A study of the endocytosis mechanism and transendothelial activity of lung-targeted GALA-modified liposomes

Beyond the EPR effect: Intravital microscopy analysis of nanoparticle drug delivery to tumors

Delivery of nanoparticles (NPs) to solid tumors has long relied on enhanced permeability and retention (EPR) effect, involving permeation of NPs through a leaky vasculature with prolonged retention by reduced lymphatic drainage in tumor. Recent research studies and clinical data challenge EPR concept, revealing alternative pathways and approaches of NP delivery. The area was significantly impacted by the implementation of intravital optical microscopy, unraveling delivery mechanisms at cellular level in vivo. This review presents analysis of the reasons for EPR heterogeneity in tumors and describes non-EPR based concepts for drug delivery, which can supplement the current paradigm. One of the approaches is targeting tumor endothelium by NPs with subsequent intravascular drug release and gradient-driven drug transport to tumor interstitium. Others exploit various immune cells for tumor infiltration and breaking endothelial barriers. Finally, we discuss the involvement of active transcytosis through endothelial cells in NP delivery. This review aims to inspire further understanding of the process of NP extravasation in tumors and provide insights for developing next-generation nanomedicines with improved delivery.

A Susceptible Cell-Selective Delivery (SCSD) of mRNA-Encoded Cas13d Against Influenza Infection

To bolster the capacity for managing potential infectious diseases in the future, it is critical to develop specific antiviral drugs that can be rapidly designed and delivered precisely. Herein, a CRISPR/Cas13d system for broad-spectrum targeting of influenza A virus (IAV) from human, avian, and swine sources is designed, incorporating Cas13d mRNA and a tandem CRISPR RNA (crRNA) specific for the highly conserved regions of viral polymerase acidic (PA), nucleoprotein (NP), and matrix (M) gene segments, respectively. Given that the virus targets cells with specific receptors but is not limited to a single organ, a Susceptible Cell Selective Delivery (SCSD) system is developed by modifying a lipid nanoparticle with a peptide mimicking the function of the hemagglutinin of influenza virus to target sialic acid receptors. The SCSD system can precisely deliver an all-RNA-based CRISPR/Cas13d system into potentially infected cells. This drug is shown to reduce the viral load in the lungs by 2.37 log10 TCID50 mL-1 and protect 100% of mice from lethal influenza infection. The SCSD-based CRISPR/Cas13d system shows promise for the flexible and efficient therapy of infections caused by rapidly evolving and novel viruses.

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.

Exploring and Analyzing the Systemic Delivery Barriers for Nanoparticles

Most nanomedicines require efficient in vivo delivery to elicit diagnostic and therapeutic effects. However, en route to their intended tissues, systemically administered nanoparticles often encounter delivery barriers. To describe these barriers, we propose the term "nanoparticle blood removal pathways" (NBRP), which summarizes the interactions between nanoparticles and the body's various cell-dependent and cell-independent blood clearance mechanisms. We reviewed nanoparticle design and biological modulation strategies to mitigate nanoparticle-NBRP interactions. As these interactions affect nanoparticle delivery, we studied the preclinical literature from 2011-2021 and analyzed nanoparticle blood circulation and organ biodistribution data. Our findings revealed that nanoparticle surface chemistry affected the in vivo behavior more than other nanoparticle design parameters. Combinatory biological-PEG surface modification improved the blood area under the curve by ~418%, with a decrease in liver accumulation of up to 47%. A greater understanding of nanoparticle-NBRP interactions and associated delivery trends will provide new nanoparticle design and biological modulation strategies for safer, more effective, and more efficient nanomedicines.

