Design Of Gene Delivery Systems Research Articles

Synthesis and properties of oligopropylamines with photosensitive o-nitrobenzyl ester core

The o-nitrobenzyl ester group is known for more than 50 years as a convenient protecting group and fragment for the design of photosensitive systems, including drug delivery agents. Polymeric amines with these groups are promising systems for medical applications, but the lack of basic knowledge about the possible degradation of these compounds under physiological conditions restrains the development of real preparations. We synthesized five new polyamines with the insertion of the o-nitrobenzyl ester group into the chain, including an oligomeric mixture with a weight average number of amine groups equal to 21. The ester group in the polyamine chain was found to be sensitive to hydrolysis at neutral and alkaline pH values. The presence of an amine group near the ester group facilitates hydrolysis through coordination with a hydroxyl ion or water molecule. The catalytic action of the amine moieties is prevented by protonation of the amine at low pH values or by interaction with polymeric acid. The study of photodegradation of new polyamines by HPLC-MS showed the formation of a number of products, most of which were not considered in previous works with o-nitrobenzyl ester derivatives. The o-nitrobenzyl ester group is used in the design of gene delivery systems and other biomedical preparations as a fragment that can be degraded by light. Our results indicate that photodegradation of o-nitrobenzyl esters can produce a number of compounds whose structure and safety for living organisms must be evaluated before use. On the other hand, the discovered hydrolyzability of o-nitrobenzyl esters catalyzed by a neighboring amine group may find application in the development of drug delivery systems. We have shown that the lifetime of o-nitrobenzyl ester containing polyamines is sufficient for gene delivery. Self-degradation of the delivery agent after penetration into a living cell is a desirable case for the release of the delivered agent.

A catch-and-release nano-based gene delivery system.

The design of nanomaterial-based nucleic acid formulations is one of the biggest endeavours in the search for clinically applicable gene delivery systems. Biopolymers represent a promising subclass of gene carriers due to their physicochemical properties, biodegradability and biocompatibility. By modifying melanin-like polydopamine nanoparticles with poly-L-arginine and poly-L-histidine blends, we obtained a novel catch-and-release gene delivery system for efficient trafficking of pDNA to human cells. A synergistic interplay of nanoparticle-bound poly-L-arginine and poly-L-histidine was observed and evaluated for pDNA binding affinity, cell viability, gene release and transfection. Although the functionalisation with poly-L-arginine was crucial for pDNA binding, the resulting nanocarriers failed to release pDNA intracellularly, resulting in limited protein expression. However, optimal pDNA release was achieved through the co-formulation with poly-L-histidine, essential for pDNA release. This effect enabled the design of gene delivery systems, which were comparable to Lipofectamine in terms of transfection efficacy and the catch-and-release surface modification strategy can be translated to other nanocarriers and surfaces.

Safe and efficient DNA delivery based on tannic acid-ion coordination encapsulation

ABSTRACT Polyethyleneimine (PEI) is a non-viral gene vector of frequent concern because of its high transfection efficiency. However, its clinical application is limited by the cytotoxicity caused by high positive charge density. Therefore, reducing toxicity and maintaining high transfection efficiency through appropriate strategies are of great significance to promote the development of PEI as gene vector. In order to reduce the toxicity of PEI, this work studied the feasibility of encapsulating PEI/DNA complexes by using the coordination between tannic acid (TA) and metal ions (Mn+). Firstly, TA formed a coating layer on the surface of PEI/DNA complex through electrostatic action, and then the quaternary complex (Mn+(TA/PEI/DNA)) system was prepared by the coordination between metal ions and TA. In order to better construct a gene delivery system with high transfection efficiency and low toxicity, the effects of PEI molecular weight, mass ratio of PEI/DNA, mass ratio of TA, and types of metal ions on the transfection efficiency, cytotoxicity, particle size, zeta potential, and cell uptake pathway of the quaternary complex were studied. The results showed that the quaternary complex based on PEI70k and encapsulated by coordination between TA and potassium ions showed better safety than PEI70k/DNA while maintaining high transfection efficiency. This showed that the strategy of coordination encapsulation of TA and ions to improve the safety of PEI as gene carrier is feasible, which provides a new reference for the design of gene delivery system based on PEI.

