Potentiation of cationic liposome-mediated gene delivery by polycations

Enhancing siRNA cancer therapy: Multifaceted strategies with lipid and polymer-based carrier systems

Cancers are increasing in prevalence and many challenges remain for their treatment, such as chemoresistance and toxicity. In this context, siRNA-based therapeutics have many potential advantages for cancer therapies as a result of their ability to reduce or prevent expression of specific cancer-related genes. However, the direct delivery of naked siRNA is hindered by issues like enzymatic degradation, insufficient cellular uptake, and poor pharmacokinetics. Hence, the discovery of a safe and efficient delivery vehicle is essential. This review explores various lipid and polymer-based delivery systems for siRNA in cancer treatment. Both polymers and lipids have garnered considerable attention as carriers for siRNA delivery. While all of these systems protect siRNA and enhance transfection efficacy, each exhibits its unique strengths. Lipid-based delivery systems, for instance, demonstrate high entrapment efficacy and utilize cost-effective materials. Conversely, polymeric-based delivery systems offer advantages through chemical modifications. Nonetheless, certain drawbacks still limit their usage. To address these limitations, combining different materials in formulations (lipid, polymer, or targeting agent) could enhance pharmaceutical properties, boost transfection efficacy, and reduce side effects. Furthermore, co-delivery of siRNA with other therapeutic agents presents a promising strategy to overcome cancer resistance. Lipid-based delivery systems have been demonstrated to encapsulate many therapeutic agents and with high efficiency, but most are limited in terms of the functionalities they display. In contrast, polymeric-based delivery systems can be chemically modified by a wide variety of routes to include multiple components, such as release or targeting elements, from the same materials backbone. Accordingly, by incorporating multiple materials such as lipids, polymers, and/or targeting agents in RNA formulations it is possible to improve the pharmaceutical properties and therapeutic efficacy while reducing side effects. This review focuses on strategies to improve siRNA cancer treatments and discusses future prospects in this important field.

DNA functionalized programmable hybrid biomaterials for targeted multiplexed applications

With the advent of DNA nanotechnology, DNA-based biomaterials have emerged as a unique class of materials at the center of various biological advances. Owing to DNA's high modification capacity via programmable Watson-Crick base-pairing, DNA structures of desired design with increased complexity have been developed. However, the limited scalability, along with poor mechanical properties, high synthesis costs, and poor stability, reduced the adaptability of DNA-based materials to complex biological applications. DNA-based hybrid biomaterials were designed to overcome these limitations by conjugating DNA with functional materials. Today, DNA-based hybrid materials have attracted significant attention in biological engineering with broad application prospects in biomedicine, clinical diagnosis, and nanodevices. Here, we summarize the recent advances in DNA-based hybrid materials with an in-depth understanding of general molecular design principles, functionalities, and applications. Finally, the challenges and prospects associated with DNA-based hybrid materials are discussed at the end of this review.

A repertoire of nanoengineered short peptide-based hydrogels and their applications in biotechnology

Peptide nanotechnology has currently bridged the gap between materials and biological worlds. Bioinspired self-assembly of short-peptide building blocks helps take the leap from molecules to materials by taking inspiration from nature. Owing to their intrinsic biocompatibility, high water content, and extracellular matrix mimicking fibrous morphology, hydrogels engineered from the self-assembly of short peptides exemplify the actualization of peptide nanotechnology into biomedical products. However, the weak mechanical property of these hydrogels jeopardizes their practical applications. Moreover, their functional diversity is limited since they comprise only one building block. Nanoengineering the networks of these hydrogels by incorporating small molecules, polymers, and inorganic/carbon nanomaterials can augment the mechanical properties while retaining their dynamic supramolecular nature. These additives interact with the peptide building blocks supramolecularly and may enhance the branching of the networks via coassembly or crystallographic mismatch. This phenomenon expands the functional diversity of these hydrogels by synergistically combining the attributes of the individual building blocks. This review highlights such nanoengineered peptide hydrogels and their applications in biotechnology. We have included exemplary works on supramolecular modification of the peptide hydrogel networks by integrating other small molecules, synthetic/biopolymers, conductive polymers, and inorganic/carbon nanomaterials and shed light on their various utilities focusing on biotechnology. We finally envision some future prospects in this highly active field of research.

Non-Viral Carriers for Nucleic Acids Delivery: Fundamentals and Current Applications

Over the past decades, non-viral DNA and RNA delivery systems have been intensively studied as an alternative to viral vectors. Despite the most significant advantage over viruses, such as the lack of immunogenicity and cytotoxicity, the widespread use of non-viral carriers in clinical practice is still limited due to the insufficient efficacy associated with the difficulties of overcoming extracellular and intracellular barriers. Overcoming barriers by non-viral carriers is facilitated by their chemical structure, surface charge, as well as developed modifications. Currently, there are many different forms of non-viral carriers for various applications. This review aimed to summarize recent developments based on the essential requirements for non-viral carriers for gene therapy.

