Non-viral Nucleic Acid Delivery Research Articles

Targeting strategies with lipid vectors for nucleic acid supplementation therapy in Fabry disease: a systematic review.

Fabry disease (FD) results from a lack of activity of the lysosomal enzyme α-Galactosidase A (α-Gal A), leading to the accumulation of glycosphingolipids in several different cell types. Protein supplementation by pDNA or mRNA delivery presents a promising strategy to tackle the underlying genetic defect in FD. Protein-coding nucleic acids in FD can be either delivered to the most affected sites by the disease, including heart, kidney and brain, or to specialized organs that can act as a production factory of the enzyme, such as the liver. Lipid-based systems are currently at the top of the ranking of non-viral nucleic acid delivery systems, and their versatility allows the linking to the surface of a wide range of molecules to control their biodistribution after intravenous administration. This systematic review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement guidelines and provides an overview and discussion of the targeting ligands that have been employed so far to actively vectorize intravenously administered non-viral vectors based on lipid carriers to clinically relevant organs in the treatment of FD, for protein-coding nucleic acid (pDNA and mRNA) supplementation. Among the thirty-two studies included, the majority focus on targeting the liver and brain. The targeting of the heart has been reported to a lesser degree, whereas no articles addressing kidney-targeting have been recorded. Although a great effort has been made to develop organ-specific nucleic acid delivery systems, the design of active-targeted carriers with high quality, good clinical translation, and large-scale manufacturing capacity is still challenging.

Fluorinated Lipid Nanoparticles for Enhancing mRNA Delivery Efficiency.

Lipid nanoparticles (LNPs), a nonviral nucleic acid delivery system, have shown vast potential for vaccine development and disease treatment. LNPs assist mRNA to cross physiological barriers such as cell membranes and endosomes/lysosomes, promoting the intracellular presentation of mRNA. However, the endosome escape efficiency and biosafety of currently commercialized LNPs are still unsatisfactory, resulting in underutilization of mRNA. Herein, we report that fluorinated modification of the 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol)-2000 (PEG-DSPE), termed as FPD, in the LNPs can improve the delivery efficiency of mRNA. FPD accounts for only 1.5% of lipids in LNPs but could mediate a 5-fold and nearly 2-fold enhancement of mRNA expression efficiency in B16F10 tumor cells and primary dendritic cells, respectively. Mechanism studies reveal that FPD promotes the cellular internalization of LNPs as well as endosome escape. In vivo studies substantiate that FPD can augment overall mRNA expression at least 3-fold, either by intravenous or intraperitoneal injection, compared to LNPs prepared with nonfluorinated PEG-lipids at a relatively low mRNA dose. Besides, with the introduction of FPD, mRNA expression in the spleen augmented compared to that of the DMG-PEG commercial formulations. Benefiting from a prudent dosage of fluorine, the fluorinated LNPs display favorable biosafety profiles at cellular and zoological levels.

One Endothelium-Targeted Combined Nucleic Acid Delivery System for Myocardial Infarction Therapy.

Acute myocardial infarction (MI) and ischemic heart disease are the leading causes of heart failure and mortality. Currently, research on MI treatment is focused on angiogenic and anti-inflammatory therapies. Although endothelial cells (ECs) are critical for triggering inflammation and angiogenesis, no approach has targeted them for the treatment of MI. In this study, we proposed a nonviral combined nucleic acid delivery system consisting of an EC-specific polycation (CRPPR-grafted ethanolamine-modified poly(glycidyl methacrylate), CPC) that can efficiently codeliver siR-ICAM1 and pCXCL12 for the treatment of MI. Animals treated with the combination therapy exhibited better cardiac function than those treated with each nucleic acid alone. In particular, the combination therapy of CPC/siR-ICAM1 and CPC/pCXCL12 significantly improved cardiac systolic function, anti-inflammatory responses, and angiogenesis compared to the control group. In conclusion, CPC-based combined gene delivery systems show impressive performance in the treatment of MI and provide a programmed strategy for the development of codelivery systems for various EC-related diseases.

Strategies for non-viral vectors targeting organs beyond the liver.

In recent years, nanoparticles have evolved to a clinical modality to deliver diverse nucleic acids. Rising interest in nanomedicines comes from proven safety and efficacy profiles established by continuous efforts to optimize physicochemical properties and endosomal escape. However, despite their transformative impact on the pharmaceutical industry, the clinical use of non-viral nucleic acid delivery is limited to hepatic diseases and vaccines due to liver accumulation. Overcoming liver tropism of nanoparticles is vital to meet clinical needs in other organs. Understanding the anatomical structure and physiological features of various organs would help to identify potential strategies for fine-tuning nanoparticle characteristics. In this Review, we discuss the source of liver tropism of non-viral vectors, present a brief overview of biological structure, processes and barriers in select organs, highlight approaches available to reach non-liver targets, and discuss techniques to accelerate the discovery of non-hepatic therapies.