Characterization of the Physiochemical Interactions between LNPs and the Endosomal Lipids: A Rational Design of Gene Delivery Systems

Lipid nanoparticles (LNPs) are a class of materials, with each interacting in a complex fashion to form specialized bio-containers carrying therapeutic drugs and strands of nucleic acids such as small interfering RNA (siRNA)1. LNPs are at the forefront of the rapidly developing field of nanotechnology with several potential applications in drug delivery, clinical medicine, and research. Despite holding a significant promise for reaching the goal of controlled and site specific drug delivery, the engineering of efficient LNPs is limited by the lack of knowledge about the structure of LNPs, the roles of their individual components and the physical interactions with other biomolecules2. Because of this, characteristics such as the encapsulation efficiency, polydispersity, and stability of LNPs are not predictable. One of the biggest problems of LNP gene therapy is the molecular details of the cellular processes that determine the efficiency of intracellular drug delivery is still unclear. Studies have shown that LNPs enter cells via the endocytic pathway and are engulfed by endosomes. The delivery of siRNA is substantially reduced, as ∼70% of the internalized siRNA undergoes exocytosis through egress of LNPs from late endosomes/lysosomes3. In this project, we used advanced molecular dynamics simulations to understand the molecular basis of the structure of LNPs based on their composition. Our simulations also provided the first detailed molecular-level view of the interactions of the LNP components with endosomal lipids. Here, we also studied the change in interactions between the LNPs and endosomal lipids by varying ion concentration and altering pH. Results of our simulation will provide a route to the rational design of new LNPs that address safety concerns and ensure effective delivery to accelerate the translation of engineering lipid-based nanoparticles towards the clinic.

Disulfide modified self-assembly of lipopeptides with arginine-rich periphery achieve excellent gene transfection efficiency at relatively low nitrogen to phosphorus ratios.

Integrating the advantages of artificial vectors with bioinspired strategies has opened interesting perspectives in the design of gene delivery systems. Herein, disulfide modified, self-assembled lipopeptides with arginine-rich periphery are demonstrated as gene vectors (RLS). It is surprising that these carriers achieved excellent gene transfection efficacy (up to 380-fold higher than PEI) in different cell lines (HeLa and B16 cells) at relatively low N/P (∼10) ratios, compared to the analog lipopeptides without disulfide bonds (RL, N/P 40). As shown from the morphologies observed by transmission electronic microscopy and surface charge detection by dynamic light scattering, the existence of disulfide bonds may influence the configuration/conformation of the RLS assembly with decreased zeta potential (+27.2 mV), compared to that of the analogs, RL (+46.5 mV). Correspondingly, RLS/DNA complexes showed relatively lower zeta potentials than those of RL/DNA complexes at different N/P ratios. Under the transfection conditions, RLS/DNA complexes (N/P 10) showed even less cellular uptake than that of RL/DNA complexes (N/P 40), and no difference was detected in buffering effect and endosomal escape between RLS and RL complexes. Examination by gel electrophoresis and fluorescence resonance energy transfer (FRET) images in cell culture conditions confirmed that RLS lipoplexes could effectively liberate DNA. Thus, the higher gene transfection efficiency of disulfide modified vectors might be mainly attributed to the cleavage of disulfide bonds; the rapid release of DNA and the superiority of the design was closely related to the reductive conditions in the cells.

Design of gene delivery systems based on PAMAM derivatives as carrier and their transfection mechanism

Nanoparticles provide ideal platforms for drug delivery. Together with drugs, various probes, such fluorescent probes, could be incorporated in that platform for bioimaging or in situ tracking of the drugs. One important issue for the drug delivery nano-systems is the safety of the nanomaterials, including the incorporated probes. We found that nano-encapsulated fluorescent proteins could serve as an ideal safe and robust fluorescence probes for the in vivo bio-imaging, with whole body distribution and fast clearance from the body. Fluorescent proteins-encapsulated nanoparticles can deliver siRNA into cells and silence-targeted gene effectively, with some siRNA even being delivered into the cell nuclei (Figure 1).

