Intracellular co-delivery of zinc ions and plasmid DNA for enhancing gene transfection activity

Design of the Zinc Ion and Plasmid DNA Co-Delivery System by Poly(1-Vinylimidazole) Derivatives for Myoblast Differentiation

The co-delivery system of zinc ions (Zn²⁺) and plasmid DNA (pDNA) has been designed by the use of poly(1-vinylimidazole) (PVIm) derivatives for myoblast differentiation. Six PVIm derivatives were synthesized, followed by the optimization of the chemical structure. As a result, methylated and carboxymethylated PVIm (CM-PVIm-Me) delivered the highest amount of Zn²⁺ ions inside C2C12 myoblast cells. The CM-PVIm-Me also delivered pDNA inside the myoblast cells to exhibit pDNA gene expression which was upregulated by the co-delivered Zn²⁺ ions. The co-delivered Zn²⁺ ions were localized in the cell nucleus presumably to affect cellular functions. Actually, the myoblast cells treated with the Zn²⁺/CM-PVIm-Me/pDNA complexes differentiated to myotubes. These results suggest that the Zn²⁺ ions delivered by the CM-PVIm-Me inside the cells differentiated myoblasts to myotubes. Our co-delivery system of Zn²⁺ ion and pDNA without zinc transporter can be a unique tool of regenerative medicine for muscular injury.

Macrophage-Membrane-Camouflaged Nonviral Gene Vectors for the Treatment of Multidrug-Resistant Bacterial Sepsis

Sepsis is a life-threatening disease caused by systemic bacterial infections, with high morbidity and mortality worldwide. As the standard treatment for sepsis, antibiotic therapy faces the challenge of impaired macrophages and drug-resistant bacteria. In this study, we developed a membrane-camouflaged metal-organic framework (MOF) system for plasmid DNA (pDNA) delivery to combat sepsis. The antimicrobial gene LL37 was efficiently encapsulated in the pH-sensitive MOF, and the nanoparticles were decorated with macrophage membranes in a compatible manner. Macrophage membrane coating allows targeted delivery of LL37 to macrophages and creates macrophage factories for the continuous generation of antimicrobial peptides. Compared to naked nanoparticles, primary bone marrow mesenchymal macrophage membrane-modified nanoparticles greatly improved the survival rate of immunodeficient septic mice through the synergistic effect of efficient gene therapy and inflammatory cytokine sequestration. This study demonstrates an effective membrane biomimetic strategy for efficiently delivering pDNA, offering an excellent option for overcoming sepsis.

Hepatocyte-Specific Co-Delivery of Zinc Ions and Plasmid DNA by Lactosylated Poly(1-vinylimidazole) for Suppression of Insulin Receptor Internalization

The lactosylated poly(1-vinylimidazole) (PVIm-Lac) with various lactosylated degrees has been synthesized for the co-delivery of zinc ions (Zn) and plasmid DNA (pDNA). The Zn/DNA/PVIm-Lac complex formation has achieved the specific delivery of zinc ions to HepG2 cells. Especially, the resulting hepatocyte-specific delivery of zinc ions has increased the number of insulin receptors on the cell surface. Consequently, the Zn/DNA/PVIm-Lac complexes have suppressed insulin receptor internalization on the surface of the HepG2 cells, expecting to offer unique therapy to inhibit hepatic insulin clearance.

Structure-Activity Relationship of Mono-Ion Complexes for Plasmid DNA Delivery by Muscular Injection

The structure-activity relationship of mono-ion complexes (MICs) for plasmid DNA (pDNA) delivery by muscular injection is demonstrated. MICs were formed between pDNA and monocationic poly(ethylene glycol) (PEG) macromolecules. As monocationic PEGs, the ω-amide-pentylimidazolium (APe-Im) end-modified PEGs with a stable amide (Am) and hydrolytic ester (Es) bond, that is, APe-Im-Am-PEG and APe-Im-Es-PEG, respectively, are synthesized. The difference between the APe-Im-Am-PEG and APe-Im-Es-PEG was only a spacer structure between a terminal cation and a PEG chain. The resulting pDNA MICs with APe-Im-Am-PEG at a charge ratio (+/-) of 32 or 64 were more stable than those with APe-Im-Es-PEG in the presence of serum proteins. The highest gene expression by muscular injection was achieved using the APe-Im-Am-PEG/pDNA MIC at a charge ratio (+/-) of 32 with a smaller particle diameter of approximately 50 nm, as compared to that charge ratio of 64. Consequently, the pDNA MIC with the monocationic PEG with a stable amide spacer, as compared to a hydrolytic ester spacer, is considered to be suitable for the highest gene expression by muscular injection.

