Apolipoprotein E Binding Drives Structural and Compositional Rearrangement of mRNA-Containing Lipid Nanoparticles

Investigating the stability of RNA-lipid nanoparticles in biological fluids: Unveiling its crucial role for understanding LNP performance

Lipid nanoparticles (LNPs) are the most established and clinically advanced platform for RNA delivery. While significant efforts have been made to improve RNA delivery efficiency for improved protein production, the interplay between physiological stability, target specificity, and therapeutic efficacy of RNA-LNPs remains largely unexplored. This review highlights the crucial, yet often overlooked, impact of in vivo stability or instability of RNA-LNPs in contact with biological fluids on delivery performance. We discuss the various factors, including lipid composition, particle surface properties and interactions with proteins in physiological conditions, and provide an overview of the current methods for assessing RNA-LNP stability in biological fluids, such as dynamic laser light scattering, liquid chromatography, and fluorescent and radiolabeled techniques. In the final part, we propose strategies for enhancing stability, with a focus on shielding lipids. Therefore, this work highlights the importance of investigating and understanding the balance between stability and instability of LNPs in the biological context to achieve a more meaningful correlation between formulation properties and in vivo performance.

Advances in nanodelivery systems based on apoptosis strategies for enhanced rheumatoid arthritis therapy

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disorder primarily characterized by persistent synovial inflammation and progressive bone erosion. The pathogenesis of RA involves a complex cascade of cellular and molecular events, including sustained hyperactivation of macrophages, excessive recruitment and activation of neutrophils, pathological proliferation and invasion of fibroblast-like synoviocytes (FLS), and dysregulated differentiation and function of osteoclasts (OCs). The inflammatory factors secreted by these dysregulated cells significantly disrupt the joint microenvironment through multiple pathological mechanisms, primarily by promoting synovial inflammation, cartilage matrix degradation, osteoclast-mediated bone erosion, and pathological angiogenesis. Therapeutic strategies targeting the induction of apoptosis in these malignant cells have demonstrated considerable potential in preclinical studies, offering a promising approach to enhance treatment outcomes by simultaneously reducing inflammatory cytokine production and inhibiting pathogenic cell proliferation. However, conventional therapeutic drugs are limited in clinical applications because of their high toxicity and side effects. Inflammation induces morphological and functional changes in cells within the rheumatoid arthritis microenvironment (RAM), particularly the overexpression of specific receptors on cell membranes. This phenomenon has driven the development of ligand-modified targeted nanodelivery systems (NDSs), which can specifically target and induce apoptosis in specific cell types, thereby enhancing therapeutic efficacy. This paper comprehensively reviews the research progress of targeted NDSs based on apoptosis strategies for RA therapy, with a detailed discussion of their advantages in inducing apoptosis in various disease-associated cells. Furthermore, the potential of combining apoptosis of multiple cell types for RA treatment is explored. This review is expected to improve insights into the apoptosis of malignant cells to enhance RA therapy. STATEMENT OF SIGNIFICANCE: This review highlights recent advances in nanodelivery systems (NDSs) based on apoptotic strategies for enhanced rheumatoid arthritis (RA) therapy. Unlike conventional NDSs, these optimized systems specifically induce apoptosis in malignant cells within the RA microenvironment by integrating multiple therapeutic strategies. By summarizing the latest research, our work demonstrates the potential of these NDSs to suppress inflammatory responses and prevent bone destruction through targeted elimination of malignant cells, offering a novel direction for RA treatment. This review is significant as it provides a comprehensive overview for researchers and clinicians, facilitating the development of more effective therapeutic approaches for RA and other chronic inflammatory diseases.

Regulating mRNA endosomal escape through lipid rafts: A review

Messenger RNA (mRNA) therapeutics, enabled by lipid nanoparticles (LNPs) delivery systems, have revolutionized modern medicine by facilitating the delivery of genetic cargo to target cells. However, the efficient release of mRNA from LNPs within the endosomal pathways into the cytosol remains a major bottleneck in this field. Revisiting the formulation and function of mRNA-LNPs, it has been found that lipid rafts formed by cholesterol and distearoylphosphatidylcholine during the self-assembly process plan an essential role in the intracellular delivery and endosomal escape of mRNA-LNPs. These lipid rafts enhance the rigidity and stability of LNPs, facilitating mRNA encapsulation and closely contributing to improved intracellular delivery efficiency. By adjusting the composition or behavior of lipid rafts within LNPs-such as substituting cholesterol or altering the lipid phase-endosomal membranes can be destabilized, facilitating the escape of mRNA into the cytoplasm. This approach provides a promising strategy for rational design of mRNA delivery system and optimization of LNPs formulation. Additionally, methods for studying the mRNA escape process are summarized, as they serve as the foundation for achieving reliable and reproducible results.

A Post-Encapsulation Method for the Preparation of mRNA-LNPs via the Nucleic Acid-Bridged Fusion of mRNA-Free LNPs

Lipid nanoparticles with encapsulated mRNA (mRNA-LNPs) have become key modalities for personalized medicines and RNA vaccines. Once the platform technology is established, the mRNA-LNPs could be applicable to a variety of protein-based therapeutic strategies. A post-encapsulation method, in which the mRNA solution is incubated with preformed mRNA-free LNPs to prepare the mRNA-LNPs, would accelerate the development of RNA-based therapeutics since even nonexperts could manufacture the mRNA-LNPs. In this study, we describe that the post-encapsulation of mRNA into mRNA-free LNPs is accompanied by "nucleic acid-bridged fusion" of them. The adsorption of mRNA onto mRNA-free LNPs via electrostatic interactions and the internalization of mRNA into the LNPs via particle-to-particle fusion are two steps that occur at different levels of pH. To complete post-encapsulation using only one-step mixing, the pH must be controlled within a limited region where both processes occur simultaneously. The size of the mRNA-free LNPs determines the effectiveness of mRNA loading.

Sorafenib-Drug Delivery Strategies in Primary Liver Cancer

Current primary liver cancer therapies, including sorafenib and transarterial chemoembolization, face significant limitations due to chemoresistance caused by impaired drug uptake, altered metabolism, and other genetic modulations. These challenges contribute to relapse rates of 50-80% within five years. The need for improved treatment strategies (adjuvant therapy, unsatisfactory enhanced permeability and retention (EPR) effect) has driven research into advanced drug delivery systems, including targeted nanoparticles, biomaterials, and combinatory approaches. Therefore, this review evaluates recent advancements in primary liver cancer pharmacotherapy, focusing on the potential of drug delivery systems for sorafenib and its derivatives. Approaches such as leveraging Kupffer cells for tumor migration or utilizing smaller NPs for inter-/intracellular delivery, address EPR limitations. Biomaterials and targeted therapies focusing on targeting have demonstrated effectiveness in increasing tumor-specific delivery, but clinical evidence remains limited. Combination therapies have emerged as an interesting solution to overcoming chemoresistance or to broadening therapeutic functionality. Biomimetic delivery systems, employing blood cells or exosomes, provide methods for targeting tumors, preventing metastasis, and strengthening immune responses. However, significant differences between preclinical models and human physiology remain a barrier to translating these findings into clinical success. Future research must focus on the development of adjuvant therapy and refining drug delivery systems to overcome the limitations of tumor heterogeneity and low drug accumulation.

Hurdles to healing: Overcoming cellular barriers for viral and nonviral gene therapy

Gene delivery offers great potential for treating various diseases, yet its success requires overcoming several biological barriers. These hurdles span from extracellular degradation, reaching the target cells, and inefficient cellular uptake to endosomal entrapment, cytoplasmic transport, nuclear entry, and transcription limitations. Viruses and non-viral vectors deal with these barriers via different mechanisms. Viral vectors, such as adenoviruses, adeno-associated viruses, and lentiviruses use natural mechanisms to efficiently deliver genetic material but face limitations including immunogenicity, cargo capacity, and production complexity. Nonviral vectors, including lipid nanoparticles, polymers, and protein-based systems, offer scalable and safer alternatives but often fall short in overcoming intracellular barriers and achieving high transfection efficiencies. Recent advancements in vector engineering have partially overcome several of these challenges. Ionizable lipids improve endosomal escape while minimizing toxicity. Biodegradable polymers balance efficacy with safety, and engineered protein systems, inspired by viral or bacterial entry mechanisms, integrate multifunctionality for enhanced delivery. Despite these advances, challenges, particularly in achieving robust in vivo translatability, scalability, and reduced immunogenicity, remain. This review synthesizes current knowledge of cellular barriers and the approaches to overcome them, providing a roadmap for designing more efficient gene delivery systems. By addressing these barriers, the field can advance toward safer, and more effective therapies.

