A novel mechanism for the loss of mRNA activity in lipid nanoparticle delivery systems

Amplifying gene expression with RNA-targeted therapeutics

Many diseases are caused by insufficient expression of mutated genes and would benefit from increased expression of the corresponding protein. However, in drug development, it has been historically easier to develop drugs with inhibitory or antagonistic effects. Protein replacement and gene therapy can achieve the goal of increased protein expression but have limitations. Recent discoveries of the extensive regulatory networks formed by non-coding RNAs offer alternative targets and strategies to amplify the production of a specific protein. In addition to RNA-targeting small molecules, new nucleic acid-based therapeutic modalities that allow highly specific modulation of RNA-based regulatory networks are being developed. Such approaches can directly target the stability of mRNAs or modulate non-coding RNA-mediated regulation of transcription and translation. This Review highlights emerging RNA-targeted therapeutics for gene activation, focusing on opportunities and challenges for translation to the clinic.

Lipid Nanoparticle-Enabled Intracellular Delivery of Prime Editors

Prime editing is an advanced gene editing platform with potential to correct almost any disease-causing mutation. As genome editors have evolved, their size and complexity have increased, hindering delivery technologies with low-carrying capacity and endosomal escape. We formulated an array of lipid nanoparticles (LNPs) containing prime editors (PEs). We were able to encapsulate PEs in LNPs and confirmed the presence of PE mRNA and two different guide RNAs using HPLC. In addition, we developed a novel reporter cell line for rapid identification of LNPs suited for prime editing. A 54% prime editing rate was observed with enhanced LNPs (eLNPs) containing the cholesterol analog β-sitosterol at optimal ratios of RNA cargoes. eLNPs displayed a polyhedral morphology and a more fluid membrane state that led to improved endosomal escape, eventually causing onset of editing within 9 h and reaching maximum efficiency after 24 h. Hence, PEs delivered using LNPs can propel a new wave of therapies for many additional targets potentially enabling a range of new applications.

Development of an Alcohol Dilution-Lyophilization Method for the Preparation of mRNA-LNPs with Improved Storage Stability

The lipid nanoparticle (LNP) is one of the promising nanotechnologies for the delivery of RNA molecules, such as small interfering RNA (siRNA) and messenger RNA (mRNA). A series of LNPs that contain an mRNA encoding the antigen protein of SARS-CoV-2 were already approved as RNA vaccines against this infectious disease. Since LNP formulations are generally metastable, their physicochemical properties are expected to shift toward a more stable state during the long-time storage of suspensions. The current mRNA vaccines are supplied in the form of frozen formulations with a cryoprotectant for preventing deterioration. They must be stored in a freezer at temperatures from -80 °C to -15 °C. It is thought that therapeutic applications of this mRNA-LNP technology could be accelerated if a new formulation that permits mRNA-LNPs to be stored under milder conditions were available. We previously reported on a one-pot method for producing siRNA-encapsulated LNPs by combining freeze-drying technology with the conventional alcohol dilution method (referred to herein as the "alcohol dilution-lyophilization method"). In this study, this method was applied to the preparation of mRNA-LNPs to provide a freeze-dried formulation of mRNA LNPs. The resulting formulation can be stored at 4 °C for at least 4 months.

Emerging Progress of RNA-Based Antitumor Therapeutics

RNA-based therapeutics (e.g., mRNAs, siRNAs, microRNAs, ASOs, and saRNAs) have considerable potential for tumor treatment. The development and optimization of RNA modifications and delivery systems enable the stable and efficient delivery of RNA cargos in vivo to elicit an antitumor response. Targeted RNA-based therapeutics with multiple specificities and high efficacies are now available. In this review, we discuss progress in RNA-based antitumor therapeutics, including mRNAs, siRNAs, miRNAs, ASOs, saRNAs, RNA aptamers, and CRISPR-based gene editing. We focus on the immunogenicity, stability, translation efficiency, and delivery of RNA drugs, and summarize their optimization and the development of delivery systems. In addition, we describe the mechanisms by which RNA-based therapeutics induce antitumor responses. Furthermore, we review the merits and limitations of RNA cargos and their therapeutic potential for cancers.

