Enhancement of chitosan-mediated gene delivery through combination with phiC31 integrase

Application of Non-Viral Vectors in Drug Delivery and Gene Therapy

Vectors and carriers play an indispensable role in gene therapy and drug delivery. Non-viral vectors are widely developed and applied in clinical practice due to their low immunogenicity, good biocompatibility, easy synthesis and modification, and low cost of production. This review summarized a variety of non-viral vectors and carriers including polymers, liposomes, gold nanoparticles, mesoporous silica nanoparticles and carbon nanotubes from the aspects of physicochemical characteristics, synthesis methods, functional modifications, and research applications. Notably, non-viral vectors can enhance the absorption of cargos, prolong the circulation time, improve therapeutic effects, and provide targeted delivery. Additional studies focused on recent innovation of novel synthesis techniques for vector materials. We also elaborated on the problems and future research directions in the development of non-viral vectors, which provided a theoretical basis for their broad applications.

The Landscape of Non-Viral Gene Augmentation Strategies for Inherited Retinal Diseases

Inherited retinal diseases (IRDs) are a heterogeneous group of disorders causing progressive loss of vision, affecting approximately one in 1000 people worldwide. Gene augmentation therapy, which typically involves using adeno-associated viral vectors for delivery of healthy gene copies to affected tissues, has shown great promise as a strategy for the treatment of IRDs. However, the use of viruses is associated with several limitations, including harmful immune responses, genome integration, and limited gene carrying capacity. Here, we review the advances in non-viral gene augmentation strategies, such as the use of plasmids with minimal bacterial backbones and scaffold/matrix attachment region (S/MAR) sequences, that have the capability to overcome these weaknesses by accommodating genes of any size and maintaining episomal transgene expression with a lower risk of eliciting an immune response. Low retinal transfection rates remain a limitation, but various strategies, including coupling the DNA with different types of chemical vehicles (nanoparticles) and the use of electrical methods such as iontophoresis and electrotransfection to aid cell entry, have shown promise in preclinical studies. Non-viral gene therapy may offer a safer and effective option for future treatment of IRDs.

Human-derived NLS enhance the gene transfer efficiency of chitosan

Nuclear import is considered as one of the major limitations for non-viral gene delivery systems and the incorporation of nuclear localization signals (NLS) that mediate nuclear intake can be used as a strategy to enhance internalization of exogenous DNA.

In this work, human-derived endogenous NLS peptides based on insulin growth factor binding proteins (IGFBP), namely IGFBP-3 and IGFBP-5, were tested for their ability to improve nuclear translocation of genetic material by non-viral vectors. Several strategies were tested to determine their effect on chitosan mediated transfection efficiency: co-administration with polyplexes, co-complexation at the time of polyplex formation, and covalent ligation to chitosan. Our results show that co-complexation and covalent ligation of the NLS peptide derived from IGFBP-3 to chitosan polyplexes yields a 2-fold increase in transfection efficiency, which was not observed for NLS peptide derived from IGFBP-5.

These results indicate that the integration of IGFBP-NLS-3 peptides into polyplexes has potential as a strategy to enhance the efficiency of non-viral vectors.

Interleukin-1 receptor antagonist protein (IL-1Ra) and miR-140 overexpression via pNNS-conjugated chitosan-mediated gene transfer enhances the repair of full-thickness cartilage defects in a rabbit model

Objectives

Previously, we reported the improved transfection efficiency of a plasmid DNA-chitosan (pDNA-CS) complex using a phosphorylatable nuclear localization signal-linked nucleic kinase substrate short peptide (pNNS) conjugated to chitosan (pNNS-CS). This study investigated the effects of pNNS-CS-mediated miR-140 and interleukin-1 receptor antagonist protein (IL-1Ra) gene transfection both in rabbit chondrocytes and a cartilage defect model.

Methods

The pBudCE4.1-miR-140, pBudCE4.1-IL-1Ra, and negative control pBudCE4.1 plasmids were constructed and combined with pNNS-CS to form pDNA/pNNS-CS complexes. These complexes were transfected into chondrocytes or injected into the knee joint cavity.