A Comparison of Cellular Uptake Mechanisms, Delivery Efficacy, and Intracellular Fate between Liposomes and Extracellular Vesicles

A key aspect for successful drug delivery via lipid-based nanoparticles is their internalization in target cells. Two prominent examples of such drug delivery systems are artificial phospholipid-based carriers, such as liposomes, and their biological counterparts, the extracellular vesicles (EVs). Despite a wealth of literature, it remains unclear which mechanisms precisely orchestrate nanoparticle-mediated cargo delivery to recipient cells and the subsequent intracellular fate of therapeutic cargo. In this review, internalization mechanisms involved in the uptake of liposomes and EVs by recipient cells are evaluated, also exploring their intracellular fate after intracellular trafficking. Opportunities are highlighted to tweak these internalization mechanisms and intracellular fates to enhance the therapeutic efficacy of these drug delivery systems. Overall, literature to date shows that both liposomes and EVs are predominantly internalized through classical endocytosis mechanisms, sharing a common fate: accumulation inside lysosomes. Studies tackling the differences between liposomes and EVs, with respect to cellular uptake, intracellular delivery and therapy efficacy, remain scarce, despite its importance for the selection of an appropriate drug delivery system. In addition, further exploration of functionalization strategies of both liposomes and EVs represents an important avenue to pursue in order to control internalization and fate, thereby improving therapeutic efficacy.

Therapeutic Oligonucleotides: An Outlook on Chemical Strategies to Improve Endosomal Trafficking

The potential of oligonucleotide therapeutics is undeniable as more than 15 drugs have been approved to treat various diseases in the liver, central nervous system (CNS), and muscles. However, achieving effective delivery of oligonucleotide therapeutics to specific tissues still remains a major challenge, limiting their widespread use. Chemical modifications play a crucial role to overcome biological barriers to enable efficient oligonucleotide delivery to the tissues/cells of interest. They provide oligonucleotide metabolic stability and confer favourable pharmacokinetic/pharmacodynamic properties. This review focuses on the various chemical approaches implicated in mitigating the delivery problem of oligonucleotides and their limitations. It highlights the importance of linkers in designing oligonucleotide conjugates and discusses their potential role in escaping the endosomal barrier, a bottleneck in the development of oligonucleotide therapeutics.

Advanced approaches to overcome biological barriers in respiratory and systemic routes of administration for enhanced nucleic acid delivery to the lung

INTRODUCTION

Numerous delivery strategies, primarily novel nucleic acid delivery carriers, have been developed and explored to enable therapeutically relevant lung gene therapy. However, its clinical translation is yet to be achieved despite over 30 years of efforts, which is attributed to the inability to overcome a series of biological barriers that hamper efficient nucleic acid transfer to target cells in the lung.

AREAS COVERED

This review is initiated with the fundamentals of nucleic acid therapy and a brief overview of previous and ongoing efforts on clinical translation of lung gene therapy. We then walk through the nature of biological barriers encountered by nucleic acid carriers administered via respiratory and/or systemic routes. Finally, we introduce advanced strategies developed to overcome those barriers to achieve therapeutically relevant nucleic acid delivery efficiency in the lung.

EXPERT OPINION

We are now stepping close to the clinical translation of lung gene therapy, thanks to the discovery of novel delivery strategies that overcome biological barriers via comprehensive preclinical studies. However, preclinical findings should be cautiously interpreted and validated to ultimately realize meaningful therapeutic outcomes with newly developed delivery strategies in humans. In particular, individual strategies should be selected, tailored, and implemented in a manner directly relevant to specific therapeutic applications and goals.

The intracellular fate and transport mechanism of shape, size and rigidity varied nanocarriers for understanding their oral delivery efficiency

Nanocarriers have become an effective strategy to overcome epithelial absorption barriers. During the absorption process, the endocytosis mechanisms, cell internalization pathways, and transport efficiency of nanocarriers are greatly impacted by their physical properties. To understand the relationship between physical properties of nanocarriers and their abilities overcoming multiple absorption barriers, nanocarriers with variable physical properties were prepared via self-assembly of hydrolyzed α-lactalbumin peptide fragments. The impacts of size, shape, and rigidity of nanocarriers on epithelial cells endocytosis mechanisms, internalization pathways, transport efficiency, and bioavailability were studied systematically. The results showed that nanospheres were mainly internalized via clathrin-mediated endocytosis, which was then locked in lysosomes and degraded enzymatically in cytoplasm. While macropinocytosis was the primary pathway of nanotubes and transported to the endoplasmic reticulum and Golgi apparatus, resulting in a high drug concentration and sustained release in cytoplasm. Besides, nanotubes can overcome the multi-drug resistance by inhibiting the P-glycoprotein efflux. Furthermore, nanotubes can open intercellular tight-junctions instantaneously and reversibly, which promotes transport into blood circulation. The aqueous solubility of hydrophobic bioactive mangiferin (Mgf) was improved by nanocarriers. Most importantly, the bioavailability of Mgf was the highest for cross-linked short nanotube (CSNT) which outperformed free Mgf and other formulations by in vivo pharmacokinetic studies. Finally, Mgf-loaded CSNT showed an excellent therapeutic efficiency in vivo for the intervention of streptozotocin-induced diabetes. These results indicate that cross-linked α-lactalbumin nanotubes could be an effective nanocarrier delivery system for improving the epithelium cellular absorption and bioavailability of hydrophobic bioactive compounds.