Oligonucleotide mapping via mass spectrometry to enable comprehensive primary structure characterization of an mRNA vaccine against SARS-CoV-2

Oligonucleotide mapping via liquid chromatography with UV detection coupled to tandem mass spectrometry (LC-UV-MS/MS) was recently developed to support development of Comirnaty, the world's first commercial mRNA vaccine which immunizes against the SARS-CoV-2 virus. Analogous to peptide mapping of therapeutic protein modalities, oligonucleotide mapping described here provides direct primary structure characterization of mRNA, through enzymatic digestion, accurate mass determinations, and optimized collisionally-induced fragmentation. Sample preparation for oligonucleotide mapping is a rapid, one-pot, one-enzyme digestion. The digest is analyzed via LC-MS/MS with an extended gradient and resulting data analysis employs semi-automated software. In a single method, oligonucleotide mapping readouts include a highly reproducible and completely annotated UV chromatogram with 100% maximum sequence coverage, and a microheterogeneity assessment of 5' terminus capping and 3' terminus poly(A)-tail length. Oligonucleotide mapping was pivotal to ensure the quality, safety, and efficacy of mRNA vaccines by providing: confirmation of construct identity and primary structure and assessment of product comparability following manufacturing process changes. More broadly, this technique may be used to directly interrogate the primary structure of RNA molecules in general.

An Overview of the Stability and Delivery Challenges of Commercial Nucleic Acid Therapeutics

Nucleic acid (NA)-based biopharmaceuticals have emerged as promising therapeutic modalities. NA therapeutics are a diverse class of RNA and DNA and include antisense oligonucleotides, siRNA, miRNA, mRNA, small activating RNA, and gene therapies. Meanwhile, NA therapeutics have posed significant stability and delivery challenges and are expensive. This article discusses the challenges and opportunities for achieving stable formulations of NAs with novel drug delivery systems (DDSs). Here we review the current progress in the stability issues and the significance of novel DDSs associated with NA-based biopharmaceuticals, as well as mRNA vaccines. We also highlight the European Medicines Agency (EMA) and US Food and Drug Administration (FDA)-approved NA-based therapeutics with their formulation profiles. NA therapeutics could impact future markets if the remaining challenges and requirements are addressed. Regardless of the limited information available for NA therapeutics, reviewing and collating the relevant facts and figures generates a precious resource for formulation experts familiar with the NA therapeutics' stability profile, their delivery challenges, and regulatory acceptance.

Biodegradable Cationic and Ionizable Cationic Lipids: A Roadmap for Safer Pharmaceutical Excipients

Cationic and ionizable cationic lipids are broadly applied as auxiliary agents, but their use is associated with adverse effects. If these excipients are rapidly degraded to endogenously occurring metabolites such as amino acids and fatty acids, their toxic potential can be minimized. So far, synthesized and evaluated biodegradable cationic and ionizable cationic lipids already showed promising results in terms of functionality and safety. Within this review, an overview about the different types of such biodegradable lipids, the available building blocks, their synthesis and cleavage by endogenous enzymes is provided. Moreover, the relationship between the structure of the lipids and their toxicity is described. Their application in drug delivery systems is critically discussed and placed in context with the lead compounds used in mRNA vaccines. Moreover, their use as preservatives is reviewed, guidance for their design is provided, and an outlook on future developments is given.

Precise and systematic end group chemistry modifications on PAMAM and poly(l-lysine) dendrimers to improve cytosolic delivery of mRNA

Here, we aimed to chemically modify PAMAM dendrimers using lysine as a site-selective anchor for successfully delivering mRNA while maintaining a low toxicity profile. PAMAM dendrimers were multi-functionalised by amidation reactions in a regioselective, quantitative and stepwise manner with carefully selected property-modifying surface groups. Alternatively, novel lysine-based dendrimers were prepared in the same manner with the aim to unlock their potential in gene delivery. The modified dendrimers were then formulated with Cy5-EGFP mRNA by bulk mixing via liquid handling robotics across different nitrogen to phosphate ratios. The resulting dendriplexes were characterised by size, charge, mRNA encapsulation, and mRNA binding affinity. Finally, their in-vitro delivery activity was systematically investigated across key cellular trafficking stages to relate chemical design to cellular effect. We demonstrate our findings in different cell lines and benchmarked relative to a commercially available transfection agent, jetPEI®. We demonstrate that specific surface modifications are required to generate small, reliable and well-encapsulated positively charged dendriplex complexes. Furthermore, we show that introduction of fusogenic groups is essential for driving endosomal escape and achieving cellular delivery and translation of mRNA in these cell lines.

