Temperature-Sensitive Amphiphilic Non-Ionic Triblock Copolymers for Enhanced In Vivo Skeletal Muscle Transfection.

It is reported that low concentration of amphiphilic triblock copolymers of pMeOx-b-pTHF-b-pMeOx structure (TBCPs) improves gene expression in skeletal muscle upon intramuscular co-injection with plasmid DNA. Physicochemical studies carried out to understand the involved mechanism show that a phase transition of TBCPs under their unimer state is induced when the temperature is elevated from 25 to 37 °C, the body temperature. Several lines of evidences suggest that TBCP insertion in a lipid bilayer causes enough lipid bilayer destabilization and even pore formation, a phenomenon heightened during the phase transition of TBCPs. Interestingly, this property allows DNA translocation across the lipid bilayer model. Overall, the results indicate that TBCPs exhibiting a phase transition at the body temperature is promising to favor in vivo pDNA translocation in skeletal muscle cells for gene therapy applications.

Curcumin/poly(2-methyl-2-oxazoline-b-tetrahydrofuran-b-2-methyl-2-oxazoline) formulation: An improved penetration and biological effect of curcumin in F508del-CFTR cell lines.

Neutral amphiphilic triblock ABA copolymers are of great interest to solubilize hydrophobic drugs. We reported that a triblock ABA copolymer consisting of methyl-2-oxazoline (MeOx) and tetrahydrofuran (THF) (MeOx6-THF19-MeOx6) (TBCP2) can solubilize curcumin (Cur) a very hydrophobic molecule exhibiting multiple therapeutic effects but whose insolubility and low stability in water is a major drawback for clinical applications. Here, we provide evidences by flow cytometry and confocal microscopy that Cur penetration in normal and ΔF508-CFTR human airway epithelial cell lines is facilitated by TBCP2. When used on ΔF508-CFTR cell lines, the Cur/TBCP2 formulation promotes the restoration of the expression of the CFTR protein in the plasma membrane. Furthermore, patch-clamp and MQAE fluorescence experiments show that this effect is associated with a correction of a Cl- selective current at the membrane surface of F508del-CFTR cells. The results show the great potential of the neutral amphiphilic triblock copolymer MeOx6-THF19-MeOx6 as carrier for curcumin in a Cystic Fibrosis context. We anticipate that other MeOxn-THFm-MeOxn copolymers could have similar behaviours for other highly insoluble therapeutic drugs or cosmetic active ingredients.

Poly(2-methyl-2-oxazoline)-b-poly(tetrahydrofuran)-b-poly(2-methyl-2-oxazoline) amphiphilic triblock copolymers: synthesis, physicochemical characterizations, and hydrosolubilizing properties.

Block copolymers assembled into micelles have gained a lot of attention to improve drug delivery. The recent drawbacks of the poly(ethylene oxide) blocks (PEO) contained in amphiphilic pluronics derivatives made of a central poly(propylene oxide) block surrounded by two PEO blocks were recently revealed, opening the way to the design of new amphiphilic block copolymers able to self-assemble in water and to entrap molecules of interest. Here, a family of p(methyloxazoline)-b-p(tetrahydrofuran)-b-p(methyloxazoline) triblock copolymers (called TBCP) is synthesized using cationic ring opening polymerization. Studies of micelle formation using dynamic light scattering, isothermal titration calorimetry (ITC), NMR diffusion-ordered spectroscopy (DOSY), and fluorescence experiments lead us to draw a relationship between copolymer structure and the physicochemical properties of the block copolymers (critical micellar concentration (CMC), Nagg, core diameter, shell thickness, etc.). The packing parameter of the block copolymers indicates the formation of a core-corona structure. Hydrosolubilizing properties of TBCPs were exemplified with curcumin selected as a highly insoluble drug model. Curcumin, a natural polyphenolic compound, has shown a large spectrum of biological and pharmacological activity, including anti-inflammatory, antimicrobial, antioxidant, and anticarcinogenic activities. An optimized formulation process reveals that the aggregation number is the parameter affecting drug encapsulation. Patch clamp experiments carried out to study the interaction of TBCP with the cell membrane demonstrate their permeation property suitable to promote the cellular internalization of curcumin.

A robust transfection reagent for the transfection of CHO and HEK293 cells and production of recombinant proteins and lentiviral particles - PTG1.

