Optimization of storage conditions for lipid nanoparticle-formulated self-replicating RNA vaccines

A comprehensive comparison of DNA and RNA vaccines

Nucleic acid technology has revolutionized vaccine development, enabling rapid design and production of RNA and DNA vaccines for prevention and treatment of diseases. The successful deployment of mRNA and plasmid DNA vaccines against COVID-19 has further validated the technology. At present, mRNA platform is prevailing due to its higher efficacy, while DNA platform is undergoing rapid evolution because it possesses unique advantages that can potentially overcome the problems associated with the mRNA platform. To help understand the recent performances of the two vaccine platforms and recognize their clinical potentials in the future, this review compares the advantages and drawbacks of mRNA and DNA vaccines that are currently known in the literature, in terms of development timeline, financial cost, ease of distribution, efficacy, safety, and regulatory approval of products. Additionally, the review discusses the ongoing clinical trials, strategies for improvement, and alternative designs of RNA and DNA platforms for vaccination.

Unlocking the Therapeutic Applicability of LNP-mRNA: Chemistry, Formulation, and Clinical Strategies

Messenger RNA (mRNA) has emerged as an innovative therapeutic modality, offering promising avenues for the prevention and treatment of a variety of diseases. The tremendous success of mRNA vaccines in effectively combatting coronavirus disease 2019 (COVID-19) evidences the unlimited medical and therapeutic potential of mRNA technology. Overcoming challenges related to mRNA stability, immunogenicity, and precision targeting has been made possible by recent advancements in lipid nanoparticles (LNPs). This review summarizes state-of-the-art LNP-mRNA-based therapeutics, including their structure, material compositions, design guidelines, and screening principles. Additionally, we highlight current preclinical and clinical trends in LNP-mRNA therapeutics in a broad range of treatments in ophthalmological conditions, cancer immunotherapy, gene editing, and rare-disease medicine. Particular attention is given to the translation and evolution of LNP-mRNA vaccines into a broader spectrum of therapeutics. We explore concerns in the aspects of inadequate extrahepatic targeting efficacy, elevated doses, safety concerns, and challenges of large-scale production procedures. This discussion may offer insights and perspectives on near- and long-term clinical development prospects for LNP-mRNA therapeutics.

Lipid nanoparticle (LNP) mediated mRNA delivery in cardiovascular diseases: Advances in genome editing and CAR T cell therapy

Cardiovascular diseases (CVDs) are the leading cause of global mortality among non-communicable diseases. Current cardiac regeneration treatments have limitations and may lead to adverse reactions. Hence, innovative technologies are needed to address these shortcomings. Messenger RNA (mRNA) emerges as a promising therapeutic agent due to its versatility in encoding therapeutic proteins and targeting "undruggable" conditions. It offers low toxicity, high transfection efficiency, and controlled protein production without genome insertion or mutagenesis risk. However, mRNA faces challenges such as immunogenicity, instability, and difficulty in cellular entry and endosomal escape, hindering its clinical application. To overcome these hurdles, lipid nanoparticles (LNPs), notably used in COVID-19 vaccines, have a great potential to deliver mRNA therapeutics for CVDs. This review highlights recent progress in mRNA-LNP therapies for CVDs, including Myocardial Infarction (MI), Heart Failure (HF), and hypercholesterolemia. In addition, LNP-mediated mRNA delivery for CAR T-cell therapy and CRISPR/Cas genome editing in CVDs and the related clinical trials are explored. To enhance the efficiency, safety, and clinical translation of mRNA-LNPs, advanced technologies like artificial intelligence (AGILE platform) in RNA structure design, and optimization of LNP formulation could be integrated. We conclude that the strategies to facilitate the extra-hepatic delivery and targeted organ tropism of mRNA-LNPs (SORT, ASSET, SMRT, and barcoded LNPs) hold great prospects to accelerate the development and translation of mRNA-LNPs in CVD treatment.