Metal-Organic Frameworks Nanocarriers for Functional Nucleic Acid Delivery in Biomedical Applications

Metal-organic frameworks (MOFs), a distinctive funtionalmaterials which is constructed by various metal ions and organic molecules, have gradually attracted researchers' attention from they were founded. In the last decade, MOFs emerge as a biomedical material with potential applications due to their unique properties. However, the MOFs performed as nanocarriers for functional nucleic acid delivery in biomedical applications rarely summarized. In this review, we introduce recent developments of MOFs for nucleic acid delivery in various biologically relevant applications, with special emphasis on cancer therapy (including siRNA, ASO, DNAzyme, miRNA and CpG oligodeoxynucleotides), bioimaging, biosensors and separation of biomolecules. We expect the accomplishment of this review could benefit certain researchers in biomedical field to develop novel sophisticated nanocarriers for functional nucleic acid delivery based on the promising material of MOFs.

Research Advances on the Stability of mRNA Vaccines

Compared to other vaccines, the inherent properties of messenger RNA (mRNA) vaccines and their interaction with lipid nanoparticles make them considerably unstable throughout their life cycles, impacting their effectiveness and global accessibility. It is imperative to improve mRNA vaccine stability and investigate the factors influencing stability. Since mRNA structure, excipients, lipid nanoparticle (LNP) delivery systems, and manufacturing processes are the primary factors affecting mRNA vaccine stability, optimizing mRNA structure and screening excipients can effectively improve mRNA vaccine stability. Moreover, improving manufacturing processes could also prepare thermally stable mRNA vaccines with safety and efficacy. Here, we review the regulatory guidance associated with mRNA vaccine stability, summarize key factors affecting mRNA vaccine stability, and propose a possible research path to improve mRNA vaccine stability.

Ready-to-Use-Type Lyophilized Lipid Nanoparticle Formulation for the Postencapsulation of Messenger RNA

Based on the clinical success of an in vitro transcribed mRNA (IVT-mRNA) that is encapsulated in lipid nanoparticles (mRNA-LNPs), there is a growing demand by researchers to test whether their own biological findings might be applicable for use in mRNA-based therapeutics. However, the equipment and/or know-how required for manufacturing such nanoparticles is often inaccessible. To encourage more innovation in mRNA therapeutics, a simple method for preparing mRNA-LNPs is prerequisite. In this study, we report on a method for encapsulating IVT-mRNA into LNPs by rehydrating a Ready-to-Use empty freeze-dried LNP (LNPs(RtoU)) formulation with IVT-mRNA solution followed by heating. The resulting mRNA-LNPs(RtoU) had a similar intraparticle structure compared to the mRNA-LNPs prepared by conventional microfluidic mixing. In vivo genome editing, a promising application of these types of mRNA-LNPs, was accomplished using the LNPs(RtoU) containing co-encapsulated Cas9-mRNA and a small guide RNA.

Challenges and emerging trends in liquid chromatography-based analyses of mRNA pharmaceuticals

Lipid encapsulated messenger RNA (LNP mRNA) has garnered a significant amount of interest from the pharmaceutical industry and general public alike. This attention has been catalyzed by the clinical success of LNP mRNA for SARS-CoV-2 vaccination as well as future promises that might be fulfilled by the biotechnology pipeline, such as the in vivo delivery of a CRISPR/Cas9 complex that can edit patient cells to reduce levels of low-density lipoprotein. LNP mRNAs are comprised of various chemically diverse molecules brought together in a sophisticated intermolecular complex. This can make it challenging to achieve thorough analytical characterization. Nevertheless, liquid chromatography is becoming an increasingly relied upon technique for LNP mRNA analyses. Although there have been significant advances in all types of LNP mRNA analyses, this review focuses on recent developments and the possibilities of applying anion exchange (AEX) and ion pairing reversed phase (IP-RP) liquid chromatography for intact mRNAs as well as techniques for oligo mapping analysis, 5' endcap testing and lipid compositional assays.

The Storage and In-Use Stability of mRNA Vaccines and Therapeutics: Not A Cold Case

The remarkable impact of mRNA vaccines on mitigating disease and improving public health has been amply demonstrated during the COVID-19 pandemic. Many new mRNA-based vaccine and therapeutic candidates are in development, yet the current reality of their stability limitations requires their frozen storage. Numerous challenges remain to improve formulated mRNA stability and enable refrigerator storage, and this review provides an update on developments to tackle this multi-faceted stability challenge. We describe the chemistry underlying mRNA degradation during storage and highlight how lipid nanoparticle (LNP) formulations are a double-edged sword: while LNPs protect mRNA against enzymatic degradation, interactions with and between LNP excipients introduce additional risks for mRNA degradation. We also discuss strategies to improve mRNA stability both as a drug substance (DS) and a drug product (DP) including the (1) design of the mRNA molecule (nucleotide selection, primary and secondary structures), (2) physical state of the mRNA-LNP complexes, (3) formulation composition and purity of the components, and (4) DS and DP manufacturing processes. Finally, we summarize analytical control strategies to monitor and assure the stability of mRNA-based candidates, and advocate for an integrated analytical and formulation development approach to further improve their storage, transport, and in-use stability profiles.

