mRNA transcript therapy

Characterization of mRNA therapeutics

Therapeutic messenger RNAs (mRNAs) have emerged as powerful tools in the treatment of complex diseases, especially for conditions that lack efficacious treatment. The successful application of this modality can be attributed to its ability to encode entire proteins. While the large nature of these molecules has supported their success as therapeutics, its extended size creates several analytical challenges. To further support therapeutic mRNA development and its deployment in clinical trials, appropriate methods to support their characterization must be developed. In this review, we describe current analytical methods that have been used in the characterization of RNA quality, identity, and integrity. Advantages and limitations from several analytical techniques ranging from gel electrophoresis to liquid chromatography-mass spectrometry and from shotgun sequencing to intact mass measurements are discussed. We comprehensively describe the application of analytical methods in the measurements of capping efficiency, poly A tail analysis, as well as their applicability in stability studies.

Nucleic acid cancer vaccines targeting tumor related angiogenesis. Could mRNA vaccines constitute a game changer?

Tumor related angiogenesis is an attractive target in cancer therapeutic research due to its crucial role in tumor growth, invasion, and metastasis. Different agents were developed aiming to inhibit this process; however they had limited success. Cancer vaccines could be a promising tool in anti-cancer/anti-angiogenic therapy. Cancer vaccines aim to initiate an immune response against cancer cells upon presentation of tumor antigens which hopefully will result in the eradication of disease and prevention of its recurrence by inducing an efficient and long-lasting immune response. Different vaccine constructs have been developed to achieve this and they could include either protein-based or nucleic acid-based vaccines. Nucleic acid vaccines are simple and relatively easy to produce, with high efficiency and safety, thus prompting a high interest in the field. Different DNA vaccines have been developed to target crucial regulators of tumor angiogenesis. Most of them were successful in pre-clinical studies, mostly when used in combination with other therapeutics, but had limited success in the clinic. Apparently, different tumor evasion mechanisms and reduced immunogenicity still limit the potential of these vaccines and there is plenty of room for improvement. Nowadays, mRNA cancer vaccines are making remarkable progress due to improvements in the manufacturing technology and represent a powerful potential alternative. Apart from their efficiency, mRNA vaccines are simple and cheap to produce, can encompass multiple targets simultaneously, and can be quickly transferred from bench to bedside. mRNA vaccines have already accomplished amazing results in cancer clinical trials, thus ensuring a bright future in the field, although no anti-angiogenic mRNA vaccines have been described yet. This review aims to describe recent advances in anti-angiogenic DNA vaccine therapy and to provide perspectives for use of revolutionary approaches such are mRNA vaccines for anti-angiogenic treatments.

Transient growth factor expression via mRNA in lipid nanoparticles promotes hepatocyte cell therapy in mice

Primary human hepatocyte (PHH) transplantation is a promising alternative to liver transplantation, whereby liver function could be restored by partial repopulation of the diseased organ with healthy cells. However, currently PHH engraftment efficiency is low and benefits are not maintained long-term. Here we refine two male mouse models of human chronic and acute liver diseases to recapitulate compromised hepatocyte proliferation observed in nearly all human liver diseases by overexpression of p21 in hepatocytes. In these clinically relevant contexts, we demonstrate that transient, yet robust expression of human hepatocyte growth factor and epidermal growth factor in the liver via nucleoside-modified mRNA in lipid nanoparticles, whose safety was validated with mRNA-based COVID-19 vaccines, drastically improves PHH engraftment, reduces disease burden, and improves overall liver function. This strategy may overcome the critical barriers to clinical translation of cell therapies with primary or stem cell-derived hepatocytes for the treatment of liver diseases.

Effective Synthesis of High-Integrity mRNA Using In Vitro Transcription

mRNA vaccines are entering a period of rapid development. However, their synthesis is still plagued by challenges related to mRNA impurities and fragments (incomplete mRNA). Most impurities of mRNA products transcribed in vitro are mRNA fragments. Only full-length mRNA transcripts containing both a 5'-cap and a 3'-poly(A) structure are viable for in vivo expression. Therefore, RNA fragments are the primary product-related impurities that significantly hinder mRNA efficacy and must be effectively controlled; these species are believed to originate from either mRNA hydrolysis or premature transcriptional termination. In the manufacturing of commercial mRNA vaccines, T7 RNA polymerase-catalyzed in vitro transcription (IVT) synthesis is a well-established method for synthesizing long RNA transcripts. This study identified a pivotal domain on the T7 RNA polymerase that is associated with erroneous mRNA release. By leveraging the advantageous properties of a T7 RNA polymerase mutant and precisely optimized IVT process parameters, we successfully achieved an mRNA integrity exceeding 91%, thereby further unlocking the immense potential of mRNA therapeutics.

Novel Efficient Lipid-Based Delivery Systems Enable a Delayed Uptake and Sustained Expression of mRNA in Human Cells and Mouse Tissues

Over the past decade, mRNA-based therapy has displayed significant promise in a wide range of clinical applications. The most striking example of the leap in the development of mRNA technologies was the mass vaccination against COVID-19 during the pandemic. The emergence of large-scale technology and positive experience of mRNA immunization sparked the development of antiviral and anti-cancer mRNA vaccines as well as therapeutic mRNA agents for genetic and other diseases. To facilitate mRNA delivery, lipid nanoparticles (LNPs) have been successfully employed. However, the diverse use of mRNA therapeutic approaches requires the development of adaptable LNP delivery systems that can control the kinetics of mRNA uptake and expression in target cells. Here, we report effective mRNA delivery into cultured mammalian cells (HEK293T, HeLa, DC2.4) and living mouse muscle tissues by liposomes containing either 1,26-bis(cholest-5-en-3β-yloxycarbonylamino)-7,11,16,20-tetraazahexacosane tetrahydrochloride (2X3) or the newly applied 1,30-bis(cholest-5-en-3β-yloxycarbonylamino)-9,13,18,22-tetraaza-3,6,25,28-tetraoxatriacontane tetrahydrochloride (2X7) cationic lipids. Using end-point and real-time monitoring of Fluc mRNA expression, we showed that these LNPs exhibited an unusually delayed (of over 10 h in the case of the 2X7-based system) but had highly efficient and prolonged reporter activity in cells. Accordingly, both LNP formulations decorated with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG2000) provided efficient luciferase production in mice, peaking on day 3 after intramuscular injection. Notably, the bioluminescence was observed only at the site of injection in caudal thigh muscles, thereby demonstrating local expression of the model gene of interest. The developed mRNA delivery systems hold promise for prophylactic applications, where sustained synthesis of defensive proteins is required, and open doors to new possibilities in mRNA-based therapies.