Identification of film-based formulations that move mRNA lipid nanoparticles out of the freezer

COVID-19 vaccines consisting of mRNA lipid nanoparticles (LNPs) encoding the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein antigen protected millions of people from severe disease; however, they must be stored frozen prior to use. The objective of this study was to evaluate the compatibility and stability of mRNA LNPs within a polymer-based film matrix. An optimized formulation of polymer base, glycerol, surfactants, and PEGylated lipid that prevents damage to the LNP due to physical changes during the film-forming process (osmotic stress, surface tension, spatial stress, and water loss) was identified. Surfactants added to LNP stock prior to mixing with other film components contributed to this effect. Formulations prepared at pH ≥ 8.5 extended transfection efficiency beyond 4 weeks at 4°C when combined with known nucleic acid stabilizers. mRNA LNPs were most stable in films when manufactured in an environment of ∼50% relative humidity. The optimized formulation offers 16-week stability at 4°C.

On the universality of viscosity in supersaturated binary aqueous sugar solutions: Cryopreservation by vitrification

Nowadays, the physical nature of supersaturated binary aqueous sugar solutions in the vicinity of the glass transition represents a very important issue due to their biological applications in cryopreservation of cells and tissues, food science and stabilization and storage of nano genetic drugs. We present the construction of the Supplemented Phase Diagram and the non-equilibrium nature of the undersaturated-supersaturated kinetic transition. The description of its thermodynamic nature is achieved through the study of behavior of their viscosity as temperature is lowered and concentration increased. In this work, we find a universal character for the viscosities of several sugar water solutions.

Lyophilizable Stem Cell-Hybrid Liposome with Long-Term Stability and High Targeting Capacity

The hybridization of liposome with stem cell membranes is an emerging technology to prepare the nanovehicle with the capacity of disease-responsive targeting. However, the long-term storage of this hybrid liposome has received limited attention in the literature, which is essential for its potential applicability in the clinic. Therefore, the preservation of long-term activity of stem cell-hybrid liposome using freeze-drying is investigated in the present study. Mesenchymal stem cell-hybrid liposome is synthesized and its feasibility for freeze-drying under different conditions is examined. Results reveal that pre-freezing the hybrid liposome at -20 °C in Tris buffer solution (pH 7.4) containing 10% trehalose can well preserve the liposomal structure for at least three months. Notably, major membrane proteins on the hybrid liposome are protected in this formulation and CXCR4-associated targeting capacity is maintained both in vitro and in vivo. Consequently, the hybrid liposome stored for three months demonstrates a comparable tumor inhibition as the fresh-prepared one. The present study provides the first insights into the long-term storage of stem cell hybrid liposome using lyophilization, which may make an important step forward in enhancing the long-term stability of these promising biomimetic nanovehicle and ease the logistics and the freeze-storage in the potential clinical applications.

Overcoming thermostability challenges in mRNA-lipid nanoparticle systems with piperidine-based ionizable lipids

Lipid nanoparticles (LNPs) have emerged as promising platforms for efficient in vivo mRNA delivery owing to advancements in ionizable lipids. However, maintaining the thermostability of mRNA/LNP systems remains challenging. While the importance of only a small amount of lipid impurities on mRNA inactivation is clear, a fundamental solution has not yet been proposed. In this study, we investigate an approach to limit the generation of aldehyde impurities that react with mRNA nucleosides through the chemical engineering of lipids. We demonstrated that piperidine-based lipids improve the long-term storage stability of mRNA/LNPs at refrigeration temperature as a liquid formulation. High-performance liquid chromatography analysis and additional lipid synthesis revealed that amine moieties of ionizable lipids play a vital role in limiting reactive aldehyde generation, mRNA-lipid adduct formation, and loss of mRNA function during mRNA/LNP storage. These findings highlight the importance of lipid design and help enhance the shelf-life of mRNA/LNP systems.