Why mRNA-ionizable LNPs formulations are so short-lived: causes and way-out

INTRODUCTION

Messenger ribonucleic acid (mRNA) and small interfering RNA (siRNA) are biological molecules that can be heated, frozen, lyophilized, precipitated, or re-suspended without degradation. Currently, ionizable lipid nanoparticles (LNPs) are a promising approach for mRNA therapy. However, the long-term shelf-life stability of mRNA-ionizable LNPs is one of the open questions about their use and safety. At an acidic pH, ionizable lipids shield anionic mRNA. However, the stability of mRNA under storage conditions remains a mystery. Moreover, ionizable LNPs excipients also cause instability during long-term storage.

AREA COVERED

This paper aims to illustrate why mRNA-ionizable LNPs have such a limited storage half-life. For the first time, we compile the tentative reasons for the short half-life and ultra-cold storage of mRNA-LNPs in the context of formulation excipients. The article also provided possible ways of prolonging the lifespan of mRNA-ionizable LNPs during long storage.

EXPERT OPINION

mRNA-ionizable LNPs are the future of genetic medicine. Current limitations of the formulation can be overcome by an advanced drying process or a whole new hybrid formulation strategy to extend the shelf life of mRNA-ionizable LNPs. A breakthrough technology may open up new research directions for producing thermostable and safe mRNA-ionizable LNPs at room temperature.

Lyophilized mRNA-lipid nanoparticle vaccines with long-term stability and high antigenicity against SARS-CoV-2

Advanced mRNA vaccines play vital roles against SARS-CoV-2. However, most current mRNA delivery platforms need to be stored at -20 °C or -70 °C due to their poor stability, which severely restricts their availability. Herein, we develop a lyophilization technique to prepare SARS-CoV-2 mRNA-lipid nanoparticle vaccines with long-term thermostability. The physiochemical properties and bioactivities of lyophilized vaccines showed no change at 25 °C over 6 months, and the lyophilized SARS-CoV-2 mRNA vaccines could elicit potent humoral and cellular immunity whether in mice, rabbits, or rhesus macaques. Furthermore, in the human trial, administration of lyophilized Omicron mRNA vaccine as a booster shot also engendered strong immunity without severe adverse events, where the titers of neutralizing antibodies against Omicron BA.1/BA.2/BA.4 were increased by at least 253-fold after a booster shot following two doses of the commercial inactivated vaccine, CoronaVac. This lyophilization platform overcomes the instability of mRNA vaccines without affecting their bioactivity and significantly improves their accessibility, particularly in remote regions.

Characterization of BNT162b2 mRNA to Evaluate Risk of Off-Target Antigen Translation

mRNA vaccines have been established as a safe and effective modality, thanks in large part to the expedited development and approval of COVID-19 vaccines. In addition to the active, full-length mRNA transcript, mRNA fragment species can be present as a byproduct of the cell-free transcription manufacturing process or due to mRNA hydrolysis. In the current study, mRNA fragment species from BNT162b2 mRNA were isolated and characterized. The translational viability of intact and fragmented mRNA species was further explored using orthogonal expression systems to understand the risk of truncated spike protein or off-target antigen translation. The study demonstrates that mRNA fragments are primarily derived from premature transcriptional termination during manufacturing, and only full-length mRNA transcripts are viable for expression of the SARS-CoV-2 spike protein antigen.

Research progress on circular RNA vaccines

Owing to the success of linear mRNA coronavirus disease 2019 (COVID-19) vaccines, biopharmaceutical companies and research teams worldwide have attempted to develop more stable circular RNA (circRNA) vaccines and have achieved some preliminary results. This review aims to summarize key findings and important progress made in circRNA research, the in vivo metabolism and biological functions of circRNAs, and research progress and production process of circRNA vaccines. Further, considerations regarding the quality control of circRNA vaccines are highlighted herein, and the main challenges and problem-solving strategies in circRNA vaccine development and quality control are outlined to provide a reference for circRNA vaccine-related research.