Gene Therapy for Chronic Traumatic Brain Injury: Challenges in Resolving Long-term Consequences of Brain Damage

The gene therapy is alluring not only for CNS disorders but also for other pathological conditions. Gene therapy employs the insertion of a healthy gene into the identified genome to replace or replenish genes responsible for pathological disorder or damage due to trauma. The last decade has seen a drastic change in the understanding of vital aspects of gene therapy. Despite the complexity of traumatic brain injury (TBI), the advent of gene therapy in various neurodegenerative disorders has reinforced the ongoing efforts of alleviating TBI-related outcomes with gene therapy. The review highlights the genes modulated in response to TBI and evaluates their impact on the severity and duration of the injury. We have reviewed strategies that pinpointed the most relevant gene targets to restrict debilitating events of brain trauma and utilize vector of choice to deliver the gene of interest at the appropriate site. We have made an attempt to summarize the long-term neurobehavioral consequences of TBI due to numerous pathometabolic perturbations associated with a plethora of genes. Herein, we shed light on the basic pathological mechanisms of brain injury, genetic polymorphism in individuals susceptible to severe outcomes, modulation of gene expression due to TBI, and identification of genes for their possible use in gene therapy. The review also provides insights on the use of vectors and challenges in translations of this gene therapy to clinical practices.

A tale of nucleic acid-ionizable lipid nanoparticles: Design and manufacturing technology and advancement

INTRODUCTION

Ionizable lipid nanoparticles (LNPs) have been proven to have high encapsulation, cellular uptake, and effective endosomal escape and are therefore promising for nucleic acid delivery. The combination of ionizable lipids, helper lipids, cholesterol, and PEG lipids advances nucleic acid-ionizable LNPs and distinguishes them from liposomes, SLNs, NLCs, and other lipid particles. Solvent injection and microfluidics technology are the primary manufacturing techniques for commercialized ionizable LNPs. Microfluidics technology limitations restrict the rapid industrial scale-up and therapeutic effectiveness of ionized LNPs. Alternative manufacturing technologies and target-specific lipids are urgently needed.

AREA COVERED

This article provides an in-depth update on the lipid compositions, clinical trials, and manufacturing technologies for nucleic acid-ionizable LNPs. For the first time, we updated the distinction between ionizable LNPs and other lipid particles. We also proposed an alternate thermocycling technology for high industrial scale-up and the stability of nucleic acid-ionizing LNPs.

EXPERT OPINION

Nucleic acid-ionizable LNPs have a promising future for delivering nucleic acids in a target-specific manner. Though ionizing LNPs are in their early stages, they face several challenges, including only hepatic delivery, a short shelf life, and ultra-cold storage. In our opinion, ligand-based, target-specific synthesized novel lipids and advanced manufacturing technologies can easily overcome the restrictions and open up a new approach for improved therapeutic efficacy for chronic disorders.

Psychotropic drugs interaction with the lipid nanoparticle of COVID-19 mRNA therapeutics

The messenger RNA (mRNA) vaccines for COVID-19, Pfizer-BioNTech and Moderna, were authorized in the US on an emergency basis in December of 2020. The rapid distribution of these therapeutics around the country and the world led to millions of people being vaccinated in a short time span, an action that decreased hospitalization and death but also heightened the concerns about adverse effects and drug-vaccine interactions. The COVID-19 mRNA vaccines are of particular interest as they form the vanguard of a range of other mRNA therapeutics that are currently in the development pipeline, focusing both on infectious diseases as well as oncological applications. The Vaccine Adverse Event Reporting System (VAERS) has gained additional attention during the COVID-19 pandemic, specifically regarding the rollout of mRNA therapeutics. However, for VAERS, absence of a reporting platform for drug-vaccine interactions left these events poorly defined. For example, chemotherapy, anticonvulsants, and antimalarials were documented to interfere with the mRNA vaccines, but much less is known about the other drugs that could interact with these therapeutics, causing adverse events or decreased efficacy. In addition, SARS-CoV-2 exploitation of host cytochrome P450 enzymes, reported in COVID-19 critical illness, highlights viral interference with drug metabolism. For example, patients with severe psychiatric illness (SPI) in treatment with clozapine often displayed elevated drug levels, emphasizing drug-vaccine interaction.

In Vivo and Ex Vivo Gene Electrotransfer in Ophthalmological Disorders

The aim of this document is to present an overview of gene electrotransfer in ophthalmological disorders. In order to ensure an adequate variety of the assessed studies, several electronic databases were considered and studies published between January 1998 and December 2021 were analysed. Three investigators carried out data extraction and analysis, focusing on both technical (i.e., electrical protocol, type of electrode, plasmid) and medical (i.e., type of study, threated disease) aspects and highlighting the main differences in terms of results obtained. Moreover, the IGEA experience in the project “Transposon-based, targeted ex vivo gene therapy to treat age-related macular degeneration” (TargetAMD) was reported in the results section. No clinical trial was found on international literature and on ClinicalTrials.gov. Twelve preclinical studies were found including in vivo and ex-vivo applications. The studied showed that electrotransfer could be very efficient for plasmid DNA transfection. Many attempts such as modification of the electric field, buffers and electrodes have been made and the optimization of electric field setting seems to be very important. Using this technique, gene replacement can be designed in cases of retinal inheritance or corneal disease and a wide range of human eye diseases could, in the future, benefitfrom these gene therapy technologies.

Gene Therapy in Inherited Retinal Diseases: An Update on Current State of the Art

Background: Gene therapy cannot be yet considered a far perspective, but a tangible therapeutic option in the field of retinal diseases. Although still confined in experimental settings, the preliminary results are promising and provide an overall scenario suggesting that we are not so far from the application of gene therapy in clinical settings. The main aim of this review is to provide a complete and updated overview of the current state of the art and of the future perspectives of gene therapy applied on retinal diseases.

