Naked Plasmid Research Articles

Validation of Mitochondrial Gene Delivery in Liver and Skeletal Muscle via Hydrodynamic Injection Using an Artificial Mitochondrial Reporter DNA Vector

For successful mitochondrial transgene expression, two independent processes, i.e., developing a mitochondrial gene delivery system and construction of DNA vector to achieve mitochondrial gene expression, are required. To date, very few studies dealing with mitochondrial gene delivery have been reported and, in most cases, transgene expression was not validated, because the construction of a reporter DNA vector for mitochondrial gene expression is the bottleneck. In this study, mitochondrial transgene expression by the in vivo mitochondrial gene delivery of an artificial mitochondrial reporter DNA vector via hydrodynamic injection is demonstrated. In the procedure, a large volume of naked plasmid DNA (pDNA) is rapidly injected. We designed and constructed pHSP-mtLuc (CGG) as a mitochondrial reporter DNA vector that possesses a mitochondrial heavy strand promoter (HSP) and an artificial mitochondrial genome with the reporter NanoLuc (Nluc) luciferase gene that records adjustments to the mitochondrial codon system. We delivered the pDNA into mouse liver mitochondria by hydrodynamic injection, and detected exogenous mRNA in the liver using reverse transcription PCR analysis. The hydrodynamic injection of pHSP-mtLuc (CGG) resulted in the expression of the Nluc luciferase protein in liver and skeletal muscle. Our mitochondrial transgene expression reporter system would contribute to mitochondrial gene therapy and further studies directed at mitochondrial molecular biology.

Correlating cell transfectability and motility on materials with different physico-chemical properties

Gene delivery into cells can be facilitated by adding plasmid DNA/transfection reagent complexes in culture medium or pre-adsorbing the complexes on the substrate before cell seeding. Using transfection reagents, however, often causes cytotoxicity. Effective delivery of naked plasmid without any transfection reagent remains a challenge. In this study, we cultured human umbilical cord derived mesenchymal stem cells (hMSCs) on different biomaterial substrates with different physico-chemical properties and examined the transfectability of naked plasmid. Specifically, we synthesized a negatively charged polyurethane (PU) to mimic the hyaluronan-modified chitosan (CS-HA) membranes previously found to promote the transfection of naked plasmid. We observed that the PU membranes were as effective as CS-HA membranes in substrate-mediated delivery of naked plasmid into hMSCs. PU membranes with surface microgrooves further increased the gene delivery efficiency to a similar level as the commercial transfection reagent but without the harmful effect. The gene delivery efficiency was associated with the extent of activation of cellular integrins β1 and α5 on different substrates. Moreover, the delivery efficiency was positively correlated with the cell migration rate on various substrates. The substrate-mediated gene delivery by synthetic polymeric substrates supports that integrin activation and cell behavior (e.g. migration and transfectability) changes can be modulated by synthetic polymer surface with microfeatures. The transfection by PU microgrooves is easy, nontoxic, and as effective as the commercial transfection reagent.

Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

Gene-based vaccines and immunotherapeutic strategies against neurodegenerative diseases: Potential utility and limitations

There has been a recent expansion of vaccination and immunotherapeutic strategies from controlling infectious diseases to the targeting of non-infectious conditions including neurodegenerative disorders. In addition to conventional vaccine and immunotherapeutic modalities, gene-based methods that express antigens for presentation to the immune system by either live viral vectors or non-viral naked DNA plasmids have been developed and evaluated. This mini-review/commentary summarizes the advantages and disadvantages, as well as the research findings to date, of both of these gene-based vaccination approaches in terms of how they can be targeted against appropriate antigens within the Alzheimer and Parkinson disease pathogenesis processes as well as potentially against targets in other neurodegenerative diseases. Most recently, the novel utilization of these viral vector and naked DNA gene-based technologies includes the delivery of immunoglobulin genes from established biologically active monoclonal antibodies. This modified passive immunotherapeutic strategy has recently been applied to deliver passive antibody immunotherapy against the pathologically relevant amyloid β protein in Alzheimer disease. The advantages and disadvantages of this technological application of gene-based immune interventions, as well as research findings to date are also summarized. In sum, it is suggested that further evaluation of gene based vaccines and immunotherapies against neurodegenerative diseases are warranted to determine their potential clinical utility.

