Aerosol delivery of stabilized polyester-siRNA nanoparticles to silence gene expression in orthotopic lung tumors

A new era of targeting cystic fibrosis with non-viral delivery of genomic medicines

Cystic fibrosis (CF) is a complex genetic respiratory disorder that necessitates innovative gene delivery strategies to address the mutations in the gene. This review delves into the promises and challenges of non-viral gene delivery for CF therapy and explores strategies to overcome these hurdles. Several emerging technologies and nucleic acid cargos for CF gene therapy are discussed. Novel formulation approaches including lipid and polymeric nanoparticles promise enhanced delivery through the CF mucus barrier, augmenting the potential of non-viral strategies. Additionally, safety considerations and regulatory perspectives play a crucial role in navigating the path toward clinical translation of gene therapy.

Application of stem cells in the study of developmental and functional toxicity of endodermal-derived organs caused by nanoparticles

Nanoparticles have unique properties that make them useful in biomedicine. However, their extensive use raises concerns about potential hazards to the body. Therefore, it is crucial to establish effective and robust toxicology models to evaluate the developmental and functional toxicity of nanoparticles on the body. This article discusses the use of stem cells to study the developmental and functional toxicity of organs of endodermal origin due to nanoparticles. The study discovered that various types of nanoparticles have varying effects on stem cells. The application of stem cell models can provide a possibility for studying the effects of nanoparticles on organ development and function, as they can more accurately reflect the toxic mechanisms of different types of nanoparticles. However, stem cell toxicology systems currently cannot fully reflect the effects of nanoparticles on entire organs. Therefore, the establishment of organoid models and other advanced assessment models is expected to address this issue.

Polymeric Nanoparticles for Drug Delivery

The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of more sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Furthermore, polymeric nanoparticles have the ability to navigate various biological barriers to precisely target specific sites within the body, encapsulate a diverse range of therapeutic cargo and efficiently release this cargo in response to internal and external stimuli. However, despite these remarkable advantages, the presence of polymeric nanoparticles in wider clinical application is minimal. This review will provide a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles. The biological barriers affecting drug delivery will be outlined first, followed by a comprehensive description of the various nanoparticle designs and preparation methods, beginning with the polymers on which they are based. The review will meticulously explore the current performance of polymeric nanoparticles against a myriad of diseases including cancer, viral and bacterial infections, before finally evaluating the advantages and crucial challenges that will determine their wider clinical potential in the decades to come.

Novel aromatic moieties-modified poly(glycidyl amine)s with potent siRNA delivery and cancer treatment effect

The development of safe and effective delivery systems is critical for the clinical applications of siRNA-based therapeutics. Polymer-based vectors have garnered significant attention owing to their structural flexibility and functional tunability. Polyethyleneimine (PEI) has been extensively studied for nucleic acid delivery; nevertheless, its high cytotoxicity has posed challenges for clinical applications. In this study, we have reported poly(glycidyl amine) (PGAm), a linear PEI analogue, demonstrating remarkable siRNA delivery efficacy and improved biocompatibility. By introducing three aromatic moieties (tyrosine, p-hydroxybenzenepropanoic acid, and phenylalanine) at varying ratios to further modify PGAms, we successfully constructed a library comprising 36 PGAm-based carriers. In vitro evaluations revealed that PGAm-based carriers exhibited significantly enhanced biocompatibility and reduced non-specific protein absorption in comparison to PEI25k. Among them, 10 modified PGAms achieved a knockdown of target gene expressions exceeding 80%, and 26 modified PGAms maintained over 70% cell viability when utilized for the in vitro delivery of siRNA to HeLa cells. Explorations into the structure-activity relationship of PGAm-based polyplex nanoparticles (NPs) indicated that the siRNA delivery efficacy of NPs depended on factors such as the molecular weight of PGAm precursors, the type of modifying moieties, and the modification ratio. Furthermore, it was demonstrated that two top-performing NPs, namely 2T100/siLuc and 2A50/siLuc, exhibited potent silencing of target genes in tumors following i.v. injection into mice bearing HeLa-Luc xenografts. The in vivo efficacy of the selected NPs was further validated by a remarkable anti-cancer effect when employed for the delivery of siRNA targeting polo-like kinase 1 (siPLK1) to mice with PC-3 xenograft tumors. The intravenous administration of NPs resulted in a substantial inhibition of tumor growth without significant toxicity. These findings demonstrate the feasibility of employing PGAm in siRNA delivery and provide valuable insights for the development of efficient siRNA carriers based on PGAm.

Tiny Guides, Big Impact: Focus on the Opportunities and Challenges of miR-Based Treatments for ARDS

Acute Respiratory Distress Syndrome (ARDS) is characterized by lung inflammation and increased membrane permeability, which represents the leading cause of mortality in ICUs. Mechanical ventilation strategies are at the forefront of supportive approaches for ARDS. Recently, an increasing understanding of RNA biology, function, and regulation, as well as the success of RNA vaccines, has spurred enthusiasm for the emergence of novel RNA-based therapeutics. The most common types of RNA seen in development are silencing (si)RNAs, antisense oligonucleotide therapy (ASO), and messenger (m)RNAs that collectively account for 80% of the RNA therapeutics pipeline. These three RNA platforms are the most mature, with approved products and demonstrated commercial success. Most recently, miRNAs have emerged as pivotal regulators of gene expression. Their dysregulation in various clinical conditions offers insights into ARDS pathogenesis and offers the innovative possibility of using microRNAs as targeted therapy. This review synthesizes the current state of the literature to contextualize the therapeutic potential of miRNA modulation. It considers the potential for miR-based therapeutics as a nuanced approach that incorporates the complexity of ARDS pathophysiology and the multifaceted nature of miRNA interactions.