Methods: We carefully revised the entire literature to report all the relevant findings related to the experimental procedures and the future scenarios of gene therapy applied in retinal diseases. A clinical background and a detailed description of the genetic features of each retinal disease included are also reported.

Results: The current literature strongly support the hope of gene therapy options developed for retinal diseases. Although being considered in advanced stages of investigation for some retinal diseases, such as choroideremia (CHM), retinitis pigmentosa (RP), and Leber's congenital amaurosis (LCA), gene therapy is still quite far from a tangible application in clinical practice for other retinal diseases.

Conclusions: Gene therapy is an extremely promising therapeutic tool for retinal diseases. The experimental data reported in this review offer a strong hope that gene therapy will be effectively available in clinical practice in the next years.

An Activatable Host-Guest Conjugate as a Nanocarrier for Effective Drug Release through Self-Inclusion

There is a challenge in supramolecular chemotherapy for constructing a system equipped with both sufficient protection and high-efficiency release of drugs. To this end, a new strategy of an activatable host-guest conjugate with self-inclusion property is proposed. Based on the binding affinity gain of intramolecular host-guest self-inclusion, an activatable host-guest conjugate was designed, bearing cucurbit[7]uril as the host, an alkyl ammonium moiety as the guest, and the redox-responsive disulfide linkage. Oxaliplatin, a clinical antitumor drug, could be firmly encapsulated by the activatable host-guest conjugate to form the supramolecular drug with high stability. Moreover, oxaliplatin loaded in the activatable host-guest conjugate could be almost completely released by self-inclusion triggered by glutathione in a tumor microenvironment, thus exhibiting comparable antitumor bioactivity with naked oxaliplatin through in vitro cell experiments. It is highly anticipated that this line of research may open new horizons for programmable and on-demand supramolecular chemotherapy with high antitumor efficiency.

Intracellular Routing and Recognition of Lipid-Based mRNA Nanoparticles

Messenger RNA (mRNA) is being extensively used in gene therapy and vaccination due to its safety over DNA, in the following ways: its lack of integration risk, cytoplasmic expression, and transient expression compatible with fine regulations. However, clinical applications of mRNA are limited by its fast degradation by nucleases, and the activation of detrimental immune responses. Advances in mRNA applications, with the recent approval of COVID-19 vaccines, were fueled by optimization of the mRNA sequence and the development of mRNA delivery systems. Although delivery systems and mRNA sequence optimization have been abundantly reviewed, understanding of the intracellular processing of mRNA is mandatory to improve its applications. We will focus on lipid nanoparticles (LNPs) as they are the most advanced nanocarriers for the delivery of mRNA. Here, we will review how mRNA therapeutic potency can be affected by its interactions with cellular proteins and intracellular distribution.

Protamine-Based Strategies for RNA Transfection

Protamine is a natural cationic peptide mixture mostly known as a drug for the neutralization of heparin and as a compound in formulations of slow-release insulin. Protamine is also used for cellular delivery of nucleic acids due to opposite charge-driven coupling. This year marks 60 years since the first use of Protamine as a transfection enhancement agent. Since then, Protamine has been broadly used as a stabilization agent for RNA delivery. It has also been involved in several compositions for RNA-based vaccinations in clinical development. Protamine stabilization of RNA shows double functionality: it not only protects RNA from degradation within biological systems, but also enhances penetration into cells. A Protamine-based RNA delivery system is a flexible and versatile platform that can be adjusted according to therapeutic goals: fused with targeting antibodies for precise delivery, digested into a cell penetrating peptide for better transfection efficiency or not-covalently mixed with functional polymers. This manuscript gives an overview of the strategies employed in protamine-based RNA delivery, including the optimization of the nucleic acid's stability and translational efficiency, as well as the regulation of its immunostimulatory properties from early studies to recent developments.

Cytosolic delivery of nucleic acids: The case of ionizable lipid nanoparticles

Ionizable lipid nanoparticles (LNPs) are the most clinically advanced nano-delivery system for therapeutic nucleic acids. The great effort put in the development of ionizable lipids with increased in vivo potency brought LNPs from the laboratory benches to the FDA approval of patisiran in 2018 and the ongoing clinical trials for mRNA-based vaccines against SARS-CoV-2. Despite these success stories, several challenges remain in RNA delivery, including what is known as "endosomal escape." Reaching the cytosol is mandatory for unleashing the therapeutic activity of RNA molecules, as their accumulation in other intracellular compartments would simply result in efficacy loss. In LNPs, the ability of ionizable lipids to form destabilizing non-bilayer structures at acidic pH is recognized as the key for endosomal escape and RNA cytosolic delivery. This is motivating a surge in studies aiming at designing novel ionizable lipids with improved biodegradation and safety profiles. In this work, we describe the journey of RNA-loaded LNPs across multiple intracellular barriers, from the extracellular space to the cytosol. In silico molecular dynamics modeling, in vitro high-resolution microscopy analyses, and in vivo imaging data are systematically reviewed to distill out the regulating mechanisms underlying the endosomal escape of RNA. Finally, a comparison with strategies employed by enveloped viruses to deliver their genetic material into cells is also presented. The combination of a multidisciplinary analytical toolkit for endosomal escape quantification and a nature-inspired design could foster the development of future LNPs with improved cytosolic delivery of nucleic acids.