Recent Progress in Nucleic Acid Pulmonary Delivery toward Overcoming Physiological Barriers and Improving Transfection Efficiency

Pulmonary delivery of therapeutic agents has been considered the desirable administration route for local lung disease treatment. As the latest generation of therapeutic agents, nucleic acid has been gradually developed as gene therapy for local diseases such as asthma, chronic obstructive pulmonary diseases, and lung fibrosis. The features of nucleic acid, specific physiological structure, and pathophysiological barriers of the respiratory tract have strongly affected the delivery efficiency and pulmonary bioavailability of nucleic acid, directly related to the treatment outcomes. The development of pharmaceutics and material science provides the potential for highly effective pulmonary medicine delivery. In this review, the key factors and barriers are first introduced that affect the pulmonary delivery and bioavailability of nucleic acids. The advanced inhaled materials for nucleic acid delivery are further summarized. The recent progress of platform designs for improving the pulmonary delivery efficiency of nucleic acids and their therapeutic outcomes have been systematically analyzed, with the application and the perspectives of advanced vectors for pulmonary gene delivery.

Analytical techniques for the characterization of nanoparticles for mRNA delivery

Nanotechnology-assisted RNA delivery has gotten a tremendous boost over the last decade and made a significant impact in the development of life-changing vaccines and therapeutics. With increasing numbers of emerging lipid- and polymer-based RNA nanoparticles progressing towards the clinic, it has become apparent that the safety and efficacy of these medications depend on the comprehensive understanding of their critical quality attributes (CQAs). However, despite the rapid advancements in the field, the identification and reliable quantification of CQAs remain a significant challenge. To support these efforts, this review aims to summarize the present knowledge on CQAs based on the regulatory guidelines and to provide insights into the available analytical characterization techniques for RNA-loaded nanoparticles. In this context, routine and emerging analytical techniques are categorized and discussed, focusing on the operation principle, strengths, and potential limitations. Furthermore, the importance of complementary and orthogonal techniques for the measurement of CQAs is discussed in order to ensure the quality and consistency of analytical methods used, and address potential technique-based differences.

Nanomedomics

Nanomaterials have attractive physicochemical properties. A variety of nanomaterials such as inorganic, lipid, polymers, and protein nanoparticles have been widely developed for nanomedicine via chemical conjugation or physical encapsulation of bioactive molecules. Superior to traditional drugs, nanomedicines offer high biocompatibility, good water solubility, long blood circulation times, and tumor-targeting properties. Capitalizing on this, several nanoformulations have already been clinically approved and many others are currently being studied in clinical trials. Despite their undoubtful success, the molecular mechanism of action of the vast majority of nanomedicines remains poorly understood. To tackle this limitation, herein, this review critically discusses the strategy of applying multiomics analysis to study the mechanism of action of nanomedicines, named nanomedomics, including advantages, applications, and future directions. A comprehensive understanding of the molecular mechanism could provide valuable insight and therefore foster the development and clinical translation of nanomedicines.

Pharmaceutical Considerations and Metabolic Fate of Parenteral Lipid Nanoparticle Dosage Forms

The physical stability of parenteral dispersions for delivery of drugs to patients is of particular clinical importance, given their general overall superior bioavailability compared to other routes of administration. Although official pharmacopeial methods for lipid injectable emulsions have been established for triglyceride oil-in-water dispersions (i.e., "mini-emulsions") through USP Chapter <729>, no pharmaceopeial guidance exists for lipid nanoparticle (LNP)-based "micro-emulsions". At present, there are several LNP-based drugs approved for clinical use, including mRNA vaccines. Moreover, the increased interest in using mRNA as a platform technology for an array of potential therapeutic drug candidates increases the importance of developing appropriate methods to ensure their physical stability, safety and efficacy. For all dispersions and by various detection mechanisms (e.g., electrical, mechanical, mathematical), the fusion or growth of droplets/particles in the large-diameter tails of the particle size distribution (PSD) signals the onset of instability. Consequently, the measurement for LNP dispersions will require the use of a modified optical detection design in order to extend the lower particle detection limit into the "relative" large-diameter tail of the PSD for both light extinction and light-scattering methods based on single-particle optical sensing techniques. Fortunately, the technology is currently available and capable of providing the requisite quantitative analysis.