Apolipoprotein E3 functionalized mesoporous silica nanoparticles for targeted and enhanced therapeutic efficacy of Levetiracetam in brain tumor-associated epilepsy: Insights into brain uptake, biodistribution and pharmacokinetic behavior

Epilepsy affects approximately 20-40 % of patients with brain-tumors, significantly impacting their quality of life and overall survival rates. To address this, Levetiracetam (LVM) has emerged as effective treatment option due to minimal negative interactions with other medications and reduced side-effects. However, its hydrophilic nature necessitates high doses and frequent administration, which can lead to drug resistance and hinder the clinical response to therapy. The present research focuses on developing a novel formulation of LVM-loaded mesoporous silica nanoparticles (LVM-MSN) conjugated with Apolipoprotein E3 (ApoE3) for enhanced brain-targeting. LVM-MSN were prepared using the calcination method after optimizing different synthesis parameters. Chitosan was employed as capping agent to form LVM-Chito-MSN, which was characterized using zeta potential, XRD, FE-SEM, and TEM study. Further, LVM-Chito-MSN was functionalized by ApoE3 as brain-targeting ligand through direct coating approach (ApoE3@LVM-Chito-MSN). In-vivo pharmacokinetic study and biodistribution study indicated an impressive 3-fold increase in brain-uptake of ApoE3@LVM-Chito-MSN, with reduced distribution to other organs compared to LVM solution. The hemolysis study and histological examination of major organs indicated safety of the formulation. Consequently, functionalization of MSN with ApoE3 represents promising strategy for enhanced brain targeting, which could lead to improved patient compliance and better overall survival rates for patients suffering from brain tumor-related epilepsy.

Splenic B cell-targeting lipid nanoparticles for safe and effective mRNA vaccine delivery

mRNA-loaded lipid nanoparticles (LNPs) have emerged as a potent and versatile platform that underpins the success of mRNA vaccines, but guidelines for designing safe and effective formulations with minimal off-target effects remain unclear. In this study, we focused on a rational design for a novel ionizable lipid library that is based on ionizable tri-oleoyl-tris (iTOT) compounds with a high yield via a simple 2-step synthesis. To further enhance the efficacy and safety of this potent library for vaccine applications, we identified the optimal composition for a vaccine by focusing on the molar ratio of specific lipid excipients in the formulation. This composition brought about a shift in delivery to the spleen, and the LNP formulation, which contained 15 mol% DSPC (15%DSPC-LNPs), was thoroughly taken up by both B cells and other splenic immune cells. This formulation requires neither additional lipid components nor targeting ligand modifications, and it is accompanied by antigen-specific cytotoxic T lymphocyte responses. The rigid, hydrophobic, and charge-neutral surface of 15%DSPC-LNPs minimizes apolipoprotein E-dependent hepatic uptake and maximizes complement receptor-mediated B-cell targeting. Furthermore, as an intramuscularly administered vaccine, 15%DSPC-LNPs induce antigen-specific immune responses and, importantly, results in significantly lower levels of hepatotoxicity compared with that of the mRNA vaccine formulations currently being marketed. In summary, this study demonstrated how the passive targeting of mRNA-LNPs to organs and cells could be regulated by designing novel ionizable lipids combined with adjusting the relative proportions of lipid components. The results of this study also emphasize how selective mRNA delivery to the spleen could avoid the liver, which highlights a promising strategy for the development of safe and effective vaccines.

Formulation and Characterization of Novel Ionizable and Cationic Lipid Nanoparticles for the Delivery of Splice-Switching Oligonucleotides

Despite increasing knowledge about the mechanistic aspects of lipid nanoparticles (LNPs) as oligonucleotide carriers, the structure-function relationship in LNPs has been generally overlooked. Understanding this correlation is critical in the rational design of LNPs. Here, a materials characterization approach is utilized, applying structural information from small-angle X-ray scattering experiments to design novel LNPs focusing on distinct lipid organizations with a minimal compositional variation. The lipid phase structures are characterized in these LNPs and their corresponding bulk lipid mixtures with small-angle scattering techniques, and the LNP-cell interactions in vitro with respect to cytotoxicity, hemolysis, cargo delivery, cell uptake, and lysosomal swelling. An LNP is identified that outperforms Onpattro lipid composition using lipid components and molar ratios which differ from the gold standard clinical LNPs. The base structure of these LNPs has an inverse micellar phase organization, whereas the LNPs with inverted hexagonal phases are not functional, suggesting that this phase formation may not be needed for LNP-mediated oligonucleotide delivery. The importance of stabilizer choice for the LNP function is demonstrated and super-resolution microscopy highlights the complexity of the delivery mechanisms, where lysosomal swelling for the majority of LNPs is observed. This study highlights the importance of advanced characterization for the rational design of LNPs to enable the study of structure-function relationships.

Lung-Specific mRNA Delivery by Ionizable Lipids with Defined Structure-Function Relationship and Unique Protein Corona Feature

Targeted delivery of mRNA with lipid nanoparticles (LNPs) holds great potential for treating pulmonary diseases. However, the lack of rational design principles for efficient lung-homing lipids hinders the prevalence of mRNA therapeutics in this organ. Herein, the combinatorial screening with structure-function analysis is applied to rationalize the design strategy for nonpermanently charged lung-targeted ionizable lipids. It is discovered that lipids carrying N-methyl and secondary amine groups in the heads, and three tails originated from epoxyalkanes, exhibiting superior pulmonary selectivity and efficiency. Representative ionizable lipids with systematically variation in chemical structures are selected to study the well-known but still puzzling "protein corona" adsorbed on the surface of LNPs. In addition to the commonly used corona-biomarker vitronectin, other arginine-glycine-aspartic acid (RGD)-rich proteins usually involved in collagen-containing extracellular matrix, such as fibrinogen and fibronectin have also been identified to have a strong correlation with lung tropism. This work provides insight into the rational design of lung-targeting ionizable lipids and reveals a previously unreported potential function of RGD-rich proteins in the protein corona of lung-homing LNPs.

Choice of organic solvent affects function of mRNA-LNP; pyridine produces highly functional mRNA-LNP

Lipid nanoparticles (LNPs) are well-known nanocarriers for mRNA delivery. mRNA-encapsulated LNPs (mRNA-LNPs) are prepared by alcohol dilution (broadly defined as solvent dilution) method, in which mRNA dissolved in acidic buffer is mixed with lipid dissolved in an organic solvent. Ethanol is the most commonly used organic solvent for dissolving lipids during the preparation of mRNA-LNPs. However, no studies have systematically investigated the effects of organic solvents that dissolve lipids during the preparation of mRNA-LNPs on the properties and functions of mRNA-LNPs. In this study, we prepared mRNA-LNPs by using a series of organic solvents and evaluated their characteristics. After screening, we discovered that pyridine, an organic solvent, improved the quality of mRNA-LNPs and their function in vitro and in vivo. Pyridine was applied versatilely to some lipid-composition combinations generally used in the preparation of mRNA-LNPs and can also be adapted to microfluidic-based preparation. Furthermore, with appropriate purification, the amount of pyridine remaining in the final preparation of the mRNA-LNPs was extremely low and did not affect safety. Although further mechanism-based studies are required, we conclude that pyridine is a solvent that can be applied to the production of mRNA-LNPs as a pharmaceutical product.

