation of an adenovirus vector expressing LacZ with DS/dioleoylphosphatidylethanolamine (DOPE) delivered at day 0 allowed re-administration of adenovirus vector expressing alkaline phosphatase at day 21. Formulation with 3beta [N-(N', N'-dimethylaminoethane) carbamoy] cholesterol (DC-Chol) DC-cholesterol (DC-Chol))/DOPE or dexamethasone in the first dosing at day 0 resulted in moderate alkaline phosphatase expression at day 24. Neutralizing antibodies against adenovirus vector in serum at day 28 were greatly reduced by all three formulations in mice receiving a single dose of adenovirus at day 0. Also, homologous adenovirus vector re-administration at day 14 produced less neutralizing antibody at day 28 when adenovirus was formulated with DS/DOPE at day 0. The use of DS/DOPE at day 0 dramatically reduced CD4 and CD8 T-cell infiltration in mice receiving adenovirus at day 0 followed by vector re-administration at day 14. Transgene-specific T-cell activation was markedly reduced by the DC-Chol/DOPE formulation. Overall, DS/DOPE) facilitated homologous vector re-administration through a combination of liposomal and glucocorticoid mechanisms.

Dexamethasone-conjugated low molecular weight polyethylenimine as a nucleus-targeting lipopolymer gene carrier

Dexamethasone, a glucocorticoid steroid, can dilate the nuclear pore complexes and translocate into the nucleus when it is bound to its glucocorticoid receptor, suggesting that the transport of DNA into the nucleus may be facilitated by the reagent. In this research, dexamethasone was conjugated to low molecular weight polyethylenimine (2 kDa) for efficient translocation of the polymer/DNA complex into the nucleus. Polyethylenimine (PEI)-dexamethasone (PEI-Dexa) was synthesized by one-step reaction using the Traut's reagent. In gel retardation assay, the PEI-Dexa/DNA complex was completely retarded at or above 0.3/1 weight ratio (polymer/DNA). The average size distributions and zeta-potential values of the complexes were measured at various weight ratios. In vitro transfection assay showed that the PEI-Dexa/DNA complex had higher gene delivery efficiency compared to PEI 2kDa/DNA complex. The localization of PEI-Dexa/plasmid DNA complexes in the nucleus was confirmed by using total internal reflection fluorescence and Nomarski differential interference contrast microscope as well as confocal microscope. Therefore, with efficient nuclear translocation and low cytotoxicity, PEI-Dexa may be useful for nonviral gene therapy.

Matrices and scaffolds for DNA delivery in tissue engineering

Regenerative medicine aims to create functional tissue replacements, typically through creating a controlled environment that promotes and directs the differentiation of stem or progenitor cells, either endogenous or transplanted. Scaffolds serve a central role in many strategies by providing the means to control the local environment. Gene delivery from the scaffold represents a versatile approach to manipulating the local environment for directing cell function. Research at the interface of biomaterials, gene therapy, and drug delivery has identified several design parameters for the vector and the biomaterial scaffold that must be satisfied. Progress has been made towards achieving gene delivery within a tissue engineering scaffold, though the design principles for the materials and vectors that produce efficient delivery require further development. Nevertheless, these advances in obtaining transgene expression with the scaffold have created opportunities to develop greater control of either delivery or expression and to identify the best practices for promoting tissue formation. Strategies to achieve controlled, localized expression within the tissue engineering scaffold will have broad application to the regeneration of many tissues, with great promise for clinical therapies.