A potential platform of combining sialic acid derivative-modified paclitaxel cationic liposomes with antibody-drug conjugates inspires robust tumor-specific immunological memory in solid tumors

The recent approvals for antibody-drug conjugates (ADCs) in multiple malignancies in the past few years have fueled the ongoing development of this class of drug. However, the limitation of ADCs is selectivity toward cancer cells especially overexpressing the antigen of interest. To broaden the anti-cancer spectrum of ADCs, combinatorial strategies of ADCs with chemotherapy have become a central focus of the current preclinical and clinical research. Here, we used the microtubule stabilizer paclitaxel and enfortumab vedotin-ejfv (EV), an ADC carrying the microtubule inhibitor payload monomethyl auristatin E (MMAE), for co-administration under the consideration of their mechanism of action associated with microtubules. We designed a sialic acid-cholesterol (SA-CH) conjugate-modified cationic liposome platform loaded with PTX (PTX-SAL) for efficiently targeting tumor-associated immune cells. Compared with monotherapy, PTX-SAL-mediated combination therapy with ADCs significantly inhibited S180 tumor growth in mice, with complete tumor regression occurring. The formation of a durable tumor-specific immunological memory response in mice that experienced complete tumor regression was assessed by secondary tumor cell rechallenge, and the production of memory T cells in the spleen was detected as related to the increased CD4⁺T memory cells and the enhanced serum IFN-γ. All our preliminary results throw light on the tremendous application potential for the application of this combination therapy regimen capable of mounting a durable immune response and stimulating a robust T cell-mediated tumor-specific immunological memory.

Innovative System for Delivering Nucleic Acids/Genes Based on Controlled Intracellular Trafficking as Well as Controlled Biodistribution for Nanomedicines

This review paper summarizes progress that has been made in the new field of "Controlled Intracellular Trafficking." This involves the development of new systems for delivering plasmid DNA (pDNA), small interfering RNA (siRNA), mRNA, proteins, their escape from endosomes, the mechanism for how they enter the nucleus, how they enter mithochondria and how materials subsequently function within a cell. In addition, strategies for delivering these materials to a selective tissue after intravenous administration was also intensively investigated not only to the liver but also to tumors, lungs, adipose tissue and the spleen. In 2020, a new mRNA vaccine was developed against coronavirus disease 2019 (COVID-19), where ionizable cationic lipids were used as a delivery system. Our strategy to identify an efficient ionizable cationic lipids (iCL) based on a lipid library as well as their applications concerning the delivery of siRNA/mRNA/pDNA is also described.

Self-homing nanocarriers for mRNA delivery to the activated hepatic stellate cells in liver fibrosis

Herein, we report on the development of a platform for the selective delivery of mRNA to the hard-to-transfect Activated Hepatic Stellate Cells (aHSCs), the fundamental player in the progression of liver fibrosis. Using a microfluidic device (iLiNP), we prepared a series of lipid nanoparticles (LNPs) based on a diverse library of pH-sensitive lipids. After an in-depth in vivo optimization of the LNPs, their mRNA delivery efficiency, selectivity, potency, robustness, and biosafety were confirmed. Furthermore, some mechanistic aspects of their selective delivery to aHSCs were investigated. We identified a promising lipid candidate, CL15A6, that has a high affinity to aHSCs. Tweaking the composition and physico-chemical properties of the LNPs enabled the robust and ligand-free mRNA delivery to aHSCs in vivo post intravenous administration, with a high biosafety at mRNA doses of up to 2 mg/Kg, upon either acute or chronic administrations. The mechanistic investigation suggested that CL15A6 LNPs were taken up by aHSCs via Clathrin-mediated endocytosis through the Platelet-derived growth factor receptor beta (PDGFRβ) and showed a pKa-dependent cellular uptake. The novel and scalable platform reported in this study is highly promising for clinical applications.