A Comprehensive Review on Intracellular Delivery

Intracellular delivery is considered an indispensable process for various studies, ranging from medical applications (cell-based therapy) to fundamental (genome-editing) and industrial (biomanufacture) approaches. Conventional macroscale delivery systems critically suffer from such issues as low cell viability, cytotoxicity, and inconsistent material delivery, which have opened up an interest in the development of more efficient intracellular delivery systems. In line with the advances in microfluidics and nanotechnology, intracellular delivery based on micro- and nanoengineered platforms has progressed rapidly and held great promises owing to their unique features. These approaches have been advanced to introduce a smorgasbord of diverse cargoes into various cell types with the maximum efficiency and the highest precision. This review differentiates macro-, micro-, and nanoengineered approaches for intracellular delivery. The macroengineered delivery platforms are first summarized and then each method is categorized based on whether it employs a carrier- or membrane-disruption-mediated mechanism to load cargoes inside the cells. Second, particular emphasis is placed on the micro- and nanoengineered advances in the delivery of biomolecules inside the cells. Furthermore, the applications and challenges of the established and emerging delivery approaches are summarized. The topic is concluded by evaluating the future perspective of intracellular delivery toward the micro- and nanoengineered approaches.

Advances in microfluidic synthesis and coupling with synchrotron SAXS for continuous production and real-time structural characterization of nano-self-assemblies

Microfluidic platforms have become highly attractive tools for synthesis of nanoparticles, including lipid nano-self-assemblies, owing to unique features and at least three important aspects inherent to miniaturized micro-devices. Firstly, the fluids flow under controlled conditions in the microchannels, providing well-defined flow profiles and shorter diffusion lengths that play important roles in enhancing the continuous production of lipid and polymer nanoparticles with relatively narrow size distributions. Secondly, various geometries adapted to microfluidic device designs can be utilized for enhancing the colloidal stability of nanoparticles and improving their drug loading. Thirdly, microfluidic devices are usually compatible with in situ characterization methods for real-time monitoring of processes occurring inside the microchannels. This is unlike conventional nanoparticle synthesis methods, where a final solution or withdrawn aliquots are separately analysed. These features inherent to microfluidic devices provide a tool-set allowing not only precise nanoparticle size control, but also real-time analyses for process optimization. In this review, we focus on recent advances and developments in the use of microfluidic devices for synthesis of lipid nanoparticles. We present different designs based on hydrodynamic flow focusing, droplet-based methods and controlled microvortices, and discuss integration of microfluidic platforms with synchrotron small-angle X ray scattering (SAXS) for in situ structural characterization of lipid nano-self-assemblies under continuous flow conditions, along with major challenges and future directions in this research area.

Small interfering RNA for cancer treatment: overcoming hurdles in delivery

In many ways, cancer cells are different from healthy cells. A lot of tactical nano-based drug delivery systems are based on the difference between cancer and healthy cells. Currently, nanotechnology-based delivery systems are the most promising tool to deliver DNA-based products to cancer cells. This review aims to highlight the latest development in the lipids and polymeric nanocarrier for siRNA delivery to the cancer cells. It also provides the necessary information about siRNA development and its mechanism of action. Overall, this review gives us a clear picture of lipid and polymer-based drug delivery systems, which in the future could form the base to translate the basic siRNA biology into siRNA-based cancer therapies.

Nanomedicine-Based Approaches for mRNA Delivery

Messenger RNA (mRNA) has immense potential for developing a wide range of therapies, including immunotherapy and protein replacement. As mRNA presents no risk of integration into the host genome and does not require nuclear entry for transfection, which allows protein production even in nondividing cells, mRNA-based approaches can be envisioned as safe and practical therapeutic strategies. Nevertheless, mRNA presents unfavorable characteristics, such as large size, immunogenicity, limited cellular uptake, and sensitivity to enzymatic degradation, which hinder its use as a therapeutic agent. While mRNA stability and immunogenicity have been ameliorated by direct modifications on the mRNA structure, further improvements in mRNA delivery are still needed for promoting its activity in biological settings. In this regard, nanomedicine has shown the ability for spatiotemporally controlling the function of a myriad of bioactive agents in vivo. Direct engineering of nanomedicine structures for loading, protecting, and releasing mRNA and navigating in biological environments can then be applied for promoting mRNA translation toward the development of effective treatments. Here, we review recent approaches aimed at enhancing mRNA function and its delivery through nanomedicines, with particular emphasis on their applications and eventual clinical translation.

Validation of Gene Therapy for Mutant Mitochondria by Delivering Mitochondrial RNA Using a MITO-Porter

Here, we report on validating a mitochondrial gene therapy by delivering nucleic acids to mitochondria of diseased cells by a MITO-Porter, a liposome-based carrier for mitochondrial delivery. We used cells derived from a patient with a mitochondrial disease with a G625A heteroplasmic mutation in the tRNA^Phe of the mitochondrial DNA (mtDNA). It has been reported that some mitochondrial gene diseases are caused by heteroplasmic mutations, in which both mutated and wild-type (WT) genes are present, and the accumulation of pathological mutations leads to serious, intractable, multi-organ diseases. Therefore, the decrease of the mutated gene rate is considered to be a useful gene therapy strategy. To accomplish this, wild-type mitochondrial pre-tRNA^Phe (pre-WT-tRNA^Phe), prepared by in vitro transcription, was encapsulated in the MITO-Porter. The pre-WT-tRNA^Phe encapsulated in the MITO-Porter was transfected into diseased mitochondrial cells, and the resulting mutant levels were examined by an amplification refractory mutation system (ARMS)-quantitative PCR. The mutation rate of tRNA^Phe was decreased, and this therapeutic effect was sustained even on the 8th day after transfection. Furthermore, mitochondrial respiratory activity of the disease cells was increased after the transfection of therapeutic pre-WT-tRNA^Phe. These results support the conclusion that the mitochondrial delivery of therapeutic nucleic acids represents a viable strategy for mitochondrial gene therapy.

