Emerging Concepts of Nanobiotechnology in mRNA Delivery

Synthesis of novel cholesterol-based ionizable lipids for mRNA delivery

The safe and effective delivery of messenger ribonucleic acid (mRNA) is crucial for its therapeutic effects in vivo. In this study, we developed a new type of ionizable lipid S-1, which contains an amino head, a cholesterol matrix, and a long hydrophobic carbon tail. We employed microfluidics to rapidly mix an ethanol phase containing S-1 lipid with an aqueous mRNA to form mRNA/S-1 lipid nanoparticles (LNPs, 100-200 nm). We observed low cytotoxicity and high transfection efficiency in RAW264.7 and HCT-116 cell lines for mRNA/S-1 LNPs, comparable to mRNA/SM-102 LNPs. Based on the obtained findings, mRNA/S-1 LNPs have good stability, low cytotoxicity, high transfection efficiency, and enhanced cellular uptake. The synthesized S-1 lipid ensures efficient assembly of lipid nanoparticles, protects mRNA from RNase degradation, and enables the delivery of mRNA into the cytoplasm for translation.

Emerging mRNA Technology for Liver Disease Therapy

Liver diseases have consistently posed substantial challenges to global health. It is crucial to find innovative methods to effectively prevent and treat these diseases. In recent times, there has been an increasing interest in the use of mRNA formulations that accumulate in liver tissue for the treatment of hepatic diseases. In this review, we start by providing a detailed introduction to the mRNA technology. Afterward, we highlight types of liver diseases, discussing their causes, risks, and common therapeutic strategies. Additionally, we summarize the latest advancements in mRNA technology for the treatment of liver diseases. This includes systems based on hepatocyte growth factor, hepatitis B virus antibody, left-right determination factor 1, human hepatocyte nuclear factor α, interleukin-12, methylmalonyl-coenzyme A mutase, etc. Lastly, we provide an outlook on the potential of mRNA technology for the treatment of liver diseases, while also highlighting the various technical challenges that need to be addressed. Despite these difficulties, mRNA-based therapeutic strategies may change traditional treatment methods, bringing hope to patients with liver diseases.

The paths toward non-viral CAR-T cell manufacturing: A comprehensive review of state-of-the-art methods

Although CAR-T cell therapy has emerged as a game-changer in cancer immunotherapy several bottlenecks limit its widespread use as a front-line therapy. Current protocols for the production of CAR-T cells rely mainly on the use of lentiviral/retroviral vectors. Nevertheless, according to the safety concerns around the use of viral vectors, there are several regulatory hurdles to their clinical use. Large-scale production of viral vectors under "Current Good Manufacturing Practice" (cGMP) involves rigorous quality control assessments and regulatory requirements that impose exorbitant costs on suppliers and as a result, lead to a significant increase in the cost of treatment. Pursuing an efficient non-viral method for genetic modification of immune cells is a hot topic in cell-based gene therapy. This study aims to investigate the current state-of-the-art in non-viral methods of CAR-T cell manufacturing. In the first part of this study, after reviewing the advantages and disadvantages of the clinical use of viral vectors, different non-viral vectors and the path of their clinical translation are discussed. These vectors include transposons (sleeping beauty, piggyBac, Tol2, and Tc Buster), programmable nucleases (ZFNs, TALENs, and CRISPR/Cas9), mRNA, plasmids, minicircles, and nanoplasmids. Afterward, various methods for efficient delivery of non-viral vectors into the cells are reviewed.

Engineered Silica Nanoparticles for Nucleic Acid Delivery

The development of nucleic acid-based drugs holds great promise for therapeutic applications, but their effective delivery into cells is hindered by poor cellular membrane permeability and inherent instability. To overcome these challenges, delivery vehicles are required to protect and deliver nucleic acids efficiently. Silica nanoparticles (SiNPs) have emerged as promising nanovectors and recently bioregulators for gene delivery due to their unique advantages. In this review, a summary of recent advancements in the design of SiNPs for nucleic acid delivery and their applications is provided, mainly according to the specific type of nucleic acids. First, the structural characteristics and working mechanisms of various types of nucleic acids are introduced and classified according to their functions. Subsequently, for each nucleic acid type, the use of SiNPs for enhancing delivery performance and their biomedical applications are summarized. The tailored design of SiNPs for selected type of nucleic acid delivery will be highlighted considering the characteristics of nucleic acids. Lastly, the limitations in current research and personal perspectives on future directions in this field are presented. It is expected this opportune review will provide insights into a burgeoning research area for the development of next-generation SiNP-based nucleic acid delivery systems.