A Polysorbate-Based Lipid Nanoparticle Vaccine Formulation Induces In Vivo Immune Response Against SARS-CoV-2

Background: Lipid nanoparticles (LNPs) have proven effective in delivering RNA-based modalities. Rapid approval of the COVID-19 vaccines highlights the promise of LNPs as a delivery platform for nucleic acid-based therapies and vaccines. Nevertheless, improved LNP designs are needed to advance next-generation vaccines and other gene therapies toward greater clinical success. Lipid components and LNP formulation excipients play a central role in biodistribution, immunogenicity, and stability. Therefore, it is important to understand, identify, and assess the appropriate lipid components for developing a safe and effective formulation. Herein, this study focused on developing a novel Polysorbate-80 (PS-80)-based LNP. We hypothesized that substituting conventional linear PEG-lipids with PS-80, a widely used, biocompatible injectable surfactant featuring a branched PEG-like structure, may change the LNPs biodistribution pattern and enhance long-term stability. By leveraging PS-80's unique structural properties, this study aimed to develop an mRNA-LNP platform with improved extrahepatic delivery and robust freeze/thaw tolerance. Methods: We employed a stepwise optimization to establish both the lipid composition and formulation buffer to yield a stable, high-performing PS-80-based SARS-CoV-2 mRNA-LNP (SC2-PS80 LNP). We compared phosphate- versus tris-based buffers for long-term stability, examined multiple lipid ratios, and evaluated the impact of incorporating PS-80 (a branched PEG-lipid) on in vivo biodistribution. Various analytical assays were performed to assess particle size, encapsulation efficiency, mRNA purity, and in vitro potency of the developed formulation and a humanized mouse model was used to measure its immunogenicity over six months of storage at -80 °C. Results: Replacing the standard 1,2-dimyristoyl-rac-glycero-3-methoxy polyethylene glycol-2000 (PEG-DMG) lipid with PS-80 increased spleen-specific expression of the mRNA-LNPs after intramuscular injection. Formulating in a tris-sucrose-salt (TSS) buffer preserved the LNP's physicochemical properties and in vitro potency over six months at -80 °C, whereas a conventional PBS-sucrose (PSS) buffer was less protective under frozen conditions. Notably, TSS-based SC2-PS80 LNPs elicited potent humoral immunity in mice, including high anti-spike IgG titers and robust pseudovirus neutralization, comparable to freshly prepared formulations. Conclusions: A PS-80-based mRNA-LNP platform formulated in TSS buffer confers improved extrahepatic delivery, long-term frozen stability, and strong immunogenicity against SARS-CoV-2 following six months. These findings offer a promising pathway for the design of next-generation mRNA vaccines and therapeutics with enhanced stability and clinical potential.

Lipid-siRNA Organization Modulates the Intracellular Dynamics of Lipid Nanoparticles

Lipid nanoparticles (LNPs) are widely used for delivering therapeutic nucleic acids, yet the relationship between their internal structure and intracellular behavior, particularly before RNA release, remains unclear. Here, we elucidate how lipid-siRNA organization within LNPs can modulate their intracellular delivery dynamics. We use cryo-electron microscopy and photochemical assays to reveal that increased siRNA loading can reduce helper lipids' distribution to the LNP surface, while siRNA consistently localizes near the surface. These alterations in lipid-siRNA organization affect LNP membrane fluidity, enhancing LNP fusion with cellular membranes and promoting cytosolic siRNA delivery, primarily via macropinocytosis. Using photosensitive lipids and live cell imaging, we demonstrate that lipid-siRNA organization regulates LNP responsiveness to external stimuli, significantly affecting siRNA endosomal escape efficiency upon light activation. We further confirm this observation using convex lens-induced confinement microscopy and single-particle imaging. Overall, our findings provide critical insights into how lipid-siRNA organization shapes LNP intracellular dynamics, offering rational design principles for optimizing LNP-based RNA therapeutics.

The Interplay of Endosomal Escape and RNA Release from Polymeric Nanoparticles

Ribonucleic acid (RNA) nanocarriers, specifically lipid nanoparticles and polymeric nanoparticles, enable RNA transfection both in vitro and in vivo; however, only a small percentage of RNA endocytosed by a cell is delivered to the cytosolic machinery, minimizing its effect. RNA nanocarriers face two major obstacles after endocytosis: endosomal escape and RNA release. Overcoming both obstacles simultaneously is challenging because endosomal escape is usually achieved by using high positive charge to disrupt the endosomal membrane. However, this high positive charge typically also inhibits RNA release because anionic RNA is strongly bound to the nanocarrier by electrostatic interactions. Many nanocarriers address one over the other despite a growing body of evidence demonstrating that both are crucial for RNA transfection. In this review, we survey the various strategies that have been employed to accomplish both endosomal escape and RNA release with a focus on polymeric nanomaterials. We first consider the various requirements a nanocarrier must achieve for RNA delivery including protection from degradation, cellular internalization, endosomal escape, and RNA release. We then discuss current polymers used for RNA delivery and examine the strategies for achieving both endosomal escape and RNA release. Finally, we review various stimuli-responsive strategies for RNA release. While RNA release continues to be a challenge in achieving efficient RNA transfection, many new innovations in polymeric materials have elucidated promising strategies.

ATP-responsive tumor targeted lipid nanoparticle for enhanced siRNA delivery and improved treatment efficacy in melanoma

Small interfering RNA (siRNA) plays a crucial role in tumor therapy, especially for non-druggable targets with obvious advantages. Nevertheless, its molecular weight, negative charge, and susceptibility to degradation hinder effective delivery to tumor cells for therapeutic action. Lipid nanoparticles (LNPs) serve as an excellent delivery mechanism for siRNA but still face problems such as suboptimal tumor targeting and inefficient intracellular release. To enhance melanoma treatment, we designed lipid nanoparticles modified with phenylboronic acid (PBA) for efficient delivery of siRNA targeting "undruggable" microphthalmia-associated transcription factor (MITF). This nanocarrier successfully encapsulated siRNA and improved tumor targeting by allowing phenylboronic acid to interact with sialic acid residues overexpressed in tumor cells. Furthermore, PBA-modified lipid nanoparticles facilitated the ATP-responsive release of siRNA intracellular. These two aspects enhance gene silencing efficiency. The in vivo targeting and gene silencing capabilities of PBA-modified lipid nanoparticles significantly surpassed those of unmodified LNP. Additionally, PBA-modified nanoparticles exhibited considerable anti-tumor and anti-metastatic effects in animal models, offering an alternative approach for siRNA therapy.

Lipid Nanocarriers as Precision Delivery Systems for Brain Tumors

Brain tumors, particularly glioblastomas, represent the most complicated cancers to treat and manage due to their highly invasive nature and the protective barriers of the brain, including the blood-brain barrier (BBB). The efficacy of currently available treatments, viz., radiotherapy, chemotherapy, and immunotherapy, are frequently limited by major side effects, drug resistance, and restricted drug penetration into the brain. Lipid nanoparticles (LNPs) have emerged as a promising and targeted delivery system for brain tumors. Lipid nanocarriers have gained tremendous attention for brain tumor therapeutics due to multiple drug encapsulation abilities, controlled release, better biocompatibility, and ability to cross the BBB. Herein, a detailed analysis of the design, mechanisms, and therapeutic benefits of LNPs in brain tumor treatment is discussed. Moreover, we also discuss the safety issues and clinical developments of LNPs and their current and future challenges. Further, we also focused on the clinical transformation of LNPs in brain tumor therapy by eliminating side effects and engineering the LNPs to overcome the related biological barriers, which provide personalized, affordable, and low-risk treatment options.

Lipid Nanoparticles for mRNA Delivery in Cancer Immunotherapy

Cancer immunotherapy is poised to be one of the major modalities for cancer treatment. Messenger RNA (mRNA) has emerged as a versatile and promising platform for the development of effective cancer immunotherapy. Delivery systems for mRNA therapeutics are pivotal for their optimal therapeutic efficacy and minimal adverse side effects. Lipid nanoparticles (LNPs) have demonstrated a great success for mRNA delivery. Numerous LNPs have been designed and optimized to enhance mRNA stability, facilitate transfection, and ensure intracellular delivery for subsequent processing. Nevertheless, challenges remain to, for example, improve the efficiency of endosomal escape and passive targeting. This review highlights key advancements in the development of mRNA LNPs for cancer immunotherapy. We delve into the design of LNPs for mRNA delivery, encompassing the chemical structures, characterization, and structure-activity relationships (SAR) of LNP compositions. We discuss the key factors influencing the transfection efficiency, passive targeting, and tropism of mRNA-loaded LNPs. We also review the preclinical and clinical applications of mRNA LNPs in cancer immunotherapy. This review can enhance our understanding in the design and application of LNPs for mRNA delivery in cancer immunotherapy.