Synthesis and structure-activity relationships of a series of increasingly hydrophobic cationic steroid lipofection reagents

The use of cholesterol-based cationic lipids and the ability of glucocorticoids to reduce local inflammatory response to lipoplexes motivated an investigation of structure-activity relationships for cationic steroids. A one-step synthetic scheme using iminothiolane was developed to link spermine to the 21-OH position of steroids via an amidine linkage. Five steroids (cortisol, dexamethasone, corticosterone, 11-deoxycortisol, and 11-deoxycorticosterone) with increasing hydrophobicity of the parent steroid (Log P(ster) from 1.51 to 3.01) were conjugated with spermine, formulated with dioleoylphosphatidylethanolamine (DOPE) at DOPE : steroid mole ratios (R) of R = 0.5 to 2, and then complexed with 1 microg enhanced green fluorescent protein (EGFP) plasmid DNA at charge ratios (CR) = 2 to 24 amines per phosphate (0.5 to 6 steroids per phosphate). The resulting 105 different formulations of the cationic steroid series were used to lipofect bovine aortic endothelial cells. Transgene expression data at either 24 or 48 h post-lipofection for all formulations was collapsed onto master curves when plotted against a single empirical dimensionless parameter, the lipofection index (LI) = CR (Log P(liposome))(Log P(ster)/|DeltaLog P|) [R/(R + 1)] where DeltaLog P = Log P(DOPE)- Log P(ster) and Log P(liposome) is a mole-weighted average of the DOPE/cationic steroid liposome hydrophobicity. For 7 < LI < 29, the EGFP expression at 24 or 48 h post-lipofection increased linearly with LI (EGFP approximately 0 for LI < 7), but did not increase further for LI > 29, thus providing a predictive design rule based on Log P of the hydrophobic moiety of the cationic steroid lipid.

The nuclear barrier is structurally and functionally highly responsive to glucocorticoids

Nuclear pore complexes mediate and control transport between the cytosol and the nucleus. They form a highly selective and, thus, tight nuclear barrier between these compartments. The nuclear barrier provides the cell with the opportunity to control access to its DNA, a defining feature of eukaryotes. The tightness of the nuclear barrier is therefore physiologically pivotal and any remarkable change in its structure and permeability can prove pathophysiological, e.g. as a result of viral attack. However, there is accumulating evidence that nuclear barrier structure and permeability are highly responsive to hydrophobic cargos of crucial physiological and therapeutic relevance, glucocorticoids (steroid hormones). The present review highlights the glucocorticoid-induced effects on the nuclear barrier structure and permeability concluding that they are physiologically essential to mediate glucocorticoid action.

Design of modular non-viral gene therapy vectors

Gene delivery has numerous potential applications both clinically and for basic science research. Non-viral vectors represent the long-term future of gene therapy and biomaterials are a critical component for the development of efficient delivery systems. Biomaterial development combined with fundamental studies of virus function and cellular processes will enable the molecular level design of modular vectors. Vectors are being developed based on cationic polymers or lipids that contain functional groups to mediate appropriate interactions with the extracellular environment or to interface with specific cellular processes. This review describes recent progress on the development of biomaterials for non-viral vectors and highlights opportunities for future development. Ultimately, efficient vectors will expand the traditional applications of gene therapy within the clinic and may enable numerous other opportunities within diagnostics, biotechnology, and basic science research.

Targeting Viral-Mediated Transduction to the Lung Airway Epithelium with the Anti-inflammatory Cationic Lipid Dexamethasone–Spermine

We formulated adenovirus (AdV) vectors with cationic steroid liposomes containing dexamethasone-spermine (DS)/dioleoylphosphatidylethanolamine (DOPE) in an effort to overcome the lack of apically expressed AdV vector receptors on airway epithelial cells and to reduce the inflammation associated with AdV vector exposure. An AdV vector (1 to 2.5 x 10(11) genome copies) expressing human placental alkaline phosphatase or beta-galactosidase (LacZ) was delivered alone or complexed with DS/DOPE, DC-Chol/DOPE, or dexamethasone to C57Bl/6 mice via intranasal instillation. Formulation of the AdV vector with DS/DOPE and DC-Chol/DOPE resulted in transgene expression targeted only to the airway epithelial cells with minimal expression in alveolar cells, while AdV alone caused high alveolar transduction. The DS/DOPE and dexamethasone formulations greatly reduced cellular infiltrates compared to AdV vector alone, while formulation with DC-Chol/DOPE did not. IFN-gamma was significantly elevated at day 7 in mice receiving only the AdV vector compared to the AdV vector formulated with DS/DOPE, DC-Chol/DOPE, or dexamethasone. Lipid formulation of adeno-associated virus vector expressing LacZ also produced airway epithelial targeting, similar to the AdV vector. Viral vectors can be formulated with DS/DOPE to improve targeting to the airway epithelium in vivo and to attenuate vector-induced inflammation through the pharmacological activity of DS.