Closer to The Heart: Harnessing the Power of Targeted Extracellular Vesicle Therapies

Extracellular vesicles (EVs) have emerged as novel diagnostic and therapeutic approaches for cardiovascular diseases. EVs derived from various origins exhibit distinct effects on the cardiovascular system. However, the application of native EVs is constrained due to their poor stabilities and limited targeting capabilities. Currently, targeted modification of EVs primarily involves genetic engineering, chemical modification (covalent, non-covalent), cell membrane modification, and biomaterial encapsulation. These techniques enhance the stability, biological activity, target-binding capacity, and controlled release of EVs at specific cells and tissues. The diverse origins of cardioprotective EVs are covered, and the applications of cardiac-targeting EV delivery systems in protecting against cardiovascular diseases are discussed. This review summarizes the current stage of research on the potential of EV-based targeted therapies for addressing cardiovascular disorders.

Development of polypeptide-based materials toward messenger RNA delivery

Messenger RNA (mRNA)-based therapeutic agents have demonstrated significant potential in recent times, particularly in the context of the COVID-19 pandemic outbreak. As a promising prophylactic and therapeutic strategy, polypeptide-based mRNA delivery systems attract significant interest because of their low cost, simple preparation, tuneable sizes and morphology, convenient large-scale production, biocompatibility, and biodegradability. In this review, we begin with a brief discussion of the synthesis of polypeptides, followed by a review of commonly used polypeptides in mRNA delivery, including classical polypeptides and cell-penetrating peptides. Then, the challenges against mRNA delivery, including extracellular, intracellular, and clinical barriers, are discussed in detail. Finally, we highlight a range of strategies for polypeptide-based mRNA delivery, offering valuable insights into the advancement of polypeptide-based mRNA carrier development.

A liposomal platform for the delivery of ion channel proteins for treatment of channelopathies - Application in therapy of cystic fibrosis

Channelopathies arise from ion channel dysfunction. Successful treatment entails delivery of functional ion channels to replace dysfunctional ones. Glycine receptor (GlyR)-rich cell membrane fragments (CMF) were previously delivered to target cell membranes using fusogenic liposomes. Here, cystic fibrosis transmembrane conductance regulator (CFTR)-bearing CMF were similarly delivered to target cells. We studied the effect of lipid composition on liposomes' ability to incorporate CMF and fuse with target cell membranes to deliver functional CFTR. Four formulations were prepared using thin-film hydration out of different lecithin sources, egg and soy lecithin (EL and SL), in the presence and absence of cholesterol (CHOL): EL + CHOL, EL-CHOL, SL + CHOL, and SL-CHOL. EL liposomes incorporated more CMF than SL liposomes, with CHOL only increasing CMF incorporation in SL liposomes. SL + CHOL fused better with target cell membranes than EL + CHOL. SL + CHOL and EL + CHOL equally delivered CFTR to target cell membranes, owing to the former's superior fusogenic capacity and the latter's superior CMF-incorporation capacity. SL-CHOL and EL-CHOL delivered CFTR to a lesser extent, indicating the importance of CHOL for fusion. Patch-clamp electrophysiology and confocal laser scanning microscopy (CLSM) confirmed CFTR delivery to target cell membranes by SL + CHOL. Therefore, CMF-bearing fusogenic liposomes offer a promising universal platform for the treatment of channelopathies.

Cellular Trafficking of Nanotechnology-Mediated mRNA Delivery

Messenger RNA (mRNA)-based therapy has emerged as a powerful, safe, and rapidly scalable therapeutic approach that involves technologies for both mRNA itself and the delivery vehicle. Although there are some unique challenges for different applications of mRNA therapy, a common challenge for all mRNA therapeutics is the transport of mRNA into the target cell cytoplasm for sufficient protein expression. This review is focused on the behaviors at the cellular level of nanotechnology-mediated mRNA delivery systems, which have not been comprehensively reviewed yet. First, the four main therapeutic applications of mRNA are introduced, including immunotherapy, protein replacement therapy, genome editing, and cellular reprogramming. Second, common types of mRNA cargos and mRNA delivery systems are summarized. Third, strategies to enhance mRNA delivery efficiency during the cellular trafficking process are highlighted, including accumulation to the cell, internalization into the cell, endosomal escape, release of mRNA from the nanocarrier, and translation of mRNA into protein. Finally, the challenges and opportunities for the development of nanotechnology-mediated mRNA delivery systems are presented. This review can provide new insights into the future fabrication of mRNA nanocarriers with desirable cellular trafficking performance.