Reducing off-target expression of mRNA therapeutics and vaccines in the liver with microRNA binding sites

Lipid nanoparticles (LNPs) are often liver tropic, presenting challenges for LNP-delivered mRNA therapeutics intended for other tissues, as off-target expression in the liver may increase side effects and modulate immune responses. To avoid off-target expression in the liver, miR-122 binding sites have been used by others in viral and non-viral therapeutics. Here, we use a luciferase reporter system to compare different copy numbers and insertion locations of miR-122 binding sequences to restrict liver expression. We inserted one to five miR-122 binding sites into the 5' or 3' untranslated regions (UTRs) of luciferase mRNAs and tested them in LNPs in vitro and in vivo via systemic intravenous and local intramuscular injections in mice. Our results showed no significant differences in de-targeting efficacy between mRNAs harboring one or multiple miR-122 binding sites or between those with 5' or 3' UTR placements. To test the impact of miR-122 binding sites on antibody response to a mRNA vaccine, Ebola virus matrix protein VP40 mRNAs were modified with or without miR-122 binding sites and injected in mice intramuscularly. This work reinforces the utility of miR-122 binding sites while providing a comparison of these sites to aid the future development of LNP-mRNA therapies for non-hepatic tissues.

Why do lipid nanoparticles target the liver? Understanding of biodistribution and liver-specific tropism

Lipid nanoparticles (LNPs) are now highly effective transporters of nucleic acids to the liver. This liver-specificity is largely due to their association with certain serum proteins, most notably apolipoprotein E (ApoE), which directs them to liver cells by binding to the low-density lipoprotein (LDL) receptors on hepatocytes. The liver's distinct anatomy, with its various specialized cell types, also influences how LNPs are taken up from the circulation, cleared, and how effective they are in delivering treatments. In this review, we consider factors that facilitate LNP's effective liver targeting and explore the latest advances in liver-targeted LNP technologies. Understanding how LNPs are targeted to the liver can help for effective design and optimization of nanoparticle-based therapies. Comprehension of the cellular interaction and biodistribution of LNPs not only leads to better treatments for liver diseases but also delivers insight for directing nanoparticles to other tissues, potentially broadening their range of therapeutic applications.

Identification of Cell Receptors Responsible for Recognition and Binding of Lipid Nanoparticles

Effective delivery of lipid nanoparticles (LNPs) and their organ- or cell-type targeting are paramount for therapeutic success. Achieving this requires a comprehensive understanding of protein corona dynamics and the identification of cell receptors involved in the recognition and uptake of LNPs. We introduce a simple, fast, and in situ strategy by a biosensor-based "Fishing" method to uncover protein corona formation on LNPs and identify key receptors of human blood cells that are responsible for the recognition and binding of human plasma corona on the surface of LNPs. Unexpectedly, we observed a significant presence of immunoglobulins with high abundance, especially anti-PEG antibodies, within the LNP corona. These antibodies, along with complement opsonization, drive colony-stimulating factor 2 receptor β (CSF2RB)-mediated phagocytosis by human myeloid cells. These compositions of the human plasma corona and their interactions with neighboring proteins are critical for the recognition and binding of LNPs by cell receptors and cellular uptake. Our findings highlight the pivotal role of anti-PEG antibodies in the circulation and phagocytosis of LNPs in vivo. This approach offers profound insights into nanomaterial behavior in vivo, paving the way for the enhanced design and efficacy of LNP-based therapies.

Technological breakthroughs and advancements in the application of mRNA vaccines: a comprehensive exploration and future prospects

mRNA vaccines utilize single-stranded linear DNA as a template for in vitro transcription. The mRNA is introduced into the cytoplasm via the corresponding delivery system to express the target protein, which then performs its relevant biological function. mRNA vaccines are beneficial in various fields, including cancer vaccines, infectious disease vaccines, protein replacement therapy, and treatment of rare diseases. They offer advantages such as a simple manufacturing process, a quick development cycle, and ease of industrialization. Additionally, mRNA vaccines afford flexibility in adjusting antigen designs and combining sequences of multiple variants, thereby addressing the issue of frequent mutations in pathogenic microorganisms. This paper aims to provide an extensive review of the global development and current research status of mRNA vaccines, with a focus on immunogenicity, classification, design, delivery vector development, stability, and biomedical application. Moreover, the study highlights current challenges and offers insights into future directions for development.

Ether bond-modified lipid nanoparticles for enhancing the treatment effect of hepatic fibrosis

Lipid nanoparticle (LNP)-mediated RNA delivery holds significant potential for the treatment of various liver diseases. Ionizable lipids play a crucial role in the formulation of LNPs and directly influence their delivery efficiency. In this study, we introduced an innovative concept by incorporating an ether bond into the hydrophobic tail of ionizable lipids for the first time. Three ionizable lipids, namely, ND-O1, ND-O2, and ND-O3, were synthesized based on 1-octylnonyl 8-[(2-hydroxyethyl)-[8-(nonyloxy)-8-oxooctyl] amino] octanoate (Lipid M). The efficacy of lipids-based LNPs for the delivery of the heat shock protein 47 (HSP47)-targeted siRNA to the liver was investigated. Compared to Lipid M-based LNP (LNP-M), it was observed that ND-O1 based LNP (LNP-O1) exhibited enhanced siRNA transfection efficiency in activated fibroblasts. In the fibrosis mice, LNP-O1 effectively suppressed HSP47 expression by approximately 84%, which was three times more effective than LNP-M, resulting in a significant decrease of collagen deposition and an amelioration of liver fibrosis. These findings highlighted the potential application of ND-O1 as an ionizable lipid for enhancing the efficient delivery of LNPs-delivered siRNA to the liver. Furthermore, this ionizable lipid design strategy offers a promising avenue for the improvement of the LNP delivery system.

Enhancing non-viral DNA delivery systems: Recent advances in improving efficiency and target specificity

DNA-based therapies are often limited by challenges such as stability, long-term integration, low transfection efficiency, and insufficient targeted DNA delivery. This review focuses on recent progress in the design of non-viral delivery systems for enhancing targeted DNA delivery and modulation of therapeutic efficiency. Cellular uptake and intracellular trafficking mechanisms play a crucial role in optimizing gene delivery efficiency. There are two main strategies employed to improve the efficiency of gene delivery vectors: (i) explore different administration routes (e.g., mucosal, intravenous, intramuscular, subcutaneous, intradermal, intratumoural, and intraocular) that best facilitates optimal uptake into the targeted cells and organs and (ii) modify the delivery vectors with cell-specific ligands (e.g., natural ligands, antibodies, peptides, carbohydrates, or aptamers) that enable targeted uptake to specific cells with higher specificity and improved biodistribution. We describe how recent progress in employing these DNA delivery strategies is advancing the field and increasing the clinical translation and ultimate clinical application of DNA therapies.

Understanding the self-assembly and molecular structure of mRNA lipid nanoparticles at real size: Insights from the ultra-large-scale simulation

Messenger RNA (mRNA) encapsulated in lipid nanoparticles (LNPs) represents a cutting-edge delivery technology that played a pivotal role during the COVID-19 pandemic and in advancing vaccine development. However, molecular structure of mRNA-LNPs at real size remains poorly understood, with conflicting results from various experimental studies. In this study, we aim to explore the assembly process and structural characteristics of mRNA-LNPs at realistic sizes using coarse-grained molecular dynamic simulations. The largest system, representing a real-sized LNPs (∼ 80 nm), reaches up to ∼6 million beads, around 30 million atoms. Moreover, the impacts of different mRNA loading levels and pH changes on the structure of mRNA-LNPs are also examined. Under acidic pH, ionizable lipid (dilinoleylmethyl-4-dimethylaminobutyrate, MC3), helper lipid (cholesterol, CHOL, distearoylphosphatidyl choline, DSPC), and mRNA rapidly self-assemble into spherical-like LNPs within 50 ns, with a diameter of 51.2 nm (2 mRNA) and 75.8 nm (4 mRNA). Inside the LNPs, a continuous lipid phase is observed alongside an aqueous phase, forming a bicontinuous structure. CHOL and DSPC form lipid rafts distributed within the shell or core layer of the LNPs, enhancing rigidity and stability. Notably, mRNA aggregation within the LNPs occurs independently of the lipid environment, and different mRNA payloads significantly influence the lipid composition between the core and shell. At neutral pH, lipid clustering slightly reduces the retention capacity of LNPs for mRNA. Our findings highlight the presence of a bicontinuous structure and lipid rafts in self-assembled LNPs, which critically influence LNPs rigidity, fluidity, and mRNA delivery efficiency. This structural insight provides a foundation for the rational design of LNPs to optimize mRNA delivery in future applications.