Clinical Safety and Preliminary Efficacy of Plasmid pUDK-HGF Expressing Human Hepatocyte Growth Factor (HGF) in Patients with Critical Limb Ischemia

Critical limb ischemia (CLI) is the most severe form of peripheral arterial disease and a major unmet public health care need. This phase I clinical study was performed to assess the safety and preliminary efficacy of naked plasmid DNA (pUDK-HGF) expressing human hepatocyte growth factor (HGF) in patients with critical limb ischemia (CLI). Twenty-one patients with CLI were enrolled and randomly divided into four dose groups (4-16 mg) to receive local injection of pUDK-HGF into ischemic calf and/or thigh muscles twice on days 1 and 15. Safety, including adverse events and physiological parameters, and preliminary efficacy, including pain severity score (VAS), ulcer size, transcutaneous oxygen pressure (TcPO2), and ankle brachial index (ABI), were evaluated throughout a 3 month follow up period. All doses of pUDK-HGF were well tolerated by the patients. None of the adverse effects was considered to be related to pUDK-HGF injection. Two significant clinical results were observed after pUDK-HGF administration. The mean VAS value of all patients decreased from 4.52 at baseline to 0.30 (p < .01), and pain had disappeared in 14 out of 17 evaluable patients by day 91. Two of four ulcers had completely healed, with the other two patients having more than 25% ulcer size reduction in the long axis diameter. Of five patients with gangrene, one gangrenous wound had healed completely and two patients showed marked size reduction by day 91. The mean hemodynamic parameters (ABI, TcPO2) were also improved. Intramuscular injection of pUDK-HGF is safe, and may provide symptomatic relief for CLI patients. A larger, randomized, double blinded phase II trial will provide more information on safety and efficacy.

Nanosheet transfection: effective transfer of naked DNA on silica glass

Existing gene delivery technologies using nonviral vectors or physical stimulation are limited by cytotoxicity. Here, we reveal an easy and new method to fabricate silica upright nanosheets, which can be easily scaled up and used for gene delivery. We demonstrate that naked DNA can be transferred into difficult-to-transfect cells (for example, stem cells) by plating cells on silica glass with the upright nanosheets without using any vector. Gene entry is probably achieved through the integrin-FAK-Rho signaling axis, which can be activated by the cytoskeleton rearrangement on nanosheets in a limited time frame (‘transfection window’). Transfecting naked GATA4-binding protein 4 plasmids into stem cells can upregulate the other two important cardiac marker genes myocyte enhancer factor 2C and T-box 5. The transfected mesenchymal stem cells express the cardiac marker proteins at 7 days after transfection, which confirms the success of the innovative gene delivery approach. The vector-free silica nanosheet-induced transfection is simple and effective but faster and safer than the conventional technologies. ‘Naked’ DNA strands can directly transfer into host cells using surfaces embedded with freestanding silica nanosheets, finds a new study. Gene therapy has the potential to elimate disease by altering a patient's genetic code, but getting designer DNA plasmids past cellular membranes is difficult. Now, Shan-hui Hsu from the National Taiwan University and co-workers in Japan have developed a strategy to improve gene delivery with a procedure that elimates the need to use viruses or other biocompatible molecules to carry nucleic acids into cells. Adding naked DNA plasmid onto glass substrates covered with rough nanosheet textures enhanced entry of cardiac marker gene (GATA4) into stem cells by mediating cell-membrane receptors. This low-cost strategy introduced genes to 70% of starting cells within 24 hours, making it attractive for scalable in vivo gene delivery with limited cytotoxicity side effects. A nanosheet structure on a glass plate can transfer naked DNA into difficult-to-transfect cells (for example, stem cells) in limited time after contact (‘transfection window’) without any vector. The transfected cells express the specific proteins a week later. The gene uptake and expression are associated with the cytoskeleton arrangement on the silica nanosheets by activating the cell-membrane integrin receptor.