Branched hydrophobic tails in lipid nanoparticles enhance mRNA delivery for cancer immunotherapy

Efficient and safe delivery of vulnerable mRNA is a long-standing challenge for the broad application of the emerging mRNA-based therapeutics. Herein, a combinatorial library containing 119 novel lipids was constructed via sequential aza-Michael addition reactions of arylates and varying amines to tackle the ongoing challenge in mRNA delivery. Through in vitro screening of the lipid library on IGROV 1 cells, we identified several synthetic lipids with superior mRNA delivery efficacy. The delivery capability of these lipids was verified by the potent expression of luciferase in BALB/c mice upon intravenous administration of luciferase-encoding mRNA lipid nanoparticles (LNPs). Further investigations on the structure-activity relationship revealed that lipids with branched hydrophobic tails were better at delivering mRNA than those containing linear tails at the similar total number of carbons. In comparison to linear tails, the branched tails endowed LNPs with less inner hydrophobicity, fewer surface charges, and proper stability, which benefits the cellular uptake of LNPs and the intracellular trafficking of mRNA, thus improves the delivery efficacy of mRNA. The therapeutical potential of the lead LNPs was evaluated by delivering ovalbumin (OVA)-encoding mRNA to mice bearing B16-OVA melanoma tumors. The results demonstrated that the administration of OVA mRNA LNPs significantly activated CD8+ T cells in tumor microenvironment and substantially prohibited the growth of the aggressive B16-OVA tumors. The robust antitumor efficacy highlights the great potential of these LNPs in cancer immunotherapy.

Lipid carriers for mRNA delivery

Messenger RNA (mRNA) is the template for protein biosynthesis and is emerging as an essential active molecule to combat various diseases, including viral infection and cancer. Especially, mRNA-based vaccines, as a new type of vaccine, have played a leading role in fighting against the current global pandemic of COVID-19. However, the inherent drawbacks, including large size, negative charge, and instability, hinder its use as a therapeutic agent. Lipid carriers are distinguishable and promising vehicles for mRNA delivery, owning the capacity to encapsulate and deliver negatively charged drugs to the targeted tissues and release cargoes at the desired time. Here, we first summarized the structure and properties of different lipid carriers, such as liposomes, liposome-like nanoparticles, solid lipid nanoparticles, lipid-polymer hybrid nanoparticles, nanoemulsions, exosomes and lipoprotein particles, and their applications in delivering mRNA. Then, the development of lipid-based formulations as vaccine delivery systems was discussed and highlighted. Recent advancements in the mRNA vaccine of COVID-19 were emphasized. Finally, we described our future vision and perspectives in this field.

The clinical progress and challenges of mRNA vaccines

Owing to the breakthroughs in the prevention and control of the COVID-19 pandemic, messenger RNA (mRNA)-based vaccines have emerged as promising alternatives to conventional vaccine approaches for infectious disease prevention and anticancer treatments. Advantages of mRNA vaccines include flexibility in designing and manipulating antigens of interest, scalability in rapid response to new variants, ability to induce both humoral and cell-mediated immune responses, and ease of industrialization. This review article presents the latest advances and innovations in mRNA-based vaccines and their clinical translations in the prevention and treatment of infectious diseases or cancers. We also highlight various nanoparticle delivery platforms that contribute to their success in clinical translation. Current challenges related to mRNA immunogenicity, stability, and in vivo delivery and the strategies for addressing them are also discussed. Finally, we provide our perspectives on future considerations and opportunities for applying mRNA vaccines to fight against major infectious diseases and cancers. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Biology-Inspired Nanomaterials > Lipid-Based Structures.

Bivalent mRNA vaccines against three SARS-CoV-2 variants mediated by new ionizable lipid nanoparticles

Lipid nanoparticles (LNPs)-based mRNA vaccines have shown great potential in the fight against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. However, it remains still a challenge to improve the delivery efficiency of LNPs and the long-term stability of their mediated mRNA vaccines. Herein, a novel ionizable lipid 2-hexyldecyl 6-(ethyl(3-((2-hexyldecyl)oxy)-2-hydroxypropyl)amino)hexanoate (HEAH) derived LNPs were developed for delivering the receptor binding domain (RBD) mRNAs. In vitro cell assays confirmed that the ionizable lipid HEAH with one ether bond and one ester bond derived LNPs possessed higher mRNA delivery efficiency compared with the approved ALC-0315 with two ester bonds used in the BNT162b2 vaccine. Notably, the HEAH-derived LNPs powder lyophilized did not significantly change for 30 days after storage at 37 °C indicating good thermostability. After two RBD mRNAs of Delta and Omicron variants were encapsulated into the HEAH-derived LNPs, a bivalent mRNA vaccine was obtained as a nanoparticle formulation. Importantly, the bivalent mRNA vaccine not only resisted Delta and Omicron and also generated protective antibodies against ancestral SARS-CoV-2. The HEAH-mediated bivalent vaccine induced stronger humoral and cellular immunity than those of the ALC-0315 group. Taken together, the ionizable lipid HEAH-derived LNPs show outstanding potential in improving the delivery efficiency of mRNA and the stability of mRNA vaccine.