Atomic Insights into pH-Dependent and Water Permeation of mRNA-Lipid Nanoparticles

The exposure of mRNA to water is likely to contribute to the instability of RNA vaccines upon storage under nonfrozen conditions. Using atomistic molecular dynamics (MD) simulations, we investigated the pH-dependent structural transition and water penetration behavior of mRNA-lipid nanoparticles (LNPs) with the compositions of Moderna and Pfizer vaccines against COVID-19 in an aqueous solution. It was revealed that the ionizable lipid (IL) membranes of LNPs were extremely sensitive to pH, and the increased acidity could cause a rapid membrane collapse and hydration swelling of LNP, confirming the high releasing efficiency of both LNP vaccines. The free energy profiles of water penetration showed that the conical structure of IL played a key role in obstructing water from entering the inner core of LNPs: the molecular geometry with more tail chains, lower linearity, and looser packing structure resulted in higher water permeability, leading to lower stability in nonfrozen liquid environment. On the other hand, the geometry of IL also dominated the fusion behavior of LNP with endosomal membrane during the endosomal escape. Thus, for LNP-based vaccines with both high release efficiency and high stability, a suitable molecular structure of ILs should be selected to seek a balance between the packing tightness and fusion rate of membranes.

Roadmap to discovery and early development of an mRNA loaded LNP formulation for liver therapeutic genome editing

INTRODUCTION

mRNA therapeutics were a niche area in drug development before COVID vaccines. They are now used in vaccine development, for non-viral therapeutic genome editing, in vivo chimeric antigen receptor T (CAR T) cell therapies and protein replacement.  mRNA is large, charged, and easily degraded by nucleases. It cannot get into cells, escape the endosome, and be translated to a disease-modifying protein without a delivery system such as lipid nanoparticles (LNPs).

AREAS COVERED

This article covers how to design, select, and develop an LNP for therapeutic genome editing in the liver. The roadmap is divided into selecting the right LNP for discovery via a design, make, test, and analyze cycle (DMTA). The design elements are focused on ionizable lipids in a 4-component LNP, and insights are provided for how to set an in vitro and in vivo testing strategy. The second section focuses on transforming the LNP into a clinical drug product and covers formulation, analytical development, and process optimization, with brief notes on supply and regulator strategies.

EXPERT OPINION

The perspective discusses the impact that academic-industry collaborations can have on developing new medicines for therapeutic genome editing in the liver. From the cited collaborations an enhanced understanding of intracellular trafficking, notably endosomal escape, and the internal structure of LNPs were attained and are deemed key to designing effective and safe LNPs. The knowledge gained will also enable additional assays and structural activity relationships, which would lead to the design of the next-generation delivery systems for nucleic acid therapies.

Recent advances in drying and development of solid formulations for stable mRNA and siRNA lipid nanoparticles

Current RNA lipid nanoparticle (LNP) based products are typically liquid formulations that require ultra-cold storage temperatures for stability. To address this limitation, recent efforts have focused on enhancing stability and enabling room temperature storage by converting these formulations into solid forms through drying processes such as lyophilization, spray drying, and spray-freeze drying. Nevertheless, the drying process itself can influence the stability of RNA/LNP formulations. Therefore, understanding the factors that contribute to instability during drying is essential. The choice of drying technique for LNPs depends on factors such as the mode of delivery, lipid components, and desired final product characteristics. Additionally, the drying mechanism and associated stresses must also be carefully considered. Drying methods involve a range of process parameters related to formulation, process settings, and the manufacturing environment. It is essential to understand how these parameters influence the final solid-state products' attributes, including appearance, moisture content, flow properties, and reconstitution time, as these can significantly affect the physical and chemical stability of the formulation. This review focuses on various drying techniques and their impact on the stability of RNA/LNP-based systems.

Impact of administration routes and dose frequency on the toxicology of SARS-CoV-2 mRNA vaccines in mice model

The increasing use of SARS-CoV-2 mRNA vaccines has raised concerns about their potential toxicological effects, necessitating further investigation to ensure their safety. To address this issue, we aimed to evaluate the toxicological effects of SARS-CoV-2 mRNA vaccine candidates formulated with four different types of lipid nanoparticles in ICR mice, focusing on repeated doses and administration routes. We conducted an extensive analysis in which mice received the mRNA vaccine candidates intramuscularly (50 μg/head) twice at 2-week intervals, followed by necropsy at 2 and 14 dpsi (days post-secondary injection). In addition, we performed a repeated dose toxicity test involving three, four, or five doses and compared the toxicological outcomes between intravenous and intramuscular routes. Our findings revealed that all vaccine candidates significantly induced SARS-CoV-2 spike protein-specific IgG and T cell responses. However, at 2 dpsi, there was a notable temporary decrease in lymphocyte and reticulocyte counts, anemia-related parameters, and significant increases in cardiac damage markers, troponin-I and NT-proBNP. Histopathological analysis revealed severe inflammation and necrosis at the injection site, decreased erythroid cells in bone marrow, cortical atrophy of the thymus, and increased spleen cellularity. While most toxicological changes observed at 2 dpsi had resolved by 14 dpsi, spleen enlargement and injection site damage persisted. Furthermore, repeated doses led to the accumulation of toxicity, and different administration routes resulted in distinct toxicological phenotypes. These findings highlight the potential toxicological risks associated with mRNA vaccines, emphasizing the necessity to carefully consider administration routes and dosage regimens in vaccine safety evaluations, particularly given the presence of bone marrow and immune organ toxicity, which, though eventually reversible, remains a serious concern.

Computational biology and artificial intelligence in mRNA vaccine design for cancer immunotherapy

Messenger RNA (mRNA) vaccines offer an adaptable and scalable platform for cancer immunotherapy, requiring optimal design to elicit a robust and targeted immune response. Recent advancements in bioinformatics and artificial intelligence (AI) have significantly enhanced the design, prediction, and optimization of mRNA vaccines. This paper reviews technologies that streamline mRNA vaccine development, from genomic sequencing to lipid nanoparticle (LNP) formulation. We discuss how accurate predictions of neoantigen structures guide the design of mRNA sequences that effectively target immune and cancer cells. Furthermore, we examine AI-driven approaches that optimize mRNA-LNP formulations, enhancing delivery and stability. These technological innovations not only improve vaccine design but also enhance pharmacokinetics and pharmacodynamics, offering promising avenues for personalized cancer immunotherapy.

Peptide-Functionalized Lipid Nanoparticles for Targeted Systemic mRNA Delivery to the Brain

Systemic delivery of large nucleic acids, such as mRNA, to the brain remains challenging in part due to the blood-brain barrier (BBB) and the tendency of delivery vehicles to accumulate in the liver. Here, we design a peptide-functionalized lipid nanoparticle (LNP) platform for targeted mRNA delivery to the brain. We utilize click chemistry to functionalize LNPs with peptides that target receptors overexpressed on brain endothelial cells and neurons, namely the RVG29, T7, AP2, and mApoE peptides. We evaluate the effect of LNP targeting on brain endothelial and neuronal cell transfection in vitro, investigating factors such as serum protein adsorption, intracellular trafficking, endothelial transcytosis, and exosome secretion. Finally, we show that LNP peptide functionalization enhances mRNA transfection in the mouse brain and reduces hepatic delivery after systemic administration. Specifically, RVG29 LNPs improved neuronal transfection in vivo, establishing its potential as a nonviral platform for delivering mRNA to the brain.