Sucrose Treatment Enhances the Electrotransfer of DNA by Activating Phospholipase A2

Our previous study discovered that sucrose and other non-reducing sugars (e.g., trehalose and raffinose) could be used to improve the electrotransfer (ET) of molecular cargo, including DNA, mRNA, and ribonucleoprotein in various cell lines and primary human cells in vitro and in vivo. To understand the molecular mechanisms of this improvement, we used RNA sequencing technology to analyze changes in the cell transcriptome after sucrose treatment. The results from our analysis demonstrated that the sucrose treatment upregulated phospholipase A2 and V-ATPase gene families, which could potentially influence the acidity of intracellular vesicles through augmenting vesicle fusion and the influx of proton, respectively. To determine how this upregulation affects ET efficiency, we treated cells with pharmaceutical inhibitors of phospholipase A2 and V-ATPase. The data demonstrated that the treatment with the phospholipase A2 inhibitor could reverse the ET improvement elicited by the sucrose treatment. The V-ATPase inhibitor treatment either had little influence or further enhanced the effect of the sucrose treatment on the ET efficiency. These observations provide a molecular explanation for our previous findings, demonstrating that the sucrose treatment primarily enhanced the ET efficiency by promoting vesicle trafficking and fusion through the activation of phospholipase A2.

Lipid Nanoparticle Encapsulation Empowers Poly(I:C) to Activate Cytoplasmic RLRs and Thereby Increases Its Adjuvanticity

Poly(I:C) is a synthetic analogue of dsRNA capable of activating both TLR3 and RLRs, such as MDA-5 and RIG-I, as pathogen recognition receptors. While poly(I:C) is known to provoke a robust type I IFN, type III IFN, and Th1 cytokine response, its therapeutic use as a vaccine adjuvant is limited due to its vulnerability to nucleases and poor uptake by immune cells. is encapsulated poly(I:C) into lipid nanoparticles (LNPs) containing an ionizable cationic lipid that can electrostatically interact with poly(I:C). LNP-formulated poly(I:C) triggered both lysosomal TLR3 and cytoplasmic RLRs, in vitro and in vivo, whereas poly(I:C) in an unformulated soluble form only triggered endosomal-localized TLR3. Administration of LNP-formulated poly(I:C) in mouse models led to efficient translocation to lymphoid tissue and concurrent innate immune activation following intramuscular (IM) administration, resulting in a significant increase in innate immune activation compared to unformulated soluble poly(I:C). When used as an adjuvant for recombinant full-length SARS-CoV-2 spike protein, LNP-formulated poly(I:C) elicited potent anti-spike antibody titers, surpassing those of unformulated soluble poly(I:C) by orders of magnitude and offered complete protection against a SARS-CoV-2 viral challenge in vivo, and serum from these mice are capable of significantly reducing viral infection in vitro.

Lipid Nanoparticle (LNP) Delivery Carrier-Assisted Targeted Controlled Release mRNA Vaccines in Tumor Immunity

In recent years, lipid nanoparticles (LNPs) have attracted extensive attention in tumor immunotherapy. Targeting immune cells in cancer therapy has become a strategy of great research interest. mRNA vaccines are a potential choice for tumor immunotherapy, due to their ability to directly encode antigen proteins and stimulate a strong immune response. However, the mode of delivery and lack of stability of mRNA are key issues limiting its application. LNPs are an excellent mRNA delivery carrier, and their structural stability and biocompatibility make them an effective means for delivering mRNA to specific targets. This study summarizes the research progress in LNP delivery carrier-assisted targeted controlled release mRNA vaccines in tumor immunity. The role of LNPs in improving mRNA stability, immunogenicity, and targeting is discussed. This review aims to systematically summarize the latest research progress in LNP delivery carrier-assisted targeted controlled release mRNA vaccines in tumor immunity to provide new ideas and strategies for tumor immunotherapy, as well as to provide more effective treatment plans for patients.