Development of a nanoparticle that releases nucleic acids in response to a mitochondrial environment

The delivery of nucleic acids targeting mutant mtDNA represent a potential strategy for addressing a variety of mitochondria-related diseases. We previously developed a MITO-Porter, a nano carrier that is capable of delivering nanoparticles of nucleic acids to mitochondria of human cells. Here, we report on an investigation of a series of nanoparticles formed with various poly cationic peptides that can release nucleic acids in response to a mitochondrial environment. A significant relationship was found between the number of and the location of arginine and histidine residues in the peptide sequence and the release of nucleic acids in a mitochondrial environment.

New Water-Soluble Oxyamino Chitosans as Biocompatible Vectors for Efficacious Anticancer Therapy via Co-Delivery of Gene and Drug

Among the many nonviral gene delivery vectors, chitosan, being a polysaccharide of natural origin, has gained special importance. In this report, chitosan (CS) has been solubilized in water by preparing its O-carboxymethyl derivative, CS(CH₂COOH), with an optimum degree of carboxymethylation. This has been further derivatized to get the pyridine-substituted product (py)CS(CH₂COOH), where the degree of pyridine substitution (47%) was optimized based on zeta potential measurements. The optimized formulation showed a high gene binding ability, forming nanosized positively charged polyelectrolyte complexes with DNA. These polyplexes were stable to DNase and physiological polyanions such as heparin. They also exhibited minimal toxicity in vitro and showed transfection levels comparable to the commercial standard Lipofectamine 2000 and much higher than polyethylenimine (MW, 25 kDa). Additionally, in this study, a hitherto unknown oxyamine derivative of chitosan has been prepared by phthaloyl protection, tosylation, and Gabriel's phthalimide synthesis. Nearly 40% of the primary alcohols were successfully converted to oxyamino functionality, which was used for forming oxime with the anticancer drug doxorubicin. The pH sensitivity of the oxime ether linkage and stability under biologically relevant conditions were then used to establish the compound as a versatile drug delivery vector. Co-delivery of functional gene (p53) and drug (doxorubicin) was accomplished in vitro and in vivo with the chitosan-pyridine imine vector (py)CS(CH₂COOH) and the newly synthesized doxorubicin oxime ether CS(Dox). Complete tumor regression with no tumor recurrence and appreciable survivability point to the in vivo effectiveness and biocompatibility of the designed composite formulation. Overall, the pH sensitivity of the oxime linkage aiding slow and steady drug release, together with the sustained gene expression by pyridine-tethered carboxymethyl chitosan, allows us to generate a nanobiocomposite with significantly high anticancer therapeutic potential.

Development of Antibody-Modified Nanobubbles Using Fc-Region-Binding Polypeptides for Ultrasound Imaging

Ultrasound (US) imaging is a widely used imaging technique. The use of US contrast agents such as microbubbles, which consist of phospholipids and are filled with perfluorocarbon gases, has become an indispensable component of clinical US imaging, while molecular US imaging has recently attracted significant attention in combination with efficient diagnostics. The avidin–biotin interaction method is frequently used to tether antibodies to microbubbles, leading to the development of a molecular targeting US imaging agent. However, avidin still has limitations such as immunogenicity. We previously reported that lipid-based nanobubbles (NBs) containing perfluorocarbon gas are suitable for US imaging and gene delivery. In this paper, we report on the development of a novel antibody modification method for NBs using Fc-region-binding polypeptides derived from protein A/G. First, we prepared anti-CD146 antibody-modified NBs using this polypeptide, resulting in high levels of attachment to human umbilical vein endothelial cells expressing CD146. To examine their targeting ability and US imaging capability, the NBs were administered to tumor-bearing mice. The contrast imaging of antibody-modified NBs was shown to be prolonged compared with that of non-labeled NBs. Thus, this antibody modification method using an Fc-binding polypeptide may be a feasible tool for developing a next-generation antibody-modified US imaging agent.

Interaction of Anionic Bulk Nanobubbles with Cationic Liposomes: Evidence for Reentrant Condensation

We investigated the interaction of bulk nanobubbles with cationic liposomes composed of 1,2-dioleoyl- sn-glycero-3-ethylphosphocholine and anionic liposomes assembled from 1-palmitoyl-2-oleoyl- sn-glycero-3-phospho-(1'- rac-glycerol). We employed dynamic light scattering and fluorescence microscopy to investigate both the hydrodynamic and electrophoretic properties of the nanobubble/liposome complexes. These optical techniques permit direct visualization of structural changes as a function of the bubble/liposome ratio. We observed reentrant condensation with cationic liposomes and gas nucleation with anionic liposomes. This is the first report of charge inversion and reentrant condensation of cationic liposomes induced by bulk nanobubbles.

