Ionization and structural properties of mRNA lipid nanoparticles influence expression in intramuscular and intravascular administration

Influence of ionizable lipid tail length on lipid nanoparticle delivery of mRNA of varying length

RNA-based therapeutics have gained traction for the prevention and treatment of a variety of diseases. However, their fragility and immunogenicity necessitate a drug carrier. Lipid nanoparticles (LNPs) have emerged as the predominant delivery vehicle for RNA therapeutics. An important component of LNPs is the ionizable lipid (IL), which is protonated in the acidic environment of the endosome, prompting cargo release into the cytosol. Currently, there is growing evidence that the structure of IL lipid tails significantly impacts the efficacy of LNP-mediated mRNA translation. Here, we optimized IL tail length for LNP-mediated delivery of three different mRNA cargos. Using C12-200, a gold standard IL, as a model, we designed a library of ILs with varying tail lengths and evaluated their potency in vivo. We demonstrated that small changes in lipophilicity can drastically increase or decrease mRNA translation. We identified that LNPs formulated with firefly luciferase mRNA (1929 base pairs) and C10-200, an IL with shorter tail lengths than C12-200, enhance liver transfection by over 10-fold. Furthermore, different IL tail lengths were found to be ideal for transfection of LNPs encapsulating mRNA cargos of varying sizes. LNPs formulated with erythropoietin (EPO), responsible for stimulating red blood cell production, mRNA (858 base pairs), and the C13-200 IL led to EPO translation at levels similar to the C12-200 LNP. The LNPs formulated with Cas9 mRNA (4521 base pairs) and the C9-200 IL induced over three times the quantity of indels compared with the C12-200 LNP. Our findings suggest that shorter IL tails may lead to higher transfection of LNPs encapsulating larger mRNAs, and that longer IL tails may be more efficacious for delivering smaller mRNA cargos. We envision that the results of this project can be utilized as future design criteria for the next generation of LNP delivery systems for RNA therapeutics.

β-catenin mRNA encapsulated in SM-102 lipid nanoparticles enhances bone formation in a murine tibia fracture repair model

Fractures continue to be a global economic burden as there are currently no osteoanabolic drugs approved to accelerate fracture healing. In this study, we aimed to develop an osteoanabolic therapy which activates the Wnt/β-catenin pathway, a molecular driver of endochondral ossification. We hypothesize that using an mRNA-based therapeutic encoding β-catenin could promote cartilage to bone transformation formation by activating the canonical Wnt signaling pathway in chondrocytes. To optimize a delivery platform built on recent advancements in liposomal technologies, two FDA-approved ionizable phospholipids, DLin-MC3-DMA (MC3) and SM-102, were used to fabricate unique ionizable lipid nanoparticle (LNP) formulations and then tested for transfection efficacy both in vitro and in a murine tibia fracture model. Using firefly luciferase mRNA as a reporter gene to track and quantify transfection, SM-102 LNPs showed enhanced transfection efficacy in vitro and prolonged transfection, minimal fracture interference and no localized inflammatory response in vivo over MC3 LNPs. The generated β-cateninGOF mRNA encapsulated in SM-102 LNPs (SM-102-β-cateninGOF mRNA) showed bioactivity in vitro through upregulation of downstream canonical Wnt genes, axin2 and runx2. When testing SM-102-β-cateninGOF mRNA therapeutic in a murine tibia fracture model, histomorphometric analysis showed increased bone and decreased cartilage composition with the 45 μg concentration at 2 weeks post-fracture. μCT testing confirmed that SM-102-β-cateninGOF mRNA promoted bone formation in vivo, revealing significantly more bone volume over total volume in the 45 μg group. Thus, we generated a novel mRNA-based therapeutic encoding a β-catenin mRNA and optimized an SM-102-based LNP to maximize transfection efficacy with a localized delivery.