378. Isocitrate Dehydrogenase 2 Overexpression Ameliorates Ischemia Reperfusion Injury to the Kidney

Acute Kidney Injury (AKI) is a significant contributor to morbidity and mortality, affecting 35% of critical care patients and 7% of hospital admissions nationwide. Furthermore, the 60 day mortality rate for AKI patients requiring renal replacement therapy was as high as 53.6%. Understanding the molecular underpinnings responsible for the variation in response to injury is an important step to addressing AKI. Previous work on AKI resistant Brown Norway s rats indicated that several proteins active in metabolism were overexpressed post-injury. Among these was Isocitrate Dehydrogenase 2 (IDH2), a mitochondria-enzyme that has a crucial role in metabolism.. In order to assess the contribution of heightened expression of IDH2 to AKI resistance, the protein was overexpressed in a highly oxygen-dependent cell line derived from mouse proximal tubule (S3 cells). Overexpression was confirmed via western blotting. The membrane potential of the mitochondria was assessed by use of the cationic dye JC-1. Mitochondrial polarization, as measured by the red-shift of JC-1 dye, was increased by 11% (p<0.02, n=16) in cells overexpressing IDH2 versus those that were sham transfected. Initial assessment of cell death performed by propidium iodide staining and Hoechst counterstaining followed by flow cytometry analysis indicated a reduction in the fraction of cells that had undergone cell death. Subsequent imaging studies were performed utilizing both propidium iodide and Hoechst to assess apoptotic versus necrotic cell death as determined by cellular morphology. Once the protective effect of IDH2 overexpression was confirmed in cell culture, the in vivo efficacy was tested using hydrodynamic delivery to kidneys of Sprague Dawley rats. Delivery of naked IDH2 plasmid DNA (600 μg in 500 μl) to the left kidney was achieved by rapid injection into the renal vein while blood flow into, and out of the kidney was occluded. Uptake and overexpression of IDH2 was confirmed by western blot analysis using the right kidney as a control. After one week of recovery, a 40 minute ischemia/reperfusion injury was induced by bilateral renal pedicle cross clamping. In comparison to the sham gene delivery group, IDH2 overexpressing animals exhibited an 82% reduction in peak post-injury serum creatinine levels (p<0.01). TMRM staining coupled with intravital microscopy confirmed increased mitochondrial potential seen in the earlier JC-1 experiments and histology indicated that proximal tubule architecture was preserved.Our work indicates that modulating levels of IDH2 helps decrease susceptibility to and severity of AKI. This finding coupled with the new gene delivery technique of hydrodynamic delivery offers an avenue towards devising rational gene therapies to protect susceptible populations and the possibility that, with other candidate genes, regeneration of the kidney can be induced.