Intracellular delivery of therapeutic proteins. New advancements and future directions

Achieving the full potential of therapeutic proteins to access and target intracellular receptors will have enormous benefits in advancing human health and fighting disease. Existing strategies for intracellular protein delivery, such as chemical modification and nanocarrier-based protein delivery approaches, have shown promise but with limited efficiency and safety concerns. The development of more effective and versatile delivery tools is crucial for the safe and effective use of protein drugs. Nanosystems that can trigger endocytosis and endosomal disruption, or directly deliver proteins into the cytosol, are essential for successful therapeutic effects. This article aims to provide a brief overview of the current methods for intracellular protein delivery to mammalian cells, highlighting current challenges, new developments, and future research opportunities.

Mesoporous Organosilica Nanoparticles with Tetrasulphide Bond to Enhance Plasmid DNA Delivery

Cellular delivery of plasmid DNA (pDNA) specifically into dendritic cells (DCs) has provoked wide attention in various applications. However, delivery tools that achieve effective pDNA transfection in DCs are rare. Herein, we report that tetrasulphide bridged mesoporous organosilica nanoparticles (MONs) have enhanced pDNA transfection performance in DC cell lines compared to conventional mesoporous silica nanoparticles (MSNs). The mechanism of enhanced pDNA delivery efficacy is attributed to the glutathione (GSH) depletion capability of MONs. Reduction of initially high GSH levels in DCs further increases the mammalian target of rapamycin complex 1 (mTORc1) pathway activation, enhancing translation and protein expression. The mechanism was further validated by showing that the increased transfection efficiency was apparent in high GSH cell lines but not in low GSH ones. Our findings may provide a new design principle of nano delivery systems where the pDNA delivery to DCs is important.

Mesoporous Organosilica Nanoparticles with Tetrasulphide Bond to Enhance Plasmid DNA Delivery

Cellular delivery of plasmid DNA (pDNA) specifically into dendritic cells (DCs) has provoked wide attention in various applications. However, delivery tools that achieve effective pDNA transfection in DCs are rare. Herein, we report that tetrasulphide bridged mesoporous organosilica nanoparticles (MONs) have enhanced pDNA transfection performance in DC cell lines compared to conventional mesoporous silica nanoparticles (MSNs). The mechanism of enhanced pDNA delivery efficacy is attributed to the glutathione (GSH) depletion capability of MONs. Reduction of initially high GSH levels in DCs further increases the mammalian target of rapamycin complex 1 (mTORc1) pathway activation, enhancing translation and protein expression. The mechanism was further validated by showing that the increased transfection efficiency was apparent in high GSH cell lines but not in low GSH ones. Our findings may provide a new design principle of nano delivery systems where the pDNA delivery to DCs is important.

Supramolecular Polyphenol-DNA Microparticles for In Vivo Adjuvant and Antigen Co-Delivery and Immune Stimulation

DNA-based materials have attracted interest due to the tunable structure and encoded biological functionality of nucleic acids. A simple and general approach to synthesize DNA-based materials with fine control over morphology and bioactivity is important to expand their applications. Here, we report the synthesis of DNA-based particles via the supramolecular assembly of tannic acid (TA) and DNA. Uniform particles with different morphologies are obtained using a variety of DNA building blocks. The particles enable the co-delivery of cytosine-guanine adjuvant sequences and the antigen ovalbumin in model cells. Intramuscular injection of the particles in mice induces antigen-specific antibody production and T cell responses with no apparent toxicity. Protein expression in cells is shown using capsules assembled from TA and plasmid DNA. This work highlights the potential of TA as a universal material for directing the supramolecular assembly of DNA into gene and vaccine delivery platforms.