Lipid Nanoparticles Optimized for Targeting and Release of Nucleic Acid

Lipid nanoparticles (LNPs) are currently the most promising clinical nucleic acids drug delivery vehicles. LNPs prevent the degradation of cargo nucleic acids during blood circulation. Upon entry into the cell, specific components of the lipid nanoparticles can promote the endosomal escape of nucleic acids. These are the basic properties of lipid nanoparticles as nucleic acid carriers. As LNPs exhibit hepatic aggregation characteristics, enhancing targeting out of the liver is a crucial way to improve LNPs administrated in vivo. Meanwhile, endosomal escape of nucleic acids loaded in LNPs is often considered inadequate, and therefore, much effort is devoted to enhancing the intracellular release efficiency of nucleic acids. Here, different strategies to efficiently deliver nucleic acid delivery from LNPs are concluded and their mechanisms are investigated. In addition, based on the information on LNPs that are in clinical trials or have completed clinical trials, the issues that are necessary to be approached in the clinical translation of LNPs are discussed, which it is hoped will shed light on the development of LNP nucleic acid drugs.

Comparative Analysis of the Physicochemical and Biological Characteristics of Freeze-Dried PEGylated Cationic Solid Lipid Nanoparticles

Cationic solid-lipid nanoparticles (cSLNs) have become a promising tool for gene and RNA therapies. PEGylation (PEG) is crucial in enhancing particle stability and protection. We evaluated the impact of PEG on the physicochemical and biological characteristics of cholesteryl-oleate cSLNs (CO-cSLNs). Several parameters were analyzed, including the particle size, polydispersity index, zeta potential, shape, stability, cytotoxicity, and loading efficiency. Five different formulations with specific PEGs were developed and compared in both suspended and freeze-dried states. Small, homogeneous, and cationic suspended nanoparticles were obtained, with the Gelucire 50/13 (PEG-32 hydrogenated palm glycerides; Gelucire) and DSPE-mPEG2000 (1,2-distearoyl-phosphatidylethanolamine-methyl-polyethyleneglycol conjungate-2000; DSPE) formulations exhibiting the smallest particle size (~170 nm). Monodisperse populations of freeze-dried nanoparticles were also achieved, with particle sizes ranging from 200 to 300 nm and Z potential values of 30-35 mV. Notably, Gelucire again produced the smallest particle size (211.1 ± 22.4), while the DSPE and Myrj S100 (polyoxyethylene (100) stearate; PEG-100 Stearate) formulations had similar particle sizes to CO-cSLNs (~235 nm). The obtained PEGylated nanoparticles showed suitable properties: they were nontoxic, had acceptable morphology, were capable of forming SLNplexes, and were stable in both suspended and lyophilized states. These PEG-cSLNs are a potential resource for in vivo assays and have the advantage of employing cost-effective PEGs. Optimizing the lyophilization process and standardizing parameters are also recommended to maintain nanoparticle integrity.

Lipid-Based Nanoparticles for Drug/Gene Delivery: An Overview of the Production Techniques and Difficulties Encountered in Their Industrial Development

Over the past decade, the therapeutic potential of nanomaterials as novel drug delivery systems complementing conventional pharmacology has been widely acknowledged. Among these nanomaterials, lipid-based nanoparticles (LNPs) have shown remarkable pharmacological performance and promising therapeutic outcomes, thus gaining substantial interest in preclinical and clinical research. In this review, we introduce the main types of LNPs used in drug formulations such as liposomes, nanoemulsions, solid lipid nanoparticles, nanostructured lipid carriers, and lipid polymer hybrid nanoparticles, focusing on their main physicochemical properties and therapeutic potential. We discuss computational studies and modeling techniques to enhance the understanding of how LNPs interact with therapeutic cargo and to predict the potential effectiveness of such interactions in therapeutic applications. We also analyze the benefits and drawbacks of various LNP production techniques such as nanoprecipitation, emulsification, evaporation, thin film hydration, microfluidic-based methods, and an impingement jet mixer. Additionally, we discuss the major challenges associated with industrial development, including stability and sterilization, storage, regulatory compliance, reproducibility, and quality control. Overcoming these challenges and facilitating regulatory compliance represent the key steps toward LNP's successful commercialization and translation into clinical settings.