Unlocking the potential of nanocarrier-mediated mRNA delivery across diverse biomedical frontiers: A comprehensive review

Messenger RNA (mRNA) has gained marvelous attention for managing and preventing various conditions like cancer, Alzheimer's, infectious diseases, etc. Due to the quick development and success of the COVID-19 mRNA-based vaccines, mRNA has recently grown in prominence. A lot of products are in clinical trials and some are already FDA-approved. However, still improvements in line of optimizing stability and delivery, reducing immunogenicity, increasing efficiency, expanding therapeutic applications, scalability and manufacturing, and long-term safety monitoring are needed. The delivery of mRNA via a nanocarrier system gives a synergistic outcome for managing chronic and complicated conditions. The modified nanocarrier-loaded mRNA has excellent potential as a therapeutic strategy. This emerging platform covers a wide range of diseases, recently, several clinical studies are ongoing and numerous publications are coming out every year. Still, many unexplained physical, biological, and technical problems of mRNA for safer human consumption. These complications were addressed with various nanocarrier formulations. This review systematically summarizes the solved problems and applications of nanocarrier-based mRNA delivery. The modified nanocarrier mRNA meaningfully improved mRNA stability and abridged its immunogenicity issues. Furthermore, several strategies were discussed that can be an effective solution in the future for managing complicated diseases.

Potential therapeutic strategy for cancer: Multi-dimensional cross-talk between circRNAs and parental genes

In many ways, circular RNAs (circRNAs) have been demonstrated to be crucial in the onset and advancement of cancer throughout the last ten years and have become a new focus of intense research in the field of RNAs. Accumulating studies have demonstrated that circRNAs can regulate parental gene expression via a variety of biological pathways. Furthermore, research into the complex interactions between circRNAs and their parental genes will shed light on their biological roles and open up new avenues for circRNAs' potential clinical translational uses. However, to date, multi-dimensional cross-talk between circRNAs and parental genes have not been systematically elucidated. Particularly intriguing is circRNA's exploration of tumor targeting, and potential therapeutic uses based on the parental gene regulation perspective. Here, we discuss their biogenesis, take a fresh look at the molecular mechanisms through which circRNAs control the expression of their parental genes in cancer. We further highlight We further highlight the latest circRNA clinical translational applications, including prognostic diagnostic markers, cancer vaccines, gDNA, and so on. Demonstrating the potential benefits and future applications of circRNA therapy.

Strategies to reduce the risks of mRNA drug and vaccine toxicity

mRNA formulated with lipid nanoparticles is a transformative technology that has enabled the rapid development and administration of billions of coronavirus disease 2019 (COVID-19) vaccine doses worldwide. However, avoiding unacceptable toxicity with mRNA drugs and vaccines presents challenges. Lipid nanoparticle structural components, production methods, route of administration and proteins produced from complexed mRNAs all present toxicity concerns. Here, we discuss these concerns, specifically how cell tropism and tissue distribution of mRNA and lipid nanoparticles can lead to toxicity, and their possible reactogenicity. We focus on adverse events from mRNA applications for protein replacement and gene editing therapies as well as vaccines, tracing common biochemical and cellular pathways. The potential and limitations of existing models and tools used to screen for on-target efficacy and de-risk off-target toxicity, including in vivo and next-generation in vitro models, are also discussed.

Transfection of hypoxia-inducible factor-1α mRNA upregulates the expression of genes encoding angiogenic growth factors

Hypoxia-Inducible Factor-1α (HIF-1α) has presented a new direction for ischemic preconditioning of surgical flaps to promote their survival. In a previous study, we demonstrated the effectiveness of HIF-1a DNA plasmids in this application. In this study, to avoid complications associated with plasmid use, we sought to express HIF-1α through mRNA transfection and determine its biological activity by measuring the upregulation of downstream angiogenic genes. We transfected six different HIF-1a mRNAs-one predominant, three variant, and two novel mutant isoforms-into primary human dermal fibroblasts using Lipofectamine, and assessed mRNA levels using RT-qPCR. At all time points examined after transfection (3, 6, and 10 h), the levels of HIF-1α transcript were significantly higher in all HIF-1α transfected cells relative to the control (all p < 0.05, unpaired Student's T-test). Importantly, the expression of HIF-1α transcription response genes (VEGF, ANG-1, PGF, FLT1, and EDN1) was significantly higher in the cells transfected with all isoforms than with the control at six and/or ten hours post-transfection. All isoforms were transfected successfully into human fibroblast cells, resulting in the rapid upregulation of all five downstream angiogenic targets tested. These findings support the potential use of HIF-1α mRNA for protecting ischemic dermal flaps.

The clinical impact of mRNA therapeutics in the treatment of cancers, infections, genetic disorders, and autoimmune diseases

mRNA-based therapeutics have revolutionized medicine and the pharmaceutical industry. The recent progress in the optimization and formulation of mRNAs has led to the development of a new therapeutic platform with a broad range of applications. With a growing body of evidence supporting the use of mRNA-based drugs for precision medicine and personalized treatments, including cancer immunotherapy, genetic disorders, and autoimmune diseases, this emerging technology offers a rapidly expanding category of therapeutic options. Furthermore, the development and deployment of mRNA vaccines have facilitated a prompt and flexible response to medical emergencies, exemplified by the COVID-19 outbreak. The establishment of stable and safe mRNA molecules carried by efficient delivery systems is now available through recent advances in molecular biology and nanotechnology. This review aims to elucidate the advancements in the clinical applications of mRNAs for addressing significant health-related challenges such as cancer, autoimmune diseases, genetic disorders, and infections and provide insights into the efficacy and safety of mRNA therapeutics in recent clinical trials.

mRNA delivery systems for cancer immunotherapy: Lipid nanoparticles and beyond

mRNA-based vaccines are emerging as a promising alternative to standard cancer treatments and the conventional vaccines. Moreover, the FDA-approval of three nucleic acid based therapeutics (Onpattro, BNT162b2 and mRNA-1273) has further increased the interest and trust on this type of therapeutics. In order to achieve a significant therapeutic efficacy, the mRNA needs from a drug delivery system. In the last years, several delivery platforms have been explored, being the lipid nanoparticles (LNPs) the most well characterized and studied. A better understanding on how mRNA-based therapeutics operate (both the mRNA itself and the drug delivery system) will help to further improve their efficacy and safety. In this review, we will provide an overview of what mRNA cancer vaccines are and their mode of action and we will highlight the advantages and challenges of the different delivery platforms that are under investigation.

Recent advances in mRNA-based vaccine for cancer therapy; bench to bedside

The messenger RNA (mRNA) vaccines have progressed from a theoretical concept to a clinical reality over the last few decades. Compared to conventional vaccination methods, these vaccines have a number of benefits, such as substantial potency, rapid growth, inexpensive production, and safe administration. Nevertheless, their usefulness was restricted up to now due to worries about the erratic and ineffective circulation of mRNA in vivo. Thankfully, these worries have largely been allayed by recent technological developments, which have led to the creation of multiple mRNA vaccination platforms for cancer and viral infections. The mRNA vaccines have been demonstrated as a powerful alternative to traditional conventional vaccines because of their high potency, safety and efficacy, capacity for rapid clinical development, and potential for rapid, low-cost manufacturing. The paper will examine the present status of mRNA vaccine technology and suggest future paths for the advancement and application of this exciting vaccine platform as a common therapeutic choice.