Advances in lipid-based pulmonary nanomedicine for the management of inflammatory lung disorders

Inflammatory lung disorders have become one of the fastest growing global healthcare concerns, with more than 500 million annual cases of disorders such as chronic obstructive pulmonary disease, asthma and pulmonary fibrosis. Owing to environmental changes and socioeconomic disparity, the numbers are expected to grow even more in years to come. The therapeutic strategies and approved drugs currently employed in the management of inflammatory lung disorders show dose-dependent resistance and pharmacokinetic limitations. This review comprehensively discusses lipid-based pulmonary nanomedicine as a potential platform to overcome these barriers while ensuring site-specific drug delivery and minimal side effects in nontargeted tissues for the management of noninfectious inflammatory lung disorders.

Niosomal Nanocarriers for Enhanced Dermal Delivery of Epigallocatechin Gallate for Protection against Oxidative Stress of the Skin

Among green tea catechins, epigallocatechin gallate (EGCG) is the most abundant and has the highest biological activities. This study aims to develop and statistically optimise an EGCG-loaded niosomal system to overcome the cutaneous barriers and provide an antioxidant effect. EGCG-niosomes were prepared by thin film hydration method and statistically optimised. The niosomes were characterised for size, zeta potential, morphology and entrapment efficiency. Ex vivo permeation and deposition studies were conducted using full-thickness human skin. Cell viability, lipid peroxidation, antioxidant enzyme activities after UVA-irradiation and cellular uptake were determined. The optimised niosomes were spherical and had a relatively uniform size of 235.4 ± 15.64 nm, with a zeta potential of −45.2 ± 0.03 mV and an EE of 53.05 ± 4.46%. The niosomes effectively prolonged drug release and demonstrated much greater skin penetration and deposition than free EGCG. They also increased cell survival after UVA-irradiation, reduced lipid peroxidation, and increased the antioxidant enzymes’ activities in human dermal fibroblasts (Fbs) compared to free EGCG. Finally, the uptake of niosomes was via energy-dependent endocytosis. The optimised niosomes have the potential to be used as a dermal carrier for antioxidants and other therapeutic compounds in the pharmaceutical and cosmetic industries.

Liposomes and Extracellular Vesicles as Drug Delivery Systems: A Comparison of Composition, Pharmacokinetics, and Functionalization

Over the past decades, lipid-based nanoparticle drug delivery systems (DDS) have caught the attention of researchers worldwide, encouraging the field to rapidly develop improved ways for effective drug delivery. One of the most prominent examples is liposomes, which are spherical shaped artificial vesicles composed of lipid bilayers and able to encapsulate both hydrophilic and hydrophobic materials. At the same time, biological nanoparticles naturally secreted by cells, called extracellular vesicles (EVs), have emerged as promising more complex biocompatible DDS. In this review paper, the differences and similarities in the composition of both vesicles are evaluated, and critical mediators that affect their pharmacokinetics are elucidate. Different strategies that have been assessed to tweak the pharmacokinetics of both liposomes and EVs are explored, detailing the effects on circulation time, targeting capacity, and cytoplasmic delivery of therapeutic cargo. Finally, whether a hybrid system, consisting of a combination of only the critical constituents of both vesicles, could offer the best of both worlds is discussed. Through these topics, novel leads for further research are provided and, more importantly, gain insight in what the liposome field and the EV field can learn from each other.