Inhalable Gene Therapy and the Lung Surfactant Problem

Lung-targeting RNA-carrying lipid nanoparticles (LNPs) are often intravenously administered and accumulate in the pulmonary endothelium. However, most respiratory diseases are localized in the airway or the alveolar epithelium. Inhalation has been explored as a more direct delivery method, but it presents its own challenges. We believe that one reason LNPs have failed to transfect RNA into alveolar epithelial cells is their interaction with the lung surfactant (LS). We propose that inhalable LNP design should take inspiration from biological agents and other nanoparticles to overcome this barrier. Screening should first focus on LS penetration and then be optimized for cell uptake and endosomal release. This will enable more efficient applications of RNA-LNPs in lung diseases.

Optimal delivery strategies for nanoparticle-mediated mRNA delivery

Messenger RNA (mRNA) has emerged as a new and efficient agent for the treatment of various diseases. The success of lipid nanoparticle-mRNA against the novel coronavirus (SARS-CoV-2) pneumonia epidemic has proved the clinical potential of nanoparticle-mRNA formulations. However, the deficiency in the effective biological distribution, high transfection efficiency and good biosafety are still the major challenges in clinical translation of nanomedicine for mRNA delivery. To date, a variety of promising nanoparticles have been constructed and then gradually optimized to facilitate the effective biodistribution of carriers and efficient mRNA delivery. In this review, we describe the design of nanoparticles with an emphasis on lipid nanoparticles, and discuss the manipulation strategies for nanoparticle-biology (nano-bio) interactions for mRNA delivery to overcome the biological barriers and improve the delivery efficiency, because the specific nano-bio interaction of nanoparticles usually remoulds the biomedical and physiological properties of the nanoparticles especially the biodistribution, mechanism of cellular internalization and immune response. Finally, we give a perspective for the future applications of this promising technology. We believe that the regulation of nano-bio interactions would be a significant breakthrough to improve the mRNA delivery efficiency and cross biological barriers. This review may provide a new direction for the design of nanoparticle-mediated mRNA delivery systems.

The Promising Therapeutic Potential of Oligonucleotides for Pulmonary Fibrotic Diseases

INTRODUCTION

Fibrotic lung diseases represent a large subset of diseases with an unmet clinical need. Oligonucleotide therapies (ONT) are a promising therapeutic approach for the treatment of pulmonary disease as they can inhibit pathways that are otherwise difficult to target. Additionally, targeting the lung specifically with ONT is advantageous because it reduces the possibilities of systemic side effects and tolerability concerns.

AREAS COVERED

This review presents the chemical basis of designing various ONTs currently known to treat fibrotic lung diseases. Further, the authors have also discussed the delivery vehicle, routes of administration, physiological barriers of the lung, and toxicity concerns with ONTs.

EXPERT OPINION

ONTs provide a promising therapeutic approach for the treatment of fibrotic diseases of the lung, particularly because ONTs directly delivered to the lung show little systemic side effects compared to current therapeutic strategies. Dry powder aerosolized inhalers may be a good strategy for getting ONTs into the lung in humans. However, as of now, no dry powder ONTs have been approved for use in the clinical setting, and this challenge must be overcome for future therapies. Various delivery methods that can aid in direct targeting may also improve the use of ONTs for lung fibrotic diseases.

Rolling Circle Amplification-Based DNA Nano-Assembly for Targeted Drug Delivery and Gene Therapy

Combining the killing ability of chemotherapy drugs on tumor cells with the inhibiting ability of genetic drugs on tumor cell growth, a dual drug delivery system loaded with therapy drugs and siRNA has gradually received more and more research and extensive attention. In this paper, we designed a DNA nano-assembly based on rolling circle amplification that can co-deliver doxorubicin (Dox) and siRNA simultaneously. In order to fully exploit the potential of the dual loading system in cancer treatment, we selected STAT3 gene as a target and used siRNA to target STAT3 of mRNA and reduce the STAT3 expression in mouse melanoma cell line (B16); meanwhile, Dox as a chemotherapy drug was combined with multivalent aptamers specifically targeting B16 to achieve efficient delivery of siRNA and Dox. The results showed that the synergistic delivery system could achieve high efficiency in targeting and inhibiting proliferation in mouse melanoma cells. In addition, the synergistic effect of the dual delivery system on apoptosis of cancer cells was significantly better than that of single drug delivery systems.

Construction of Degradable and Amphiphilic Triblock Polymer Carriers for Effective Delivery of siRNA

The development of effective and safe delivery carriers is one of the prerequisites for the clinical translation of siRNA-based therapeutics. In this study, a library of 144 functional triblock polymers using ring-opening polymerization (ROP) and thiol-ene click reaction is constructed. These triblock polymers are composed of hydrophilic poly (ethylene oxide) (PEO), hydrophobic poly (ε-caprolactone) (PCL), and cationic amine blocks. Three effective carriers are discovered by high-throughput screening of these polymers for siRNA delivery to HeLa-Luc cells. In vitro evaluation shows that siLuc-loaded nanoparticles (NPs) fabricated with leading polymer carriers exhibit sufficient knockdown of luciferase genes and relatively low cytotoxicity. The chemical structure of polymers significantly affects the physicochemical properties of the resulting siRNA-loaded NPs, which leads to different cellular uptake of NPs and endosomal escape of loaded siRNA and thus the overall in vitro siRNA delivery efficacy. After systemic administration to mice with xenograft tumors, siRNA NPs based on P2-4.5A8 are substantially accumulated at tumor sites, suggesting that PEO and PCL blocks are beneficial for improving blood circulation and biodistribution of siRNA NPs. This functional triblock polymer platform may have great potential in the development of siRNA-based therapies for the treatment of cancers.