The immunostimulatory nature of mRNA lipid nanoparticles

mRNA-Lipid nanoparticles (LNPs) are at the forefront of global medical research. With the development of mRNA-LNP vaccines to combat the COVID-19 pandemic, the clinical potential of this platform was unleashed. Upon administering 16 billion doses that protected billions of people, it became clear that a fraction of them witnessed mild and in some cases even severe adverse effects. Therefore, it is paramount to define the safety along with the therapeutic efficacy of the mRNA-LNP platform for the successful translation of new genetic medicines based on this technology. While mRNA was the effector molecule of this platform, the ionizable lipid component of the LNPs played an indispensable role in its success. However, both of these components possess the ability to induce undesired immunostimulation, which is an area that needs to be addressed systematically. The immune cell agitation caused by this platform is a two-edged sword as it may prove beneficial for vaccination but detrimental to other applications. Therefore, a key challenge in advancing the mRNA-LNP drug delivery platform from bench to bedside is understanding the immunostimulatory behavior of these components. Herein, we provide a detailed overview of the structural modifications and immunogenicity of synthetic mRNA. We discuss the effect of ionizable lipid structure on LNP functionality and offer a mechanistic overview of the ability of LNPs to elicit an immune response. Finally, we shed some light on the current status of this technology in clinical trials and discuss a few challenges to be addressed to advance the field.

Neoantigen vaccine nanoformulations based on Chemically synthesized minimal mRNA (CmRNA): small molecules, big impact

Recently, chemically synthesized minimal mRNA (CmRNA) has emerged as a promising alternative to in vitro transcribed mRNA (IVT-mRNA) for cancer therapy and immunotherapy. CmRNA lacking the untranslated regions and polyadenylation exhibits enhanced stability and efficiency. Encapsulation of CmRNA within lipid-polymer hybrid nanoparticles (LPPs) offers an effective approach for personalized neoantigen mRNA vaccines with improved control over tumor growth. LPP-based delivery systems provide superior pharmacokinetics, stability, and lower toxicity compared to viral vectors, naked mRNA, or lipid nanoparticles that are commonly used for mRNA delivery. Precise customization of LPPs in terms of size, surface charge, and composition allows for optimized cellular uptake, target specificity, and immune stimulation. CmRNA-encoded neo-antigens demonstrate high translational efficiency, enabling immune recognition by CD8+ T cells upon processing and presentation. This perspective highlights the potential benefits, challenges, and future directions of CmRNA neoantigen vaccines in cancer therapy compared to Circular RNAs and IVT-mRNA. Further research is needed to optimize vaccine design, delivery, and safety assessment in clinical trials. Nevertheless, personalized LPP-CmRNA vaccines hold great potential for advancing cancer immunotherapy, paving the way for personalized medicine.

Transient growth factor expression via mRNA in lipid nanoparticles promotes hepatocyte cell therapy to treat murine liver diseases

Primary human hepatocyte (PHH) transplantation is a promising alternative to liver transplantation, whereby liver function could be restored by partial repopulation of the diseased organ with healthy cells. However, currently PHH engraftment efficiency is low and benefits are not maintained long-term. Here we refine two mouse models of human chronic and acute liver diseases to recapitulate compromised hepatocyte proliferation observed in nearly all human liver diseases by overexpression of p21 in hepatocytes. In these clinically relevant contexts, we demonstrate that transient, yet robust expression of human hepatocyte growth factor and epidermal growth factor in the liver via nucleoside-modified mRNA in lipid nanoparticles, whose safety was validated with mRNA-based COVID-19 vaccines, drastically improves PHH engraftment, reduces disease burden, and improves overall liver function. This novel strategy may overcome the critical barriers to clinical translation of cell therapies with primary or stem cell-derived hepatocytes for the treatment of liver diseases.

Chitosan-Based Nanocarriers for Pulmonary and Intranasal Drug Delivery Systems: A Comprehensive Overview of their Applications

The optimization of respiratory health is important, and one avenue for achieving this is through the application of both Pulmonary Drug Delivery System (PDDS) and Intranasal Delivery (IND). PDDS offers immediate delivery of medication to the respiratory system, providing advantages, such as sustained regional drug concentration, tunable drug release, extended duration of action, and enhanced patient compliance. IND, renowned for its non-invasive nature and swift onset of action, presents a promising path for advancement. Modern PDDS and IND utilize various polymers, among which chitosan (CS) stands out. CS is a biocompatible and biodegradable polysaccharide with unique physicochemical properties, making it well-suited for medical and pharmaceutical applications. The multiple positively charged amino groups present in CS facilitate its interaction with negatively charged mucous membranes, allowing CS to adsorb easily onto the mucosal surface. In addition, CS-based nanocarriers have been an important topic of research. Polymeric Nanoparticles (NPs), liposomes, dendrimers, microspheres, nanoemulsions, Solid Lipid Nanoparticles (SLNs), carbon nanotubes, and modified effective targeting systems compete as important ways of increasing pulmonary drug delivery with chitosan. This review covers the latest findings on CS-based nanocarriers and their applications.

VEGFA mRNA-LNP promotes biliary epithelial cell-to-hepatocyte conversion in acute and chronic liver diseases and reverses steatosis and fibrosis

The liver is known for its remarkable regenerative ability through proliferation of hepatocytes. Yet, during chronic injury or severe hepatocyte death, proliferation of hepatocytes is exhausted. To overcome this hurdle, we propose vascular-endothelial-growth-factor A (VEGFA) as a therapeutic means to accelerate biliary epithelial-cell (BEC)-to-hepatocyte conversion. Investigation in zebrafish establishes that blocking VEGF receptors abrogates BEC-driven liver repair, while VEGFA overexpression promotes it. Delivery of VEGFA via nonintegrative and safe nucleoside-modified mRNA encapsulated into lipid nanoparticles (mRNA-LNPs) in acutely or chronically injured mouse livers induces robust BEC-to-hepatocyte conversion and elimination of steatosis and fibrosis. In human and murine diseased livers, we further identified VEGFA-receptor KDR-expressing BECs associated with KDR-expressing cell-derived hepatocytes. This work defines KDR-expressing cells, most likely being BECs, as facultative progenitors. This study reveals unexpected therapeutic benefits of VEGFA delivered via nucleoside-modified mRNA-LNP, whose safety is widely validated with COVID-19 vaccines, for harnessing BEC-driven repair to potentially treat liver diseases.

Evaluation of self-amplifying mRNA platform for protein expression and genetic stability: Implication for mRNA therapies

The consecutive launch of mRNA vaccines like mRNA-1273, BNT 162b2, and GEMCOVAC®-19 against COVID-19 has triggered the debate of long-term expression, safety, and genomic integration of the mRNA vaccine platforms. In the present study, we examined the longevity of antigenic protein expression of mRNA-614 and mRNA-S1LC based on self-amplifying mRNA (SAM) in Expi-293F™, HEK-293 T, and ARPE-19 cells. The protein expression was checked by sandwich-ELISA, FACS, luciferase activity assay, and Western blot. The transcribed antigenic mRNA was sequenced and found to be un-mutated. Additionally, no genomic integration of the reverse transcribed mRNA was observed even up to 7 days post-transfection as verified by PCR. Furthermore, we have generated high-quality 3D structures of non-structural proteins (nsPs) in silico and the genes encoding for the nsPs were cloned and expressed using the T7 system. Findings from the current study have strengthened the fact that the alphavirus-based SAM platform has the potential to become a modality in the upcoming years.