A Chemoinformatic-Guided Synthesis of a Spleen-Expressing mRNA Lipid Nanoparticle Platform

mRNA lipid nanoparticles (LNPs) are a powerful technology that are actively being investigated for their ability to prevent, treat, and study disease. However, a major limitation remains: achieving extrahepatic mRNA expression. The development of new carriers could enable the expression of mRNA in non-liver targets, thus expanding the utility of mRNA-based medicines. In this study, we use a combination of chemoinformatic-guided material synthesis and design of experiment optimization for the development of a spleen-expressing lipid nanoparticle (SE-LNP). We begin with the synthesis of a novel cholesterol derivative followed by SE-LNP formulation and design of experiment-guided optimization to identify three lead SE-LNPs. We then evaluate their in vitro delivery mechanism, in vivo biodistribution, and protein expression in mice, ultimately achieving spleen-preferential expression. The goal of this paper is thus to create LNPs that preferentially express mRNA in the spleen upon intravenous delivery, demonstrating the potential of LNPs to modulate gene expression in extrahepatic tissues for disease treatment.

Exploring the impact of lipid nanoparticles on protein stability and cellular proteostasis

Lipid nanoparticles (LNPs) have become pivotal in advancing modern medicine, from mRNA-based vaccines to gene editing with CRISPR-Cas9 systems. Though LNPs based therapeutics offer promising drug delivery with satisfactory clinical safety profiles, concerns are raised regarding their potential nanotoxicity. Here, we explore the impacts of LNPs on protein stability in buffer and cellular protein homeostasis (proteostasis) in HepG2 cells. First, we show that LNPs of different polyethylene glycol (PEG) molar ratios to total lipid ratio boost protein aggregation propensity by reducing protein stability in cell lysate and blood plasma. Second, in HepG2 liver cells, these LNPs induce global proteome aggregation, as imaged by a cellular protein aggregation fluorescent dye (AggStain). Such LNPs induced proteome aggregation is accompanied by decrease in cellular micro-environmental polarity as quantified by a solvatochromic protein aggregation sensor (AggRetina). The observed local polarity fluctuations may be caused by the hydrophobic contents of LNPs that promote cellular proteome aggregation. Finally, we exploit RNA sequencing analysis (RNA-Seq) to reveal activation of unfolded protein response (UPR) pathway and other proteostasis genes upon LNPs treatment. Together, these findings highlight that LNPs may induce subtle proteome stress by compromising protein stability and proteostasis even without obvious damage to cell viability.

Calculating Apparent pKa Values of Ionizable Lipids in Lipid Nanoparticles

Creating new ionizable lipids for use in lipid nanoparticles (LNPs) is an active field of research. One of the critical properties for selecting suitable ionizable lipids is the apparent pKa value of the lipid as formulated in an LNP. We have developed a structure-based, computational methodology for the prediction of the apparent pKa value of ionizable lipids within LNPs and have tested it using the lipid formulations in the mRNA LNP COVID-19 vaccines COMIRNATY and Spikevax, and the siRNA LNP therapeutic Onpattro. The calculation was also applied to Lipid A, a variant of the ionizable lipid used in COMIRNATY.

Elucidating the uptake and trafficking of nanostructured lipid carriers as delivery systems for miRNA

Cationic nanostructured lipid carriers (cNLCs) represent promising non-viral carriers for nucleic acids, such as miRNAs, forming stable self-assembled miRNA complexes due to electrostatic interactions. Prepared by high-pressure homogenization, cNLC formulations, both with and without Nile Red dye demonstrated stable particle sizes in the range of 100-120 nm and positive surface charges (>30 mV), which are necessary for effective cellular uptake. The miRNA complexes formed at mass ratios of 1:2.5 and 1:5 showed similar stability and size, with positive zeta potentials, as well as high cell viability (> 80 %) in 3T3-L1 and MCF-7 cell lines. The cellular uptake studies of miRNA:cNLC complexes in both cell lines revealed that uptake was time- and concentration-dependent, with rapid initial uptake in 30 min and a zig-zag pattern over 24 h. To elucidate the endocytosis mechanism of miRNA:cNLC complexes, 3T3-L1 and MCF-7 cells were incubated with different inhibitors (chlorpromazine, 5-[N-ethyl-N-isopropyl] amiloride, dynasore, nystatin, or sodium azide with 2-deoxy-d-glucose). Results showed significant inhibition of uptake at low temperatures and with ATP depletion, suggesting endocytosis, particularly macropinocytosis, as the main uptake mechanism in 3T3-L1 cells. In MCF-7 cells, the uptake was less inhibited by the substances, indicating the need for more specific methods to fully decipher the endocytic mechanisms involved. Confocal laser scanning microscopy images revealed that the complexes are internalized in vesicles, and are primarily localized in the juxtanuclear region, suggesting trafficking through the endolysosomal system. Colocalization study with LysoTracker™ Green DND-26 showed significant colocalization of miRNA:cNLC complexes with lysosomes in 3T3-L1 cells, indicating trafficking through the endolysosomal system. In MCF-7 cells, colocalization was lower, suggesting macropinocytosis as the primary uptake mechanism. Additional studies showed partial colocalization between labeled NLCs and miRNA, indicating that about 50 % of miRNA is released from NLCs within 30 min post-transfection.

Therapeutic applications of cell engineering using mRNA technology

Engineering and reprogramming cells has significant therapeutic potential to treat a wide range of diseases, by replacing missing or defective proteins, to provide transcription factors (TFs) to reprogram cell phenotypes, or to provide enzymes such as RNA-guided Cas9 derivatives for CRISPR-based cell engineering. While viral vector-mediated gene transfer has played an important role in this field, the use of mRNA avoids safety concerns associated with the integration of DNA into the host cell genome, making mRNA particularly attractive for in vivo applications. Widespread application of mRNA for cell engineering is limited by its instability in the biological environment and challenges involved in the delivery of mRNA to its target site. In this review, we examine challenges that must be overcome to develop effective therapeutics.

Nonviral targeted mRNA delivery: principles, progresses, and challenges

Messenger RNA (mRNA) therapeutics have garnered considerable attention due to their remarkable efficacy in the treatment of various diseases. The COVID-19 mRNA vaccine and RSV mRNA vaccine have been approved on the market. Due to the inherent nuclease-instability and negative charge of mRNA, delivery systems are developed to protect the mRNA from degradation and facilitate its crossing cell membrane to express functional proteins or peptides in the cytoplasm. However, the deficiency in transfection efficiency and targeted biological distribution are still the major challenges for the mRNA delivery systems. In this review, we first described the physiological barriers in the process of mRNA delivery and then discussed the design approach and recent advances in mRNA delivery systems with an emphasis on their tissue/cell-targeted abilities. Finally, we pointed out the existing challenges and future directions with deep insights into the design of efficient mRNA delivery systems. We believe that a high-precision targeted delivery system can greatly improve the therapeutic effects and bio-safety of mRNA therapeutics and accelerate their clinical transformations. This review may provide a new direction for the design of mRNA delivery systems and serve as a useful guide for researchers who are looking for a suitable mRNA delivery system.

Time-resolved small-angle neutron scattering for characterization of molecular exchange in lipid nanoparticle therapeutics

HYPOTHESIS

Nano-scale dynamics of self-assembled therapeutics play a large role in their biological function. However, assessment of such dynamics remains absent from conventional pharmaceutical characterization. We hypothesize that time-resolved small-angle neutron scattering (TR-SANS) can reveal their kinetic properties. For lipid nanoparticles (LNP), limited molecular motion is important for avoiding degradation prior to entering cells while, intracellularly, enhanced molecular motion is then vital for effective endosomal escape. We propose TR-SANS for quantifying molecular exchange in LNPs and, therefore, enabling optimization of opposing molecular behaviors of a pharmaceutical in two distinct environments.

EXPERIMENTS

We use TR-SANS in combination with traditional SANS and small-angle x-ray scattering (SAXS) to experimentally quantify nano-scale dynamics and provided unprecedented insight to molecular behavior of LNPs.