491. Messenger RNA (mRNA)-Based Gene Therapy for Introducing Anti-Apoptotic Factor

In gene therapy, mRNA delivery lacks the risk of random integration to host genome in contrast to DNA delivery. In introduction of anti-apoptotic factors, uncontrollably enhanced and prolonged expression of such factors after genomic integration would cause cancer, and thus DNA delivery cannot be used for introducing these factors in clinical settings. In this study, we tried to treat fulminant hepatitis, a disease associated with excessive apoptosis, by mRNA-based introduction of an anti-apoptotic factor, Bcl-2. For efficient mRNA delivery with minimal inflammatory responses, mRNA was loaded into our original carrier, polyplex nanomicelles (Adv Drug Deliv Rev 2001, 47, 113, PLoS One 2013, 8, e56220), which are composed of polyethyleneglycol-coated surface and mRNA-containing core, for hydrodynamic injection into mouse liver.In a reporter assay using GFP-expressing mRNA, the nanomicelles effectively introduced mRNA into liver cells by preventing degradation of mRNA, resulting in significantly higher level of GFP expression in liver compared to that after naked mRNA injection. This result is quite different from that of naked plasmid DNA (pDNA) delivery, strongly suggesting that mRNA is unstable in mouse body, and a proper carrier is required for mRNA delivery.In tissue distribution analysis of GFP expression, mRNA delivery induced GFP expression uniformly in almost 100% of liver cells, whereas only a small percentage of liver cells became GFP positive after pDNA delivery. After delivery of Cy5-labeled pDNA, nuclear localization of pDNA was undetected in a large percentage of cells, indicating that nuclear entry was a large obstacle in DNA delivery. In contrast, protein expression from mRNA requires only cytoplasmic uptake of mRNA, and this was observed in almost all liver cells, resulting in uniform GFP expression profile.Then, we performed the treatment of fulminant hepatitis using Bcl-2-expressing gene, after preparing a mouse model of the disease by injecting Fas ligand. After mRNA-based introduction of Bcl-2, the number of apoptotic cells in liver was significantly reduced when compared to saline-treated control. In contrast, delivery of Bcl-2-expressing pDNA had almost no therapeutic effect. It is suggested that, in pDNA delivery, a large percentage of cells were unprotected from apoptotic signals because of inhomogeneous protein expression profile. Thus, these results indicate that mRNA delivery is more suitable for introducing intracellular signaling factors than DNA delivery, because such factors require homogeneous expression to obtain therapeutic effect. This is in sharp contrast to the case of secretable factors, where efficient introduction to only a small percentage of cells is sufficient to obtain therapeutic effect.In summary, mRNA delivery has two advantages over pDNA delivery: homogeneous distribution profile of protein expression, and lack of random genomic integration. Thus, mRNA delivery is promising for the treatment of various intractable diseases associated with massive apoptosis.

Synthesis, characterization, and immune efficacy of layered double hydroxide@SiO2 nanoparticles with shell-core structure as a delivery carrier for Newcastle disease virus DNA vaccine.

Layered double hydroxide (LDH)@SiO2 nanoparticles were developed as a delivery carrier for the plasmid DNA expressing the Newcastle disease virus F gene. The LDH was hydrotalcite-like materials. The plasmid DNA encapsulated in the LDH@SiO2 nanoparticles (pFDNA-LDH@SiO2-NPs) was prepared by the coprecipitation method, and the properties of pFDNA-LDH@SiO2-NPs were characterized by transmission electron microscopy, zeta potential analyzer, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The results demonstrated that the pFDNA-LDH@SiO2-NPs had a regular morphology and high stability with a mean diameter of 371.93 nm, loading capacity of 39.66%±0.45%, and a zeta potential of +31.63 mV. A release assay in vitro showed that up to 91.36% of the total plasmid DNA could be sustainably released from the pFDNA-LDH@SiO2-NPs within 288 hours. The LDH@SiO2 nanoparticles had very low toxicity. Additionally, their high transfection efficiency in vitro was detected by fluorescent microscopy. Intranasal immunization of specific pathogen-free chickens with pFDNA-LDH@SiO2-NPs induced stronger cellular, humoral, and mucosal immune responses and achieved a greater sustained release effect than intramuscular naked plasmid DNA, and the protective efficacy after challenge with the strain F48E9 with highly virulent (mean death time of chicken embryos ≤60 hours, intracerebral pathogenicity index in 1 -day-old chickens >1.6) was 100%. Based on the results, LDH@SiO2 nanoparticles can be used as a delivery carrier for mucosal immunity of Newcastle disease DNA vaccine, and have great application potential in the future.