Nanobiotechnology-Enabled mRNA Stabilization

mRNA technology has attracted enormous interest due to its great therapeutic potential. Strategies that can stabilize fragile mRNA molecules are crucial for their widespread applications. There are numerous reviews on mRNA delivery, but few focus on the underlying causes of mRNA instability and how to tackle the instability issues. Herein, the recent progress in nanobiotechnology-enabled strategies for stabilizing mRNA and better delivery is reviewed. First, factors that destabilize mRNA are introduced. Second, nanobiotechnology-enabled strategies to stabilize mRNA molecules are reviewed, including molecular and nanotechnology approaches. The impact of formulation processing on mRNA stability and shelf-life, including freezing and lyophilization, are also briefly discussed. Lastly, our perspectives on challenges and future directions are presented. This review may provide useful guidelines for understanding the structure-function relationship and the rational design of nanobiotechnology for mRNA stability enhancement and mRNA technology development.

Novel bionic inspired nanosystem construction for precise delivery of mRNA

The intracellular delivery of messenger (m)RNA holds great potential for the discovery and development of vaccines and therapeutics. Yet, in many applications, a major obstacle to clinical translation of mRNA therapy is the lack of efficient strategy to precisely deliver RNA sequence to liver tissues and cells. In this study, we synthesized virus-like mesoporous silica (V-SiO₂) nanoparticles for effectively deliver the therapeutic RNA. Then, the cationic polymer polyethylenimine (PEI) was included for the further silica surface modification (V-SiO₂-P). Negatively charged mRNA motifs were successfully linked on the surface of V-SiO₂ through electrostatic interactions with PEI (m@V-SiO₂-P). Finally, the supported lipid bilayer (LB) was completely wrapped on the bionic inspired surface of the nanoparticles (m@V-SiO₂-P/LB). Importantly, we found that, compared with traditional liposomes with mRNA loading (m@LNPs), the V-SiO₂-P/LB bionic-like morphology effectively enhanced mRNA delivery effect to hepatocytes both in vitro and in vivo, and PEI modification concurrently promoted mRNA binding and intracellular lysosomal escape. Furthermore, m@V-SiO₂-P increased the blood circulation time (t_1/2 = 7 h) to be much longer than that of the m@LNPs (4.2 h). Understanding intracellular delivery mediated by the V-SiO₂-P/LB nanosystem will inspire the next-generation of highly efficient and effective mRNA therapies. In addition, the nanosystem can also be applied to the oral cavity, forehead, face and other orthotopic injections.

Enhanced Immune Responses to Mucosa by Functionalized Chitosan-Based Composite Nanoparticles as a Vaccine Adjuvant for Intranasal Delivery

Nasal administration for vaccine delivery is a novel non-invasive vaccine administration approach that can induce local or systemic immune responses and overcome the disadvantages caused by traditional injectable administration. However, mucosal vaccine and adjuvant delivery systems with sustained-release ability and enhanced immune effects at mucosal sites have still been highly demanded. In this work, N-2-hydroxypropyl trimethyl ammonium chloride chitosan/N,O-carboxymethyl chitosan nanoparticles (N-2-HACC/CMCS NPs) with excellent mucosal absorption, high drug loading capacity, and enhanced immune responses were prepared by the ionic cross-linking method. To evaluate the potential capacity of the N-2-HACC/CMCS NPs as a vaccine adjuvant and the molecular mechanism for the induction of enhanced mucosal and systemic immune responses, bovine serum albumin (BSA) was employed as a general model antigen and loaded into the N-2-HACC/CMCS NPs to prepare a BSA-loaded N-2-HACC/CMCS adjuvant vaccine (N-2-HACC/CMCS/BSA NPs). It was well demonstrated that the N-2-HACC/CMCS/BSA NPs with great biostability and mucosal absorption could effectively promote the proliferation of lymphocytes and the secretion of related pro-inflammatory factors, resulting in the stimulation of specific mucosal and systemic immune responses. This study revealed that the chitosan-based nano-delivery system can act as the mucosal vaccine adjuvant and possesses great promise in viral infectious diseases and immunization therapy.