In silico and in vitro study of magnetic niosomes for gene delivery: The effect of ergosterol and cholesterol

A low transfection efficiency and failure to deliver therapeutic genes to target organs limit the use of vesicular systems in gene therapy. In this study, magnetic niosomes were used to improve transfection efficiency and overcome limitations. In this light, Tween 60 and Span 60 molecules were employed as the bilayer component and ergosterol and/or cholesterol as membrane-stabilizing agents. We studied the structural and dynamical properties of cholesterol-containing niosomes (ST60/Chol) and ergosterol-containing vesicles (ST60/Ergo) using the molecular dynamics (MD) simulation technique. In in vitro experiments, the protamine-condensed DNA along with magnetic nanoparticles were prepared and incorporated into the niosome to form magnetic niosome-entrapped protamine-condensed DNA (M-NPD). The MD simulation comparison of two bilayers showed that the ST60/Ergo vesicles have better properties for gene delivery. Our in vitro results confirmed the in silico results and revealed that Ergo-niosomes have smaller size, better polydispersity, and slower release of plasmid than Chol-niosome. Moreover, M-NPD-Ergo showed higher cellular uptake and gene expresssion in HEK-293T cell line compared to M-NPD-Chol vesicles.

Ternary complex of plasmid DNA with NLS-Mu-Mu protein and cationic niosome for biocompatible and efficient gene delivery: a comparative study with protamine and lipofectamine

Non-viral gene delivery methods are considered due to safety and simplicity in human gene therapy. Since the use of cationic peptide and niosome represent a promising approach for gene delivery purposes we used recombinant fusion protein and cationic niosome as a gene carrier. A multi-domain fusion protein including nuclear localization motif (NLS) and two DNA-binding (Mu) domains, namely NLS-Mu-Mu (NMM) has been designed, cloned and expressed in E. coli DE3 strain. Afterward, the interested protein was purified by affinity chromatography. Binary vectors based on protein/DNA and ternary vectors based on protein/DNA/niosome were prepared. Protamine was used as a control. DNA condensing properties of NMM and protamine were evaluated by various experiments. Furthermore, we examined cytotoxicity, hemolysis and transfection potential of the binary and ternary complexes in HEK293T and MCF-7 cell lines. Protamine and Lipofectamine™2000 were used as positive controls, correspondingly. The recombinant NMM was expressed and purified successfully and DNA was condensed efficiently at charge ratios that were not harmful to cells. Peptidoplexes showed transfection efficiency (TE) but ternary complexes had higher TE. Additionally, NMM ternary complex was more efficient compared to protamine ternary vectors. Our results showed that niosomal ternary vector of NMM is a promising non-viral gene carrier to achieve an effective and safe carrier system for gene therapy.

Novel lipoproteoplex delivers Keap1 siRNA based gene therapy to accelerate diabetic wound healing

Therapeutics utilizing siRNA are currently limited by the availability of safe and effective delivery systems. Cutaneous diseases, specifically ones with significant genetic components are ideal candidates for topical siRNA based therapy but the anatomical structure of skin presents a considerable hurdle. Here, we optimized a novel liposome and protein hybrid nanoparticle delivery system for the topical treatment of diabetic wounds with severe oxidative stress. We utilized a cationic lipid nanoparticle (CLN) composed of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and the edge activator sodium cholate (NaChol), in a 6:1 ratio of DOTAP:NaChol (DNC). Addition of a cationic engineered supercharged coiled-coil protein (CSP) in a 10:1:1 ratio of DNC:CSP:siRNA produced a stable lipoproteoplex (LPP) nanoparticle, with optimal siRNA complexation, minimal cytotoxicity, and increased transfection efficacy. In a humanized murine diabetic wound healing model, our optimized LPP formulation successfully delivered siRNA targeted against Keap1, key repressor of Nrf2 which is a central regulator of redox mechanisms. Application of LPP complexing siKeap1 restored Nrf2 antioxidant function, accelerated diabetic tissue regeneration, and augmented reduction-oxidation homeostasis in the wound environment. Our topical LPP delivery system can readily be translated into clinical use for the treatment of diabetic wounds and can be extended to other cutaneous diseases with genetic components.

Evidence for plasmid DNA exchange after polyplex mixing

The self-assembly of a plasmid DNA (pDNA) with cationic polymers or cationic liposomes forms nanosized supramolecular structures called lipoplexes, polyplexes and lipopolyplexes. Here, we report that when two polyplex preparations made using the same polymer and the same pDNA but labelled with two different fluorophores are mixed together, pDNA molecules are exchanged. Indeed, when Flu-pDNA complexed with histidinylated lPEI (Flu-pDNA/His-lPEI) polyplexes are mixed with Cy5-pDNA complexed with histidinylated lPEI (Cy5-pDNA/His-lPEI) polyplexes, a high quantity of polyplexes emitting dual fluorescence is observed and FRET indicates that one single polyplex contains two kinds of fluorescent pDNA molecules. This phenomenon depends on the polymer-type and the strength of the pDNA/polymer interaction. No exchange is observed with polylysine polyplexes, caged His-lPEI polyplexes, lipoplexes, lipopolyplexes or when His-lPEI polyplexes are mixed with lipoplexes. Our results suggest that aggregation or collapse of polyplexes occurs after their interaction leading to their unpackaging followed by the formation of new polyplexes with the exchange of pDNA.