Inner leaflet cationic lipid increases nucleic acid loading independently of outer leaflet lipid charge in asymmetric liposomes

Use of cationic lipid vesicles (liposomes) can yield large amounts of nucleic acid entrapped inside the vesicles and/or bound to the external surface of the vesicles. To show a method to prepare asymmetric lipid vesicles (liposomes) with high amounts of entrapped nucleic acid is possible, symmetric and asymmetric lipid vesicles composed of mixtures of neutral (zwitterionic), anionic, and/or cationic phospholipids were formed in the presence of oligo DNA. For symmetric large unilamellar vesicles nucleic acid association with vesicles was roughly 100 times greater for vesicles with a net cationic charge than for vesicles having a net neutral or anionic net charge. A high degree of association between nucleic acid and lipid was also achieved using asymmetric large unilamellar vesicles with a net cationic charge in their inner leaflet, even when they had an anionic charge in their outer leaflet. In contrast, asymmetric vesicles in which only the outer leaflet had a net cationic charge had only low amounts of vesicle-associated nucleic acid, similar in amount to the amount of nucleic acid associated with asymmetric vesicles with an outer leaflet having a net anionic charge. These results indicate that in asymmetric vesicles with cationic lipid enriched inner leaflets nucleic acid is largely entrapped inside the vesicle lumen rather than bound to their external surface, and that asymmetric vesicles can be used to trap high amounts of nucleic acid even when using a lipid composition in the outer leaflet of a lipid vesicle that does not associate with nucleic acids. Such asymmetrically charged vesicles should have applications in studies of membrane protein-nucleic acid interactions as well as in studies of how membrane charge asymmetry can influence membrane protein structure, orientation, and function.

In Vitro Transcribed RNA-Based Platform Vaccines: Past, Present, and Future

mRNA was discovered in 1961, but it was not used as a vaccine until after three decades. Recently, the development of mRNA vaccine technology gained great impetus from the pursuit of vaccines against COVID-19. To improve the properties of RNA vaccines, and primarily their circulation time, self-amplifying mRNA and trans-amplifying mRNA were developed. A separate branch of mRNA technology is circular RNA vaccines, which were developed with the discovery of the possibility of translation on their protein matrix. Circular RNA has several advantages over mRNA vaccines and is considered a fairly promising platform, as is trans-amplifying mRNA. This review presents an overview of the mRNA platform and a critical discussion of the more modern self-amplifying mRNA, trans-amplifying mRNA, and circular RNA platforms created on its basis. Finally, the main features, advantages, and disadvantages of each of the presented mRNA platforms are discussed. This discussion will facilitate the decision-making process in selecting the most appropriate platform for creating RNA vaccines against cancer or viral diseases.

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.

N2 modified cap analogues as translation inhibitors and substrates for preparation of therapeutic mRNA

In recent years many scientists have begun to focus on the mRNA molecule's emeregence as a new type of drug. Its fast-moving and successful career as a vaccine technology cannot be underestimated. mRNA provides new opportunities and allows for the rapid preparation of effective drugs at low cost. These extensive possibilities stem from a number of factors, but the small cap structure located at the 5' end of the mRNA is one contributing factor. Cap protects mRNA and ensures efficient recruitment to the biosynthesis machinery. Furthermore, it allows for the easy introduction of various modifications that influence the activity of the entire mRNA. Among the many different cap analogues that have been reported, those modified at the N2 position of guanosine have been systematically developed. N2-modified caps in the form of nucleoside monophosphates or dinucleotides show favorable biological properties, as well as a high capacity to inhibit the translation process in the cell-free RRL system. Modified N2 dinucleotides are efficiently incorporated into the structure of the mRNA transcript, and in specific circumstances with the correct orientation, making them an interesting alternative for ARCA-type analogues. Moreover, mRNA transcripts containing cap structures modified within the exocyclic amino group show very high translational activity. Therefore, analogues modified at the N2 position may have future applications as therapeutics against various manifestations of cancer and as desirable tools in RNA engineering.

Making the Next Generation of Therapeutics: mRNA Meets Synthetic Biology

The development of mRNA-based therapeutics centers around the natural functioning of mRNA molecules to provide the genetic information required for protein translation. To improve the efficacy of these therapeutics and minimize side effects, researchers can focus on the features of mRNA itself or the properties of the delivery agent to achieve the desired response. The tools considered for mRNA manipulation can be improved in terms of targetability, tunability, and translatability to medicine. While ongoing studies are dedicated to improving conventional approaches, innovative approaches can also be considered to unleash the full potential of mRNA-based therapeutics. Here, we discuss the opportunities that emerged from introducing synthetic biology to mRNA therapeutics. It includes a discussion of modular self-assembled mRNA nanoparticles, logic gates on a single mRNA molecule, and other possibilities.

The Safety and Effectiveness of mRNA Vaccines Against SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in numerous deaths worldwide, along with devastating economic disruptions, and has posed unprecedented challenges to healthcare systems around the world. In the wake of COVID-19's emergence in 2019, a variety of vaccine technologies were formulated and developed, including those that drew from the technology employed in messenger RNA (mRNA) vaccines, designed to curb the disease's transmission and manage the pandemic. mRNA vaccine has several advantages over traditional ones, and hence its development has received considerable attention recently. Researchers believe the mRNA vaccine technology will emerge as the leading technology because it is potent, inexpensive, rapidly developed, and safe. This article provides an overview of mRNA vaccines with a special focus on the efficacy and safety of the Moderna and Pfizer-BioNTech mRNA vaccines against the different variants of COVID-19 and compare them with the Oxford-AstraZeneca (viral vector) and Sinopharm (inactivated virus) vaccines. The clinical data reviewed in this article demonstrate that the currently authorized Moderna and Pfizer-BioNTech mRNA vaccines are highly safe and potent against different variants of COVID-19, especially in comparison with Oxford-AstraZeneca (viral vector) and Sinopharm (inactivated virus) vaccines.

mRNA therapeutics: New vaccination and beyond

The idea of mRNA therapy had been conceived for decades before it came into reality during the Covid-19 pandemic. The mRNA vaccine emerges as a powerful and general tool against new viral infections, largely due to its versatility and rapid development. In addition to prophylactic vaccines, mRNA technology also offers great promise for new applications as a versatile drug modality. However, realizing the conceptual potential faces considerable challenges, such as minimal immune stimulation, high and long-term expression, and efficient delivery to target cells and tissues. Here we review the applications of mRNA-based therapeutics, with emphasis on the innovative design and future challenges/solutions. In addition, we also discuss the next generation of mRNA therapy, including circular mRNA and self-amplifying RNAs. We aim to provide a conceptual overview and outlook on mRNA therapeutics beyond prophylactic vaccines.

Recent Advances and Innovations in the Preparation and Purification of In Vitro-Transcribed-mRNA-Based Molecules

The coronavirus disease 2019 (COVID-19) pandemic poses a disruptive impact on public health and the global economy. Fortunately, the development of COVID-19 vaccines based on in vitro-transcribed messenger RNA (IVT mRNA) has been a breakthrough in medical history, benefiting billions of people with its high effectiveness, safety profile, and ease of large-scale production. This success is the result of decades of continuous RNA research, which has led to significant improvements in the stability and expression level of IVT mRNA through various approaches such as sequence optimization and improved preparation processes. IVT mRNA sequence optimization has been shown to have a positive effect on enhancing the mRNA expression level. The innovation of IVT mRNA purification technology is also indispensable, as the purity of IVT mRNA directly affects the success of downstream vaccine preparation processes and the potential for inducing unwanted side effects in therapeutic applications. Despite the progress made, challenges related to IVT mRNA sequence design and purification still require further attention to enhance the quality of IVT mRNA in the future. In this review, we discuss the latest innovative progress in IVT mRNA design and purification to further improve its clinical efficacy.