Chemical Factory-Guaranteed Enhanced Chemodynamic Therapy for Orthotopic Liver Cancer

In the field of nanomedicine, there is a tendency of matching designed nanomaterials with a suitable type of orthotopic cancer model, not just a casual subcutaneous one. Under this condition, knowing the specific features of the chosen cancer model is the priority, then introducing a proper therapy strategy using designed nanomaterials. Here, the Fenton chemistry is combined with zinc peroxide nanoparticles in the treatment of orthotopic liver cancer which has a "chemical factory" including that liver is the main place for iron storage, metabolism, and also the main metabolic sites for the majority of ingested substances, guaranteeing customized and enhanced chemodynamic therapy and normal liver cells protection as well. The good results in vitro and in vivo can set an inspiring example for exploring and utilizing suitable nanomaterials in corresponding cancer models, ensuring well-fitness of nanomaterials for disease and satisfactory therapeutic effect.

Nanoparticle Delivery Platforms for RNAi Therapeutics Targeting COVID-19 Disease in the Respiratory Tract

Since December 2019, a pandemic of COVID-19 disease, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread across the globe. At present, the Food and Drug Administration (FDA) has issued emergency approval for the use of some antiviral drugs. However, these drugs still have limitations in the specific treatment of COVID-19, and as such, new treatment strategies urgently need to be developed. RNA-interference-based gene therapy provides a tractable target for antiviral treatment. Ensuring cell-specific targeted delivery is important to the success of gene therapy. The use of nanoparticles (NPs) as carriers for the delivery of small interfering RNA (siRNAs) to specific tissues or organs of the human body could play a crucial role in the specific therapy of severe respiratory infections, such as COVID-19. In this review, we describe a variety of novel nanocarriers, such as lipid NPs, star polymer NPs, and glycogen NPs, and summarize the pre-clinical/clinical progress of these nanoparticle platforms in siRNA delivery. We also discuss the application of various NP-capsulated siRNA as therapeutics for SARS-CoV-2 infection, the challenges with targeting these therapeutics to local delivery in the lung, and various inhalation devices used for therapeutic administration. We also discuss currently available animal models that are used for preclinical assessment of RNA-interference-based gene therapy. Advances in this field have the potential for antiviral treatments of COVID-19 disease and could be adapted to treat a range of respiratory diseases.

Biomacromolecule-mediated pulmonary delivery of siRNA and anti-sense oligos: challenges and possible solutions

Biomacromolecules have gained much attention as biomedicine carriers in recent years due to their remarkable biophysical and biochemical properties including sustainability, non-toxicity, biocompatibility, biodegradability, long systemic circulation time and ability to target. Recent developments in a variety of biological functions of biomacromolecules and progress in the study of biological drug carriers suggest that these carriers may have advantages over carriers of synthetic materials in terms of half-life, durability, protection and manufacturing facility. Despite the full pledge advancements in the applications of biomacromolecules, its clinical use is hindered by certain factors that allow the pre-mature release of loaded cargos before reaching the target site. The delivery therapeutics are degraded by systemic nucleases, cleared by reticulo-endothelial system, cleared by pulmonary mucus cilia or engulfed by lysosome during cellular uptake that has led to the failure of clinical therapy. It clearly indicates that there is a wide range of gaps in the results of experimental work and clinical applications of biomacromolecules. This review focuses mainly on the barriers (intracellular/extracellular) and hurdles to the delivery of biomacromolecules with special emphasis on siRNA as well as the delivery of antisense oligos in multiple pulmonary diseases, particularly focusing on lung cancer. Also, the challenges posed to such delivery and possible solutions have been highlighted.

Hydrophobic Optimization of Functional Poly(TPAE-co-suberoyl chloride) for Extrahepatic mRNA Delivery following Intravenous Administration

Messenger RNA (mRNA) has generated great attention due to its broad potential therapeutic applications, including vaccines, protein replacement therapy, and immunotherapy. Compared to other nucleic acids (e.g., siRNA and pDNA), there are more opportunities to improve the delivery efficacy of mRNA through systematic optimization. In this report, we studied a high-throughput library of 1200 functional polyesters for systemic mRNA delivery. We focused on the chemical investigation of hydrophobic optimization as a method to adjust mRNA polyplex stability, diameter, pKa, and efficacy. Focusing on a region of the library heatmap (PE4K-A17), we further explored the delivery of luciferase mRNA to IGROV1 ovarian cancer cells in vitro and to C57BL/6 mice in vivo following intravenous administration. PE4K-A17-0.2C8 was identified as an efficacious carrier for delivering mRNA to mouse lungs. The delivery selectivity between organs (lungs versus spleen) was found to be tunable through chemical modification of polyesters (both alkyl chain length and molar ratio in the formulation). Cre recombinase mRNA was delivered to the Lox-stop-lox tdTomato mouse model to study potential application in gene editing. Overall, we identified a series of polymer-mRNA polyplexes stabilized with Pluronic F-127 for safe and effective delivery to mouse lungs and spleens. Structure–activity relationships between alkyl side chains and in vivo delivery were elucidated, which may be informative for the continued development of polymer-based mRNA delivery.

Lipids and Lipid Derivatives for RNA Delivery

RNA-based therapeutics have shown great promise in treating a broad spectrum of diseases through various mechanisms including knockdown of pathological genes, expression of therapeutic proteins, and programmed gene editing. Due to the inherent instability and negative-charges of RNA molecules, RNA-based therapeutics can make the most use of delivery systems to overcome biological barriers and to release the RNA payload into the cytosol. Among different types of delivery systems, lipid-based RNA delivery systems, particularly lipid nanoparticles (LNPs), have been extensively studied due to their unique properties, such as simple chemical synthesis of lipid components, scalable manufacturing processes of LNPs, and wide packaging capability. LNPs represent the most widely used delivery systems for RNA-based therapeutics, as evidenced by the clinical approvals of three LNP-RNA formulations, patisiran, BNT162b2, and mRNA-1273. This review covers recent advances of lipids, lipid derivatives, and lipid-derived macromolecules used in RNA delivery over the past several decades. We focus mainly on their chemical structures, synthetic routes, characterization, formulation methods, and structure-activity relationships. We also briefly describe the current status of representative preclinical studies and clinical trials and highlight future opportunities and challenges.