RNA Nanomedicine: Delivery Strategies and Applications

Delivery of RNA using nanomaterials has emerged as a new modality to expand therapeutic applications in biomedical research. However, the delivery of RNA presents unique challenges due to its susceptibility to degradation and the requirement for efficient intracellular delivery. The integration of nanotechnologies with RNA delivery has addressed many of these challenges. In this review, we discuss different strategies employed in the design and development of nanomaterials for RNA delivery. We also highlight recent advances in the pharmaceutical applications of RNA delivered via nanomaterials. Various nanomaterials, such as lipids, polymers, peptides, nucleic acids, and inorganic nanomaterials, have been utilized for delivering functional RNAs, including messenger RNA (mRNA), small interfering RNA, single guide RNA, and microRNA. Furthermore, the utilization of nanomaterials has expanded the applications of functional RNA as active pharmaceutical ingredients. For instance, the delivery of antigen-encoding mRNA using nanomaterials enables the transient expression of vaccine antigens, leading to immunogenicity and prevention against infectious diseases. Additionally, nanomaterial-mediated RNA delivery has been investigated for engineering cells to express exogenous functional proteins. Nanomaterials have also been employed for co-delivering single guide RNA and mRNA to facilitate gene editing of genetic diseases. Apart from the progress made in RNA medicine, we discuss the current challenges and future directions in this field.

Biophysical characterization of siRNA-loaded lipid nanoparticles with different PEG content in an aqueous system

Although lipid nanoparticles (LNP) are potential carriers of various pharmaceutical ingredients, further investigation for maintaining their stability under various environmental stressors must be performed. This study evaluated the influence of PEGylation and stress conditions on the stability of siRNA-loaded LNPs with different concentrations of PEG (0.5 mol%; 0.5 % PEG-LNP and 1.0 mol%; 1.0 % PEG-LNP) anchored to their surface. We applied end-over-end agitation, elevated temperature, and repeated freeze and thaw (F/T) cycles as physicochemical stressors of pH and ionic strength. Dynamic light scattering (DLS), flow imaging microscopy (FIM), and ionic-exchange chromatography (IEX) were to determine the degree of aggregation and change in siRNA content. The results indicate that 0.5 % PEG-LNP resisted aggregation only at low pH levels or with salt, whereas 1.0 % PEG-LNP had increased colloidal stability except at pH 4. 0.5 % PEG-LNP withstood aggregation until 71 °C and three cycles of F/T. In contrast, 1.0 % PEG-LNP maintained colloidal stability at 90 °C and seven F/T cycles. Moreover, 1.0 % PEG-LNP had higher siRNA stability under all stress conditions. Therefore, to ensure the stability of LNP and encapsulated siRNA, the PEG concentration must be carefully controlled while considering LNPs' colloidal instability mechanisms under various stress conditions.

mRNA Synthesis and Encapsulation in Ionizable Lipid Nanoparticles

mRNA vaccines have recently generated significant interest due to their success during the COVID-19 pandemic. Their success is due to advances in mRNA design and encapsulation into ionizable lipid nanoparticles (iLNPs). This has highlighted the potential for the use of mRNA-iLNPs in other settings such as cancer, gene therapy, or vaccines for different infectious diseases. Here, we describe the production of mRNA-iLNPs using commercially available reagents that are suitable for use as vaccines and therapeutics. This article contains detailed protocols for the synthesis of mRNA by in vitro transcription with enzymatic capping and tailing and the encapsulation of the mRNA into iLNPs using the ionizable lipid DLin-MC3-DMA. DLin-MC3-DMA is often used as a benchmark for new formulations and provides an efficient delivery vehicle for screening mRNA design. The protocol also describes how the formulation can be adapted to other lipids. Finally, a stepwise methodology is presented for the characterization and quality control of mRNA-iLNPs, including measuring mRNA concentration and encapsulation efficiency, particle size, and zeta potential. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Synthesis of mRNA by in vitro transcription and enzymatic capping and tailing Basic Protocol 2: Encapsulation of mRNA into ionizable lipid nanoparticles Alternate Protocol: Small-scale encapsulation of mRNA using preformed vesicles Basic Protocol 3: Characterization and quality control of mRNA ionizable lipid nanoparticles.