Prolyl hydroxylase domain-2 silencing induced by hydrodynamic limb vein injection enhances vascular regeneration in critical limb ischemia mice through activation of multiple genes.

Therapeutic revascularization had been considered as the most potential strategy for treating ischemic diseases. Reconstruction of mature blood vessels, which is the key for functional revascularization, is a complex process involving multiple angiogenesis factors. Attempts had been made to promote functional revascularization by delivering vectors or other macromolecules that could positively regulate angiogenesis; however, the delivery method of these therapeutic angiogenesis factors had been mostly limited to direct intramuscular injection. In this study, we showed that compared to intramuscular injection, the hydrodynamic limb vein (HLV) injection of naked short-hairpin RNA expression plasmid targeting PHD2 (shPHD2) into critical himblimb ischemia mice could increase not only the expressions of HIF-dependent and HIF-independent angiogenic factors, but also tissue protective factors involved in various endogenous pathways more efficiently. We also found that PHD2-silencing enhanced innate endogenous recovery mechanism, as the expression levels of these factors had been slightly upregulated merely by the ischemic condition. Finally, we showed that HLV injection of shPHD2 promoted the formation of mature and functional vessels, and thus, enhances the recovery of ischemic hindlimbs more efficiently. These results suggest that HLV delivery of shPHD2 might become a promising treatment strategy to promote vascular regeneration in critical limb ischemia disease via enhancing innate endogenous pathways.

Mesenchymal stromal cells overexpressing vascular endothelial growth factor in ovine myocardial infarction.

Mesenchymal stromal cells (MSCs) are cardioprotective in acute myocardial infarction (AMI). Besides, we have shown that intramyocardial injection of plasmid-VEGF(165) (pVEGF) in ovine AMI reduces infarct size and improves left ventricular (LV) function. We thus hypothesized that MSCs overexpressing VEGF(165) (MSCs-pVEGF) would afford greater cardioprotection than non-modified MSCs or pVEGF alone. Sheep underwent an anteroapical AMI and, 1 week later, received intramyocardial MSCs-pVEGF in the infarct border. One month post treatment, infarct size (magnetic resonance) decreased by 31% vs pre-treatment. Of note, myocardial salvage occurred predominantly at the subendocardium, the myocardial region displaying the largest contribution to systolic performance. Consistently, LV ejection fraction recovered to almost its baseline value because of marked decrease in end-systolic volume. None of these effects were observed in sheep receiving non-transfected MSCs or pVEGF. Although myocardial retention of MSCs decreased steeply over time, the treatment induced significant capillary and arteriolar proliferation, which reduced subendocardial fibrosis. We conclude that in ovine AMI, allogeneic VEGF-overexpressing MSCs induce subendocardial myocardium salvage through microvascular proliferation, reducing infarct size and improving LV function more than non-transfected MSCs or the naked plasmid. Importantly, the use of a plasmid rather than a virus allows for repeated treatments, likely needed in ischemic heart disease.

Magnetic nanosphere-guided site-specific delivery of vascular endothelial growth factor gene attenuates restenosis in rabbit balloon-injured artery