The next generation therapy for lung cancer: taking medicine by inhalation

The inhalation administration method which has been applied to treat respiratory diseases has the characteristics of painlessness high efficiency and non-invasiveness, and the drug can also be targeted at the organ level first to reduce the loss of drug during circulation. Therefore, delivering medicine by inhalation administration has brought a new turnaround for lung cancer treatment. Herein from the perspective of combining traditional drug delivery design strategies with new drug delivery methods how to improve lung targeting efficiency and treatment efficacy is discussed. We also discuss the comparative advantages of inhaled drug delivery and traditional administration in the treatment of lung cancer such as intravenous injection. And the researches are divided into different forms of inhalation administration studied in the treatment of lung cancer in recent years, such as single-component loaded and multi-component loaded systems and their advantages. Finally, the obstacles of the application of carrier materials for inhalation administration and the prospects for improvement of lung cancer treatment methods are presented.

Optimization of PEGylated KL4 Peptide for siRNA Delivery with Improved Pulmonary Tolerance

Pulmonary delivery of small interfering RNA (siRNA) is a promising therapeutic strategy for treating various respiratory diseases but an effective carrier for the delivery of siRNA into the cells of the lungs and a robust gene-silencing effect is still lacking. Previously, we reported that the KL4 peptide, a synthetic cationic peptide with a repeating KLLLL sequence, can mediate effective siRNA transfection in lung epithelial cells but its high hydrophobic leucine content, and hence poor water solubility, limits its application as a delivery vector. Here, we show that the covalent attachment of monodisperse poly(ethylene glycol) (PEG) improves the solubility of KL4 and the uptake of its complex with siRNA into lung epithelial cells, such that very robust silencing is produced. All PEGylated KL4 peptides, with PEG length varying between 6 and 24 monomers, could bind and form nanosized complexes with siRNA, but the interaction between siRNA and peptides became weaker as the PEG chain length increased. All PEGylated KL4 peptides exhibited satisfactory siRNA transfection efficiency on three human lung epithelial cell lines, including A549 cells, Calu-3 cells, and BEAS-2B cells. The PEG₁₂KL4 peptide, which contains 12 monomers of PEG, was optimal for siRNA delivery and also demonstrated a low risk of inflammatory response and toxicity in vivo following pulmonary administration.

Polymeric nanoparticles for RNA delivery

As exemplified by recent clinical approval of RNA drugs including the latest COVID-19 mRNA vaccines, RNA therapy has demonstrated great promise as an emerging medicine. Central to the success of RNA therapy is the delivery of RNA molecules into the right cells at the right location. While the clinical success of nanotechnology in RNA therapy has been limited to lipid-based nanoparticles currently, polymers, due to their tunability and robustness, have also evolved as a class of promising material for the delivery of various therapeutics including RNAs. This article overviews different types of polymers used in RNA delivery and the methods for the formulation of polymeric nanoparticles and highlights recent progress of polymeric nanoparticle-based RNA therapy.

pH-sensitive zwitterionic polycarboxybetaine as a potential non-viral vector for small interfering RNA delivery

Small interfering RNA (siRNA) has great potential for the treatment of various diseases. However, its intrinsic deficiencies seriously limit its application. Herein, pH-sensitive zwitterionic polymer polycarboxybetaine (PCB) was developed as a non-viral vector for siRNA. The PCB could be protonated in an acidic environment and become positively charged from a cancer site. After protonation, PCB could complex siRNA via electrostatic interaction, and its loading ability was enhanced with a decrease of pH value. Compared with the PEI 10k, PCB₅₀ with a similar molecular weight had comparable siRNA loading ability and lower cytotoxicity. Besides, siRNA loaded by PCB₅₀ could escape from endosomes and reduce the loss of drugs, and based on the excellent uptake and obvious apoptotic effect on HeLa cells, the pH-sensitive PCB with low cytotoxicity could be used as a non-viral vector for safe siRNA delivery for cancer treatment.

pH-sensitive zwitterionic polycarboxybetaine could complex siRNA in an acidic environment and could be used as a non-viral vector for safe siRNA delivery.

Nanoapproaches to Modifying Epigenetics of Epithelial Mesenchymal Transition for Treatment of Pulmonary Fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a chronically progressive interstitial lung that affects over 3 M people worldwide and rising in incidence. With a median survival of 2-3 years, IPF is consequently associated with high morbidity, mortality, and healthcare burden. Although two antifibrotic therapies, pirfenidone and nintedanib, are approved for human use, these agents reduce the rate of decline of pulmonary function but are not curative and do not reverse established fibrosis. In this review, we discuss the prevailing epithelial injury hypothesis, wherein pathogenic airway epithelial cell-state changes known as Epithelial Mesenchymal Transition (EMT) promotes the expansion of myofibroblast populations. Myofibroblasts are principal components of extracellular matrix production that result in airspace loss and mortality. We review the epigenetic transition driving EMT, a process produced by changes in histone acetylation regulating mesenchymal gene expression programs. This mechanistic work has focused on the central role of bromodomain-containing protein 4 in mediating EMT and myofibroblast transition and initial preclinical work has provided evidence of efficacy. As nanomedicine presents a promising approach to enhancing the efficacy of such anti-IPF agents, we then focus on the state of nanomedicine formulations for inhalable delivery in the treatment of pulmonary diseases, including liposomes, polymeric nanoparticles (NPs), inorganic NPs, and exosomes. These nanoscale agents potentially provide unique properties to existing pulmonary therapeutics, including controlled release, reduced systemic toxicity, and combination delivery. NP-based approaches for pulmonary delivery thus offer substantial promise to modify epigenetic regulators of EMT and advance treatments for IPF.