Future prospects in mRNA vaccine development

The recent advancements in messenger ribonucleic acid (mRNA) vaccine development have vastly enhanced their use as alternatives to conventional vaccines in the prevention of various infectious diseases and treatment of several types of cancers. This is mainly due to their remarkable ability to stimulate specific immune responses with minimal clinical side effects. This review gives a detailed overview of mRNA vaccines currently in use or at various stages of development, the recent advancements in mRNA vaccine development, and the challenges encountered in their development. Future perspectives on this technology are also discussed.

Ionizable Amino Lipids Distribution and Effects on DSPC/Cholesterol Membranes: Implications for Lipid Nanoparticle Structure

Lipid nanoparticles (LNPs) containing ionizable aminolipids are among the leading platforms for the successful delivery of nucleic-acid-based therapeutics, including messenger RNA (mRNA). The two recently FDA-approved COVID-19 vaccines developed by Moderna and Pfizer/BioNTech belong to this category. Ionizable aminolipids, cholesterol, and DSPC lipids are among the key components of such formulations, crucially modulating physicochemical properties of these formulations and, consequently, the potency of these therapeutics. Despite the importance of these components, the distribution of these molecules in LNPs containing mRNA is not clear. In this study, we used all-atom molecular dynamics (MD) simulations to investigate the distribution and effects of the Lipid-5 (apparent pKa of the lipid nanoparticle = 6.56), a rationally designed and previously reported ionizable aminolipid by Moderna, on lipid bilayers [Mol. Ther. 2018, 26, 1509-1519]. The simulations were conducted with half of the aminolipids charged and half neutral approximately to the expected ionization in the microenvironment of the LNP surface. In all five simulated systems in this work, the cholesterol content was kept constant, whereas the DSPC and Lipid-5 concentrations were changed systematically. We found that at higher concentrations of the ionizable aminolipids, the neutral aminolipids form a disordered aggregate in the membrane interior that preferentially includes cholesterol. The rules underlying the lipid redistribution could be used to rationally choose lipids to optimize the LNP function.

Recent Advances in Messenger Ribonucleic Acid (mRNA) Vaccines and Their Delivery Systems: A Review

Messenger ribonucleic acid (mRNA) was found as the intermediary that transfers genetic information from DNA to ribosomes for protein synthesis in 1961. The emergency use authorization of the two covid-19 mRNA vaccines, BNT162b2 and mRNA-1273, is a significant achievement in the history of vaccine development. Because they are generated in a cell-free environment using the in vitro transcription (IVT) process, mRNA vaccines are risk-free. Moreover, chemical modifications to the mRNA molecule, such as cap structures and changed nucleosides, have proved critical in overcoming immunogenicity concerns, achieving sustained stability, and achieving effective, accurate protein production in vivo. Several vaccine delivery strategies (including protamine, lipid nanoparticles (LNPs), polymers, nanoemulsions, and cell-based administration) were also optimized to load and transport RNA into the cytosol. LNPs, which are composed of a cationic or a pH-dependent ionizable lipid layer, a polyethylene glycol (PEG) component, phospholipids, and cholesterol, are the most advanced systems for delivering mRNA vaccines. Moreover, modifications of the four components that make up the LNPs showed to increase vaccine effectiveness and reduce side effects. Furthermore, the introduction of biodegradable lipids improved LNP biocompatibility. Furthermore, mRNA-based therapies are expected to be effective treatments for a variety of refractory conditions, including infectious diseases, metabolic genetic diseases, cancer, cardiovascular and cerebrovascular diseases. Therefore, the present review aims to provide the scientific community with up-to-date information on mRNA vaccines and their delivery systems.

Terminal hairpins improve protein expression in IRES-initiated mRNA in the absence of a cap and polyadenylated tail

Synthesizing mRNA in vitro is a standard and simple procedure. Adding the 5' cap and 3' polyadenylated (poly(A)) tail to make this mRNA functional for use as a vaccine or therapy increases the time and cost of production and usually decreases the yield, however. We designed mRNA that lacked a cap and poly(A) tail but included an internal ribosomal entry site (IRES) to initiate protein translation. To protect the 5' and 3' ends of mRNA from exonucleases, we added stable terminal hairpins. When compared against typical mRNA (i.e., mRNA that contained a cap and poly(A) tail but lacked hairpins), expression of the delivered reporter protein in HEK293 cells was similar. Using a triple instead of a single hairpin at each end increased protein expression even more. This method has the potential to simplify the production and reduce the cost of synthesizing exogenous mRNA for use as biologics or vaccines.

Messenger RNA-Based Therapeutics and Vaccines: What's beyond COVID-19?

With the rapid success in the development of mRNA vaccines against COVID-19 and with a number of mRNA-based drugs ahead in the pipelines, mRNA has catapulted to the forefront of drug research, demonstrating its substantial effectiveness against a broad range of diseases. As the recent global pandemic gradually fades, we cannot stop thinking about what the world has gained: the realization and validation of the power of mRNA in modern medicine. A significant amount of research has now been concentrated on developing mRNA drugs and vaccine platforms against infectious and immune diseases, cancer, and other debilitating diseases and has demonstrated encouraging results. Here, based on the CAS Content Collection, we provide a landscape view of the current state, outline trends in the research and development of mRNA therapeutics and vaccines, and highlight some notable patents focusing on mRNA therapeutics, vaccines, and delivery systems. Analysis of diseases disclosed in patents also reveals highly investigated diseases for treatments with these medicines. Finally, we provide information about mRNA therapeutics and vaccines in clinical trials. We hope this Review will be useful for understanding the current knowledge in the field of mRNA medicines and will assist in efforts to solve its remaining challenges and revolutionize the treatment of human diseases.

Learning from cancer to address COVID-19

Patients with cancer have been disproportionately affected by the novel coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Knowledge collected during the last three decades of cancer research has helped the medical research community worldwide to respond to many of the challenges raised by COVID-19, during the pandemic. The review, briefly summarizes the underlying biology and risk factors of COVID-19 and cancer, and aims to present recent evidence on cellular and molecular relationship between the two diseases, with a focus on those that are related to the hallmarks of cancer and uncovered in the first less than three years of the pandemic (2020-2022). This may not only help answer the question "Why cancer patients are considered to be at a particularly high risk of developing severe COVID-19 illness?", but also helped treatments of patients during the COVID-19 pandemic. The last session highlights the pioneering mRNA studies and the breakthrough discovery on nucleoside-modifications of mRNA by Katalin Karikó, which led to the innovation and development of the mRNA-based SARSCoV-2 vaccines saving lives of millions and also opened the door for a new era of vaccines and a new class of therapeutics.