Balestra F, Huertas P, López-Cornejo P. Metallo-Liposomes of Ruthenium Used as Promising Vectors of Genetic Material

Gene therapy is a therapeutic process consisting of the transport of genetic material into cells. The design and preparation of novel carriers to transport DNA is an important research line in the medical field. Hybrid compounds such as metallo-liposomes, containing a mixture of lipids, were prepared and characterized. Cationic metal lipids derived from the [Ru(bpy)₃]²⁺ complex, RuC11C11 or RuC19C19, both with different hydrophobic/lipophilic ratios, were mixed with the phospholipid DOPE. A relation between the size and the molar fraction α was found and a multidisciplinary study about the interaction between the metallo-liposomes and DNA was performed. The metallo-liposomes/DNA association was quantified and a relationship between K_app and α was obtained. Techniques such as AFM, SEM, zeta potential, dynamic light scattering and agarose gel electrophoresis demonstrated the formation of lipoplexes and showed the structure of the liposomes. L/D values corresponding to the polynucleotide’s condensation were estimated. In vitro assays proved the low cell toxicity of the metallo-liposomes, lower for normal cells than for cancer cell lines, and a good internalization into cells. The latter as well as the transfection measurements carried out with plasmid DNA pEGFP-C1 have demonstrated a good availability of the Ru(II)-based liposomes for being used as non-toxic nanovectors in gene therapy.

Plasmid DNA Mono-Ion Complex for in Vivo Sustainable Gene Expression

To cleave biocompatible poly(ethylene glycol) (PEG) from the mono-ion complex (MIC) for sustainable cellular uptake in vivo, ω-amide-pentylimidazolium end-modified PEG with an ester bond, that is, APe-Im-E-PEG, has been synthesized. The hydrolysis of the resulting APe-Im-E-PEG proceeded during the incubation for 2 weeks under physiological conditions, which was confirmed by gel filtration chromatography. APe-Im-E-PEG formed the MIC with plasmid DNA (pDNA), assessed by agarose gel retardation assay. Furthermore, dynamic light scattering measurement and transmission electron microscopy observations have estimated that the particle size of the resulting MIC was approximately 30 nm, with a rather flexible structure. The APe-Im-E-PEG/pDNA MIC incubated for 2 weeks exhibited hemolytic activity at endosomal pH, presumably because the pH-sensitive carboxyl groups revealed after the hydrolysis of an ester bond of APe-Im-E-PEG. The APe-Im-E-PEG/pDNA MIC enhanced the gene expression 2 weeks after transfection in vivo by intramuscular administration in mice. Consequently, in vivo sustainable gene expression has been achieved by the molecular design of APe-Im-E-PEG for cellular uptake and endosomal escape proceeded by temporal hydrolysis of the ester bond.

Zn(ii)-cyclen complex-based liposomes for gene delivery: the advantage of Zn coordination

Zn-Coordination significantly improves the gene transfection efficiency and reduces the cytotoxicity of cyclen-based cationic liposomes.

Zinc ion coordination significantly improved the transfection efficiency of low molecular weight polyethylenimine

A zinc ion coordination-contained polycationic gene delivery system.

Zn(II)-dipicolylamine-based metallo-lipids as novel non-viral gene vectors

In this study, a series of Zn(II)-dipicolylamine (Zn-DPA) based cationic lipids bearing different hydrophobic tails (long chains, α-tocopherol, cholesterol or diosgenin) were synthesized. Structure-activity relationship (SAR) of these lipids was studied in detail by investigating the effects of several structural aspects including the type of hydrophobic tails, the chain length and saturation degree. In addition, several assays were used to study their interactions with plasmid DNA, and results reveal that these lipids could condense DNA into nanosized particles with appropriate size and zeta-potentials. MTT-based cell viability assays showed that lipoplexes 5 had low cytotoxicity. The in vitro gene transfection studies showed the hydrophobic tails clearly affected the TE, and hexadecanol-containing lipid 5b gives the best TE, which was 2.2 times higher than bPEI 25k in the presence of 10% serum. The results not only demonstrate that these lipids might be promising non-viral gene vectors, but also afford us clues for further optimization of lipidic gene delivery materials.

Screening for Methylated Poly(l-histidine) with Various Dimethylimidazolium/Methylimidazole/Imidazole Contents as DNA Carrier

Methylated poly(l-histidine) (PLH-Me), our original polypeptide, has controlled the contents of dimethylimidazolium, τ/π-methylimidazole and imidazole groups for efficient gene delivery. The screening for the PLH-Me as DNA carrier has been carried out by use of the PLH with 25 mol% (τ-methyl, 16 mol%; π-methyl, 17 mol%; deprotonated imidazole, 41 mol%), 68 mol% (τ-methyl, 16 mol%; π-methyl, 8 mol%; deprotonated imidazole, 8 mol%) and 87 mol% (τ-methyl, 7 mol%; π-methyl, 4 mol%; deprotonated imidazole, 2 mol%) dimethylimidazolium groups, that is, PLH-Me(25), PLH-Me(68) and PLH-Me(87), respectively. The screening of the chemical structure of PLH-Me has been carried out for DNA carrier properties, which are the stability of its DNA polyion complexes and gene expression. The DNA complexes with the 25 mol% and 68 mol% dimethylated PLH-Me possessed almost same ability to retain DNA, as compared with the 87 mol% dimethylated PLH-Me, which was examined by competitive exchange with dextran sulfate. From the gene transfection experiment against HepG2 cells, human hepatoma cell line, the PLH-Me(25)/DNA complex was revealed to mediate highest gene expression. These results suggest that the dimethyl-imidazolium/methylimidazole/imidazole balance of the PLH-Me is important for DNA carrier design.