Inhalable cryptotanshinone spray-dried swellable microparticles for pulmonary fibrosis therapy by regulating TGF-β1/Smad3, STAT3 and SIRT3 pathways

Cryptotanshinone (CTS) is a promising therapeutic option for pulmonary fibrosis (PF). However, clinical applications of CTS are limited owing to high photosensitivity and poor oral bioavailability. Pulmonary drug delivery, especially sustained pulmonary drug delivery, is promising for local treatment of chronic lung diseases. In this study, CTS was encapsulated in an optimized chitosan/L-leucine-based swellable microparticles (SMs) system, which exhibited an appropriate aerosolization performance, sustained release and storage stability. SMs enhanced the in vitro anti-fibrosis efficacy of CTS as shown by the improved cellular uptake. The effect of PF status on in vivo fate of the pulmonary delivered drug was also assessed. Pharmacokinetics and tissue distribution of oral and pulmonary delivery CTS in bleomycin-induced PF rats were compared. Pulmonary delivery exhibited high drug concentrations in pulmonary lesion areas, with reduced exposure to blood and non-targeted tissues after administration at a significantly lower dose compared with oral delivery. Moreover, PF pathological status enhanced activity of SMs, implying that pulmonary delivery was highly effective for PF treatment. Compared to oral delivery, Inhaled SMs showed comparable or even better efficacies at approximately 60-fold low dose compared with oral delivery. A sustained efficacy was observed under a prolonged administration interval (corresponding to half the total dose). Inhalation safety of SMs was established, and important mechanism-related signaling pathways against PF were investigated in vitro and in vivo. In summary, the findings showed that the developed CTS-loaded sustained pulmonary delivery system is a safe and effective strategy for chronic PF treatment.

Kinetics of pore formation in stearoyl-oleoyl-phosphatidylcholine vesicles by pH sensitive cell penetrating peptide GALA

In order to engineer endosomal escape of drug carrying liposomes into the cytoplasm of target cells, the kinetics of bilayer poration by cell penetrating peptides needs to be well understood. To this end, we have studied pH-dependent pore formation in stearoyl-oleoyl-phosphatidylcholine vesicles as a function of concentration of the peptide GALA. Using laser scanning confocal microscopy, we measured the rate of fluorophore transport from the suspending medium into giant unilamellar vesicles across bilayer pores induced by GALA under acidic pH conditions. We also measured the mean pore size of GALA-induced pores in large unilamellar vesicles by electron microscopy. We fitted a mathematical model of pore formation kinetics to the measured rate of fluorophore transport across the giant vesicle bilayer to estimate the rate of pore formation as a function of GALA concentration. We observed that the number of pores per vesicle and the pore density increased with increasing GALA concentration.

Preparation of mRNA Polyplexes with Post-conjugated Endosome-Disruptive Peptides

Successful delivery of mRNA into the cytosol of professional antigen-presenting cells (APCs) poses one of the biggest challenges in developing effective mRNA vaccines to treat various cancers and viral infectious diseases. However, most polymeric mRNA delivery systems fail to transfect APCs. We have discovered that decoration of pH-sensitive endosome-disruptive GALA peptides on the surface of mRNA polyplexes leads to efficient targeting and transfection of APCs. GALA peptides not only enhance specific uptake in APCs through binding to sialic acid moieties, they also facilitate the endosomal escape of mRNA especially in dendritic cells (DCs). Here, we describe in detail the production of stabilized mRNA polyplexes post-conjugated with GALA peptides via copper-free click chemistry. Methods described here include the synthesis and purification of GALA peptides and its conjugation to mRNA polyplexes.

Nanomedicine-based delivery strategies for nucleic acid gene inhibitors in inflammatory diseases

Thanks to their abilities to modulate the expression of virtually any genes, RNA therapeutics have attracted considerable research efforts. Among the strategies focusing on nucleic acid gene inhibitors, antisense oligonucleotides and small interfering RNAs have reached advanced clinical trial phases with several of them having recently been marketed. These successes were obtained by overcoming stability and cellular delivery issues using either chemically modified nucleic acids or nanoparticles. As nucleic acid gene inhibitors are promising strategies to treat inflammatory diseases, this review focuses on the barriers, from manufacturing issues to cellular/subcellular delivery, that still need to be overcome to deliver the nucleic acids to sites of inflammation other than the liver. Furthermore, key examples of applications in rheumatoid arthritis, inflammatory bowel, and lung diseases are presented as case studies of systemic, oral, and lung nucleic acid delivery.