Nanoformulations targeting immune cells for cancer therapy: mRNA therapeutics

The approved worldwide use of two messenger RNA (mRNA) vaccines (BNT162b2 and mRNA-1273) in late 2020 has proven the remarkable success of mRNA therapeutics together with lipid nanoformulation technology in protecting people against coronaviruses during COVID-19 pandemic. This unprecedented and exciting dual strategy with nanoformulations and mRNA therapeutics in play is believed to be a promising paradigm in targeted cancer immunotherapy in future. Recent advances in nanoformulation technologies play a prominent role in adapting mRNA platform in cancer treatment. In this review, we introduce the biologic principles and advancements of mRNA technology, and chemistry fundamentals of intriguing mRNA delivery nanoformulations. We discuss the latest promising nano-mRNA therapeutics for enhanced cancer immunotherapy by modulation of targeted specific subtypes of immune cells, such as dendritic cells (DCs) at peripheral lymphoid organs for initiating mRNA cancer vaccine-mediated antigen specific immunotherapy, and DCs, natural killer (NK) cells, cytotoxic T cells, or multiple immunosuppressive immune cells at tumor microenvironment (TME) for reversing immune evasion. We highlight the clinical progress of advanced nano-mRNA therapeutics in targeted cancer therapy and provide our perspectives on future directions of this transformative integrated technology toward clinical implementation.

Growth Hormone Accelerates Recovery From Acetaminophen-Induced Murine Liver Injury

Background and Aims

Acetaminophen (APAP) overdose is the leading cause of acute liver failure, with one available treatment, N-acetyl cysteine (NAC). Yet, NAC effectiveness diminishes about ten hours after APAP overdose, urging for therapeutic alternatives. This study addresses this need by deciphering a mechanism of sexual dimorphism in APAP-induced liver injury, and leveraging it to accelerate liver recovery via growth hormone (GH) treatment. GH secretory patterns, pulsatile in males and near-continuous in females, determine the sex bias in many liver metabolic functions. Here, we aim to establish GH as a novel therapy to treat APAP hepatotoxicity.

Approach and Results

Our results demonstrate sex-dependent APAP toxicity, with females showing reduced liver cell death and faster recovery than males. Single-cell RNA sequencing analyses reveal that female hepatocytes have significantly greater levels of GH receptor expression and GH pathway activation compared to males. In harnessing this female-specific advantage, we demonstrate that a single injection of recombinant human GH protein accelerates liver recovery, promotes survival in males following sub-lethal dose of APAP, and is superior to standard-of-care NAC. Alternatively, slow-release delivery of human GH via the safe nonintegrative lipid nanoparticle-encapsulated nucleoside-modified mRNA (mRNA-LNP), a technology validated by widely used COVID-19 vaccines, rescues males from APAP-induced death that otherwise occurred in control mRNA-LNP-treated mice.

Conclusions

Our study demonstrates a sexually dimorphic liver repair advantage in females following APAP overdose, leveraged by establishing GH as an alternative treatment, delivered either as recombinant protein or mRNA-LNP, to potentially prevent liver failure and liver transplant in APAP-overdosed patients.

VEGFA mRNA-LNP promotes biliary epithelial cell-to-hepatocyte conversion in acute and chronic liver diseases and reverses steatosis and fibrosis

The liver is known for its remarkable regenerative ability through proliferation of hepatocytes. Yet, during chronic injury or severe hepatocyte death, proliferation of hepatocytes is exhausted. To overcome this hurdle, we propose vascular-endothelial-growth-factor A (VEGFA) as a therapeutic means to accelerate biliary epithelial cell (BEC)-to-hepatocyte conversion. Investigation in zebrafish establishes that blocking VEGF receptors abrogates BEC-driven liver repair, while VEGFA overexpression promotes it. Delivery of VEGFA via non-integrative and safe nucleoside-modified mRNA encapsulated into lipid-nanoparticles (mRNA-LNP) in acutely or chronically injured mouse livers induces robust BEC-to-hepatocyte conversion and reversion of steatosis and fibrosis. In human and murine diseased livers, we further identified VEGFA-receptor KDR-expressing BECs associated with KDR-expressing cell-derived hepatocytes. This defines KDR-expressing cells, most likely being BECs, as facultative progenitors. This study reveals novel therapeutic benefits of VEGFA delivered via nucleoside-modified mRNA-LNP, whose safety is widely validated with COVID-19 vaccines, for harnessing BEC-driven repair to potentially treat liver diseases.

Highlights

Complementary mouse and zebrafish models of liver injury demonstrate the therapeutic impact of VEGFA-KDR axis activation to harness BEC-driven liver regeneration.VEGFA mRNA LNPs restore two key features of the chronic liver disease in humans such as steatosis and fibrosis.Identification in human cirrhotic ESLD livers of KDR-expressing BECs adjacent to clusters of KDR+ hepatocytes suggesting their BEC origin.KDR-expressing BECs may represent facultative adult progenitor cells, a unique BEC population that has yet been uncovered.

Efficient delivery of VEGF-A mRNA for promoting diabetic wound healing via ionizable lipid nanoparticles

Diabetes is often accompanied by chronic non-healing wounds, and vascularendothelial growth factor A (VEGF-A) is crucial in the treatment of chronic diabetic wounds. However, the application of VEGF-A protein in clinic is limited due to poor absorption and short half-life of protein macromolecule. Herein, we employed an emerging protein replacement therapy by delivering VEGF-A mRNA into the body to express the desired protein to accelerate diabetic wound healing. Primarily, VEGF-A mRNA was synthesized by an in vitro transcription (IVT) method and encapsulated with an ionizable lipid-mediated nanoparticles (LNP) delivery system via a microfluidic method. The resultant LNP/VEGF-A mRNA were characterized by using dynamic light scattering (DLS) and transmission electron microscope(TEM). The nanoparticles have regular spherical morphology with an average particle size of 101.17 nm, a narrow polydispersity (PDI) of 0.17 and negative Zeta potential of -3.05 mV. The bioactivities of the nanoparticles formulation were evaluated against HUVEC cells through cell proliferation, migration and tube formation assays. It was found that the LNP/VEGF-A mRNA nanoparticles could promote endothelial cell proliferation. In addition, they exhibited successful mRNA delivery and high VEGF-A protein expression in vitro and in vivo by means of Western Blot assay and in vivo imaging system (IVIS). Finally, C57BL/6 diabetic mice model was established and intradermally treated with the LNP/VEGF-A mRNA nanoparticles. It was found that the LNP/VEGF-A mRNA treated wounds were almost healed after 14 days with an average wound area of 2.4 %, compared with the PBS group of 21.4 %. Apparently, the nanoparticles formulation was able to significantly expedite diabetic wound healing. The histological analysis containing H&E, Masson's trichrome staining and CD31 further confirmed the healing efficacy and low toxicity of the formulation. Taken together, the LNP/VEGF-A mRNA nanoparticles can be taken up by cells to express protein effectively and improve diabetic wound healing, which might have potential application in the treatment of chronic diabetic wounds as a protein replacement therapy.