Inhaled RNA Therapy: From Promise to Reality

RNA-based medicine is receiving growing attention for its diverse roles and potential therapeutic capacity. The largest obstacle in its clinical translation remains identifying a safe and effective delivery system. Studies investigating RNA therapeutics in pulmonary diseases have rapidly expanded and drug administration by inhalation allows the direct delivery of RNA therapeutics to the target site of action while minimizing systemic exposure. In this review, we highlight recent developments in pulmonary RNA delivery systems with the use of nonviral vectors. We also discuss the major knowledge gaps that require thorough investigation and provide insights that will help advance this exciting field towards the bedside.

An Activatable Nano-Prodrug for Treating Tyrosine-Kinase-Inhibitor-Resistant Non-Small Cell Lung Cancer and for Optoacoustic and Fluorescent Imaging

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and the cause of high rate of mortality. The epidermal growth factor receptor (EGFR)-targeted tyrosine kinase inhibitors are used to treat NSCLC, yet their curative effects are usually compromised by drug resistance. This study demonstrates a nanodrug for treating tyrosine-kinase-inhibitor-resistant NSCLC through inhibiting upstream and downstream EGFR signaling pathways. The main molecule of the nanodrug is synthesized by linking a tyrosine kinase inhibitor gefitinib and a near-infrared dye (NIR) on each side of a disulfide via carbonate bonds, and the nanodrug is then obtained through nanoparticle formation of the main molecule in aqueous medium and concomitant encapsulation of a serine threonine protein kinase (Akt) inhibitor celastrol. Upon administration, the nanodrug accumulates at the tumor region of NSCLC-bearing mice and releases the drugs for tumor inhibition, and the dye for fluorescence and optoacoustic imaging. Through suppressing the phosphorylation of upstream EGFR and downstream Akt in the EGFR pathway by gefitinib and celastrol, respectively, the nanodrug exhibits high inhibition efficacy against orthotopic NSCLC in mouse models.

Inhaled Micro/Nanoparticulate Anticancer Drug Formulations: An Emerging Targeted Drug Delivery Strategy for Lung Cancers

Local delivery of drug to the target organ via inhalation offers enormous benefits in the management of many diseases. Lung cancer is the most common of all cancers and it is the leading cause of death worldwide. Currently available treatment systems (intravenous or oral drug delivery) are not efficient in accumulating the delivered drug into the target tumor cells and are usually associated with various systemic and dose-related adverse effects. The pulmonary drug delivery technology would enable preferential accumulation of drug within the cancer cell and thus be superior to intravenous and oral delivery in reducing cancer cell proliferation and minimising the systemic adverse effects. Site-specific drug delivery via inhalation for the treatment of lung cancer is both feasible and efficient. The inhaled drug delivery system is non-invasive, produces high bioavailability at a low dose and avoids first pass metabolism of the delivered drug. Various anticancer drugs including chemotherapeutics, proteins and genes have been investigated for inhalation in lung cancers with significant outcomes. Pulmonary delivery of drugs from dry powder inhaler (DPI) formulation is stable and has high patient compliance. Herein, we report the potential of pulmonary drug delivery from dry powder inhaler (DPI) formulations inhibiting lung cancer cell proliferation at very low dose with reduced unwanted adverse effects.

PEI fluorination reduces toxicity and promotes liver-targeted siRNA delivery

Polyethyleneimine (PEI) has been extensively investigated as an efficient carrier for nucleic acid delivery. Yet, it suffers from a high toxicity profile that hinders clinical translation. Fluorination has proven to be a valid approach to reduce the cytotoxicity of PEI and improve the in vitro siRNA delivery potency. Hydrophobicity and lipophobicity can be controllably introduced into the side chains of PEI. However, the effect of fluorination on siRNA delivery in vivo, particularly the biodistribution of siRNA polyplex nanoparticles with fluorinated PEIs, has not been extensively explored. Here, we introduce two series of fluorinated PEIs via amidation with ethyl trifluoroacetate and perfluorobutyryl chloride. Fluorination substantially improved the performance of PEI for siRNA delivery by reducing the cytotoxicity to MDA-MB-231 cells. Importantly, fluorinated PEI enabled the major accumulation of siRNA polyplex nanoparticles in the liver while non-fluorinated PEI delivered siRNA nanoparticles mainly to the lungs after intravenous administration to mice. It is envisioned that fluorination may be an important general strategy for lowering toxicity of cationic polymers, and that the fluorination-induced alteration of biodistribution may be applicable for improved delivery to different organs. Graphical abstract.

Lipid-Modified Aminoglycosides for mRNA Delivery to the Liver

Cationic lipid nanoparticles (LNPs) are widely used as carriers for delivery of nucleic acids. Most synthetic routes toward cationic lipids have derived from simple amine cores. Greater chemical diversity can be obtained through starting with natural products containing basic nitrogen atoms, which offers routes to more complex molecules. Natural building blocks are not extensively explored, such as aminoglycosides, which are both structurally and functionally interesting for developing new carriers for nucleic acid delivery. Herein, cationic lipid-modified aminoglycosides (CLAs) are explored as a family of vehicles for messenger RNA (mRNA) delivery. CLAs are synthesized from natural existing aminoglycosides coupling with alkyl epoxides and acrylates. The top hit (GT-EP10) is able to deliver Luc mRNA to C57BL/6 mice at a dose of 0.05 mg kg-1 to achieve a 107 average luminescence intensity in the liver. The Lox-Stop-Lox tdTomato mouse model is used to further demonstrate that this efficient mRNA delivery system can be potentially used for gene editing. Successful delivery of human erythropoietin mRNA shows that CLA-based LNPs have promising opportunities for delivery of therapeutic nucleic acids in the future.

Emerging therapies for smoke inhalation injury: a review

Background

Smoke inhalation injury increases overall burn mortality by up to 20 times. Current therapy remains supportive with a failure to identify an optimal or targeted treatment protocol for smoke inhalation injury. The goal of this review is to describe emerging therapies that are being developed to treat the pulmonary pathology induced by smoke inhalation injury with or without concurrent burn injury.