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.

mRNA COVID-19 Vaccines-Facts and Hypotheses on Fragmentation and Encapsulation

BACKGROUND

The adventure of the mRNA vaccine began thirty years ago in the context of influenza. This consisted in encapsulating the mRNA coding for a viral protein in a lipid particle. We show how the mRNA encoding S protein has been modified for that purpose in the context of the anti-SARS-CoV-2 vaccination.

RESULTS

by using data coming from genetic and epidemiologic databases, we show the theoretical possibility of fragmentation of this mRNA into small RNA sequences capable of inhibiting important bio-syntheses such as the production of beta-globin.

DISCUSSION

we discuss two aspects related to mRNA vaccine: (i) the plausibility of mRNA fragmentation, and (ii) the role of liposomal nanoparticles (LNPs) used in the vaccine and their impact on mRNA biodistribution.

CONCLUSION

we insist on the need to develop lipid nanoparticles allowing personalized administration of vaccines and avoiding adverse effects due to mRNA fragmentation and inefficient biodistribution. Hence, we recommend (i) adapting the mRNA of vaccines to the least mutated virus proteins and (ii) personalizing its administration to the categories of chronic patients at risk most likely to suffer from adverse effects.

Innate immune mechanisms of mRNA vaccines

The lipid nanoparticle (LNP)-encapsulated, nucleoside-modified mRNA platform has been used to generate safe and effective vaccines in record time against COVID-19. Here, we review the current understanding of the manner whereby mRNA vaccines induce innate immune activation and how this contributes to protective immunity. We discuss innate immune sensing of mRNA vaccines at the cellular and intracellular levels and consider the contribution of both the mRNA and the LNP components to their immunogenicity. A key message that is emerging from recent observations is that the LNP carrier acts as a powerful adjuvant for this novel vaccine platform. In this context, we highlight important gaps in understanding and discuss how new insight into the mechanisms underlying the effectiveness of mRNA-LNP vaccines may enable tailoring mRNA and carrier molecules to develop vaccines with greater effectiveness and milder adverse events in the future.

Stability Study of mRNA-Lipid Nanoparticles Exposed to Various Conditions Based on the Evaluation between Physicochemical Properties and Their Relation with Protein Expression Ability

Lipid nanoparticles (LNPs) are currently in the spotlight as delivery systems for mRNA therapeutics and have been used in the Pfizer/BioNTech and Moderna COVID-19 vaccines. mRNA-LNP formulations have been indicated to require strict control, including maintenance at fairly low temperatures during their transport and storage. Since it is a new pharmaceutical modality, there is a lack of information on the systematic investigation of how storage and handling conditions affect the physicochemical properties of mRNA-LNPs and their protein expression ability. In this study, using the mRNA-LNPs with standard composition, we evaluated the effects of temperature, cryoprotectants, vibration, light exposure, and syringe aspiration from the vials on the physicochemical properties of nanoparticles in relation to their in vitro/in vivo protein expression ability. Among these factors, storage at -80 °C without a cryoprotectant caused a decrease in protein expression, which may be attributed to particle aggregation. Exposure to vibration and light also caused similar changes under certain conditions. Exposure to these factors can occur during laboratory and hospital handling. It is essential to have sufficient knowledge of the stability of mRNA-LNPs in terms of their physical properties and protein expression ability at an early stage to ensure reproducible research and development and medical care.

Simultaneous quantification of multiple RNA cargos co-loaded into nanoparticle-based delivery systems

Robust, sensitive, and versatile analytical methods are essential for quantification of RNA drug cargos loaded into nanoparticle-based delivery systems. However, simultaneous quantification of multiple RNA cargos co-loaded into nanoparticles remains a challenge. Here, we developed and validated the use of ion-pair reversed-phase high-performance liquid chromatography combined with UV detection (IP-RP-HPLC-UV) for simultaneous quantification of single- and double-stranded RNA cargos. Complete extraction of RNA cargo from the nanoparticle carrier was achieved using a phenol:chloroform:isoamyl alcohol mixture. Separations were performed using either a C₁₈ or a PLRP-S column, eluted with 0.1 M triethylammonium acetate (TEAA) solution as ion-pairing reagent (eluent A), and 0.1 M TEAA containing 25 % (v/v) CH₃CN as eluent B. These methods were applied to quantify mRNA and polyinosinic:polycytidylic acid co-loaded into lipid-polymer hybrid nanoparticles, and single-stranded oligodeoxynucleotide donors and Alt-R CRISPR single guide RNAs co-loaded into lipid nanoparticles. The developed methods were sensitive (limit of RNA quantification < 60 ng), linear (R² > 0.997), and accurate (≈ 100 % recovery of RNA spiked in nanoparticles). Hence, the present study may facilitate convenient quantification of multiple RNA cargos co-loaded into nanoparticle-based delivery systems.