Transfection efficiency and uptake process of polyplexes in human lung endothelial cells: a comparative study in non-polarized and polarized cells

BACKGROUND

Following systemic administration, polyplexes must cross the endothelium barrier to deliver genes to the target cells underneath. To design an efficient gene delivery system into lung epithelium, we evaluated capture and transfection efficiencies of DNA complexed with either Jet-PEI (PEI-polyplexes) or histidylated polylysine (His-polyplexes) in human lung microvascular endothelial cells (HLMEC) and tracheal epithelial cells.

METHODS

After optimizing growth conditions to obtain a tight HLMEC monolayer, we characterized uptake of polyplexes by flow cytometry and evaluated their transfection efficiency. Polyplexes were formulated as small particles. YOYO-labelled plasmid fluorescence intensity and luciferase activity were used as readouts for uptake and gene expression, respectively.

RESULTS

PEI-polyplexes were more efficiently taken up than His-polyplexes by both non-polarized (2-fold) and polarized HLMEC (10-fold). They were mainly internalized by a clathrin-dependent pathway whatever the cell state. In non-polarized cells, His-polyplexes entered also mainly via a clathrin-dependent pathway but with an involvement of cholesterol. The cell polarization decreased this way and a clathrin-independent pathway became predominant. PEI-polyplexes transfected more efficiently HLMEC than His-polyplexes (10(7) vs. 10(5) relative light units (RLU)/mg of proteins) with a more pronounced difference in polarized cells. In contrast, no negative effect of the cell polarization was observed with tracheal epithelial cells in which both polyplexes had comparable efficiency.

CONCLUSIONS

We show that the efficiency of polyplex uptake by HLMEC and their internalization mechanism are polymer-dependent. By contrast with His-polyplexes, the HLMEC polarization has little influence on the uptake process and on the transfection efficiency of PEI-polyplexes.

Common co-lipids, in synergy, impart high gene transfer properties to transfection-incompetent cationic lipids

Efficacious cationic transfection lipids usually need either DOPE or cholesterol as co-lipid to deliver DNA inside the cell cytoplasm in non-viral gene delivery. If both of these co-lipids fail in imparting gene transfer properties, the cationic lipids are usually considered to be transfection inefficient. Herein, using both the reporter gene assay in CHO, COS-1 and HepG2 cells and the whole cell histochemical X-gal staining assay in representative CHO cells, we demonstrate that common co-lipids DOPE, Cholesterol and DOPC, when act in synergy, are capable of imparting improved gene transfer properties to a novel series of cationic lipids (1-5). Contrastingly, lipids 1-5 became essentially transfection-incompetent when used in combination with each of the pure co-lipid components alone.

Nonviral genetic modification mediates effective transgene expression and functional RNA interference in human mesenchymal stem cells

BACKGROUND

Human mesenchymal stem cells (hMSC) are increasingly the focus of both basic and clinical research due to their ability to strike a balance between self-renewal and commitment to mesodermal differentiation. However, the promising therapeutic utility of hMSC in regenerative medical approaches requires detailed knowledge about their molecular characteristics. Therefore, genetic modification of hMSC provides a powerful tool to understand their complex molecular regulation mechanisms.