Bioproduction of recombinant proteins (r-proteins) and recombinant lentiviral particles (r-lentiviral particles) requires robust transfections consisting of efficient protocols that are easy to implement, with good reproducibility for a maximum production of proteins and lentiviral particles in a short time with low cytotoxicity. This study evaluates the capacity of histidinylated polyethyleneimine I (PTG1) to facilitate robust DNA transfection, with low cytotoxicity, of Chinese hamster ovary (CHO) and human embryonic kidney (HEK293T) cells for the production of r-proteins and r-lentiviral particles. We report that PTG1 transfection of cells in suspension with a plasmid DNA encoding enhanced green fluorescent protein leads to 72 and 97% of transfected CHO and HEK293T cells respectively, and does not significantly affect cell viability. PTG1 transfection of 100 mL of CHO-S cell culture in suspension at a cell density of 2 × 10(6) cells /mL resulted in a high level of transfected cells and protein expression after transfection with 0.75 µg/mL plasmid DNA. Transfection with PTG1 is more efficient than LipofectAmine2000™, and gene expression is higher than observed with FreeStyle™ and JetPEI®. Tri-transfection of HEK293T packaging cells leads to the production of a higher level of r-lentiviral particles compared to the calcium phosphate method, and permits two harvests of viral particles within three days. These results show that PTG1 is a powerful new transfection reagent for cell lines frequently used for recombinant protein and lentiviral particle production. PTG1 could be used in protocols for bioproduction of therapeutic proteins such as antibodies for cancer treatments and viral vectors for gene therapy applications.

Influence of pDNA availability on transfection efficiency of polyplexes in non-proliferative cells.

We succeeded in visualizing plasmid DNA (pDNA) in the nucleus and cytosol of non-proliferative cells after transfection with linear polyethylenemine (lPEI) and histidinylated lPEI (His16-lPEI). This was possible with confocal microscope by using pDNA labelled with quantum dots. Indeed pDNA labelled with Cy3 leads to false positive nuclear localization because the saturation of the fluorescence signal overestimated the volume occupied by Cy3-pDNA. Moreover, Cy3 brightness was too weak to detect low amount of pDNA. About 20 to 40 pDNA copies were detected in the nucleus after the transfection of pDNA labelled with quantum dots. Transfection efficiency and cellular imaging data suggested that the cytosolic availability of pDNA, including endosome escape and/or polyplexes dissociation, is crucial for its nuclear delivery. In vitro transcription assay and transfection of cells allowing cytosolic gene expression concluded to better cytosolic availability of pDNA within His16-lPEI polyplexes. Cryo-TEM analyses revealed that His16-lPEI polyplexes exhibited a spherical shape and an amorphous internal structure which differed from the high degree of order of lPEI polyplexes. Altogether, this comparative study indicated that the high transfection efficiency of non-proliferative cells with His16-lPEI polyplexes was related to the amorphous structure and the facilitated dissociation of the assemblies.

Lipopolyplexes comprising imidazole/imidazolium lipophosphoramidate, histidinylated polyethyleneimine and siRNA as efficient formulation for siRNA transfection.

Lipopolyplexes formulations resulting from association of nucleic acid, cationic liposomes and a cationic polymer are attracting formulations for siRNA delivery. Herein, imidazole- and imidazolium-based liposomes in association with histidinylated polymers are studied to produce siRNA lipopoplyplexes (LPRi) subsequently used for gene silencing. Several kinds of imidazole/histidine liposomes and cationic polymers are tested. The gene silencing effect is evaluated with synthetic siRNA directed against EGFP or luciferase mRNA, in HeLa cells stably expressing EGFP or B16F10 melanoma cells stably expressing luciferase, respectively. SiRNA formulations are compared with those prepared using some commercial transfection reagents. One formulation called His-lPEI LPRi100 comprising siRNA, histidinylated lPEI (His-lPEI) and liposomes 100 made with O,O-dioleyl-N-[3N-(N-methylimidazolium iodide)propylene] phosphoramidate and O,O-dioleyl-N-histamine phosphoramidate appears to give the best specific inhibition of gene expression at 10nM siRNA in a dose-dependent manner with low cytotoxicity. This formulation exhibits a size and a zeta potential of 60 nm and +84 mV, respectively. According to our previous works, histidinylated lipopolyplexes appears as a versatile formulation for DNA, mRNA and siRNA transfection.

Gene transfer by chemical vectors, and endocytosis routes of polyplexes, lipoplexes and lipopolyplexes in a myoblast cell line.

Chemical vectors are widely developed for providing safe DNA delivery systems. It is well admitted that their endocytosis and intracellular trafficking are critical for the transfection efficiency. Here, we have compared the endocytic pathways of lipoplexes, polyplexes and lipopolyplexes formed with carriers of various chemical compositions. Engineered C2C12 mouse myoblast cells expressing Rab5-EGFP, Rab7-EGFP or Cav1-GFP were used to monitor the location of the plasmid DNA into the endocytic compartments by real time fluorescence confocal microscopy. We observed that (i) DNA complexes made with dioleyl succinyl paromomycin:O,O-dioleyl-N-histamine phosphoramidate (DOSP/MM27) liposomes or histidinylated lPEI (His-lPEI) allowing the highest transfection efficiency displayed a positive ζ potential and were internalized by clathrin-mediated endocytosis, (ii) DOSP/MM27 lipoplexes were 6-times more internalized than His-lPEI polyplexes, (iii) all negatively charged DNA complexes lead to less efficient transfection and entered the cells via caveolae and (iv) lipopolyplexes allowing high transfection efficiency were weakly internalized via caveolae. Our results indicate that the transfection efficiency is better correlated with the nature of the endocytic pathway than with the uptake efficacy. This study shows also that engineered cells expressing specific fluorescent compartments are convenient tools to monitor endocytosis of a fluorescent plasmid DNA by real time fluorescence confocal microscopy.