Design Strategies for and Stability of mRNA-Lipid Nanoparticle COVID-19 Vaccines

Messenger RNA (mRNA) vaccines have shown great preventive potential in response to the novel coronavirus (COVID-19) pandemic. The lipid nanoparticle (LNP), as a non-viral vector with good safety and potency factors, is applied to mRNA delivery in the clinic. Among the recently FDA-approved SARS-CoV-2 mRNA vaccines, lipid-based nanoparticles have been shown to be well-suited to antigen presentation and enhanced immune stimulation to elicit potent humoral and cellular immune responses. However, a design strategy for optimal mRNA-LNP vaccines has not been fully elaborated. In this review, we comprehensively and systematically discuss the research strategies for mRNA-LNP vaccines against COVID-19, including antigen and lipid carrier selection, vaccine preparation, quality control, and stability. Meanwhile, we also discuss the potential development directions for mRNA-LNP vaccines in the future. We also conduct an in-depth review of those technologies and scientific insights in regard to the mRNA-LNP field.

mRNA vaccines in the prevention and treatment of diseases

Messenger ribonucleic acid (mRNA) vaccines made their successful public debut in the effort against the COVID-19 outbreak starting in late 2019, although the history of mRNA vaccines can be traced back decades. This review provides an overview to discuss the historical course and present situation of mRNA vaccine development in addition to some basic concepts that underly mRNA vaccines. We discuss the general preparation and manufacturing of mRNA vaccines and also discuss the scientific advances in the in vivo delivery system and evaluate popular approaches (i.e., lipid nanoparticle and protamine) in detail. Next, we highlight the clinical value of mRNA vaccines as potent candidates for therapeutic treatment and discuss clinical progress in the treatment of cancer and coronavirus disease 2019. Data suggest that mRNA vaccines, with several prominent advantages, have achieved encouraging results and increasing attention due to tremendous potential in disease management. Finally, we suggest some potential directions worthy of further investigation and optimization. In addition to basic research, studies that help to facilitate storage and transportation will be indispensable for practical applications.

Biomaterial-Mediated Protein Expression Induced by Peptide-mRNA Nanoparticles Embedded in Lyophilized Collagen Scaffolds

In our aging society, the number of patients suffering from poorly healing bone defects increases. Bone morphogenetic proteins (BMPs) are used in the clinic to promote bone regeneration. However, poor control of BMP delivery and thus activity necessitates high doses, resulting in adverse effects and increased costs. It has been demonstrated that messenger RNA (mRNA) provides a superior alternative to protein delivery due to local uptake and prolonged expression restricted to the site of action. Here, we present the development of porous collagen scaffolds incorporating peptide-mRNA nanoparticles (NPs). Nanoparticles were generated by simply mixing aqueous solutions of the cationic cell-penetrating peptide PepFect14 (PF14) and mRNA. Peptide-mRNA complexes were uniformly distributed throughout the scaffolds, and matrices fully preserved cell attachment and viability. There was a clear dependence of protein expression on the incorporated amount of mRNA. Importantly, after lyophilization, the mRNA formulation in the collagen scaffolds retained activity also at 4 °C over two weeks. Overall, our results demonstrate that collagen scaffolds incorporating peptide-mRNA complexes hold promise as off-the-shelf functional biomaterials for applications in regenerative medicine and constitute a viable alternative to lipid-based mRNA formulations.

A Biopharmaceutical Perspective on Higher-Order Structure and Thermal Stability of mRNA Vaccines

Preservation of the integrity of macromolecular higher-order structure is a tenet central to achieving biologic drug and vaccine product stability toward manufacturing, distribution, storage, handling, and administration. Given that mRNA lipid nanoparticles (mRNA-LNPs) are held together by an intricate ensemble of weak forces, there are some intriguing parallels to biologic drugs, at least at first glance. However, mRNA vaccines are not without unique formulation and stabilization challenges derived from the instability of unmodified mRNA and its limited history as a drug or vaccine. Since certain learning gained from biologic drug development may be applicable for the improvement of mRNA vaccines, we present a perspective on parallels and contrasts between the emerging role of higher-order structure pertaining to mRNA-LNPs compared to pharmaceutical proteins. In a recent publication, the location of mRNA encapsulated within lipid nanoparticles was identified, revealing new insights into the LNP structure, nanoheterogeneity, and microenvironment of the encapsulated mRNA molecules [Brader et al. Biophys. J. 2021, 120, 2766]. We extend those findings by considering the effect of encapsulation on mRNA thermal unfolding with the observation that encapsulation in LNPs increases mRNA unfolding temperatures.