Aerosol Delivery of siRNA to the Lungs. Part 2: Nanocarrier-based Delivery Systems

In this article, applications of engineered nanoparticles containing siRNA for inhalation delivery are reviewed and discussed. Diseases with identified protein malfunctions may be mitigated through the use of well-designed siRNA therapeutics. The inhalation route of administration provides local delivery of siRNA therapeutics to the lungs for various pulmonary diseases. A siRNA delivery system can be used to overcome the barriers of pulmonary delivery, such as anatomical barriers, mucociliary clearance, cough clearance, and alveolar macrophage clearance. Apart from naked siRNA aerosol delivery, previously studied siRNA carrier systems include those of lipidic, polymeric, peptide, or inorganic origin. These delivery systems can achieve pulmonary delivery through the generation of an aerosol via an inhaler or nebulizer. The preparation methodologies for these siRNA nanocarrier systems will be discussed herein. The use of inhalable nanocarrier siRNA delivery systems have barriers to their effective delivery, but overcoming these constraints while formulating a safe and effective delivery system will offer unique advances to the field of inhaled medicine.

Low Molecular Weight PEI-Based Vectors via Acid-Labile Ortho Ester Linkage for Improved Gene Delivery

A series of novel pH-sensitive gene delivery vectors (POEI 1, 2, and 3) are synthesized through Michael addition from low molecular weight PEI (LMW PEI) via acid-labile ortho ester linkage with terminal acrylates (OEAc) by various feed molar ratios. The obtained POEI 1 and POEI 2 can efficiently condense plasmid DNA into nanoparticles with size range of 200-300 nm and zeta-potentials of about +15 mV while protecting DNA from enzymatic digestion compared with POEI 3. Significantly, ortho ester groups of POEI main-chains can make an instantaneous degradation-response to acidic endosomal pH (≈5.0), resulting in accelerated disruption of polyplexes and intracellular DNA release. MTT assay reveals that all POEIs exhibit much lower cytotoxicity in different cells than branched PEI (25 KDa). As expected, POEI 1 and POEI 2 perform improved gene transfection in vitro, suggesting that such polycations might be promising gene vectors based on overcoming toxicity-efficiency contradiction.

Lipopolyplex for Therapeutic Gene Delivery and Its Application for the Treatment of Parkinson's Disease

Lipopolyplex is a core-shell structure composed of nucleic acid, polycation and lipid. As a non-viral gene delivery vector, lipopolyplex combining the advantages of polyplex and lipoplex has shown superior colloidal stability, reduced cytotoxicity, extremely high gene transfection efficiency. Following intravenous administration, there are many strategies based on lipopolyplex to overcome the complex biological barriers in systemic gene delivery including condensation of nucleic acids into nanoparticles, long circulation, cell targeting, endosomal escape, release to cytoplasm and entry into cell nucleus. Parkinson's disease (PD) is the second most common neurodegenerative disorder and severely influences the patients' life quality. Current gene therapy clinical trials for PD employing viral vectors didn't achieve satisfactory efficacy. However, lipopolyplex may become a promising alternative approach owing to its stability in blood, ability to cross the blood-brain barrier (BBB) and specific targeting to diseased brain cells.

Effect of charge ratio on lipoplex-mediated gene delivery and liver toxicity

BACKGROUND

The vast majority of studies investigating gene delivery have utilized cationic delivery vehicles, but anionic nanoparticles can also possess high transfection activity, and offer significant benefits in terms of ease of preparation and reduced toxicity.

RESULTS

Our study on lipoplexes possessing cholesterol nanodomains demonstrates that in vitro transfection after exposure to serum can be high at anionic charge ratios, and that this effect is also evident in studies assessing delivery to tumors in vivo, despite reduced circulation times. In addition, accumulation in the liver and lungs is reduced as compared with lipoplexes formulated at cationic charge ratios.

CONCLUSION

Lipoplexes prepared at anionic charge ratios offer comparable tumor delivery and reduced liver toxicity despite shorter circulation times.

Composite nanoparticles for gene delivery

Nanoparticle-mediated gene and siRNA delivery has been an appealing area to gene therapists when they attempt to treat the diseases by manipulating the genetic information in the target cells. However, the advances in materials science could not keep up with the demand for multifunctional nanomaterials to achieve desired delivery efficiency. Researchers have thus taken an alternative approach to incorporate various materials into single composite nanoparticle using different fabrication methods. This approach allows nanoparticles to possess defined nanostructures as well as multiple functionalities to overcome the critical extracellular and intracellular barriers to successful gene delivery. This chapter will highlight the advances of fabrication methods that have the most potential to translate nanoparticles from bench to bedside. Furthermore, a major class of composite nanoparticle-lipid-based composite nanoparticles will be classified based on the components and reviewed in details.