Development of an SS-Cleavable pH-Activated Lipid-Like Material (ssPalm) as a Nucleic Acid Delivery Device

Gene and nucleic acid-based medication is an ultimate strategy in the field of personalized medicine. A gene or short interference RNA (siRNA) molecule needs to be delivered to the appropriate organelle (i.e., nucleus and cytoplasm, respectively). We recently focused on improving the intrinsic activity of my original material (ssPalm) in terms of endosomal/lysosomal membrane destabilization activity by chemically modifying the tertiary amine structure. In parallel, I have been expanding the range of applications of ssPalms. The first application is a DNA or RNA vaccine. My crucial finding is that the vitamin E-scaffold ssPalm (ssPalmE) is highly immune-stimulative when combined with DNA. Thereafter, I redesigned the hydrophobic scaffold structure, and found that an oleic acid-scaffold ssPalm (ssPalmO) can confer anti-inflammatory characteristics. Based on this result, I further upgraded the ssPalmO, by inserting a newly designed linker with self-degradable properties.

Nanoparticle Delivery Systems with Cell-Specific Targeting for Pulmonary Diseases

Respiratory disorders are among the most important medical problems threatening human life. The conventional therapeutics for respiratory disorders are hindered by insufficient drug concentrations at pathological lesions, lack of cell-specific targeting, and various biobarriers in the conducting airways and alveoli. To address these critical issues, various nanoparticle delivery systems have been developed to serve as carriers of specific drugs, DNA expression vectors, and RNAs. The unique properties of nanoparticles, including controlled size and distribution, surface functional groups, high payload capacity, and drug release triggering capabilities, are tailored to specific requirements in drug/gene delivery to overcome major delivery barriers in pulmonary diseases. To avoid off-target effects and improve therapeutic efficacy, nanoparticles with high cell-targeting specificity are essential for successful nanoparticle therapies. Furthermore, low toxicity and high degradability of the nanoparticles are among the most important requirements in the nanoparticle designs. In this review, we provide the most up-to-date research and clinical outcomes in nanoparticle therapies for pulmonary diseases. We also address the current critical issues in key areas of pulmonary cell targeting, biosafety and compatibility, and molecular mechanisms for selective cellular uptake.

Biodistribution, inter-/intra-cellular localization and respiratory dysfunction induced by Ti3C2 nanosheets: Involvement of surfactant protein down-regulation in alveolar epithelial cells

Two-dimensional Ti₃C₂ nanosheets have been extensively used in biomedical fields and are mostly designed to enter the circulatory system. However, few studies have focused on the in vivo anatomical location and physiological function of major organs on exposure to Ti₃C₂ nanosheets. This study attempts to determine whether and how Ti₃C₂ nanosheets disrupt the physiological function of the involved organs. Our studies demonstrated that Ti₃C₂ nanosheets were mainly distributed in the lungs and liver after entering circulation. In the lungs, they were retained in the cytoplasm of alveolar epithelial cells and endothelial cells, and inhibited pulmonary surfactant protein B (SP-B) expression on alveolar epithelial cell, causing increased airway resistance-induced respiratory disorder following a 28-day Ti₃C₂ nanosheet exposure. Furthermore, our data showed that Ti₃C₂ nanosheets did not cause abnormal proinflammatory cytokines and histopathological changes. These findings demonstrated that Ti₃C₂ nanosheets might disturb respiration without inflammatory responses and pathological lesions, suggesting that these effects may occur by decreasing SP-B-mediated airway resistance. This indicates that organ function maintenance differs from biological safety for Ti₃C₂ nanosheets, an important consideration during potential clinical application and human exposure.

Assembly strategy of liposome and polymer systems for siRNA delivery

In recent years, gene therapy has made tremendous progress in the development of disease treatment. Among them, siRNA offers specificity of gene silencing, ease of synthesis, and short development period, and has been intensively studied worldwide. However, siRNA as the hydrophilic polyanion is easily degraded in vivo and poorly taken up into cells and so, the benefits of its powerful gene silencing ability will not be realized until better carriers are developed that are capable of protecting siRNA and delivering it intact to the cytoplasm of the target cells. Cationic liposomes (CL) and cationic polymers (CP) are the main non-viral siRNA vectors, there have been a lot of reports on the use of these two carriers to deliver siRNA. Whereas, as far as we know, there have been few review articles that provide an in-depth summary of the siRNA loading principle and internal structures of the siRNA delivery system. We summarize the formation principle and assembly structure of the cationic liposome-siRNA and polymer-siRNA complexes, and point out their advantages and characteristics and also show how to perfect their assembly and improve their clinical application in the future. It supports some useful suggestions for siRNA therapy, specifically, safe and efficient delivery.