New and efficient strategies to protect endothelium or to enhance endothelial regrowth are important for treatment of restenosis after percutaneous transluminal angioplasty. Magnetic DNA microspheres are used to accelerate vascular endothelial growth factor (VEGF) re-endothelialization and to attenuate intimal hyperplasia in balloon-injured artery. This study aimed to assess DNA-gelatin magnetic nanospheres containing VEGF expression plasmids in vascular restenosis attenuation. Ninety-six rabbits underwent balloon injury and were randomly divided for gene transfer with naked VEGF plasmids (NAK group), magnetic VEGF microspheres (MIC group), and LacZ (CON group: naked LacZ plasmid and LacZ nanosphere subgroups). Serum and tissue VEGF levels were measured. Also, the ratios of intima area to media area were determined to assess neointima formation. Microsphere gene delivery through the artery by a magnet resulted in VEGF overexpression in transfected arterial segments. Tissue VEGF integral optical densities were significantly increased in MIC rabbits compared with NAK animals. Serum VEGF was below detection in all animals. X-Gal staining showed higher transfection efficiency in the CON group. The impact of neointimal thickening was evaluated by light microscopy as the ratio of intima area to media area in cross sections. Significant differences in the ratio of intima area to media area were obtained between the NAK group (0.12 ± 0.02, 0.41 ± 0.03, 0.61 ± 0.05, and 0.72 ± 0.04 at 1, 2, 3, and 4 weeks, respectively) and the MIC group (0.06 ± 0.03, 0.20 ± 0.05, 0.25 ± 0.04, and 0.26 ± 0.03 at 1, 2, 3, and 4 weeks, respectively) at 2, 3, and 4 weeks (P < .05). Intra-arterial VEGF gene delivery by magnetic microspheres significantly increased DNA stability, transfection efficiency, and targeting specificity, resulting in exogenous VEGF overexpression and attenuated intimal hyperplasia in balloon-injured artery.

Gene Gun Her2/neu DNA Vaccination: Evaluation of Vaccine Efficacy in a Syngeneic Her2/neu Mouse Tumor Model.

Genetic vaccination using naked plasmid DNA is an immunization strategy both against infectious diseases and cancer. In order to improve the efficacy of DNA vaccines, particularly in large animals and humans, different strategies have been pursued. These vaccination strategies are based on different application routes, schedules, and coexpression of immunomodulatory molecules as adjuvants. Our mouse tumor model offers the possibility to investigate Her2/neu DNA vaccines in different settings, i.e., intramuscular or intradermal application with or without coexpression of adjuvants. Protection from tumor growth in tumor challenge experiments and both T cell and humoral immune responses against Her2/neu peptides are used as surrogate parameters for vaccine efficacy.

Tapping the Potential of DNA Delivery with Electroporation for Cancer Immunotherapy.

Cancer is a worldwide leading cause of death, and current conventional therapies are limited. The search for alternative preventive or therapeutic solutions is critical if we are going to improve outcomes for patients. The potential for DNA vaccines in the treatment and prevention of cancer has gained great momentum since initial findings almost 2 decades ago that revealed that genetically engineered DNA can elicit an immune response. The combination of adjuvants and an effective delivery method such as electroporation is overcoming past setbacks for naked plasmid DNA (pDNA) as a potential preventive or therapeutic approach to cancer in large animals and humans. In this chapter, we aim to focus on the novel advances in recent years for DNA cancer vaccines, current preclinical data, and the importance of adjuvants and electroporation with emphasis on prostate, melanoma, and cervical cancer.

Gene transfer on inorganic/organic hybrid silica nanosheets.

Gene delivery is often accomplished by the forward or reverse transfection protocol. In either protocol, a transfection reagent (usually cationic) is added to increase the delivery efficiency. In this study, we employed a series of nanosheet networks to facilitate the delivery of naked plasmid DNA into human mesenchymal stem cells (hMSCs). By adding different chemicals into the reaction mixture for etching the silica glass, we were able to fabricate inorganic/organic hybrid nanosheet networks with different physico-chemical characteristics. We then analyzed the transfection efficiency on different nanosheets and the possible dependence of the transfection efficiency on the physico-chemical parameters of nanosheets. The results showed that all nanosheet networks were noncytotoxic and demonstrated a high cell survival rate (∼90%) after transfection. The transfection efficiency was critically determined by the aspect ratio (height/thickness of the wall) of the nanosheets. The effects of chemistry or other surface properties were not significant. Moreover, the transfection efficiency may be successfully predicted by the initial cell migration rate and the activation of integrin β3 on the nanosheets. Compared to the conventional method, transfection using concurrent cell/plasmid seeding on the nanosheets is not only more effective but also much safer. Future efforts may focus on combining the inorganic/organic hybrid nanosheets with soft substrates for in situ transfection.