Engineering nanoparticle toolkits for mRNA delivery

The concept of using mRNA to produce its own medicine in situ in the body makes it an ideal drug candidate, holding great potential to revolutionize the way we approach medicine. The unique characteristics of mRNA, as well as its customizable biomedical functions, call for the rational design of delivery systems to protect and transport mRNA molecules. In this review, a nanoparticle toolkit is presented for the development of mRNA-based therapeutics from a drug delivery perspective. Nano-delivery systems derived from either natural systems or chemical synthesis, in the nature of organic or inorganic materials, are summarised. Delivery strategies in controlling the tissue targeting and mRNA release, as well as the role of nanoparticles in building and boosting the activity of mRNA drugs, have also been introduced. In the end, our insights into the clinical and translational development of mRNA nano-drugs are presented.

In vitro and in vivo evaluation of clinically-approved ionizable cationic lipids shows divergent results between mRNA transfection and vaccine efficacy

Ionizable cationic lipids (ICLs) play an essential role in the effectiveness of lipid nanoparticles (LNPs) for delivery of mRNA therapeutics and vaccines; therefore, critical evaluations of their biological performance would extend the existing knowledge in the field. In the present study, we examined the effects of the three clinically-approved ICLs, Dlin-MC3-DMA, ALC-0315 and SM-102, as well as DODAP, on the in vitro and in vivo performance of LNPs for mRNA delivery and vaccine efficacy. mRNA-LNPs containing these lipids were successfully prepared, which were all found to be very similar in their physicochemical properties and mRNA encapsulation efficiencies. Furthermore, the results of the in vitro studies indicated that these mRNA-LNPs were efficiently taken up by immortalized and primary immune cells with comparable efficiency; however, SM-102-based LNPs were superior in inducing protein expression and antigen-specific T cell proliferation. In contrast, in vivo studies revealed that LNPs containing ALC-0315 and SM-102 yielded almost identical protein expression levels in zebrafish embryos, which were significantly higher than Dlin-MC3-DMA-based LNPs. Additionally, a mouse immunization study demonstrated that a single-dose subcutaneous administration of the mRNA-LNPs resulted in a high production of intracellular cytokines by antigen-specific T cells, but no significant differences among the three clinically-approved ICLs were observed, suggesting a weak correlation between in vitro and in vivo outcomes. This study provides strong evidence that ICLs modulate the performance of mRNA-LNPs and that in vitro data does not adequately predict their behavior in vivo.

Modified mRNA Formulation and Stability for Cardiac and Skeletal Muscle Delivery

Directly injecting naked or lipid nanoparticle (LNP)-encapsulated modified mRNA (modRNA) allows rapid and efficient protein expression. This non-viral technology has been used successfully in modRNA vaccines against SARS-CoV-2. The main challenges in using modRNA vaccines were the initial requirement for an ultra-cold storage to preserve their integrity and concerns regarding unwanted side effects from this new technology. Here, we showed that naked modRNA maintains its integrity when stored up to 7 days at 4 °C, and LNP-encapsulated modRNA for up to 7 days at room temperature. Naked modRNA is predominantly expressed at the site of injection when delivered into cardiac or skeletal muscle. In comparison, LNP-encapsulated modRNA granted superior protein expression but also additional protein expression beyond the cardiac or skeletal muscle injection site. To overcome this challenge, we developed a skeletal-muscle-specific modRNA translation system (skeletal muscle SMRTs) for LNP-encapsulated modRNA. This system allows controlled protein translation predominantly at the site of injection to prevent potentially detrimental leakage and expression in major organs. Our study revealed the potential of the SMRTs platform for controlled expression of mRNA payload delivered intramuscularly. To conclude, our SMRTs platform for LNP-encapsulated modRNA can provide safe, stable, efficient and targeted gene expression at the site of injection.