PH-Responsive polymer boosts cytosolic siRNA release for retinal neovascularization therapy

Small interfering RNA (siRNA) has a promising future in the treatment of ocular diseases due to its high efficiency, specificity, and low toxicity in inhibiting the expression of target genes and proteins. However, due to the unique anatomical structure of the eye and various barriers, delivering nucleic acids to the retina remains a significant challenge. In this study, we rationally design PACD, an A-B-C type non-viral vector copolymer composed of a hydrophilic PEG block (A), a siRNA binding block (B) and a pH-responsive block (C). PACDs can self-assemble into nanosized polymeric micelles that compact siRNAs into polyplexes through simple mixing. By evaluating its pH-responsive activity, gene silencing efficiency in retinal cells, intraocular distribution, and anti-angiogenesis therapy in a mouse model of hypoxia-induced angiogenesis, we demonstrate the efficiency and safety of PACD in delivering siRNA in the retina. We are surprised to discover that, the PACD/siRNA polyplexes exhibit remarkable intracellular endosomal escape efficiency, excellent gene silencing, and inhibit retinal angiogenesis. Our study provides design guidance for developing efficient nonviral ocular nucleic acid delivery systems.

Cationic Polymers as Transfection Reagents for Nucleic Acid Delivery.

Nucleic acid therapy can achieve lasting and even curative effects through gene augmentation, gene suppression, and genome editing. However, it is difficult for naked nucleic acid molecules to enter cells. As a result, the key to nucleic acid therapy is the introduction of nucleic acid molecules into cells. Cationic polymers are non-viral nucleic acid delivery systems with positively charged groups on their molecules that concentrate nucleic acid molecules to form nanoparticles, which help nucleic acids cross barriers to express proteins in cells or inhibit target gene expression. Cationic polymers are easy to synthesize, modify, and structurally control, making them a promising class of nucleic acid delivery systems. In this manuscript, we describe several representative cationic polymers, especially biodegradable cationic polymers, and provide an outlook on cationic polymers as nucleic acid delivery vehicles.

Non-viral nucleic acid delivery approach: A boon for state-of-the-art gene delivery

Non-viral nucleic acid delivery approach: A boon for state-of-the-art gene delivery

Efficient mRNA delivery using lipid nanoparticles modified with fusogenic coiled-coil peptides.

Gene delivery has great potential in modulating protein expression in specific cells to treat diseases. Such therapeutic gene delivery demands sufficient cellular internalization and endosomal escape. Of various nonviral nucleic acid delivery systems, lipid nanoparticles (LNPs) are the most advanced, but still, are very inefficient as the majority are unable to escape from endosomes/lysosomes. Here, we develop a highly efficient gene delivery system using fusogenic coiled-coil peptides. We modified LNPs, carrying EGFP-mRNA, and cells with complementary coiled-coil lipopeptides. Coiled-coil formation between these lipopeptides induced fast nucleic acid uptake and enhanced GFP expression. The cellular uptake of coiled-coil modified LNPs is likely driven by membrane fusion thereby omitting typical endocytosis pathways. This direct cytosolic delivery circumvents the problems commonly observed with the limited endosomal escape of mRNA. Therefore fusogenic coiled-coil peptide modification of existing LNP formulations to enhance nucleic acid delivery efficiency could be beneficial for several gene therapy applications.

One-pot synthesis of dynamically cross-linked polymers for serum-resistant nucleic acid delivery.

Cationic polymers used for nucleic acid delivery often suffer from complicated syntheses, undesired intracellular cargo release and low serum stability. Herein, a series of ternary polymers were synthesized via facile green chemistry to achieve efficient plasmid DNA and mRNA delivery in serum. During the one-pot synthesis of the ternary polymer, acetylphenylboric acid (APBA), polyphenol and low-molecular weight polyethyleneimine (PEI 1.8k) were dynamically cross-linked with each other due to formation of an imine between PEI 1.8k and APBA and formation of a boronate ester between APBA and polyphenol. Series of polyphenols, including ellagic acid (EA), epigallocatechin gallate (EGCG), nordihydroguaiaretic acid (NDGA), rutin (RT) and rosmarinic acid (RA), and APBA molecules, including 2-acetylphenylboric acid (2-APBA), 3-acetylphenylboric acid (3-APBA) and 4-acetylphenylboric acid (4-APBA), were screened and the best-performing ternary polymer, 2-PEI-RT, constructed from RT and 2-APBA, was identified. The ternary polymer featured efficient DNA condensation to favor cellular internalization, and the acidic environment in endolysosomes triggered effective degradation of the polymer to promote cargo release. Thus, 2-PEI-RT showed robust plasmid DNA transfection efficiencies in various tumor cells in serum, outperforming the commercial reagent PEI 25k by 1-3 orders of magnitude. Moreover, 2-PEI-RT mediated efficient cytosolic delivery of Cas9-mRNA/sgRNA to enable pronounced CRISPR-Cas9 genome editing in vitro. Such a facile and robust platform holds great potential for non-viral nucleic acid delivery and gene therapy.