Xanthan gum enhances humoral immune response elicited by a DNA vaccine against leptospirosis in mice

Background Traditional vaccines (killed or inactivated) played vital roles in controlling and eradicating infectious diseases for a long time. Antigen-specific T cell response can be induced when mice are intramuscularly inoculated with naked plasmid DNA. Therefore, DNA vaccines were evaluated in many studies, demonstrating its safety, stability and easy production. Furthermore, it has been reported that the gene expression lasted for one year after intramuscular injection of the plasmid DNA. However, some disadvantages such as the low transfection rate and low immunogenicity make the use of multiple doses necessary [1]. In light of this context, several studies have been performed to improve the immune response induced by DNA vaccines. The xanthan gum is an extracellular polysaccharide produced during fermentation of bacteria of the genus Xanthomonas and has been studied as a new vaccine adjuvant [2]. However, it has not yet been evaluated as an adjuvant for DNA vaccines. The aim of this study was to evaluate the capacity of the xanthan gum to increase the humoral immune response of mice inoculated with a DNA vaccine against a fragment of the leptospiral antigen LigAni cloned in the mammalian expression plasmid pTARGET.

Equilibration of complexes of DNA and H-NS proteins on charged surfaces: A coarse-grained model point of view

The Histone-like Nucleoid Structuring protein (H-NS) is a nucleoid-associated protein, which is involved in both gene regulation and DNA compaction. Although it is a key player in genome organization by forming bridges between DNA duplexes, the precise structure of complexes of DNA and H-NS proteins is still not well understood. In particular, it is not clear whether the structure of DNA/H-NS complexes in the living cell is similar to that of complexes deposited on mica surfaces, which may be observed by AFM microscopy. A coarse-grained model, which helps getting more insight into this question, is described and analyzed in the present paper. This model is able of describing both the bridging of bacterial DNA by H-NS in the bulk and the deposition and equilibration of the complex on a charged surface. Simulations performed with the model reveal that a slight attraction between DNA and the charged surface is sufficient to let DNA/H-NS complexes reorganize from 3D coils to planar plasmids bridged by H-NS proteins similar to those observed by AFM microscopy. They furthermore highlight the antagonistic effects of the interactions between DNA and the surface. Indeed, increasing these interactions slows down the equilibration of naked plasmids on the surface but, on the other hand, enables a faster equilibration of DNA/H-NS complexes. Based on the distribution of the lifetimes of H-NS bridges and the time evolution of the number of trans-binding protein dimers during equilibration of the complexes on the surface, it is argued that the decrease of the equilibration time of the complex upon increase of the interaction strength between DNA and the surface is ascribable to the associated decrease of the probability to form new bridges between DNA and the proteins.

Condensation of plasmid DNA enhances mitochondrial association in skeletal muscle following hydrodynamic limb vein injection.

Mitochondrial gene therapy and diagnosis have the potential to provide substantial medical benefits. However, the utility of this approach has not yet been realized because the technology available for mitochondrial gene delivery continues to be a bottleneck. We previously reported on mitochondrial gene delivery in skeletal muscle using hydrodynamic limb vein (HLV) injection. HLV injection, a useful method for nuclear transgene expression, involves the rapid injection of a large volume of naked plasmid DNA (pDNA). Moreover, the use of a condensed form of pDNA enhances the nuclear transgene expression by the HLV injection. The purpose of this study was to compare naked pDNA and condensed pDNA for mitochondrial association in skeletal muscle, when used in conjunction with HLV injection. PCR analysis showed that the use of condensed pDNA rather than naked pDNA resulted in a more effective mitochondrial association with pDNA, suggesting that the physicochemical state of pDNA plays a key role. Moreover, no mitochondrial toxicities in skeletal muscle following the HLV injection of condensed pDNA were confirmed, as evidenced by cytochrome c oxidase activity and mitochondrial membrane potential. These findings have the potential to contribute to the development for in vivo mitochondrial gene delivery system.