Lipid Nanoparticles for Cell-Specific in Vivo Targeted Delivery of Nucleic Acids

The last few years have witnessed a great advance in the development of nonviral systems for in vivo targeted delivery of nucleic acids. Lipid nanoparticles (LNPs) are the most promising carriers for producing clinically approved products in the future. Compared with other systems used for nonviral gene delivery, LNPs provide several advantages including higher stability, low toxicity, and greater efficiency. Additionally, systems based on LNPs can be modified with ligands and devices for controlled biodistribution and internalization into specific cells. Efforts are ongoing to improve the efficiency of lipid-based gene vectors. These efforts depend on the appropriate design of nanocarriers as well as the development of new lipids with improved gene delivery ability. Several ionizable lipids have recently been developed and have shown dramatically improved efficiency. However, enhancing the ability of nanocarriers to target specific cells in the body remains the most difficult challenge. Systemically administered LNPs can access organs in which the capillaries are characterized by the presence of fenestrations, such as the liver and spleen. The liver has received the most attention to date, although targeted delivery to the spleen has recently emerged as a promising tool for modulating the immune system. In this review, we discuss recent advances in the use of LNPs for cell-specific targeted delivery of nucleic acids. We focus mainly on targeting liver hepatocytes and spleen immune cells as excellent targets for gene therapy. We also discuss the potential of endothelial cells as an alternate approach for targeting organs with a continuous endothelium.

Construction and characterization of folate-functionalized curdlan-trilysine siRNA delivery platform for in vivo hepatic carcinoma treatment

RNA interference technology is a powerful tool with substantially clinical prospects for carcinoma therapy, in which efficiency and specificity of delivery of dsRNA remains a critical issue. Herein, aiming at delivery of dsRNA in efficient and safe way, we constructed targeting delivery platform (CTL-PEG-FA) by grafting curdlan with trilysine through click reaction, then modifying with PEG linked folic acid. The CTL-PEG-FA vector exhibited excellent gene binding capacity to condense siRNA and dramatically reduced cytotoxicity. Increased cell uptake of CTL-PEG-FA/Bcl-2 siRNA was achieved by the synergism of folate mediated endocytosis and charge interaction, and further causing severe HepG2 cells injury through apoptosis mechanism after down-regulation of Bcl-2 protein. In vivo experiments, CTL-PEG-FA/Bcl-2 siRNA complex distinctly accumulated in tumor site and significantly inhibited the growth of tumor, while no obvious toxicity was observed. Therefore, well-performed CTL-PEG-FA with excellent biocompatibility, has the potential to be the candidate of gene therapy for clinical applications.

Nanocarrier‐Mediated Cytosolic Delivery of Biopharmaceuticals

Biopharmaceuticals have emerged to play a vital role in disease treatment and have shown promise in the rapidly expanding pharmaceutical market due to their high specificity and potency. However, the delivery of these biologics is hindered by various physiological barriers, owing primarily to the poor cell membrane permeability, low stability, and increased size of biologic agents. Since many biological drugs are intended to function by interacting with intracellular targets, their delivery to intracellular targets is of high relevance. In this review, the authors summarize and discuss the use of nanocarriers for intracellular delivery of biopharmaceuticals via endosomal escape and, especially, the routes of direct cytosolic delivery by means including the caveolae‐mediated pathway, contact release, intermembrane transfer, membrane fusion, direct translocation, and membrane disruption. Strategies with high potential for translation are highlighted. Finally, the authors conclude with the clinical translation of promising carriers and future perspectives.