METHODS

Here we describe a proof of concept approach of separate and combined gene transfer and gene silencing by nonviral DNA transfection of enhanced green fluorescent protein (EGFP) and EGFP-targeted small interfering RNAs (siRNAs) in hMSC. For optimization of nonviral DNA and siRNA transfer different liposomal-based transfection strategies were validated.

RESULTS

The highest fraction of EGFP-expressing hMSC was obtained using Lipofectamine 2000 (50%) which also mediated the highest transfection rates of siRNAs into hMSC (>or=92%). Stably EGFP-expressing hMSC maintained their proliferation capacity paired with the ability to differentiate into different mesodermal lineages (bone, cartilage, and fat) without loss of transgene expression. Based on our nonviral nucleic acid delivery technique we showed efficient, functional, and long-term RNA interference (RNAi) in hMSC by gene specific knock-down of transiently and stably expressed EGFP (88-98%).

CONCLUSIONS

This is the first demonstration of efficient nonviral transfer of both nucleic acids (DNA and siRNA) into hMSC, exhibiting the potential of targeted modification of hMSC. In particular, the combination of these techniques represents a powerful gene transfer/silencing strategy, thus facilitating detailed genetic approaches to study regulatory networks in stem cell differentiation processes.

Nuclear envelope barrier leak induced by dexamethasone

Nuclear pore complexes (NPCs) are multiprotein channels that span the nuclear envelope. They strongly limit the efficiency of gene transfection by restriction of nuclear delivery of exogenously applied therapeutic macromolecules. NPC dilation could significantly increase this efficiency. Recently, it was shown in oocytes of Xenopus laevis that NPCs dilate from about 82 to 110 nm within min after injection of the glucocorticoid analog dexamethasone (dex). In the present paper we analyzed by means of atomic force microscopy the structural details of NPC dilation and correlated them with functional changes in nuclear envelope permeability. 5-11 min after Dex injection NPC dilation was found at its maximum (approximately 140 nm). In addition, a yet unknown configuration, so-called giant pore, up to 300 nm in diameter, was visualized. Giant pore formation was paralleled by an increase in nuclear envelope permeability tested by electrophysiology and confocal fluorescence microscopy. Even large macromolecules lacking any nuclear localization signal (77 kDa FITC-dextran, molecule diameter up to 36 nm) could gain access to the nucleus. We conclude that dex transiently opens unspecific pathways for large macromolecules. Dex treatment could be potentially useful for improving the efficiency of nuclear gene transfection.

Toxicity of Cationic Lipid‐DNA Complexes

As with any conventional drug, the body's response to cationic lipid-DNA complexes is highly dependent on both the dose administered and the route of delivery. At relatively low doses there is little to no effect on organ function or tissue architecture, but at higher doses, acute inflammation and tissue damage can occur that is sometimes quite profound. Of the two most common routes of delivery, intravenous (IV) or intrapulmonary, IV administration tends to cause more severe adverse effects and can be lethal at higher doses of complex. Both routes activate an innate immune response that includes the induction of proinflammatory cytokines and immune cell activation, a major portion of which has been attributed to the presence of immunostimulatory CpG motifs within the plasmid DNA vector. Removing CpGs from the plasmid vector reduces several, but not all of the acute inflammatory responses to cationic lipid-DNA complexes. Therefore, other strategies are required to improve the therapeutic potential of these vectors, such as transient immune suppression, aerosolization of the complex, and novel formulations that have increased efficiency of transduction and decreased interaction with immune cells.

Modular design of non-viral vectors with bioactive components

Inefficient gene delivery continues to limit gene therapy applications to both basic and applied sciences. Approaches for engineering vectors increasingly include bioactive components that bind cellular receptors, disrupt membranes, or enhance nuclear transport. Recently, a novel cationic lipid was developed by modifying the glucocorticoid dexamethasone. This cationic corticosteroid condenses plasmids for gene delivery, while also modulating inflammation. Modular vectors containing bioactive components that target various cellular processes can overcome the barriers limiting gene transfer.