An imidazole modified lipid confers enhanced mRNA-LNP stability and strong immunization properties in mice and non-human primates

The mRNA vaccine technology has promising applications to fight infectious diseases as demonstrated by the licensing of two mRNA-based vaccines, Comirnaty® (Pfizer/BioNtech) and Spikevax® (Moderna), in the context of the Covid-19 crisis. Safe and effective delivery systems are essential to the performance of these vaccines and lipid nanoparticles (LNPs) able to entrap, protect and deliver the mRNA in vivo are considered by many as the current "best in class". Nevertheless, current mRNA/LNP vaccine technology has still some limitations, one of them being thermostability, as evidenced by the ultracold distribution chain required for the licensed vaccines. We found that the thermostability of mRNA/LNP, could be improved by a novel imidazole modified lipid, DOG-IM4, in combination with standard helper lipids. DOG-IM4 comprises an ionizable head group consisting of imidazole, a dioleoyl lipid tail and a short flexible polyoxyethylene spacer between the head and tail. Here we describe the synthesis of DOG-IM4 and show that DOG-IM4 LNPs confer strong immunization properties to influenza HA mRNA in mice and macaques and a remarkable stability to the encapsulated mRNA when stored liquid in phosphate buffered saline at 4 °C. We speculate the increased stability to result from some specific attributes of the lipid's imidazole head group.

Diving into the Structural Details of In Vitro Transcribed mRNA Using Liquid Chromatography–Mass Spectrometry-Based Oligonucleotide Profiling

The production process of in vitro transcribed messenger RNA (IVT-mRNA)-based vaccines has matured in recent years, partly due to the fight against infectious diseases such as COVID-19. One key to success has been the use of modified, next to canonical, nucleotides and the efficient addition of a Cap-structure and poly A tail to the 5’ and 3’ end, respectively, of this massive biomolecule. These important features affect mRNA stability and impact translation efficiency, consequently boosting the optimization and implementation of liquid chromatography–mass spectrometry (LC–MS)-based oligonucleotide profiling methods for their characterization. This article will provide an overview of these LC–MS methods at a fundamental and application level. It will be shown how LC–MS is implemented in mRNA-based vaccine analysis to determine the capping efficiency and the poly A tail length, and how it allows, via RNA mapping, (i) to determine the mRNA sequence, (ii) to screen the fidelity of the manufactured modifications, and (iii) to identify and quantify unwanted modifications resulting from manufacturing or storage, and sequence variants resulting from mutation or transcription errors.

Development of functionally relevant potency assays for monovalent and multivalent vaccines delivered by evolving technologies

A potency or potency-indicating assay is a regulatory requirement for the release of every lot of a vaccine. Potency is a critical quality attribute that is also monitored as a stability indicator of a vaccine product. In essence, a potency measurement is a test of the functional integrity of the antigen and is intended to ensure that the antigen retains immunocompetence, i.e., the ability to stimulate the desired immune response, in its final formulation. Despite its central importance, there is incomplete clarity about the definition and expectation of a potency assay. This article provides a perspective on the purpose, value, and challenges associated with potency testing for vaccines produced by new technologies. The focus is on messenger RNA vaccines in the light of experience gained with recombinant protein-based vaccines, which offer the opportunity to directly correlate in vitro antigenicity with in vivo immunogenicity. The challenges with developing immunologically relevant in vitro assays are discussed especially for multivalent vaccine products, the importance of which has been reinforced by the ongoing emergence of SARS-CoV-2 variants of concern. Immunoassay-based release of multivalent vaccine products, such as those containing multiple antigens from different variants or serotypes of the same virus, require antibodies that are selective for each antigen and do not significantly cross-react with the others. In the absence of such exclusively specific antibodies, alternative functional assays with demonstrable correlation to immunogenicity may be acceptable. Initiatives for geographically distributed vaccine technology facilities should include establishing these assay capabilities to enable rapid delivery of vaccines globally.