An optimized protocol for the electroporation of NCI H929 multiple myeloma cells

Multiple myeloma cell lines are difficult to transfect with non-viral nucleic acid delivery methods. While electroporation is the most efficient tool for the transfection of most hard-to-transfect cells, human multiple myeloma cells differ in their permissiveness and each cell type require different electroporation conditions for an efficient transgene delivery. In this study, various parameters for NCI H929 human multiple myeloma cells are tested to generate an optimized electroporation protocol. Findings from this paper showed that besides the voltage and capacitance settings, cell count, the cell cycle status of cells, the amount of nucleic acid and removal of death cells all impacted the electroporation efficiency and viable cell count. These results are expected to serve as a starting point and a guide for researchers.

Excipient-Free Ionizable Polyester Nanoparticles for Lung-Selective and Innate Immune Cell Plasmid DNA and mRNA Transfection.

Extrahepatic nucleic acid delivery using polymers typically requires the synthesis and purification of custom monomers, post-synthetic modifications, and incorporation of additional excipients to augment their stability, endosomal escape, and in vivo effectiveness. Here, we report the development of a single-component and excipient-free, polyester-based nucleic acid delivery nanoparticle platform comprising ionizable N-methyldiethanolamine (MDET) and various hydrophobic alkyl diols (Cp) that achieves lung-selective nucleic acid transfection in vivo. PolyMDET and polyMDET-Cp polyplexes displayed high serum and enzymatic stability, while delivering pDNA or mRNA to "hard-to-transfect" innate immune cells. PolyMDET-C4 and polyMDET-C6 mediated high protein expression in lung alveolar macrophages and dendritic cells without inducing tissue damage or systemic inflammatory responses. Improved strategies using readily available starting materials to produce a simple, excipient-free, non-viral nucleic acid delivery platform with lung-selective and innate immune cell tropism has the potential to expedite clinical deployment of polymer-based genetic medicines.

Cationic Micelles Outperform Linear Polymers for Delivery of Antisense Oligonucleotides in Serum: An Exploration of Polymer Architecture, Cationic Moieties, and Cell Addition Order.

Antisense oligonucleotides (ASOs) are an important emerging therapeutic; however, they struggle to enter cells without a delivery vehicle, such as a cationic polymer. To understand the role of polymer architecture for ASO delivery, five linear polymers and five diblock polymers (capable of self-assembly into micelles) were synthesized with varying cationic groups. After complexation of each polymer/micelle with ASO, it was found that less bulky cationic moieties transfected the ASO more effectively. Interestingly, however the ASO internalization trend was the opposite of the transfection trend for cationic moiety, indicating internalization is not the major factor in determining transfection efficiency for this series. Micelleplexes (micelle-ASO complexes) generally enable higher transfection efficacy as compared to polyplexes (linear polymer-ASO complexes). Additionally, the order of addition of cells and complexes was explored. Linear polyplexes showed better transfection efficiency in adhered cells, whereas micelleplexes delivered the ASO more efficiently when the cells and micelleplexes were added simultaneously. This phenomenon may be due to increased cell-complex interactions as micelleplexes have increased colloidal stability compared to polyplexes. These findings emphasize the importance of polymer composition and architecture in governing the cellular interactions necessary for transfection, thus allowing advancement in the design principles for nonviral nucleic acid delivery formulations.

Co-Formulation of Amphiphilic Cationic and Anionic Cyclodextrins Forming Nanoparticles for siRNA Delivery in the Treatment of Acute Myeloid Leukaemia.