Nonlysosomal Route of mRNA Delivery and Combining with Epigenetic Regulation Optimized Antitumor Immunoprophylactic Efficacy

Currently, mRNA-based tumor therapies are in full flow because in vitro-transcribed (IVT) mRNA has the potential to express tumor antigens to initiate the adaptive immune responses. However, the efficacy of such therapy relies heavily on the delivery system. Here, a pardaxin-modified liposome loaded with tumor antigen-encoding mRNA and adjuvant (2',3'-cGAMP, (cyclic [G(2',5')pA(3',5')p])), termed P-Lipoplex-CDN is reported. Due to an nonlysosomal delivery route, the transfection efficiency on dendritic cells (DCs) is improved by reducing the lysosome disruption of cargos. The mRNA modified DCs efficiently induce tumor antigen-specific immune responses both in vitro and in vivo. As prophylactic vaccines, mRNA transfected DCs significantly delay the occurrence and development of tumors, and several immunized mice are even completely resistant to tumors. Interestingly, the efficacy depends on the major histocompatibility complex class I (MHC-I) expression level on tumor cells. Furthermore, epigenetic modification (decitabine, DAC) is applied as a combination strategy to deal with malignant tumor progression caused by deficient tumor MHC-I expression. This study highlights the close relationship between mRNA-DCs vaccine efficacy and the expression level of tumor cell MHC-I molecules. Moreover, a feasible strategy for tumor MHC-I expression deficiency is proposed, which may provide clinical guidance for the design and application of mRNA-based tumor therapies.

N2 modified dinucleotide cap analogs as a potent tool for mRNA engineering

mRNA-based vaccines are relatively new technologies that have been in the field of interest of research centers and pharmaceutical companies in recent years. Such therapeutics are an attractive alternative for DNA-based vaccines since they provide material that can be used with no risk of genomic integration. Additionally, mRNA can be quite easily engineered to introduce modifications for different applications or to modulate its properties, for example, to increase translational efficiency or stability, which is not available for DNA vectors. Here, we describe the use of N2 modified dinucleotide cap analogs as components of mRNA transcripts. The compounds obtained showed very promising biological properties while incorporated into mRNA. The presented N2-guanine modifications within the cap structure ensure proper attachment of the dinucleotide to the transcripts in the IVT reaction, guarantees their incorporation only in the correct orientation, and enables highly efficient translation of mRNA both in the in vitro translation system and in human HEK293 cells.

Advances of mRNA vaccine in tumor: a maze of opportunities and challenges

High-frequency mutations in tumor genomes could be exploited as an asset for developing tumor vaccines. In recent years, with the tremendous breakthrough in genomics, intelligence algorithm, and in-depth insight of tumor immunology, it has become possible to rapidly target genomic alterations in tumor cell and rationally select vaccine targets. Among a variety of candidate vaccine platforms, the early application of mRNA was limited by instability low efficiency and excessive immunogenicity until the successful development of mRNA vaccines against SARS-COV-2 broken of technical bottleneck in vaccine preparation, allowing tumor mRNA vaccines to be prepared rapidly in an economical way with good performance of stability and efficiency. In this review, we systematically summarized the classification and characteristics of tumor antigens, the general process and methods for screening neoantigens, the strategies of vaccine preparations and advances in clinical trials, as well as presented the main challenges in the current mRNA tumor vaccine development.

Matrices Activated with Messenger RNA

Over two decades of preclinical and clinical experience have confirmed that gene therapy-activated matrices are potent tools for sustained gene modulation at the implantation area. Matrices activated with messenger RNA (mRNA) are the latest development in the area, and they promise an ideal combination of efficiency and safety. Indeed, implanted mRNA-activated matrices allow a sustained delivery of mRNA and the continuous production of therapeutic proteins in situ. In addition, they are particularly interesting to generate proteins acting on intracellular targets, as the translated protein can directly exert its therapeutic function. Still, mRNA-activated matrices are incipient technologies with a limited number of published records, and much is still to be understood before their successful implementation. Indeed, the design parameters of mRNA-activated matrices are crucial for their performance, as they affect mRNA stability, device immunogenicity, translation efficiency, and the duration of the therapy. Critical design factors include matrix composition and its mesh size, mRNA chemical modification and sequence, and the characteristics of the nanocarriers used for mRNA delivery. This review aims to provide some background relevant to these technologies and to summarize both the design space for mRNA-activated matrices and the current knowledge regarding their pharmaceutical performance. Furthermore, we will discuss potential applications of mRNA-activated matrices, mainly focusing on tissue engineering and immunomodulation.

Efficient delivery of VEGFA mRNA for promoting wound healing via ionizable lipid nanoparticles

Vascular endothelial growth factor A (VEGFA) plays an important role in the healing of skin wound. However, the application of VEGFA protein in clinic is limited because of its high cost manufacturing, complicated purification and poor pharmacokinetic profile. Herein, we developed nucleoside-modified mRNA encoding VEGFA encapsulated ionizable lipid nanoparticles (LNP) to improve angiogenesis and increase wound healing rate. First, VEGFA mRNA was synthesized by an in vitro transcription (IVT) method. After that, VEGFA mRNA-LNP was prepared by encapsulating mRNA in ionizable lipid based nanoparticles via a microfluidic mixer. The physicochemical properties of VEGFA mRNA-LNP were investigated via dynamic light scattering (DLS) and transmission electron microscopy (TEM). The results showed that the VEGFA mRNA-LNP possessed regular spherical morphology with an average size of 112.67 nm and a negative Zeta potential of -3.43 mV. The LNP delivery system had excellent lysosome escape capability and high transfection efficiency. ELISA and Western Blot analysis indicated that the mRNA-LNP could express VEGFA protein in Human umbilical vein endothelial cells (HUVECs). Besides, endothelial tube formation, cell proliferation and scratch assays were performed. The results revealed VEGFA mRNA-LNP boosted angiogenesis, cell proliferation and cell migration by expressing VEGFA protein. Finally, C57BL/6 mouse model of skin wound was established and intradermally treated with VEGFA mRNA-LNP. The VEGFA mRNA-LNP treated wounds were almost healed with an average wound size of 1.56 mm² compared with the blank of 18.66 mm² after 9 days. The results indicated that the VEGFA mRNA-LNP was able to significantly expedite wound healing. Histological analysis further demonstrated tissue epithelialization, collagen deposition and enhancement of vascular density after treatment. Taken together, VEGFA mRNA-LNP can be uptaken by cells to express protein effectively and promote wound healing, which may provide a promising strategy for clinical remedy.

Protein Transduction Domain-Mediated Delivery of Recombinant Proteins and In Vitro Transcribed mRNAs for Protein Replacement Therapy of Human Severe Genetic Mitochondrial Disorders: The Case of Sco2 Deficiency

Mitochondrial disorders represent a heterogeneous group of genetic disorders with variations in severity and clinical outcomes, mostly characterized by respiratory chain dysfunction and abnormal mitochondrial function. More specifically, mutations in the human SCO2 gene, encoding the mitochondrial inner membrane Sco2 cytochrome c oxidase (COX) assembly protein, have been implicated in the mitochondrial disorder fatal infantile cardioencephalomyopathy with COX deficiency. Since an effective treatment is still missing, a protein replacement therapy (PRT) was explored using protein transduction domain (PTD) technology. Therefore, the human recombinant full-length mitochondrial protein Sco2, fused to TAT peptide (a common PTD), was produced (fusion Sco2 protein) and successfully transduced into fibroblasts derived from a SCO2/COX-deficient patient. This PRT contributed to effective COX assembly and partial recovery of COX activity. In mice, radiolabeled fusion Sco2 protein was biodistributed in the peripheral tissues of mice and successfully delivered into their mitochondria. Complementary to that, an mRNA-based therapeutic approach has been more recently considered as an innovative treatment option. In particular, a patented, novel PTD-mediated IVT-mRNA delivery platform was developed and applied in recent research efforts. PTD-IVT-mRNA of full-length SCO2 was successfully transduced into the fibroblasts derived from a SCO2/COX-deficient patient, translated in host ribosomes into a nascent chain of human Sco2, imported into mitochondria, and processed to the mature protein. Consequently, the recovery of reduced COX activity was achieved, thus suggesting the potential of this mRNA-based technology for clinical translation as a PRT for metabolic/genetic disorders. In this review, such research efforts will be comprehensibly presented and discussed to elaborate their potential in clinical application and therapeutic usefulness.