Main body

A comprehensive literature search was performed using PubMed (1995–present) for therapies not approved by the U.S. Food and Drug Administration (FDA) for smoke inhalation injury with or without concurrent burn injury. Therapies were divided based on therapeutic strategy. Models included inhalation alone with or without concurrent burn injury. Specific animal model, mechanism of action of medication, route of administration, therapeutic benefit, safety, mortality benefit, and efficacy were reviewed. Multiple potential therapies for smoke inhalation injury with or without burn injury are currently under investigation. These include stem cell therapy, anticoagulation therapy, selectin inhibition, inflammatory pathway modulation, superoxide and peroxynitrite decomposition, selective nitric oxide synthase inhibition, hydrogen sulfide, HMG-CoA reductase inhibition, proton pump inhibition, and targeted nanotherapies. While each of these approaches shows a potential therapeutic benefit to treating inhalation injury in animal models, further research including mortality benefit is needed to ensure safety and efficacy in humans.

Conclusions

Multiple novel therapies currently under active investigation to treat smoke inhalation injury show promising results. Much research remains to be conducted before these emerging therapies can be translated to the clinical arena.

Engineering Tumor-Targeting Nanoparticles as Vehicles for Precision Nanomedicine

As a nascent and emerging field that holds great potential for precision oncology, nanotechnology has been envisioned to improve drug delivery and imaging capabilities through precise and efficient tumor targeting, safely sparing healthy normal tissue. In the clinic, nanoparticle formulations such as the first-generation Abraxane® in breast cancer, Doxil® for sarcoma, and Onivyde® for metastatic pancreatic cancer, have shown advancement in drug delivery while improving safety profiles. However, effective accumulation of nanoparticles at the tumor site is sub-optimal due to biological barriers that must be overcome. Nanoparticle delivery and retention can be altered through systematic design considerations in order to enhance passive accumulation or active targeting to the tumor site. In tumor niches where passive targeting is possible, modifications in the size and charge of nanoparticles play a role in their tissue accumulation. For niches in which active targeting is required, precision oncology research has identified targetable biomarkers, with which nanoparticle design can be altered through bioconjugation using antibodies, peptides, or small molecule agonists and antagonists. This review is structured to provide a better understanding of nanoparticle engineering design principles with emphasis on overcoming tumor-specific biological barriers.

Recent advances in polymeric materials for the delivery of RNA therapeutics

Introduction: The delivery of nucleic acid therapeutics through non-viral carriers face multiple biological barriers that reduce their therapeutic efficiency. Despite great progress, there remains a significant technological gap that continues to limit clinical translation of these nanocarriers. A number of polymeric materials are being exploited to efficiently deliver nucleic acids and achieve therapeutic effects. Areas covered: We discuss the recent advances in the polymeric materials for the delivery of nucleic acid therapeutics. We examine the use of common polymer architectures and highlight the challenges that exist for their development from bench side to clinic. We also provide an overview of the most notable improvements made to circumvent such challenges, including structural modification and stimuli-responsive approaches, for safe and effective nucleic acid delivery. Expert opinion: It has become apparent that a universal carrier that follows 'one-size' fits all model cannot be expected for delivery of all nucleic acid therapeutics. Carriers need to be designed to exhibit sensitivity and specificity toward individual targets diseases/indications, and relevant subcellular compartments, each of which possess their own unique challenges. The ability to devise synthetic methods that control the molecular architecture enables the future development that allow for the construction of 'intelligent' designs.

Toxicological assessment of nanoparticle interactions with the pulmonary system

Nanoparticle(NP)-based materials have breakthrough applications in many fields of life, such as in engineering, communications and textiles industries; food and bioenvironmental applications; medicines and cosmetics, etc. Biomedical applications of NPs are very active areas of research with successful translation to pharmaceutical and clinical uses overcoming both pharmaceutical and clinical challenges. Although the attractiveness and enhanced applications of these NPs stem from their exceptional properties at the nanoscale size, i.e. 1-1000 nm, they exhibit completely different physicochemical profiles and, subsequently, toxicological profiles from their parent bulk materials. Hence, the clinical evaluation and toxicological assessment of NPs interactions within biological systems are continuously evolving to ensure their safety at the nanoscale. The pulmonary system is one of the primary routes of exposure to airborne NPs either intentionally, via aerosolized nanomedicines targeting pulmonary pathologies such as cancer or asthma, or unintentionally, via natural NPs and anthropogenic (man-made) NPs. This review presents the state-of-the-art, contemporary challenges, and knowledge gaps in the toxicological assessment of NPs interactions with the pulmonary system. It highlights the main mechanisms of NP toxicity, factors influencing their toxicity, the different toxicological assessment methods and their drawbacks, and the recent NP regulatory guidelines based on literature collected from the research pool of NPs interactions with lung cell lines, in vivo inhalation studies, and clinical trials.

Recent advances in aerosol gene delivery systems using non-viral vectors for lung cancer therapy

INTRODUCTION

Lung cancer commonly occurs at a high incidence worldwide. Application of aerosol gene delivery systems using various kinds of vectors can improve the patient's quality of life by prolonging the survival rate.

AREAS COVERED

This review provides a recent update on aerosol gene delivery strategies using various kinds of vectors and gene-modification technologies. Peptide-mediated gene therapy achieves specific targeting of cells and highly improves efficacy. Promoter-operating expression and the CRISPR/Cas9 system are novel gene therapy strategies for effective lung cancer treatment. Furthermore, hybrid systems with a combination of vectors or drugs have been recently applied as new trends in gene therapy.

EXPERT OPINION

Although aerosol gene delivery has many advantages, physiological barriers in the lungs pose formidable challenges. Targeted gene delivery and gene-editing technology are promising strategies for lung cancer therapy. These strategies may allow the development of safety and high efficiency for clinical application. Recently, hybrid gene therapy combining novel and specific vectors has been developed as an advanced strategy. Although gene therapy for lung cancer is being actively researched, aerosol gene therapy strategies are currently lacking, and further studies on aerosol gene therapy are needed to treat lung cancer.