Characterization of stability, safety and immunogenicity of the mRNA lipid nanoparticle vaccine Iribovax® against COVID-19 in nonhuman primates

mRNA-lipid nanoparticle (mRNA-LNP) vaccines have proved their efficacy, versatility and unprecedented manufacturing speed during the COVID-19 pandemic. Here we report on the physicochemical properties, thermostability, immunogenicity, and protective efficacy of the nucleoside-modified mRNA-LNP vaccine candidate Iribovax® (also called SNEG2c). Injection of BALB/c mice, rabbits and nonhuman primates with two doses of SNEG2c induced production of high-titers of SARS-CoV-2 spike-specific and receptor-binding domain (RBD)-neutralizing antibodies in immunized animals. In addition to the strong humoral response, SNEG2c elicited substantial Th1-biased T-cell response. Sera from rhesus macaques immunized with a low dose of the vaccine showed robust spike-specific antibody titers 3-24× as high as those in convalescent sera from a panel of COVID-19 patients and 50% virus neutralization geometric mean titer of 1024 against SARS-CoV-2. Strikingly, immunization with SNEG2c completely cleared infectious SARS-CoV-2 from the upper and lower respiratory tracts of challenged macaques and protected them from viral-induced lung and trachea lesions. In contrast, the non-vaccinated macaques developed moderate to severe pulmonary pathology after the viral challenge. We present the results of repeat-dose and local tolerance toxicity and thermostability studies showing how the physicochemical properties of the mRNA-LNPs change over time and demonstrating that SNEG2 is safe, well tolerated and stable for long-term. These results support the planned human trials of SNEG2c.

Biomaterial-based gene therapy

Gene therapy, a medical approach that involves the correction or replacement of defective and abnormal genes, plays an essential role in the treatment of complex and refractory diseases, such as hereditary diseases, cancer, and rheumatic immune diseases. Nucleic acids alone do not easily enter the target cells due to their easy degradation in vivo and the structure of the target cell membranes. The introduction of genes into biological cells is often dependent on gene delivery vectors, such as adenoviral vectors, which are commonly used in gene therapy. However, traditional viral vectors have strong immunogenicity while also presenting a potential infection risk. Recently, biomaterials have attracted attention for use as efficient gene delivery vehicles, because they can avoid the drawbacks associated with viral vectors. Biomaterials can improve the biological stability of nucleic acids and the efficiency of intracellular gene delivery. This review is focused on biomaterial-based delivery systems in gene therapy and disease treatment. Herein, we review the recent developments and modalities of gene therapy. Additionally, we discuss nucleic acid delivery strategies, with a focus on biomaterial-based gene delivery systems. Furthermore, the current applications of biomaterial-based gene therapy are summarized.

Lipid-functionalized gold nanorods with plug-to-direct mitochondria targeting ligand for synergetic photothermal-chemotherapy of tumor therapy

Mitochondria targeting therapeutic strategies are promising for more effective and precise cancer therapy. Photothermal therapy are extensively studied as noninvasive cancer treatment. With regards to all-in-one nanocarrier-mediated drug delivery platform, it is still a challenge to enhance one of the features but not compromise other merits. Herein, we present a mitochondrial targeting photothermal-chemotherapy all-in-one nanoplatform involving lipid-functionalized gold nanorods (AuNR) with plug-to-direct mitochondria targeting ligand for synergetic enhanced tumor therapy. Firstly, AuNR were modified by DSPE-PEG-SH owing to the special affinity of sulfhydryl group and gold. And then, DSPE-PEG-DOX with mitochondrial targeting character was directly inserted into DSPE-PEG-SH layer. Meanwhile, paclitaxel (PTX) was loaded in hydrophobic region of the lipid layer. Quite different from introducing additional mitochondrial targeting molecules, we incorporated amphiphilic DSPE-PEG-DOX into a DSPE-PEG-SH layer modified around AuNR to achieve both mitochondrial targeting, photothermal and dual drug loading in a simple AuNR-lipid-DOX/PTX platform, in the case that efficiently enhanced production of reactive oxygen species (ROS) in mitochondria and excellent anti-tumor efficacy were achieved. With good biocompatibility, the constructed nanoplatform based on lipid-functionalized AuNR synergistically combined mitochondrial targeted DSPE-PEG-DOX with mitochondrial-acted PTX and photothermal therapy (PTT), which provided a feasible strategy for organelle-targeted combination PTT-chemotherapy to improve therapeutic effects.

Development, Safety, Issues, and Challenges of the SARS-CoV-2 Vaccine

It has been reported that some mutant strains of the new coronavirus escape from neutralizing antibodies acquired by recoverees and vaccine recipients, in which the Omicron strain (B [...]