Nonviral Delivery Systems of mRNA Vaccines for Cancer Gene Therapy

In recent years, the use of messenger RNA (mRNA) in the fields of gene therapy, immunotherapy, and stem cell biomedicine has received extensive attention. With the development of scientific technology, mRNA applications for tumor treatment have matured. Since the SARS-CoV-2 infection outbreak in 2019, the development of engineered mRNA and mRNA vaccines has accelerated rapidly. mRNA is easy to produce, scalable, modifiable, and not integrated into the host genome, showing tremendous potential for cancer gene therapy and immunotherapy when used in combination with traditional strategies. The core mechanism of mRNA therapy is vehicle-based delivery of in vitro transcribed mRNA (IVT mRNA), which is large, negatively charged, and easily degradable, into the cytoplasm and subsequent expression of the corresponding proteins. However, effectively delivering mRNA into cells and successfully activating the immune response are the keys to the clinical transformation of mRNA therapy. In this review, we focus on nonviral nanodelivery systems of mRNA vaccines used for cancer gene therapy and immunotherapy.

The Potential of Nanomedicine to Unlock the Limitless Applications of mRNA

The year 2020 was a turning point in the way society perceives science. Messenger RNA (mRNA) technology finally showed and shared its potential, starting a new era in medicine. However, there is no doubt that commercialization of these vaccines would not have been possible without nanotechnology, which has finally answered the long-term question of how to deliver mRNA in vivo. The aim of this review is to showcase the importance of this scientific milestone for the development of additional mRNA therapeutics. Firstly, we provide a full description of the marketed vaccine formulations and disclose LNPs’ pharmaceutical properties, including composition, structure, and manufacturing considerations Additionally, we review different types of lipid-based delivery technologies currently in preclinical and clinical development, namely lipoplexes and cationic nanoemulsions. Finally, we highlight the most promising clinical applications of mRNA in different fields such as vaccinology, immuno-oncology, gene therapy for rare genetic diseases and gene editing using CRISPR Cas9.

Stability Modelling of mRNA Vaccine Quality Based on Temperature Monitoring throughout the Distribution Chain

The vaccine distribution chains in several low- and middle-income countries are not adequate to facilitate the rapid delivery of high volumes of thermosensitive COVID-19 mRNA vaccines at the required low and ultra-low temperatures. COVID-19 mRNA vaccines are currently distributed along with temperature monitoring devices to track and identify deviations from predefined conditions throughout the distribution chain. These temperature readings can feed into computational models to quantify mRNA vaccine critical quality attributes (CQAs) and the remaining vaccine shelf life more accurately. Here, a kinetic modelling approach is proposed to quantify the stability-related CQAs and the remaining shelf life of mRNA vaccines. The CQA and shelf-life values can be computed based on the conditions under which the vaccines have been distributed from the manufacturing facilities via the distribution network to the vaccination centres. This approach helps to quantify the degree to which temperature excursions impact vaccine quality and can also reduce vaccine wastage. In addition, vaccine stock management can be improved due to the information obtained on the remaining shelf life of mRNA vaccines. This model-based quantification of mRNA vaccine quality and remaining shelf life can improve the deployment of COVID-19 mRNA vaccines to low- and middle-income countries.

mRNA Therapeutic Modalities Design, Formulation and Manufacturing under Pharma 4.0 Principles

In the quest for a formidable weapon against the SARS-CoV-2 pandemic, mRNA therapeutics have stolen the spotlight. mRNA vaccines are a prime example of the benefits of mRNA approaches towards a broad array of clinical entities and druggable targets. Amongst these benefits is the rapid cycle "from design to production" of an mRNA product compared to their peptide counterparts, the mutability of the production line should another target be chosen, the side-stepping of safety issues posed by DNA therapeutics being permanently integrated into the transfected cell's genome and the controlled precision over the translated peptides. Furthermore, mRNA applications are versatile: apart from vaccines it can be used as a replacement therapy, even to create chimeric antigen receptor T-cells or reprogram somatic cells. Still, the sudden global demand for mRNA has highlighted the shortcomings in its industrial production as well as its formulation, efficacy and applicability. Continuous, smart mRNA manufacturing 4.0 technologies have been recently proposed to address such challenges. In this work, we examine the lab and upscaled production of mRNA therapeutics, the mRNA modifications proposed that increase its efficacy and lower its immunogenicity, the vectors available for delivery and the stability considerations concerning long-term storage.