Development of lipid-like materials for RNA delivery based on intracellular environment-responsive membrane destabilization and spontaneous collapse

Messenger RNA and small interfering RNA are attractive modalities for curing diseases by complementation or knock-down of proteins. For success of these RNAs, a drug delivery system (DDS) is required to control a pharmacokinetics, to enhance cellular uptake, to overcome biological membranes, and to release the cargo into the cytoplasm. Based on past research, developing nanoparticles that are neutrally charged have been the mainstream of their development. Also, the materials are further mounted with pH- and/or reducing environment-responsive units. In this review, we summarize progress made in the molecular design of these materials. We also focus on the importance of the hydrophobic scaffold for tissue/cell targeting, intracellular trafficking, and immune responses. As a practical example, the design concept of the SS-cleavable and pH-activated lipid-like material (ssPalm) and subsequent molecular modification tailored to the RNA-based medical application is discussed.

Endocytosis: The Nanoparticle and Submicron Nanocompounds Gateway into the Cell

Nanoparticles (NPs) and submicron particles are increasingly used as carriers for delivering therapeutic compounds to cells. Their entry into the cell represents the initial step in this delivery process, being most of the nanoparticles taken up by endocytosis, although other mechanisms can contribute to the uptake. To increase the delivery efficiency of therapeutic compounds by NPs and submicron particles is very relevant to understand the mechanisms involved in the uptake process. This review covers the proposed pathways involved in the cellular uptake of different NPs and submicron particles types as well as the role that some of the physicochemical nanoparticle characteristics play in the uptake pathway preferentially used by the nanoparticles to gain access and deliver their cargo inside the cell.

Berberine encapsulated PEG-coated liposomes attenuate Wnt1/β-catenin signaling in rheumatoid arthritis via miR-23a activation

Bone erosion is a debilitating pathological process of osteopathic disorder like rheumatoid arthritis (RA). Current treatment strategies render low disease activity but with disease recurrence. To find an alternative, we designed this study with an aim to explore the underlying therapeutic effect of PEGylated liposomal BBR (PEG-BBR) against Wnt1/β-catenin mediated bone erosion in adjuvant-induced arthritic (AA) rat model and fibroblast-like synoviocytes (FLS) with reference to microRNA-23a (miR-23a) activity. Our initial studies using confocal microscopy and Near-Infrared Imaging (NIR) showed successful internalization of PEG-BBR and PEG-miR-23a in vitro and in vivo respectively and was retained till 48 h. The preferential internalization of PEG-BBR into the inflamed joint region significantly reduced the gene and protein level expression of major Wnt1 signaling mediators and reduced bone erosion in rats. Moreover, PEG-BBR treatment in FLS cells attenuated the gene and protein expression levels of FZD4, LRP5, β-catenin, and Dvl-1 through the induction of CYLD. Furthermore, inhibition of these factors resulted in reduced bone loss and increased calcium retainability by altering the RANKL/OPG axis. PEG-BBR treatment markedly inhibited the expression of LRP5 protein on par with the DKK-1 (LRP5/Wnt signaling inhibitor) and suppressed the transcriptional activation of β-catenin inside the cells. We further witnessed that miR-23a altered the expression levels of LRP5 through RNA interference. Overall, our findings endorsed that miR-23a possesses a multifaceted therapeutic efficiency like berberine in RA pathogenesis and can be considered as a potential candidate for therapeutic targeting of Wnt1/β-catenin signaling in RA disease condition.

Nanoparticles for antiparasitic drug delivery

As an emerging novel drug carrier, nanoparticles provide a promising way for effective treatment of parasitic diseases by overcoming the shortcomings of low bioavailability, poor cellular permeability, nonspecific distribution and rapid elimination of antiparasitic drugs from the body. In recent years, some kinds of ideal nanocarriers have been developed for antiparasitic drug delivery. In this review, the progress of the enhanced antiparasitic effects of different nanoparticles payload and their influencing factors were firstly summarized. Secondly, the transport and disposition process in the body were reviewed. Finally, the challenges and prospects of nanoparticles for antiparasitic drug delivery were proposed. This review will help scholars to understand the development trend of nanoparticles in the treatment of parasitic diseases and explore strategies in the development of more efficient nanocarriers to overcome the difficulty in the treatment of parasite infections in the future.