Non-viral delivery of therapeutic nucleic acids (NA), including siRNA, has potential in the treatment of diseases with high unmet clinical needs such as acute myeloid leukaemia (AML). While cationic biomaterials are frequently used to complex the nucleic acids into nanoparticles, attenuation of charge density is desirable to decrease in vivo toxicity. Here, an anionic amphiphilic CD was synthesised and the structure was confirmed by Fourier-transform infrared spectroscopy (FT-IR), Nuclear Magnetic Resonance (NMR), and high-resolution mass spectrometry (HRMS). A cationic amphiphilic cyclodextrin (CD) was initially used to complex the siRNA and then co-formulated with the anionic amphiphilic CD. Characterisation of the co-formulated NPs indicated a significant reduction in charge from 34 ± 7 mV to 24 ± 6 mV (p < 0.05) and polydispersity index 0.46 ± 0.1 to 0.16 ± 0.04 (p < 0.05), compared to the cationic CD NPs. Size was similar, 161–164 nm, for both formulations. FACS and confocal microscopy, using AML cells (HL-60), indicated a similar level of cellular uptake (60% after 6 h) followed by endosomal escape. The nano co-formulation significantly reduced the charge while maintaining gene silencing (21%). Results indicate that blending of anionic and cationic amphiphilic CDs can produce bespoke NPs with optimised physicochemical properties and potential for enhanced in vivo performance in cancer treatment.

Toward Gene Transfer Nanoparticles as Therapeutics.

Genetic medicine has great potential to treat the underlying causes of many human diseases with exquisite precision, but the field has historically been stymied by delivery as the central challenge. Nanoparticles, engineered constructs the size of natural viruses, are being designed to more closely mimic the delivery efficiency of viruses, while enabling the advantages of increased safety, cargo-carrying flexibility, specific targeting, and ease in manufacturing. The speed in which nonviral gene transfer nanoparticles are making progress in the clinic is accelerating, with clinical validation of multiple nonviral nucleic acid delivery nanoparticle formulations recently FDA approved for both expression and for silencing of genes. While much of this progress has been with lipid nanoparticle formulations, significant development is being made with other nanomaterials for gene transfer as well, with favorable attributes such as biodegradability, scalability, and cell targeting. This review highlights the state of the field, current challenges in delivery, and opportunities for engineered nanomaterials to meet these challenges, including enabling long-term therapeutic gene editing. Delivery technology utilizing different kinds of nanomaterials and varying cargos for gene transfer (DNA, mRNA, and ribonucleoproteins) are discussed. Clinical applications are presented, including for the treatment of genetic diseases such as cystic fibrosis.

Nanoparticle designs for delivery of nucleic acid therapeutics as brain cancer therapies.

Glioblastoma (GBM) is an aggressive central nervous system cancer with a dismal prognosis. The standard of care involves surgical resection followed by radiotherapy and chemotherapy, but five-year survival is only 5.6% despite these measures. Novel therapeutic approaches, such as immunotherapies, targeted therapies, and gene therapies, have been explored to attempt to extend survival for patients. Nanoparticles have been receiving increasing attention as promising vehicles for non-viral nucleic acid delivery in the context of GBM, though delivery is often limited by low blood-brain barrier permeability, particle instability, and low trafficking to target brain structures and cells. In this review, nanoparticle design considerations and new advances to overcome nucleic acid delivery challenges to treat brain cancer are summarized and discussed.

One-Component Multifunctional Sequence-Defined Ionizable Amphiphilic Janus Dendrimer Delivery Systems for mRNA.

Efficient viral or nonviral delivery of nucleic acids is the key step of genetic nanomedicine. Both viral and synthetic vectors have been successfully employed for genetic delivery with recent examples being DNA, adenoviral, and mRNA-based Covid-19 vaccines. Viral vectors can be target specific and very efficient but can also mediate severe immune response, cell toxicity, and mutations. Four-component lipid nanoparticles (LNPs) containing ionizable lipids, phospholipids, cholesterol for mechanical properties, and PEG-conjugated lipid for stability represent the current leading nonviral vectors for mRNA. However, the segregation of the neutral ionizable lipid as droplets in the core of the LNP, the "PEG dilemma", and the stability at only very low temperatures limit their efficiency. Here, we report the development of a one-component multifunctional ionizable amphiphilic Janus dendrimer (IAJD) delivery system for mRNA that exhibits high activity at a low concentration of ionizable amines organized in a sequence-defined arrangement. Six libraries containing 54 sequence-defined IAJDs were synthesized by an accelerated modular-orthogonal methodology and coassembled with mRNA into dendrimersome nanoparticles (DNPs) by a simple injection method rather than by the complex microfluidic technology often used for LNPs. Forty four (81%) showed activity in vitro and 31 (57%) in vivo. Some, exhibiting organ specificity, are stable at 5 °C and demonstrated higher transfection efficiency than positive control experiments in vitro and in vivo. Aside from practical applications, this proof of concept will help elucidate the mechanisms of packaging and release of mRNA from DNPs as a function of ionizable amine concentration, their sequence, and constitutional isomerism of IAJDs.