Formulation of RNA interference-based drugs for pulmonary delivery: challenges and opportunities

With recent advances in the field of RNAi-based therapeutics, it is possible to make any target gene 'druggable', at least in principle. The present review focuses on aspects critical for pulmonary delivery of formulations of nucleic acid-based drugs. The first part introduces the therapeutic potential of RNAi-based drugs for the treatment of lung diseases. Subsequently, we discuss opportunities for formulation-enabled pulmonary delivery of RNAi drugs in light of key physicochemical properties and physiological barriers. In the following section, an overview is included of methodologies for imparting inhalable characteristics to nucleic acid formulations. Finally, we review one of the bottlenecks in the early preclinical testing of inhalable nucleic acid-based formulations, in other words, devices suitable for pulmonary administration of powder-based formulations in rodents.

Establishment of an Evaluation Method for Gene Silencing by Serial Pulmonary Administration of siRNA and pDNA Powders: Naked siRNA Inhalation Powder Suppresses Luciferase Gene Expression in the Lung

In order to evaluate the in vivo effect of inhaled formulations, it is a gold standard to create a lung metastasis model by intravenously injecting cancer cells into an animal. Because the cancer grows from the blood vessel side, there is a possibility of underestimating the effect of an inhaled formulation administered to the lung epithelium side. In addition, the metastasis model has disadvantages in terms of preparation time and expense. The present study aimed to establish a new method to evaluate the effect of an inhaled small interfering RNA (siRNA) formulation that is more correct, more rapid, and less expensive. We investigated whether siRNA can suppress gene expression of plasmid DNA (pDNA) by serial pulmonary administration of siRNA and pDNA powders prepared by spray-freeze-drying. We revealed that formulations of dry siRNA powder significantly suppressed gene expression of pDNA powder compared with a control group with no siRNA. Naked siRNA inhalation powder with no vector showed the suppression of gene expression equivalent to that of an siRNA-polyethyleneimine complex without damaging tissues. These results show that the present method is suitable for evaluating the gene-silencing effect of inhaled siRNA powders.

Nanocarrier-based systems for targeted and site specific therapeutic delivery

Systemic drug delivery methods such as oral or parenteral administration of free drugs possess relatively low treatment efficiency and marked adverse side effects. The use of nanoparticles for drug delivery in most cases substantially enhances drug efficacy, improves pharmacokinetics and drug release and limits their side effects. However, further enhancement in drug efficacy and significant limitation of adverse side effects can be achieved by specific targeting of nanocarrier-based delivery systems especially in combination with local administration. The present review describes major advantages and limitations of organic and inorganic nanocarriers or living cell-based drug and nucleic acid delivery systems. Among these, different nanoparticles, supramolecular gels, therapeutic cells as living drug carriers etc. have emerged as a new frontier in modern medicine.

Nanotechnology in the diagnosis and treatment of lung cancer

Lung cancer is an umbrella term for a subset of heterogeneous diseases that are collectively responsible for the most cancer-related deaths worldwide. Despite the tremendous progress made in understanding lung tumour biology, advances in early diagnosis, multimodal therapy and deciphering molecular mechanisms of drug resistance, overall curative outcomes remain low, especially in metastatic disease. Nanotechnology, in particular nanoparticles (NPs), continue to progressively impact the way by which tumours are diagnosed and treated. The unique physicochemical properties of materials at the nanoscale grant access to a diverse molecular toolkit that can be manipulated for use in respiratory oncology. This realisation has resulted in several clinically approved NP formulations and many more in clinical trials. However, NPs are not a panacea and have yet to be utilised to maximal effect in lung cancer, and medicine in a wider context. This review serves to: describe the complexity of lung cancer, the current diagnostic and therapeutic environment, and highlight the recent advancements of nanotechnology based approaches in diagnosis and treatment of respiratory malignancies. Finally, a brief outlook on the future directions of nanomedicine is provided; presently the full potential of the field is yet to be realised. By gleaning lessons and integrating advancements from neighbouring disciplines, nanomedicine can be elevated to a position where the current barriers that stymie full clinical impact are lifted.

Nucleic Acid-Based Therapeutics for Pulmonary Diseases

Nucleic acid-based therapeutics present huge potential in the treatment of pulmonary diseases ranging from lung cancer to asthma and chronic pulmonary diseases, which are often fatal and widely prevalent. The susceptibility of nucleic acids to degradation and the complex structure of lungs retard the effective pulmonary delivery of nucleic acid drug. To overcome these barriers, different strategies have been exploited to increase the delivery efficiency using chemically synthesized nucleic acids, vector encapsulation, proper formulation, and administration route. However, several limitations regarding off-target effects and immune stimulation of nucleic acid drugs hamper their translation into the clinical practice. Therefore, their successful clinical application will ultimately rely on well-developed carriers and methods to ensure safety and efficacy. In this review, we provide a comprehensive overview of the nucleic acid application for pulmonary diseases, covering action mechanism of the nucleic acid drugs, the novel delivery systems, and the current formulation for the administration to lungs. The latest advances of nucleic acid drugs under clinical evaluation to treat pulmonary disorders will also be detailed.

RNAi-based therapeutics for lung cancer: biomarkers, microRNAs, and nanocarriers

INTRODUCTION

Despite the current advances in the discovery of the lung cancer biomarkers and, consequently, in the diagnosis, this pathology continues to be the primary cause of cancer-related death worldwide. In most cases, the illness is diagnosed in an advanced stage, which limits the current treatment options available and reduces the survival rate. Therefore, RNAi-based therapy arises as a promising option to treat lung cancer.

AREAS COVERED

This review provides an overview on the exploitation of lung cancer biology to develop RNAi-based therapeutics to be applied in the treatment of lung cancer. Furthermore, the review analyzes the main nanocarriers designed to deliver RNAi molecules and induce antitumoral effects in lung cancer, and provides updated information about current RNAi-based therapeutics for lung cancer in clinical trials.