Results

High IL-1Ra and miR-140 expression levels were detected both in vitro and in vivo. In vitro, compared with the pBudCE4.1 group, the transgenic group presented with significantly increased chondrocyte proliferation and glycosaminoglycan (GAG) synthesis, as well as increased collagen type II alpha 1 chain (COL2A1), aggrecan (ACAN), and TIMP metallopeptidase inhibitor 1 (TIMP-1) levels. Nitric oxide (NO) synthesis was reduced, as were a disintegrin and metalloproteinase with thrombospondin type 1 motif 5 (ADAMTS-5) and matrix metalloproteinase (MMP)-13 levels. In vivo, the exogenous genes reduced the synovial fluid GAG and NO concentrations and the ADAMTS-5 and MMP-13 levels in cartilage. In contrast, COL2A1, ACAN, and TIMP-1 levels were increased, and the cartilage Mankin score was decreased in the transgenic group compared with the pBudCE4.1 group. Double gene combination produced greater efficacies than each single gene, both in vitro and in vivo.

Conclusion

This study suggests that pNNS-CS is a good candidate for treating cartilage defects via gene therapy, and that IL-1Ra in combination with miR-140 produces promising biological effects on cartilage defects.

Cite this article: R. Zhao, S. Wang, L. Jia, Q. Li, J. Qiao, X. Peng. Interleukin-1 receptor antagonist protein (IL-1Ra) and miR-140 overexpression via pNNS-conjugated chitosan-mediated gene transfer enhances the repair of full-thickness cartilage defects in a rabbit model. Bone Joint Res 2019;8:165–178. DOI: 10.1302/2046-3758.83.BJR-2018-0222.R1.

Pharmaceutical applications of chitosan

Chitosan (CS) is a linear polysaccharide which is achieved by deacetylation of chitin, which is the second most plentiful compound in nature, after cellulose. It is a linear copolymer of β-(1 → 4)-linked 2-acetamido-2-deoxy-β-d-glucopyranose and 2-amino-2-deoxy-β-d-glucopyranose. It has appreciated properties such as biocompatibility, biodegradability, hydrophilicity, nontoxicity, high bioavailability, simplicity of modification, favorable permselectivity of water, outstanding chemical resistance, capability to form films, gels, nanoparticles, microparticles and beads as well as affinity to metals, proteins and dyes. Also, the biodegradable CS is broken down in the human body to safe compounds (amino sugars) which are easily absorbed. At present, CS and its derivatives are broadly investigated in numerous pharmaceutical and medical applications including drug/gene delivery, wound dressings, implants, contact lenses, tissue engineering and cell encapsulation. Besides, CS has several OH and NH₂ functional groups which allow protein binding. CS with a deacetylation degree of ~50% is soluble in aqueous acidic environment. While CS is dissolved in acidic medium, its amino groups in the polymeric chains are protonated and it becomes cationic which allows its strong interaction with different kinds of molecules. It is believed that this positive charge is responsible for the antimicrobial activity of CS through the interaction with the negatively charged cell membranes of microorganisms. This review presents properties and numerous applications of chitosan-based compounds in drug delivery, gene delivery, cell encapsulation, protein binding, tissue engineering, preparation of implants and contact lenses, wound healing, bioimaging, antimicrobial food additives, antibacterial food packaging materials and antibacterial textiles. Moreover, some recent molecular dynamics simulations accomplished on the pharmaceutical applications of chitosan were presented.

Nanomaterial coatings applied on stent surfaces

The advent of percutaneous coronary intervention and intravascular stents has revolutionized the field of interventional cardiology. Nonetheless, in-stent restenosis, inflammation and late-stent thrombosis are the major obstacles with currently available stents. In order to enhance the hemocompatibility of stents, advances in the field of nanotechnology allow novel designs of nanoparticles and biomaterials toward localized drug/gene carriers or stent scaffolds. The current review focuses on promising polymers used in the fabrication of newer generations of stents with a short synopsis on atherosclerosis and current commercialized stents, nanotechnology's impact on stent development and recent advancements in stent biomaterials is discussed in context.

CRISPR/Cas9-Based Genome Editing for Disease Modeling and Therapy: Challenges and Opportunities for Nonviral Delivery

Genome editing offers promising solutions to genetic disorders by editing DNA sequences or modulating gene expression. The clustered regularly interspaced short palindromic repeats (CRISPR)/associated protein 9 (CRISPR/Cas9) technology can be used to edit single or multiple genes in a wide variety of cell types and organisms in vitro and in vivo. Herein, we review the rapidly developing CRISPR/Cas9-based technologies for disease modeling and gene correction and recent progress toward Cas9/guide RNA (gRNA) delivery based on viral and nonviral vectors. We discuss the relative merits of delivering the genome editing elements in the form of DNA, mRNA, or protein, and the opportunities of combining viral delivery of a transgene encoding Cas9 with nonviral delivery of gRNA. We highlight the lessons learned from nonviral gene delivery in the past three decades and consider their applicability for CRISPR/Cas9 delivery. We also include a discussion of bioinformatics tools for gRNA design and chemical modifications of gRNA. Finally, we consider the extracellular and intracellular barriers to nonviral CRISPR/Cas9 delivery and propose strategies that may overcome these barriers to realize the clinical potential of CRISPR/Cas9-based genome editing.