Confined polyelectrolytes: The complexity of a simple system.

The interaction between polyelectrolytes and counterions in confined situations and the mutual relationship between chain conformation and ion condensation is an important issue in several areas. In the biological field, it assumes particular relevance in the understanding of the packaging of nucleic acids, which is crucial in the design of gene delivery systems. In this work, a simple coarse-grained model is used to assess the cooperativity between conformational change and ion condensation in spherically confined backbones, with capsides permeable to the counterions. It is seen that the variation on the degree of condensation depends on counterion valence. For monovalent counterions, the degree of condensation passes through a minimum before increasing as the confining space diminishes. In contrast, for trivalent ions, the overall tendency is to decrease the degree of condensation as the confinement space also decreases. Most of the particles reside close to the spherical wall, even for systems in which the density is higher closer to the cavity center. This effect is more pronounced, when monovalent counterions are present. Additionally, there are clear variations in the charge along the concentric layers that cannot be totally ascribed to polyelectrolyte behavior, as shown by decoupling the chain into monomers. If both chain and counterions are confined, the formation of a counterion rich region immediately before the wall is observed. Spool and doughnut-like structures are formed for stiff chains, within a nontrivial evolution with increasing confinement.

Bis-quaternary gemini surfactants as components of nonviral gene delivery systems: A comprehensive study from physicochemical properties to membrane interactions

Gemini surfactants have been successfully used as components of gene delivery systems. In the present work, a family of gemini surfactants, represented by the general structure [CmH2m+1(CH3)2N+(CH2)sN+(CH3)2CmH2m+1]2Br−, or simply m–s–m, was used to prepare cationic gene carriers, aiming at their application in transfection studies. An extensive characterization of the gemini surfactant-based complexes, produced with and without the helper lipids cholesterol and DOPE, was carried out in order to correlate their physico-chemical properties with transfection efficiency. The most efficient complexes were those containing helper lipids, which, combining amphiphiles with propensity to form structures with different intrinsic curvatures, displayed a morphologically labile architecture, putatively implicated in the efficient DNA release upon complex interaction with membranes. While complexes lacking helper lipids were translocated directly across the lipid bilayer, complexes containing helper lipids were taken up by cells also by macropinocytosis. This study contributes to shed light on the relationship between important physico-chemical properties of surfactant-based DNA vectors and their efficiency to promote gene transfer, which may represent a step forward to the rational design of gene delivery systems.

Label-free quantitative analysis for studying the interactions between nanoparticles and plasma proteins

A shotgun proteomics approach was used to compare human plasma protein binding capability with cationic liposomes, DNA-cationic lipid complexes (lipoplexes), and lipid-polycation-DNA (LPD) complexes. Nano-high-performance liquid chromatography coupled with a high-resolution LTQ Orbitrap XL mass spectrometer was used to characterize and compare their protein corona. Spectral counting and area under curve methods were used to perform label-free quantification. Substantial qualitative and quantitative differences were found among proteins bound to the three different systems investigated. Protein variety found on lipoplexes and LPD complexes was richer than that found on cationic liposomes. There were also significant differences between the amounts of protein. Such results could help in the design of gene-delivery systems, because some proteins could be more selectively bound rather than others, and their bio-distribution could be driven in vivo for more efficient and effective gene therapy.

Synthetic Viruslike Particles for Targeted Gene Delivery to αvβ3 Integrin-Presenting Endothelial Cells

Progress in the design of gene delivery systems is of utmost importance for cancer gene therapy since several physiological and intracellular barriers remain. We previously developed a technology for condensing a single gene into a single and stable globular nanometric system. In this manuscript, we have decorated the nanometric particles with cyclic RGD ligands in order to target endothelial cells. The potential of these artificial viruses as targeted gene delivery vehicles is demonstrated in vitro with alpha(v)beta(3) integrin-expressing primary endothelial cells.