FINDINGS

LNPs have molecular exchange dynamics relevant to storage and delivery which can be captured using TR-SANS. Cholesterol exchanges on the time-scale of hours even at neutral pH. As pH drops below the effective pKa of the ionizable lipid, molecular exchange occurs faster. The results give insight into behavior enabling delivery and provide a quantifiable metric by which to compare formulations. Successful analysis of this multi-component system also expands the opportunities for using TR-SANS to characterize complex therapeutics.

Nano Plasma Membrane Vesicle-Lipid Nanoparticle Hybrids for Enhanced Gene Delivery and Expression

Lipid nanoparticles (LNPs) have emerged as the leading nonviral nucleic acid (NA) delivery system, gaining widespread attention for their use in COVID-19 vaccines. They are recognized for their efficient NA encapsulation, modifiability, and scalable production. However, LNPs face efficacy and potency limitations due to suboptimal intracellular processing, with endosomal escape efficiencies (ESE) below 2.5%. Additionally, up to 70% of NPs undergo recycling and exocytosis after cellular uptake. In contrast, cell-derived vesicles offer biocompatibility and high-delivery efficacy but are challenging to load with exogenous NAs and to manufacture at large-scale. To leverage the strengths of both systems, a hybrid system is designed by combining cell-derived vesicles, such as nano plasma membrane vesicles (nPMVs), with LNPs through microfluidic mixing and subsequent dialysis. These hybrids demonstrate up to tenfold increase in ESE and an 18-fold rise in reporter gene expression in vitro and in vivo in zebrafish larvae (ZFL) and mice, compared to traditional LNPs. These improvements are linked to their unique physico-chemical properties, composition, and morphology. By incorporating cell-derived vesicles, this strategy streamlines the development process, significantly enhancing the efficacy and potency of gene delivery systems without the need for extensive screening.

Rescue of the endogenous FVIII expression in hemophilia A mice using CRISPR-Cas9 mRNA LNPs

Gene editing provides a promising alternative approach that may achieve long-term FVIII expression for hemophilia A (HemA) treatment. In this study, we investigated in vivo correction of a mutant factor VIII (FVIII) gene in HemA mice. We first developed MC3-based LNPs for efficient mRNA delivery into liver sinusoidal endothelial cells (LSECs), the major site of FVIII biosynthesis. To target a five base pair deletion in FVIII exon 1 in a specific HemA mouse strain, we injected LNPs encapsulating Cas9 mRNA and specifically designed sgRNAs intravenously for in vivo gene editing of the mutant FVIII. Indel variants generated at the mutant site contained mostly a single base-pair deletion, resulting in frameshift correction of FVIII gene. Sustained endogenous FVIII activity up to 6% was achieved over 26 weeks in treated HemA mice. Sequencing data indicated an average gene editing rate of 15.3% in LSECs. Our study suggests that optimized MC3 LNP formulations, combined with CRISPR-Cas9 technology, can effectively correct the mutant FVIII gene in LSECs and restore FVIII activity for therapeutic treatment of HemA.

Advances in the study of LNPs for mRNA delivery and clinical applications

Messenger ribonucleic acid (mRNA) was discovered in 1961 as an intermediary for transferring genetic information from DNA to ribosomes for protein synthesis. The COVID-19 pandemic brought worldwide attention to mRNA vaccines. The emergency use authorization of two COVID-19 mRNA vaccines, BNT162b2 and mRNA-1273, were major achievements in the history of vaccine development. Lipid nanoparticles (LNPs), one of the most superior non-viral delivery vectors available, have made many exciting advances in clinical translation as part of the COVID-19 vaccine and therefore has the potential to accelerate the clinical translation of many gene drugs. In addition, due to these small size, biocompatibility and excellent biodegradability, LNPs can efficiently deliver nucleic acids into cells, which is particularly important for current mRNA therapeutic regimens. LNPs are composed cationic or pH-dependent ionizable lipid bilayer, polyethylene glycol (PEG), phospholipids, and cholesterol, represents an advanced system for the delivery of mRNA vaccines. Furthermore, optimization of these four components constituting the LNPs have demonstrated enhanced vaccine efficacy and diminished adverse effects. The incorporation of biodegradable lipids enhance the biocompatibility of LNPs, thereby improving its potential as an efficacious therapeutic approach for a wide range of challenging and intricate diseases, encompassing infectious diseases, liver disorders, cancer, cardiovascular diseases, cerebrovascular conditions, among others. Consequently, this review aims to furnish the scientific community with the most up-to-date information regarding mRNA vaccines and LNP delivery systems.

Comprehensive analysis of lipid nanoparticle formulation and preparation for RNA delivery

Nucleic acid-based therapeutics are a common approach that is increasingly popular for a wide spectrum of diseases. Lipid nanoparticles (LNPs) are promising delivery carriers that provide RNA stability, with strong transfection efficiency, favorable and tailorable pharmacokinetics, limited toxicity, and established translatability. In this review article, we describe the lipid-based delivery systems, focusing on lipid nanoparticles, the need of their use, provide a comprehensive analysis of each component, and highlight the advantages and disadvantages of the existing manufacturing processes. We further summarize the ongoing and completed clinical trials utilizing LNPs, indicating important aspects/questions worth of investigation, and analyze the future perspectives of this significant and promising therapeutic approach.

Extracellular vesicles versus lipid nanoparticles for the delivery of nucleic acids

Extracellular vesicles (EVs) are increasingly investigated for delivering nucleic acid (NA) therapeutics, leveraging their natural role in transporting NA and protein-based cargo in cell-to-cell signaling. Their synthetic counterparts, lipid nanoparticles (LNPs), have been developed over the past decades as NA carriers, culminating in the approval of several marketed formulations such as patisiran/Onpattro® and the mRNA-1273/BNT162 COVID-19 vaccines. The success of LNPs has sparked efforts to develop innovative technologies to target extrahepatic organs, and to deliver novel therapeutic modalities, such as tools for in vivo gene editing. Fueled by the recent advancements in both fields, this review aims to provide a comprehensive overview of the basic characteristics of EV and LNP-based NA delivery systems, from EV biogenesis to structural properties of LNPs. It addresses the primary challenges encountered in utilizing these nanocarriers from a drug formulation and delivery perspective. Additionally, biodistribution profiles, in vitro and in vivo transfection outcomes, as well as their status in clinical trials are compared. Overall, this review provides insights into promising research avenues and potential dead ends for EV and LNP-based NA delivery systems.

Nano-encapsulation of drugs to target hepatic stellate cells: Toward precision treatments of liver fibrosis

Liver fibrosis is characterized by excessive extracellular matrix (ECM) deposition triggered by hepatic stellate cells (HSCs). As central players in fibrosis progression, HSCs are the most important therapeutic targets for antifibrotic therapy. However, owing to the limitations of systemic drug administration, there is still no suitable and effective clinical treatment. In recent years, nanosystems have demonstrated expansive therapeutic potential and evolved into a clinical modality. In liver fibrosis, nanosystems have undergone a paradigm shift from targeting the whole liver to locally targeted modifying processes. Nanomedicine delivered to HSCs has significant potential in managing liver fibrosis, where optimal management would benefit from targeted delivery, personalized therapy based on the specific site of interest, and minor side effects. In this review, we present a brief overview of the role of HSCs in the pathogenesis of liver fibrosis, summarize the different types of nanocarriers and their specific delivery applications in liver fibrosis, and highlight the biological barriers associated with the use of nanosystems to target HSCs and approaches available to solve this issue. We further discuss in-depth all the molecular target receptors overexpressed during HSC activation in liver fibrosis and their corresponding ligands that have been used for drug or gene delivery targeting HSCs.