Histidinylated linear PEI: a new efficient non-toxic polymer for gene transfer.

A series of linear polyethylenimine (lPEI) substituted with histidine residue (His-lPEI) was synthesized using the Michael reaction in order to provide new highly efficient vectors for gene therapy applications (up to 95% of transfected cells) with remarkable low cytotoxicity compared to lPEI-based polyplexes.

A novel cationic triblock copolymer as noncovalent coating for the separation of proteins by CE.

A novel noncovalent adsorbed coating for CE has been prepared and explored. This coating was based on quaternized poly(2-(dimethylamino)ethyl methacrylate)-block-poly(ethylene oxide)-block-poly(2-(dimethylamino)ethyl methacrylate) (QDED) triblock copolymer which was synthesized by atomic transfer radical polymerization (ATRP) in our laboratory. The polycationic polymer and the negatively charged fused-silica surface attracted each other through electrostatic interactions and hydrogen bonds. It was demonstrated that the coated capillaries provided an electroosmotic flow with reverse direction, and the magnitude of the electroosmotic flow can be modulated by varying the molecular mass of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) block and pH value of the buffer. The effects of the molecular mass of PDMAEMA block in QDED triblock copolymer and pH value of the buffer on the separation of basic proteins were investigated in detail. The triblock copolymer coatings showed higher separation efficiency, better migration time repeatability and would apply to wider range of pH than bare fused-silica capillary when used in separating proteins. Proteins from egg white were also separated through this QDED triblock copolymer-coated capillary. These results demonstrated that the QDED triblock copolymer coatings are suitable for analyzing biosamples.

Evidence of DNA transfer across a model membrane by a neutral amphiphilic block copolymer.

BACKGROUND: Neutral amphiphilic triblock copolymers have been shown to be efficient for gene transfection in vivo, especially by direct injection into the muscle. To contribute to a better understanding of the underlying mechanisms, in the present study, we investigated the properties of a poly(ethylene oxide-b-4-vinylpyridine) diblock copolymer as vector for nucleic acid transfer, with the particular aim of shedding some light on a possible mechanism explaining the internalization of DNA by the transfected cells. METHODS: Complexation of plasmid DNA with the PEO-b-P4VP diblock copolymer was investigated by ethidium bromide exclusion and gel electrophoresis assays. Interaction of the copolymer with a lipid model membrane was evaluated by electrophysiological assays and quantification of plasmid DNA was performed by quantitative polymerase chain reaction. In vivo luciferase transfection assays were finally performed. RESULTS: The diblock copolymer was found to poorly interact with DNA up to a mass ratio (copolymer/DNA) as high as 150. At a concentration of 36 µg/ml, it induced the formation of mainly transient (but sometimes permanent) pores and the formation of those pores allowed the translocation of plasmid DNA across the model membrane. However, only low transgene expression was obtained; the luciferase levels observed with the diblock being of the same order of magnitude as those observed with the corresponding PEO and P4VP homopolymers. CONCLUSIONS: These results strongly suggest that gene transfection by neutral block copolymers may involve the formation of cellular pores; in addition, they also highlight that in vivo gene transfection requires the use of adequately soluble block copolymers.

Chemical and physicochemical investigation of an aminoalkylalkoxysilane as strengthening agent for cellulosic materials.

AMDES (aminopropylmethyldiethoxysilane) was used to investigate the physicochemical and chemical events related to the introduction of aminoalkylalkoxysilanes in cellulosic materials. Using (29)Si CP-MAS and (1)H NMR to study the reactivity and structural modification of AMDES in the paper it was shown that polymerization occurs in situ. The distribution of the active compound on the surface of the fibers and throughout the fibers' thickness was visualized by SEM-EDS. A relation between moisture content, fiber swelling, and uptake of AMDES was found. To better represent old and brittle documents, the paper was predegraded by oxidation with sodium hypochlorite. XRD confirmed the advanced destruction of the amorphous areas of cellulose. Adding AMDES in the oxidized paper resulted in improved mechanical properties, a roughly unmodified degree of polymerization of cellulose, but a slight increase in the yellowing, probably due to several possible reaction products such as imines, amine, amides, and Maillard reactions products. The deacidification efficacy was established and the strengthening effect was shown to arise from the interaction of AMDES with the cellulose fibers.