The use of lactoferrin as a ligand for targeting the polyamidoamine-based gene delivery system to the brain

Development of an efficient gene vector is a key-limiting factor of brain gene therapy. In this study, lactoferrin (Lf), for the first time, was investigated as a brain-targeting ligand in the design of polyamidoamine (PAMAM)-based non-viral gene vector to the brain. Using polyethyleneglycol (PEG) as a spacer, PAMAM–PEG–Lf was successfully synthesized. This vector showed a concentration-dependent manner in the uptake in brain capillary endothelial cells (BCECs). The brain uptake of PAMAM–PEG–Lf was 2.2-fold compared to that of PAMAM–PEG–transferrin (Tf) in vivo. The transfection efficiency of PAMAM–PEG–Lf/DNA complex was higher than that of PAMAM–PEG–Tf/DNA complex in vitro and in vivo. The results of frozen sections showed the widespread expression of an exogenous gene in mouse brain via intravenous administration. With a PAMAM/DNA weight ratio of 10:1, the brain gene expression of the PAMAM–PEG–Lf/DNA complex was about 2.3-fold when compared to that of the PAMAM–PEG–Tf/DNA complex. These results provide evidence that PAMAM–PEG–Lf can be exploited as a potential non-viral gene vector targeting to the brain via noninvasive administration. Lf is a promising ligand for the design of gene delivery systems targeting to the brain.

Targeted Gene Delivery to Cancer Cells with Nanometric DNA Particles Enveloped with Folic Acid Using a Polymerisable Anchor

Progress in the design of gene delivery system is vital for cancer gene therapy since many physiological and intracellular barriers remain. We have developed a technology for condensing genes into nanometric delivery systems. In this paper, we present a novel strategy for decorating 30 nm DNA particles with folic acid for cancer cell recognition. Physicochemical and biological experiments show that these DNA complexes selectively bind to cells expressing the corresponding folic acid receptor.

Gene medicine : a new field of molecular medicine.

Gene therapy has emerged as a new concept of therapeutic strategies to treat diseases which do not respond to the conventional therapies. The principle of gene therapy is to introduce genetic materials into patient cells to produce therapeutic proteins in these cells. Gene therapy is now at the stage where a number of dinical trials have been carried out to patients with gene-deficiency disease or cancer. Genetic materials for gene therapy are generally composed of gene expression system and gene delivery system. For the dinical application of gene therapy in a way which conventional drugs are used, researches have been focused on the design of gene delivery system which can offer high transfection efficiency with minimal toxicity. Currently, viral delivery systems generally provide higher transfection efficiency compared with non-viral delivery systems while non-viral delivery systems are less toxic, less immunogenic and manufacturable in large scale compared with viral systems. Recently, novel strategies towards the design of new non-viral delivery system, combination of viral and non-viral delivery systems and targeted delivery system have been extensively studied. The continued effort in this area will lead us to develop gene medicine as 'gene as a drug' in the near future.

Woodchuck hepatitis virus posttranscriptional regulatory element enhances expression of transgenes delivered by retroviral vectors.

The expression of genes delivered by retroviral vectors is often inefficient, a potential obstacle for their widespread use in human gene therapy. Here, we explored the possibility that the posttranscriptional regulatory element of woodchuck hepatitis virus (WPRE) might help resolve this problem. Insertion of the WPRE in the 3' untranslated region of coding sequences carried by either oncoretroviral or lentiviral vectors substantially increased their levels of expression in a transgene-, promoter- and vector-independent manner. The WPRE thus increased either luciferase or green fluorescent protein production five- to eightfold, and effects of a comparable magnitude were observed with either the immediate-early cytomegalovirus or the herpesvirus thymidine kinase promoter and with both human immunodeficiency virus- and murine leukemia virus-based vectors. The WPRE exerted this influence only when placed in the sense orientation, consistent with its predicted posttranscriptional mechanism of action. These results demonstrate that the WPRE significantly improves the performance of retroviral vectors and emphasize that posttranscriptional regulation of gene expression should be taken into account in the design of gene delivery systems.