Gelatin Nanoparticles for Complexation and Enhanced Cellular Delivery of mRNA

Messenger RNA (mRNA) is increasingly gaining interest as a modality in vaccination and protein replacement therapy. In regenerative medicine, the mRNA-mediated expression of growth factors has shown promising results. In contrast to protein delivery, successful mRNA delivery requires a vector to induce cellular uptake and subsequent endosomal escape to reach its end destination, the ribosome. Current non-viral vectors such as lipid- or polymer-based nanoparticles have been successfully used to express mRNA-encoded proteins. However, to advance the use of mRNA in regenerative medicine, it is required to assess the compatibility of mRNA with biomaterials that are typically applied in this field. Herein, we investigated the complexation, cellular uptake and maintenance of the integrity of mRNA complexed with gelatin nanoparticles (GNPs). To this end, GNPs with positive, neutral or negative surface charge were synthesized to assess their ability to bind and transport mRNA into cells. Positively charged GNPs exhibited the highest binding affinity and transported substantial amounts of mRNA into pre-osteoblastic cells, as assessed by confocal microscopy using fluorescently labeled mRNA. Furthermore, the GNP-bound mRNA remained stable. However, no expression of mRNA-encoded protein was detected, which is likely related to insufficient endosomal escape and/or mRNA release from the GNPs. Our results indicate that gelatin-based nanomaterials interact with mRNA in a charge-dependent manner and also mediate cellular uptake. These results create the basis for the incorporation of further functionality to yield endosomal release.

Cationic polymer synergizing with a disulfide-containing enhancer achieved efficient nucleic acid and protein delivery

To improve the efficiency of nucleic acid and protein delivery by cationic polymers, there is a trade-off between increasing the positive charge density of cationic polymers and decreasing cytotoxicity. In this work, a strategy to introduce multiple interactions between the cell membrane and a delivery system based on cationic polymers was proposed. A novel delivery system consisting of PEI1.8k and an enhancer (LA-RT) was fabricated. The introduction of LA-RT contributed to multiple interactions between the delivery system and the cell membrane including electrostatic interactions, hydrogen bonding, hydrophobic interaction, and dynamic sulfur exchange reactions, which enabled efficient intracellular delivery of nucleic acids and proteins. For nucleic acid delivery, plasmid DNA and mRNA were loaded to realize CRISPR/Cas 9 gene editing in vivo and protein expression in vivo, respectively. For protein delivery, the delivery system carrying OVA protein and CpG formed a nano-vaccine, which induced enhanced humoral and cellular immunity in vivo. In addition, the delivery system based on PEI1.8k revealed negligible cytotoxicity. This work provided a novel strategy to prepare efficient delivery systems based on cationic polymers via the introduction of a multifunctional enhancer.

Trojan Horse Delivery of Spherical Nucleic Acid Probes into the Cytoplasm for High-Fidelity Imaging of MicroRNAs

We report a Trojan horse strategy to efficiently deliver the spherical nucleic acid probes (namely, nanoflares) into the cytoplasm for microRNA (miRNA) imaging with high fidelity, breaking through the cytoplasmic transport dilemma of RNA probes in living cells. The nanoflare is encapsulated into a "Trojan horse" consisting of zwitterionic choline phosphates (CPs) and acid-degradable crosslinkers; the former effectively promotes cell uptake and the latter triggers instantaneous liberation of the nanoflare probes from the lysosome to the cytoplasm. The exposed nanoflares in the cytoplasm can be lightened up by the target miRNAs specifically. Compared with the conventional nanoflares as well as the improved ones in previous reports, the "Trojan horse" nanoflares avoid nuclease degradation and thiol displacement during the delivery process, providing unprecedentedly high accuracy for intracellular miRNA imaging.

Delivery of mRNA for regulating functions of immune cells

Abnormal immune cell functions are commonly related to various diseases, including cancer, autoimmune diseases, and infectious diseases. Messenger RNA (mRNA)-based therapy can regulate the functions of immune cells or assign new functions to immune cells, thereby generating therapeutic immune responses to treat these diseases. However, mRNA is unstable in physiological environments and can hardly enter the cytoplasm of target cells; thus, effective mRNA delivery systems are critical for developing mRNA therapy. The two mRNA vaccines of Pfizer-BioNTech and Moderna have demonstrated that lipid nanoparticles (LNPs) can deliver mRNA into dendritic cells (DCs) to induce immunization against severe acute respiratory syndrome coronavirus 2, which opened the floodgates to the development of mRNA therapy. Apart from DCs, other immune cells are promising targets for mRNA therapy. This review summarized the barriers to mRNA delivery and advances in mRNA delivery for regulating the functions of different immune cells.