Nucleic acid drugs: recent progress and future perspectives

High efficacy, selectivity and cellular targeting of therapeutic agents has been an active area of investigation for decades. Currently, most clinically approved therapeutics are small molecules or protein/antibody biologics. Targeted action of small molecule drugs remains a challenge in medicine. In addition, many diseases are considered 'undruggable' using standard biomacromolecules. Many of these challenges however, can be addressed using nucleic therapeutics. Nucleic acid drugs (NADs) are a new generation of gene-editing modalities characterized by their high efficiency and rapid development, which have become an active research topic in new drug development field. However, many factors, including their low stability, short half-life, high immunogenicity, tissue targeting, cellular uptake, and endosomal escape, hamper the delivery and clinical application of NADs. Scientists have used chemical modification techniques to improve the physicochemical properties of NADs. In contrast, modified NADs typically require carriers to enter target cells and reach specific intracellular locations. Multiple delivery approaches have been developed to effectively improve intracellular delivery and the in vivo bioavailability of NADs. Several NADs have entered the clinical trial recently, and some have been approved for therapeutic use in different fields. This review summarizes NADs development and evolution and introduces NADs classifications and general delivery strategies, highlighting their success in clinical applications. Additionally, this review discusses the limitations and potential future applications of NADs as gene therapy candidates.

Effect of Lipid Nanoparticle Physico-Chemical Properties and Composition on Their Interaction with the Immune System

Lipid nanoparticles (LNPs) have shown promise as a delivery system for nucleic acid-based therapeutics, including DNA, siRNA, and mRNA vaccines. The immune system plays a critical role in the response to these nanocarriers, with innate immune cells initiating an early response and adaptive immune cells mediating a more specific reaction, sometimes leading to potential adverse effects. Recent studies have shown that the innate immune response to LNPs is mediated by Toll-like receptors (TLRs) and other pattern recognition receptors (PRRs), which recognize the lipid components of the nanoparticles. This recognition can trigger the activation of inflammatory pathways and the production of cytokines and chemokines, leading to potential adverse effects such as fever, inflammation, and pain at the injection site. On the other hand, the adaptive immune response to LNPs appears to be primarily directed against the protein encoded by the mRNA cargo, with little evidence of an ongoing adaptive immune response to the components of the LNP itself. Understanding the relationship between LNPs and the immune system is critical for the development of safe and effective nucleic acid-based delivery systems. In fact, targeting the immune system is essential to develop effective vaccines, as well as therapies against cancer or infections. There is a lack of research in the literature that has systematically studied the factors that influence the interaction between LNPs and the immune system and further research is needed to better elucidate the mechanisms underlying the immune response to LNPs. In this review, we discuss LNPs' composition, physico-chemical properties, such as size, shape, and surface charge, and the protein corona formation which can affect the reactivity of the immune system, thus providing a guide for the research on new formulations that could gain a favorable efficacy/safety profile.

Diblock Copolymer Targeted Lipid Nanoparticles: Next-Generation Nucleic Acid Delivery System Produced by Confined Impinging Jet Mixers

Despite the recent advances and clinical demonstration of lipid nanoparticles (LNPs) for therapeutic and prophylactic applications, the extrahepatic delivery of nucleic acids remains a significant challenge in the field. This limitation arises from the rapid desorption of lipid-PEG in the bloodstream and clearance to the liver, which hinders extrahepatic delivery. In response, we explore the substitution of lipid-PEG with biodegradable block copolymers (BCPs), specifically poly(ε-caprolactone)-block-poly(ethylene glycol) (PCL-b-PEG). BCPs offer strong anchoring for large macromolecules, potentially enhancing cell-specific targeting. To develop and optimize BCP-stabilized LNPs (BCP-LNPs), we employed a Design of Experiment (DOE) approach. Through a systematic exploration, we identified optimal formulations for BCP-LNPs, achieving desirable physicochemical properties and encapsulation efficiency. Notably, BCP-LNPs exhibit surprising trends in transfection efficiency, with certain formulations showing up to a 40-fold increase in transfection in Hela cells, while maintaining minimal cytotoxicity. The lipid compositions that optimized PCL-b-PEG LNP transfection were different from the compositions that optimized PEG-lipid LNP transfection. Furthermore, our study confirms the versatility of BCP-LNPs in encapsulating and delivering both mRNA and pDNA, demonstrating their cargo-agnostic nature. Lastly, we showcased the targeted BCP-LNPs using a Cetuximab-conjugated formulation. These targeted LNPs show significant promise in delivering cargo specific to EGFR-overexpressing cells (A549 cells), with up to 2.4 times higher transfection compared to nontargeted LNPs. This finding underscores the potential of BCP-LNPs in targeted gene therapy, especially in challenging scenarios such as tumor targeting. Overall, our study establishes the viability of BCP-LNPs as a versatile, efficient, and targeted delivery platform for nucleic acids, opening avenues for advanced therapeutic applications.

Modified PEG-Lipids Enhance the Nasal Mucosal Immune Capacity of Lipid Nanoparticle mRNA Vaccines

BACKGROUND/OBJECTIVES

Omicron, the predominant variant of SARS-CoV-2, exhibits strong immune-evasive properties, leading to the reduced efficacy of existing vaccines. Consequently, the development of versatile vaccines is imperative. Intranasal mRNA vaccines offer convenient administration and have the potential to enhance mucosal immunity. However, delivering vaccines via the nasal mucosa requires overcoming complex physiological barriers. The aim of this study is to modify PEGylated lipids to enhance the mucosal immune efficacy of the vaccine.

METHODS

The PEGylated lipid component of lipid nanoparticle (LNP) delivery vectors was modified with chitosan or mannose to generate novel LNPs that enhance vaccine adhesion or targeting on mucosal surfaces. The impact of the mRNA encoding the receptor-binding domain of Omicron BA.4/BA.5 on the immune response was examined.

RESULTS

Compared to the unmodified LNP group, the IgG and IgA titers in the chitosan or mannose-modified LNP groups showed an increasing trend. The chitosan-modified group showed better effects. Notably, the PEGylated lipid with 1.5 mol% of chitosan modification produced high levels of IgG1 and IgG2a antibodies, promoting Th1/Th2 responses while also generating high levels of IgA, which can induce stronger cellular immunity, humoral immunity, and mucosal immunity.

CONCLUSIONS

The 1.5 mol% of chitosan-modified LNPs (mRNA-LNP-1.5CS) can serve as a safe and effective carrier for intranasal mRNA vaccines, offering a promising strategy for combating the Omicron variant.

Toward understanding lipid reorganization in RNA lipid nanoparticles in acidic environments

The use of lipid nanoparticles (LNPs) for therapeutic RNA delivery has gained significant interest, particularly highlighted by recent milestones such as the approval of Onpattro and two mRNA-based SARS-CoV-2 vaccines. However, despite substantial advancements in this field, our understanding of the structure and internal organization of RNA-LNPs -and their relationship to efficacy, both in vitro and in vivo- remains limited. In this study, we present a coarse-grained molecular dynamics (MD) approach that allows for the simulations of full-size LNPs. By analyzing MD-derived structural characteristics in conjunction with cellular experiments, we investigate the effect of critical parameters, such as pH and composition, on LNP structure and potency. Additionally, we examine the mobility and chemical environment within LNPs at a molecular level. Our findings highlight the significant impact that LNP composition and internal molecular mobility can have on key stages of LNP-based intracellular RNA delivery.

Delivery of Synthetic Interleukin-22 mRNA to Hepatocytes via Lipid Nanoparticles Alleviates Liver Injury

Hepatocellular injury, a pivotal contributor to liver diseases, particularly hepatitis, lacks effective pharmacological treatments. Interleukin-22 (IL-22), crucial for liver cell survival, shows potential in treating liver diseases by regulating repair and regeneration through signal transducer and activator of transcription 3 (STAT3) activation. However, the short half-life and off-target effects limit its clinical applications. To address these issues, lipid nanoparticles are employed to deliver synthetic IL-22 mRNA (IL-22/NP) for in situ IL-22 expression in hepatocytes. The study reveals that IL-22/NP exhibits liver-targeted IL-22 expression, with increased IL-22 levels detected in the liver as early as 3 h postintravenous injection, lasting up to 96 h. Furthermore, IL-22/NP activates STAT3 signaling in an autocrine or paracrine manner to upregulate downstream factors Bcl-xL and CyclinD1, inhibiting hepatocyte apoptosis and promoting cell proliferation. The therapeutic efficacy of IL-22/NP is demonstrated in both chronic and acute liver injury models, suggesting IL-22 mRNA delivery as a promising treatment strategy for hepatitis and liver diseases involving hepatocellular injury.