EXPERT OPINION

RNAi-based therapy uses nanocarriers to perform a targeted and efficient delivery of therapeutic genes into lung cancer cells, by taking advantage of the known biomarkers in lung cancer. These therapeutic genes are key regulatory molecules of crucial cellular pathways involved in cell proliferation, migration, and apoptosis. Thereby, the characteristics and functionalization of the nanocarrier and the knowledge of lung cancer biology have direct influence in improving the therapeutic effect of this therapy.

Virus Spike and Membrane-Lytic Mimicking Nanoparticles for High Cell Binding and Superior Endosomal Escape

Virus-inspired mimics for gene therapy have attracted increasing attention because viral vectors show robust efficacy owing to the highly infectious nature and efficient endosomal escape. Nonetheless, until now, synthetic materials have failed to achieve high "infectivity," and especially, the mimicking of virus spikes for "infection" is underappreciated. Herein, a virus spike mimic by a zinc (Zn) coordinative ligand that shows high affinity toward phosphate-rich cell membranes is reported. Surprisingly, this ligand also demonstrates superior functionality of destabilizing endosomes. Therefore, the Zn coordination is more likely to imitate the virus nature with high cell binding and endosomal membrane disruption. Following this, the Zn coordinative ligand is functionalized on a bioreducible cross-linked peptide with alkylation that imitates the viral lipoprotein shell. The ultimate virus-mimicking nanoparticle closely imitates the structures and functions of viruses, leading to robust transfection efficiency both in vitro and in vivo. More importantly, apart from targeting ligand- and cell-penetrating peptide, the metal coordinative ligand may provide another option to functionalize diverse biomaterials for enhanced efficacy, demonstrating its broad referential significance to pursue nonviral vectors with high performance.

Self-stabilized silk sericin-based nanoparticles: In vivo biocompatibility and reduced doxorubicin-induced toxicity

A variety of colloid stabilizers and cryoprotectants confer improved nanoparticle (NP) colloidal stability and redisperability. However, discounted tumor targetability, delivery efficacy and possible side effects limit the application in vascular delivery of NPs. Here we present water-soluble silk sericin (SS) not only as a material for the preparation of NPs, but also both a dispersion stabilizer and a cryoprotectant. In the absence of any stabilizers, SS-based NPs (SSC@NPs) can resist the adsorption of serum proteins, preventing the formation of particle agglomerates. Following freeze-drying without addition of cryoprotectants, SSC@NPs powder can be easily resuspended into NP dispersion with a nearly monodispersed distribution. Additionally, SSC@NPs do not result in acute toxicity in mice at a dose of 400 mg/kg with a slow injection. Moreover, doxorubicin (DOX)-loaded SSC@NPs (DOX-SSC@NPs) diminish the biodistribution of DOX in the heart, mitigating DOX-induced cardiotoxicity of mice without compromising therapeutic efficacy. Our results suggest that the self-stabilized SSC@NPs could be a secure and effective drug carrier for intravenous administration when deprived of protective agents.

STATEMENT OF SIGNIFICANCE

During manufacturing process such as freeze-drying, or interaction with complex fluids like blood, NPs for systemic drug delivery need to be highly dispersible and structurally intact. In this work, we have demonstrated the self-stability of SSC@NPs subjected to biological media and freeze-drying. This study represents the first work showing water-soluble SS could both act as a dispersion stabilizer and a cryoprotectant due to its hydrophilicity. Plus, good in vivo biocompatibility of SSC@NPs has been confirmed. Therefore, it may be promising that water-soluble SS can be generally used as a safe biomaterial against serum adsorption.

Biodegradable Polymeric Nanoparticles for Therapeutic Cancer Treatments

Polymeric nanoparticles have tremendous potential to improve the efficacy of therapeutic cancer treatments by facilitating targeted delivery to a desired site. The physical and chemical properties of polymers can be tuned to accomplish delivery across the multiple biological barriers required to reach diverse subsets of cells. The use of biodegradable polymers as nanocarriers is especially attractive, as these materials can be designed to break down in physiological conditions and engineered to exhibit triggered functionality when at a particular location or activated by an external source. We present how biodegradable polymers can be engineered as drug delivery systems to target the tumor microenvironment in multiple ways. These nanomedicines can target cancer cells directly, the blood vessels that supply the nutrients and oxygen that support tumor growth, and immune cells to promote anticancer immunotherapy.

Development of Cationic Quaternary Ammonium Sulfonamide Amino Lipids for Nucleic Acid Delivery

Lipid nanoparticles (LNPs) currently comprise the most effective carrier class for the delivery of small RNAs. Among lipid carriers, charge-unbalanced lipids are relatively unexplored synthetically. Herein, we developed and evaluated a novel collection of compounds for small interfering RNA (siRNA) delivery, termed cationic quaternary ammonium sulfonamide amino lipids (CSALs). The formulated CSAL LNPs containing cholesterol, 1,2-distearoyl-sn-glycero-3-phosphocholine, and lipid poly(ethylene glycol) exhibited biophysical property trends directly related to the CSAL chemical structure. Lead CSAL LNPs were identified using an siRNA delivery screen. Further chemical synthesis using a rational structure-guided design showed that the head group structure could alter the pK_a and other physical properties that modulated delivery efficacy. Shorter-chained dimethylamino head groups, acetate side chains, and higher tail carbon numbers were favorable for delivery. This led to a further study of A3-OAc-C2Me LNPs, which enabled in vivo delivery to normal mouse lungs and subcutaneous and orthotopic lung tumors. Incorporation of CSALs into liver-targeting formulations shifted the in vivo delivery of these carriers to the lungs. This study highlights the importance of the cationic lipid structure in LNPs and provides further design guidelines for nucleic acid carriers.