Design and Synthesis of Shikimoylated-Polypeptides for Nuclear Specific Internalization

Targeted delivery of therapeutics such as small molecule drugs or nucleic acids exclusively to the nucleus of diseased mammalian cells poses a significant challenge. The development of targeting ligands that can specifically enter certain cancer cells via a specific receptor-mediated endocytosis and then traffic exclusively to the nucleus to deliver the cargo inside it can achieve this goal. We have developed an end-functionalized shikimoylated-polypeptide with pendant shikimoyl moieties that can enter mammalian cells via the mannose receptors and are then exclusively trafficked into the nucleus. The presence of the shikimoyl group in the polypeptide, which traffics it exclusively to the nucleus, contrasts with the mannosylated or galactosylated glycopolypeptides that are distributed all over the cytoplasm or the mannose-6-phosphate containing polypeptide that is exclusively trafficked to the lysosome. Using challenge experiments, we demonstrate that these polypeptides can enter both dendritic and cancer cells through mannose-receptors and subsequently enter the cell nucleus via the interaction with a nuclear pore complex (NPC) protein importin-α/β1. To the best of our knowledge, this represents the first example of a synthetic polyvalent glycopolypeptide mimic that performs the dual function of entering mammalian cells through specific receptors and subsequently traffics into the nucleus. The conjugation of these end-functionalized shikimoylated-polypeptides to other biological entities, such as recombinant anticancer drugs, DNA, RNA, and CRISPR-Cas9, may be a suitable alternative for delivery of these biological entities into cells affected by cancer and other genetic diseases.

Synthesis of siRNA nanoparticles to silence plaque-destabilizing gene in atherosclerotic lesional macrophages

Macrophages in atherosclerotic lesions promote plaque progression and are an attractive therapeutic target in cardiovascular research. Here we present a protocol for synthesis of small interfering RNA (siRNA) nanoparticles (NP) that target lesional macrophages as a potential treatment for atherosclerosis. Ca²⁺/calmodulin-dependent protein kinase γ (CaMKIIγ) activity in macrophages of advanced human and mouse atherosclerotic plaques drives necrosis by downregulating the expression of the efferocytosis receptor MerTK. Therefore, selective inhibition of CaMKIIγ in lesional macrophages holds great promise for the treatment of advanced atherosclerosis. We recently developed a siRNA NP platform that can selectively silence CaMKIIγ in macrophages, resulting in increased plaque stability. We provide a detailed protocol for the synthesis of NP components, the preparation and characterization (physicochemical and in vitro) of siRNA NPs, and the evaluation of in vivo therapeutic effects of siRNA NPs and their biocompatibility in atherosclerotic mice. Our siRNA-loaded polymer-lipid hybrid NPs are constructed via a robust self-assembly method, exhibiting excellent in vivo features for systemic siRNA delivery. Following this protocol, it takes 3-5 d to prepare the siRNA NPs, 8-10 d to characterize the NPs and 4-5 weeks to evaluate their therapeutic effects in established atherosclerotic mice. By changing the RNA molecules loaded in the NPs, lesional macrophages can be targeted for the exploration and validation of new targets/pathways in atherosclerosis.

Construction of nanocarriers based on nucleic acids and their application in nanobiology delivery systems

In recent years, nanocarriers based on nucleic acids (NCNAs) have emerged as powerful and novel nanocarriers that are able to meet the demand for cancer cell-specific targeting. Functional dynamics analysis revealed good biocompatibility, low toxicity, and programmable structures, and their advantages include controllable size and modifiability. The development of novel hybrids has focused on the distinct roles of biosensing, drug and gene delivery, vaccine transport, photosensitization, counteracting drug resistance and functioning as carriers and logic gates. This review is divided into three parts: (1) DNA nanocarriers, (2) RNA nanocarriers, and (3) DNA/RNA hybrid nanocarriers and their biological applications. We also provide perspectives on possible future directions for growth in this field.

Nature-inspired dynamic gene-loaded nanoassemblies for the treatment of brain diseases

Gene therapy has great potential to treat brain diseases. However, genetic drugs need to overcome a cascade of barriers for their full potential. The conventional delivery systems often struggle to meet expectations. Natural biological particles that are highly optimized for specific functions in body, can inspire optimization of dynamic gene-loaded nanoassemblies (DGN). The DGN refer to gene loaded nanoassemblies whose functions and structures are changeable in response to the biological microenvironments or can dynamically interact with tissues or cells. The nature-inspired DGN can meet the needs in brain diseases treatment, including i) Non-elimination in blood (N), ii) Across the blood-brain barrier (A), iii) Targeting cells (T), iv) Efficient uptake (U), v) Controllable release (R), vi) Eyeable (E)-abbreviated as the "NATURE". In this Review, from nature to "NATURE", we mainly summarize the specific application of nature-inspired DGN in the "NATURE" cascade process. Furthermore, the Review provides an outlook for this field.