Ultrasound-mediated gene delivery of naked plasmid DNA in skeletal muscles: A case for bolus injections

Localized gene delivery has many potential clinical applications. However, the nucleic acids (e.g. pDNA and siRNA) are incapable of passively crossing the endothelium, cell membranes and other biological barriers which must be crossed to reach their intracellular targets. A possible solution is the use of ultrasound to burst circulating microbubbles inducing transient permeabilization of surrounding tissues which mediates nucleic acid extravasation and cellular uptake. In this study we report on an optimization of the ultrasound gene delivery technique. Naked pDNA (200μg) encoding luciferase and SonoVue® microbubbles were co-injected intravenously in mice. The hindlimb skeletal muscles were exposed to ultrasound from a non-focused transducer (1MHz, 1.25MPa, PRI 30s) and injection protocols and total amounts as well as ultrasound parameters were systemically varied. Gene expression was quantified relative to a control using a bioluminescence camera system at day 7 after sonication. Bioluminescence ratios in sonicated/control muscles of up to 101× were obtained. In conclusion, we were able to specifically deliver genetic material to the selected skeletal muscles and overall, the use of bolus injections and high microbubble numbers resulted in increased gene expression reflected by stronger bioluminescence signals. Based on our data, bolus injections seem to be required in order to achieve transient highly concentrated levels of nucleic acids and microbubbles at the tissue of interest which upon ultrasound exposure should lead to increased levels of gene delivery. Thus, ultrasound mediated gene delivery is a promising technique for the clinical translation of localized drug delivery.

Strong HCV NS3/4a, NS4b, NS5a, NS5b-specific cellular immune responses induced in Rhesus macaques by a novel HCV genotype 1a/1b consensus DNA vaccine

Chronic HCV is a surreptitious disease currently affecting approximately 3% of the world's population that can lead to liver failure and cancer decades following initial infection. However, there are currently no vaccines available for the prevention of chronic HCV. From patients who acutely resolve HCV infection, it is apparent that a strong and broad cytotoxic T lymphocyte (CTL) response is important in HCV clearance. DNA vaccines are naked plasmid DNA molecules that encode pathogen antigens to induce a pathogen-specific immune response. They are inexpensive to produce and have an excellent safety profile in animals and humans. Additionally, DNA vaccines are able to induce strong CTL responses, making them well-suited for an HCV vaccine. We aimed to maximize vaccine recipients' opportunity to induce a broad T cell response with a novel antigenic sequence, multi-antigen vaccine strategy. We have generated DNA plasmids encoding consensus sequences of HCV genotypes 1a and 1b non-structural proteins NS3/4a, NS4b, NS5a, and NS5b. Rhesus macaques were used to study the immunogenicity of these constructs. Four animals were immunized 3 times, 6 weeks apart, at a dose of 1.0mg per antigen construct, as an intramuscular injection followed by in vivo electroporation, which greatly increases DNA uptake by local cells. Immune responses were measured 2 weeks post-immunization regimen (PIR) in immunized rhesus macaques and showed a broad response to multiple HCV nonstructural antigens, with up to 4680 spot-forming units per million peripheral blood mononuclear cells (PBMCs) as measured by Interferon-γ ELISpot. In addition, multiparametric flow cytometry detected HCV-specific CD4+ and CD8+ T cell responses by intracellular cytokine staining and detected HCV-specific CD107a+/GrzB+ CD8+ T cells indicating an antigen specific cytolytic response 2 weeks PIR compared with baseline measurements. At the final study time point, 6 weeks PIR, HCV-specific CD45RA- memory-like T cells remained detectable in peripheral blood. Data presented in this manuscript support the notion that vaccine immunogenicity studies using a macaque model can be used to depict key anti-HCV nonstructural antigenic cellular immune responses and support the development of DNA-based prophylactic HCV vaccines.