Synthesis and evaluation of amphiphilic poly(tetrahydrofuran-b-ethylene oxide) copolymers for DNA delivery into skeletal muscle.

PURPOSE: Amphiphilic triblock copolymers such as the pluronic poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) L64 (pEO(13)-pPO(30)-pEO(13)) have been shown to mediate more efficient gene transfer in muscle as compared to naked DNA. We were interested in studying the effect of a chemical change of the central block of pluronic polymers on the transfection activity. METHODS: We synthesized new amphiphilic copolymers in which the hydrophobic pPO block was replaced by poly(tetrahydrofuran) (pTHF) chains. The resulting triblock pEO-pTHF-pEO polymers have been characterized by NMR and SEC and assayed for in vitro and in vivo gene transfer. RESULTS: The animal experiments showed that the new copolymers are able to significantly increase the transfection efficiency of plasmid DNA after intramuscular injection. CONCLUSIONS: These results indicate that the capacity to enhance plasmid DNA transfection in skeletal muscle is not restricted to pEO-pPO-pEO arrangements.

Nuclear delivery of NFkappaB-assisted DNA/polymer complexes: plasmid DNA quantitation by confocal laser scanning microscopy and evidence of nuclear polyplexes by FRET imaging.

Quantification of a plasmid DNA (pDNA) and investigation of its polymer-associated state in the nucleus are crucial to evaluate the effectiveness of a gene-delivery system. This study was conducted with p3NF-luc-3NF, a pDNA-bearing optimized kappaB motif to favour NFkappaB-driven nuclear import. Here, a quantification of pDNA copies in the nucleus was performed by real-time confocal laser scanning microscopy in HeLa and C2C12 cells transfected with linear polyethylenimine or histidylated polylysine. Förster Resonance Energy Transfer (FRET) from the fluorescein-p3NF-luc-3NF donor to the co-localized rhodamine-polymer acceptor was carried out to investigate whether the pDNA was still condensed with the polymer in the nucleus. Upon 5 h of transfection, the nuclear amount of p3NF-luc3NF was approximately 1500 copies in both cell lines whereas that of pTAL-luc, a 3NF-free counterpart pDNA, was less than 250. This quantity of p3NF-luc-3NF dropped dramatically to that of pTAL-luc in the presence of the BAY 11-7085, an inhibitor of NFkappaB activation. These data strongly support a nuclear import of p3NF-luc3NF mediated by NFkappaB. Moreover, FRET experiments clearly revealed that most of nuclear pDNA were still condensed with the polymer raising the question of their passage through the nuclear pore complex and their impact on the gene-expression efficiency.

Amphiphilic poly[(propylene glycol)-block-(2-methyl-2-oxazoline)] copolymers for gene transfer in skeletal muscle.

Amphiphilic triblock copolymers such as poly(ethylene glycol-b-propylene glycol-b-ethylene glycol) PE6400 (PEG(13)-PPG(30)-PEG(13)) have been recently shown to promote gene transfer in muscle. Herein we investigated the effect of a chemical change of the PEG moiety on the transfection activity of these compounds. We synthesized new amphiphilic copolymers in which the PEG end blocks are replaced by more hydrophilic poly(2-methyl-2-oxazoline) (PMeOxz) chains of various lengths. The resulting triblock PMeOxz-PPG-PMeOxz compounds were characterized by NMR, SEC, TGA, and DSC techniques and assayed for in vivo muscle gene transfer. The results confirm both the block structure and the monomer unit composition (DP(PG)/DP(MeOxz)) of the new PPG(34)-PMeOxz(41) and PPG(34)-PMeOxz(21) triblock copolymers. Furthermore, in vivo experiments show that these copolymers are able to significantly increase DNA transfection efficiency, despite the fact that their chemical nature and hydrophilic character are different from the poloxamers. Overall, these results show that the capacity to enhance DNA transfection in skeletal muscle is not restricted to PEG-PPG-PEG arrangements.

Synthesis of linear polyethylenimine derivatives for DNA transfection.

A series of linear polymers containing varying amounts of ethylenimine or N-propylethylenimine units were synthesized by hydrolysis and/or reduction of polyethyloxazolines. The pK(a)s of the polyamines were determined potentiometrically. Gel mobility shift assay showed that the efficiency of DNA complexation was related to the fraction of amino groups that are protonated at neutral pH. The effects of cationic charge density and molar weight of the polymers on the transfection efficiency were evaluated on HepG2 cells. The results obtained with different copolymers show that the transfection efficiency primarily depends on the fraction of ethylenimine units included in the polymer albeit the molar weight is also of importance. On the basis of the results obtained with poly(N-propylethylenimines), we also demonstrate that the high transfection efficiency of polyethylenimines does not solely rely on their capacity to capture protons which are transferred into the endo-lysosomes during acidification.