Confined growth of ZIF-8 in dendritic mesoporous organosilica nanoparticles as bioregulators for enhanced mRNA delivery in vivo

Zeolitic imidazolate framework-8 (ZIF-8) and its composites have diverse applications. However, ZIF-8-based nanocomposites are mainly used as carriers in biomolecular delivery, with the functions of metal ions and ligands rarely used to modulate the biofunctions. In this work, dendritic mesoporous organosilica nanoparticles (DMONs) with tetrasulfide bond were used to confine ZIF-8 growth partially inside mesopores as a novel nanocomposite for mRNA delivery. Each component in the resultant DMONs-ZIF-8 contributed to mRNA delivery applications, including high loading benefitting from positively charged ZIF-8 and large mesopores of DMONs, endosomal escape promoted by the imidazole ring of ZIF-8, and long-term glutathione depletion mediated by both zinc ions and tetrasulfide bond. Combined together, DMONs-ZIF-8 demonstrated enhanced mRNA translation and better transfection efficiency than commercial products and toxic polymer-modified DMONs in vitro and in vivo.

Zn2+ -Coordination-Driven RNA Assembly with Retained Integrity and Biological Functions

Metal-coordination-directed biomolecule crosslinking in nature has been used for synthesizing various biopolymers, including DNA, peptides, proteins, and polysaccharides. However, the RNA biopolymer has been avoided so far, as due to the poor stability of the RNA molecules, the formation of a biopolymer may alter the biological function of the molecules. Herein, for the first time, we report Zn²⁺ -driven RNA self-assembly forming spherical nanoparticles while retaining the integrity and biological function of RNA. Various functional RNAs of different compositions, shapes, and lengths from 20 to nearly 1000 nucleotides were used, highlighting the versatility of this approach. The assembled nanospheres possess a superior RNA-loading efficiency, pharmacokinetics, and bioavailability. In-vitro and in-vivo evaluation demonstrated mRNA delivery for expressing GFP proteins, and microRNA delivery to triple-negative breast cancer. This coordination-directed self-assembly behavior amplifies the horizons of RNA coordination chemistry and the application scope of RNA-based therapeutics.

PEGylation of mRNA by Hybridization of Complementary PEG-RNA Oligonucleotides Stabilizes mRNA without Using Cationic Materials

Messenger RNA (mRNA) delivery strategies are required to protect biologically fragile mRNA from ribonuclease (RNase) attacks to achieve efficient therapeutic protein expression. To tackle this issue, most mRNA delivery systems have used cationic components, which form electrostatically driven complexes with mRNA and shield encapsulated mRNA strands. However, cationic materials interact with anionic biomacromolecules in physiological environments, which leads to unspecific reactions and toxicities. To circumvent this issue of cation-based approaches, herein, we propose a cation-free delivery strategy by hybridization of PEGylated RNA oligonucleotides with mRNA. The PEG strands on the mRNA sterically and electrostatically shielded the mRNA, improving mRNA nuclease stability 15-fold after serum incubation compared with unhybridized mRNA. Eventually, the PEGylated mRNA induced nearly 20-fold higher efficiency of reporter protein expression than unhybridized mRNA in cultured cells. This study provides a platform to establish a safe and efficient cation-free mRNA delivery system.

Activable Multi-Modal Nanoprobes for Imaging Diagnosis and Therapy of Tumors

Malignant tumors have become one of the major causes of human death, but there remains a lack of effective methods for tiny tumor diagnosis, metastasis warning, clinical efficacy prediction, and effective treatment. In this context, localizing tiny tumors via imaging and non-invasively extracting molecular information related to tumor proliferation, invasion, metastasis, and drug resistance from the tumor microenvironment have become the most fundamental tasks faced by cancer researchers. Tumor-associated microenvironmental physiological parameters, such as hypoxia, acidic extracellular pH, protease, reducing conditions, and so forth, have much to do with prognostic indicators for cancer progression, and impact therapeutic administrations. By combining with various novel nanoparticle-based activatable probes, molecular imaging technologies can provide a feasible approach to visualize tumor-associated microenvironment parameters noninvasively and realize accurate treatment of tumors. This review focuses on the recent achievements in the design of “smart” nanomedicine responding to the tumor microenvironment-related features and highlights state-of- the-art technology in tumor imaging diagnosis and therapy.

Nanomaterial Delivery Systems for mRNA Vaccines

The recent success of mRNA vaccines in SARS-CoV-2 clinical trials is in part due to the development of lipid nanoparticle delivery systems that not only efficiently express the mRNA-encoded immunogen after intramuscular injection, but also play roles as adjuvants and in vaccine reactogenicity. We present an overview of mRNA delivery systems and then focus on the lipid nanoparticles used in the current SARS-CoV-2 vaccine clinical trials. The review concludes with an analysis of the determinants of the performance of lipid nanoparticles in mRNA vaccines.