Self-Amplifying RNA Vaccine Candidates: Alternative Platforms for mRNA Vaccine Development

The present use of mRNA vaccines against COVID-19 has shown for the first time the potential of mRNA vaccines for infectious diseases. Here we will summarize the current knowledge about improved mRNA vaccines, i.e., the self-amplifying mRNA (saRNA) vaccines. This approach may enhance antigen expression by amplification of the antigen-encoding RNA. RNA design, RNA delivery, and the innate immune responses induced by RNA will be reviewed.

Single-domain antibody delivery using an mRNA platform protects against lethal doses of botulinum neurotoxin A

Single-domain antibodies (sdAbs, VHHs, or nanobodies) are a promising tool for the treatment of both infectious and somatic diseases. Their small size greatly simplifies any genetic engineering manipulations. Such antibodies have the ability to bind hard-to-reach antigenic epitopes through long parts of the variable chains, the third complementarity-determining regions (CDR3s). VHH fusion with the canonical immunoglobulin Fc fragment allows the Fc-fusion single-domain antibodies (VHH-Fc) to significantly increase their neutralizing activity and serum half-life. Previously we have developed and characterized VHH-Fc specific to botulinum neurotoxin A (BoNT/A), that showed a 1000-fold higher protective activity than monomeric form when challenged with five times the lethal dose (5 LD₅₀) of BoNT/A. During the COVID-19 pandemic, mRNA vaccines based on lipid nanoparticles (LNP) as a delivery system have become an important translational technology that has significantly accelerated the clinical introduction of mRNA platforms. We have developed an mRNA platform that provides long-term expression after both intramuscular and intravenous application. The platform has been extensively characterized using firefly luciferase (Fluc) as a reporter. An intramuscular administration of LNP-mRNA encoding VHH-Fc antibody made it possible to achieve its rapid expression in mice and resulted in 100% protection when challenged with up to 100 LD₅₀ of BoNT/A. The presented approach for the delivery of sdAbs using mRNA technology greatly simplifies drug development for antibody therapy and can be used for emergency prophylaxis.

Formulation of Lipid-Free Polymeric Mesoscale Nanoparticles Encapsulating mRNA

Introduction

Nanoparticle-mediated gene therapy has found substantial clinical impact, primarily focused on lipid-based nanoparticles. In comparison with lipid nanoparticles, polymeric particles may have certain advantages such as increased biocompatibility and controlled release. Our prior studies have found that polymeric mesoscale nanoparticles exhibited specific targeting to the renal proximal tubules. Thus, in this study, we sought to identify formulation parameters that allow for development of polymeric mesoscale nanoparticles encapsulating functional mRNA for delivery into tubular epithelial cells.

Methods

We evaluated particle uptake in vitro prior to exploring formulation parameters related to introduction of a primary mixture of polymer in acetonitrile and hydrophilic mRNA in water. Finally, we evaluated their functionality in a renal tubular epithelial cell line.

Results

We found that MNPs are endocytosed within 15 min and that the mesoscale nanoparticle formulation procedure was generally robust to introduction of a primary mixture and encapsulation of mRNA. These particles exhibited substantial uptake in renal cells in vitro and rapid (< 1 h) expression of a model mCherry fluorescent protein.

Conclusion

We anticipate these findings having potential in the delivery of specific gene therapies for renal disorders and cancer.

mRNA Treatment Rescues Niemann-Pick Disease Type C1 in Patient Fibroblasts

Messenger RNA (mRNA) holds great potential as a disease-modifying treatment for a wide array of monogenic disorders. Niemann-Pick disease type C1 (NP-C1) is an ultrarare monogenic disease that arises due to loss-of-function mutations in the NPC1 gene, resulting in the entrapment of unesterified cholesterol in the lysosomes of affected cells and a subsequent reduction in their capacity for cholesterol esterification. This causes severe damage to various organs including the brain, liver, and spleen. In this work, we describe the use of NPC1-encoded mRNA to rescue the protein insufficiency and pathogenic phenotype caused by biallelic NPC1 mutations in cultured fibroblasts derived from an NP-C1 patient. We first evaluated engineering strategies for the generation of potent mRNAs capable of eliciting high protein expression across multiple cell types. We observed that "GC3" codon optimization, coupled with N1-methylpseudouridine base modification, yielded an mRNA that was approximately 1000-fold more potent than wild-type, unmodified mRNA in a luciferase reporter assay and consistently superior to other mRNA variants. Our data suggest that the improved expression associated with this design strategy was due in large part to the increased secondary structure of the designed mRNAs. Both codon optimization and base modification appear to contribute to increased secondary structure. Applying these principles to the engineering of NPC1-encoded mRNA, we observed a normalization in NPC1 protein levels after mRNA treatment, as well as a rescue of the mutant phenotype. Specifically, mRNA treatment restored the cholesterol esterification capacity of patient cells to wild-type levels and induced a significant reduction in both unesterified cholesterol levels (>57% reduction compared to Lipofectamine-treated control in a cholesterol esterification assay) and lysosome size (157 μm² reduction compared to Lipofectamine-treated control). These findings show that engineered mRNA can correct the deficit caused by NPC1 mutations. More broadly, they also serve to further validate the potential of this technology to correct diseases associated with loss-of-function mutations in genes coding for large, complex, intracellular proteins.

Nanotechnology-based chimeric antigen receptor T-cell therapy in treating solid tumor

Chimeric Antigen Receptor (CAR) T cells have changed the therapeutic landscape of hematological malignancies with overwhelming success. The clinical success of CAR T-cell therapy in hematologic malignancies has fueled interest in exploring the technology in solid tumors. However, the treatment of solid tumors presents a unique set of challenges compared to hematological tumors. The biggest impediments to the success of CAR T cell treatment are the paucity of tumor-specific antigens that are produced selectively and uniformly and the immunosuppressive tumor microenvironment. To overcome these significant challenges, nanotechnology has been involved to improve the efficacy of CAR-T cells. In this review, we systematically introduced the components of different generations of CARs and summarized recent innovations in nano-based CAR-T cell therapy to conquer therapeutically resistant non-hematologic malignancies, including mRNA and hydrogel-based CAR T cells delivery, photothermal-remodeling, and tumor microenvironment-based CAR T cell therapy. These nanotechnologies remarkably facilitate in vivo generation of CAR T cells and hold promise as a therapeutic platform to treat solid tumors and even other diseases.