Non-viral strategies for ocular gene delivery

The success of gene therapy relies on efficient gene transfer and stable transgene expression. The in vivo efficiency is determined by the delivery vector, route of administration, therapeutic gene, and target cells. While some requirements are common to several strategies, others depend on the target disease and transgene product. Consequently, it is unlikely that a single system is suitable for all applications. This review examines current gene therapy strategies, focusing on non-viral approaches and the use of natural polymers with the eye, and particularly the retina, as their gene delivery target.

High transfection efficiency promoted by tailor-made cationic tri-block copolymer-based nanoparticles

Cationic polymer-based vectors have been considered a promising strategy in gene therapy area due to their inherent ability to condense genetic material and successfully transfect cells. However, they usually exhibit high cytotoxicity. In this work, it is proposed the use of a tailor-made gene carrier based on a tri-block copolymer of poly[2-(dimethylamino)ethyl methacrylate] and poly(β-amino ester) (PDMAEMA-b-PβAE-b-PDMAEMA), the influence of the PβAE length being assessed. For this purpose, three different block copolymers were prepared varying the molecular weight of this segment. The obtained materials were characterized by NMR and SEC analyzes. Different polyplexes formulations were prepared and evaluated in terms of physicochemical characterization (ethidium bromide intercalation assay, agarose gel electrophoresis assay, dynamic light scattering, zeta potential analyzes and atomic force microscopy) and biological activity (cytotoxicity, and luciferase and green fluorescent protein expression in Hela and COS-7 cell lines). Among the developed nanosystems, the best polyplex formulation revealed between 40- and 60-fold higher transgene expression, in HeLa and COS-7 cell lines, and much lower cytotoxicity than that observed with branched PEI and TurboFect™. Moreover, these nanosystems present suitable physicochemical properties for gene delivery namely reduced mean diameter and high DNA protection. The results reported here show the enormous potential of this block copolymer as gene carrier.

STATEMENT OF SIGNIFICANCE

Syntheses of PDMAEMA-b-PβAE-b-PDMAEMA block copolymers for an extremely effective non-viral vector. The block copolymer PDMAEMA₃₀₀₀-b-PβAE₁₂₀₀₀-b-PDMAEMA₃₀₀₀-based polyplexes at 100/1N/P ratio exhibits between 40- and 60-fold higher transgene expression in HeLa and COS-7 cell lines than commonly used polymeric non-viral vectors, namely branched PEI (known as the gold standard) and TurboFect™ (commercial available).

Neuroprotective therapies in glaucoma: II. Genetic nanotechnology tools

Neurotrophic factor genome engineering could have many potential applications not only in the deeper understanding of neurodegenerative disorders but also in improved therapeutics. The fields of nanomedicine, regenerative medicine, and gene/cell-based therapy have been revolutionized by the development of safer and efficient non-viral technologies for gene delivery and genome editing with modern techniques for insertion of the neurotrophic factors into clinically relevant cells for a more sustained pharmaceutical effect. It has been suggested that the long-term expression of neurotrophic factors is the ultimate approach to prevent and/or treat neurodegenerative disorders such as glaucoma in patients who do not respond to available treatments or are at the progressive stage of the disease. Recent preclinical research suggests that novel neuroprotective gene and cell therapeutics could be promising approaches for both non-invasive neuroprotection and regenerative functions in the eye. Several progenitor and retinal cell types have been investigated as potential candidates for glaucoma neurotrophin therapy either as targets for gene therapy, options for cell replacement therapy, or as vehicles for gene delivery. Therefore, in parallel with deeper understanding of the specific protective effects of different neurotrophic factors and the potential therapeutic cell candidates for glaucoma neuroprotection, the development of non-invasive and highly specific gene delivery methods with safe and effective technologies to modify cell candidates for life-long neuroprotection in the eye is essential before investing in this field.