Efficient Protein Transfection by Swarms of Chemically Powered Plasmonic Virus-Sized Nanorobots.

Transfection is based on nonviral delivery of nucleic acids or proteins into cells. Viral approaches are being used; nevertheless, their translational capacity is nowadays decreasing due to persistent fear of their safety, therefore creating space for the field of nanotechnology. However, nanomedical approaches introducing static nanoparticles for the delivery of biologically active molecules are very likely to be overshadowed by the vast potential of nanorobotics. We hereby present a rapid nonviral transfection of protein into a difficult-to-transfect prostate cancer cell line facilitated by chemically powered rectangular virus-sized (68 nm × 33 nm) nanorobots. The enhanced diffusion of these biocompatible nanorobots is the key to their fast internalization into cells, happening in a matter of minutes and being up to 6-fold more efficient compared to static nanorobots in a nonfueled environment. The Au/Ag plasmonic nature of these nanorobots makes them simply traceable and allows for their detailed subcellular localization. Protein transfection mediated by such nanorobots is an important step forward, challenging the field of nanomedicine and having potential in future translational medical research.

Photothermal Transfection for Effective Nonviral Genome Editing.

The efficient nonviral delivery of nucleic acids into the cytoplasm is needed to fully realize the potential of gene therapy. Although cationic lipids and nanoparticles have been widely used to improve the intracellular delivery of nucleic acids, they suffer from cytotoxicity and poor endosomal escape, thus limiting the transfection efficacy. Here, we developed a photothermal transfection platform for efficient and biosafe intracellular delivery of nucleic acids. Photothermal transfection was carried out by irradiation of cells co-treated with Lipofectamine-plasmid DNA complexes and PEGylated gold nanorods (GNRs) using an NIR laser for 30 min and subsequent incubation of the cells for 30 min without laser irradiation. Compared to conventional Lipofectamine-based transfection, our photothermal transfection platform significantly improved the transfection efficiency in difficult-to-transfect human primary cells including human dermal fibroblasts while maintaining the cell viability. The photothermal heating did not leave the GNRs inside the cell, thereby minimizing the cellular damage. Furthermore, the photothermal transfection platform showed superior genome editing abilities (both gene cleavage and insertion) in human dermal fibroblasts than conventional Lipofectamine-based transfection.

Contrast-Enhanced Ultrasound in the Diagnosis of Ocular Pathology: Application Prospects

Contrast-enhanced ultrasound is a highly informative method for the differential diagnosis of focal changes in various organs and tissues, which allows to visualize vascular structures and obtain new previously unavailable information when using standard b-scan. At the beginning of the 21st century after the development of a new generation of contrast agents consisting of microbubbles with inert gas contrast-enhanced ultrasound became widely used to improve visual assessment of small-caliber vessels in the diagnosis of the abdominal cavity and retroperitoneal space pathology: benign and malignant liver formations, spleen pathology, inflammatory diseases and tumors of the pancreas, defects in renal perfusion, tumor and cystic lesions of the kidneys. Assessment of intraocular tumors microcirculation and diagnosis of vitreoretinal pathology are still two main directions of using contrast-enhanced ultrasound in ophthalmology. In recent years, there has been a growing interest in the use of contrast-enhanced ultrasound in the study of perfusion of different types of uveal melanoma in an animal experiment. A promising direction in the field of genetic engineering is the use of local contrast-enhanced ultrasound exposure on retinal cells (retinal ganglion cells, retinal pigment epithelium) to promote gene transfection (non-viral nucleic acid delivery into the DNA of a cell), which is an important part of gene therapy. Despite the successes achieved in the study of contrast-enhanced ultrasound effectiveness in medicine, further research is needed to increase the informative value of this method in the diagnosis of ophthalmopathology.

What Do COVID-19 Vaccines Tell Us About Nucleic Acid Delivery In Vivo?

The utilization of the mRNA-based Pfizer-BioNTech and Moderna coronavirus disease 2019 (COVID-19) vaccines represents the culmination of many years of nonviral nucleic acid delivery, but more importantly, they signify a massive clinical scientific success. Scientists working in the area of nucleic acid delivery using lipid nanoparticles will undoubtedly be energized by the success of these vaccines and begin to collect much needed data in the realm of nonviral-based RNA and DNA delivery, specifically, the use of lipid nanoparticles, the immune response, safety, and efficacy. It is easily conceivable that in the future we can utilize these data to help streamline our approach for the delivery of DNA for gene therapy and regulatory RNAs for therapeutic and regenerative medicine (ie, wound repair) applications.