Identification of possible cytotoxicity mechanism of polyethylenimine by proteomics analysis

Polyethylenimine (PEI) is a polycation widely used for successful gene delivery both in vitro and in vivo experiments. However, different studies showed that PEI could be cytotoxic to transfected cells, and the mechanism of toxicity is poorly understood. Identification of PEI-interacting proteins may help in understanding the toxicity pathways. In this study, we investigated proteins that could interact with PEI in human colorectal adenocarcinoma cells (HT29). In order to identify the proteins interacting with PEI, PEI was immobilized to sepharose beads as solid matrix. The HT29 cell lysate were passed through the matrix. PEI-bound proteins were isolated, and further separation was performed by two-dimensional gel electrophoresis. After gel digestion, proteins were identified by matrix-assisted laser desorption/ionization-time-of-flight (TOF)/TOF mass spectrometry. Our data indicated that most of the identified PEI-interacting proteins such as shock proteins, glutathione-S-transferases, and protein disulfide isomerase are involved in apoptosis process in cells. Thus, although this is a preliminary experiment implicating the involvement of some proteins in PEI cytotoxicity, it could partly explain the mechanism of PEI cytotoxicity in cells.

Delivery of oligonucleotides with lipid nanoparticles

Since their inception in the 1980s, oligonucleotide-based (ON-based) therapeutics have been recognized as powerful tools that can treat a broad spectrum of diseases. The discoveries of novel regulatory methods of gene expression with diverse mechanisms of action are still driving the development of novel ON-based therapeutics. Difficulties in the delivery of this class of therapeutics hinder their in vivo applications, which forces drug delivery systems to be a prerequisite for clinical translation. This review discusses the strategy of using lipid nanoparticles as carriers to deliver therapeutic ONs to target cells in vitro and in vivo. A discourse on how chemical and physical properties of the lipid materials could be utilized during formulation and the resulting effects on delivery efficiency constitutes the major part of this review.

Clinical applications involving CNS gene transfer

Diseases of the central nervous system (CNS) have traditionally been the most difficult to treat by traditional pharmacological methods, due mostly to the blood-brain barrier and the difficulties associated with repeated drug administration targeting the CNS. Viral vector gene transfer represents a way to permanently provide a therapeutic protein within the nervous system after a single administration, whether this be a gene replacement strategy for an inherited disorder or a disease-modifying protein for a disease such as Parkinson's. Gene therapy approaches for CNS disorders has evolved considerably over the last two decades. Although a breakthrough treatment has remained elusive, current strategies are now considerably safer and potentially much more effective. This chapter will explore the past, current, and future status of CNS gene therapy, focusing on clinical trials utilizing adeno-associated virus and lentiviral vectors.

Protamine-oligonucleotide-nanoparticles: Recent advances in drug delivery and drug targeting

Application of oligonucleotides as active compounds has become a crucial field of pharmaceutical research in recent years. In order to improve inadequate transfection rate and to avoid rapid enzymatic degradation of antisense oligonucleotides (AS-ODNs) a novel nanoparticulate delivery system was reported by our group at the beginning of 2000. AS-ODNs are condensed by the polycationic peptide protamine into solid particles in the size range of 100-200nm. Nanoparticle formation is driven by a self-assembling process based on electrostatic interactions between the oppositely charged biomolecules. This new delivery system was named "proticles" and showed very efficient protection against enzymatic digestion, high transfection rates and significant antisense effects in vitro. Throughout broader research, this promising approach was enlarged, and AS-ODNs were replaced by siRNA or CpG-oligonucleotides to address the aspect of immune-modulation and vaccination. More recent studies on proticles verified upscaling of the self-assembling process as well as the potential of proticle formulations for active drug targeting, like tumor- or atherosclerotic plaque targeting. Thereby also the application for diagnostic purposes was emphasized. This review will focus on the characterization of the nucleoprotein protamine as well as on the variety of possible nucleotides/peptides which were already assembled into the proticle matrix. Furthermore it will provide an insight into the broad area of application where proticles can present a valuable tool for successful oligonucleotide delivery.

Lipid-based mRNA vaccine delivery systems

Synthetic mRNAs can become biopharmaceutics allowing vaccination against cancer, bacterial and virus infections. Clinical trials with direct administration of synthetic mRNAs encoding tumor antigens demonstrated safety and induction of tumor-specific immune responses. Although immune responses are generated by naked mRNAs, their formulations with chemical carriers are expected to provide more specificity and internalization in dendritic cells (DCs) for better immune responses and dose reduction. This review reports lipid-based formulations (LBFs) that have proved preclinical efficacy. The selective delivery of mRNA LBFs to favor intracellular accumulation in DCs and reduction of the effective doses is discussed, notably to decorate LBFs with carbohydrates or glycomimetics allowing endocytosis in DCs. We also report how smart intracellular delivery is achieved using pH-sensitive lipids or polymers for an efficient mRNA escape from endosomes and limitations regarding cytosolic mRNA location for translation.

Relating toxicity to transfection: using sphingosine to maintain prolonged expression in vitro

Cationic reagents are commonly used to facilitate DNA delivery, and transfection experiments are typically initiated in cell culture where the optimal charge ratio is determined. While transfection rates are often enhanced at higher +/- charge ratios, the cellular toxicity associated with the greater amounts of cationic components at elevated charge ratios is often not considered. In addition, the prolonged effects of cationic lipid uptake on cell viability are not evident in a typical 24-48 h transfection experiment. In this study, we compare the transfection efficiency of cationic lipoplexes to effects on viability of cultured cells in both the short and long term (7 days). Our results indicate that, while minimal toxicity is evident 24 h after exposure to DOTAP-based lipoplexes, cell viability continues to decline and ultimately compromises reporter gene expression at longer times. Substitution of a naturally occurring cationic amphiphile, sphingosine, for DOTAP greatly reduces toxicity and allows high expression to be maintained over prolonged periods.