Nanoemulsions and nanocapsules as carriers for the development of intranasal mRNA vaccines

The global emergency of coronavirus disease 2019 (COVID-19) has spurred extensive worldwide efforts to develop vaccines for protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our contribution to this global endeavor involved the development of a diverse library of nanocarriers, as alternatives to lipid nanoparticles (LNPs), including nanoemulsions (NEs) and nanocapsules (NCs), with the aim of protecting and delivering messenger ribonucleic acid (mRNA) for nasal vaccination purposes. A wide range of prototypes underwent rigorous screening through a series of in vitro and in vivo experiments, encompassing assessments of cellular transfection, cytotoxicity, and intramuscular administration of a model mRNA for protein translation. As a result, two promising candidates were identified for nasal administration. One of them was a NE incorporating a combination of an ionizable lipid (C12-200) and cationic lipid (DOTAP), both intended to condense mRNA, along with DOPE, which is known to facilitate endosomal escape. This NE exhibited a size of 120 nm and a highly positive surface charge (+ 50 mV). Another candidate was an NC formulation comprising the same components and endowed with a dextran sulfate shell. This formulation showed a size of 130 nm and a moderate negative surface charge (-16 mV). Upon intranasal administration of mRNA encoding for ovalbumin (mOVA) associated with optimized versions of the said NE and NCs, a robust antigen-specific CD8 + T cell response was observed. These findings underscore the potential of NEs and polymeric NCs in advancing mRNA vaccine development for combating infectious diseases.

Synthesis of novel cholesterol-based ionizable lipids for mRNA delivery

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

A Single-Dose mRNA Vaccine Employing Porous Silica Nanoparticles Induces Robust Immune Responses Against the Zika Virus

Recently, lipid nanoparticles (LNPs)-based mRNA delivery has been approved by the FDA for SARS-CoV-2 vaccines. However, there are still considerable points for improvement in LNPs. Especially, local administration of LNPs-formulated mRNA can cause off-target translation of mRNA in distal organs which can induce unintended adverse effects. With the hypothesis that large and rigid nanoparticles can be applied to enhance retention of nanoparticles at the injection site, a polyethyleneimine (PEI)-coated porous silica nanoparticles (PPSNs)-based mRNA delivery platform is designed. PPSNs not only facilitate localized translation of mRNA at the site of injection but also prolonged protein expression. It is further demonstrated that the development of a highly efficacious Zika virus (ZIKV) vaccine using mRNA encoding full-length ZIKV pre-membrane (prM) and envelope (E) protein delivered by PPSNs. The ZIKV prME mRNA-loaded PPSNs vaccine elicits robust immune responses, including high levels of neutralizing antibodies and ZIKV E-specific T cell responses in C57BL/6 mice. Moreover, a single injection of prME-PPSNs vaccine provided complete protection against the ZIKV challenge in mice.

In vivo Fate of Targeted Drug Delivery Carriers

This review aimed to systematically investigate the intracellular and subcellular fate of various types of targeting carriers. Upon entering the body via intravenous injection or other routes, a targeting carrier that can deliver therapeutic agents initiates their journey. If administered intravenously, the carrier initially faces challenges presented by the blood circulation before reaching specific tissues and interacting with cells within the tissue. At the subcellular level, the car2rier undergoes processes, such as drug release, degradation, and metabolism, through specific pathways. While studies on the fate of 13 types of carriers have been relatively conclusive, these studies are incomplete and lack a comprehensive analysis. Furthermore, there are still carriers whose fate remains unclear, underscoring the need for continuous research. This study highlights the importance of comprehending the in vivo and intracellular fate of targeting carriers and provides valuable insights into the operational mechanisms of different carriers within the body. By doing so, researchers can effectively select appropriate carriers and enhance the successful clinical translation of new formulations.

Tailored Monoacyl Poly(2-oxazoline)- and Poly(2-oxazine)-Lipids as PEG-Lipid Alternatives for Stabilization and Delivery of mRNA-Lipid Nanoparticles

The successful use of lipid nanoparticles (LNPs) for clinical development of the COVID-19 mRNA vaccines marked a breakthrough in mRNA-LNP therapeutics. As one of the vital components of LNPs, poly(ethylene glycol)-lipid conjugates (PEG-lipids) influence particle biophysical properties and stability, as well as interactions within biological environments. Reports suggesting that anti-PEG antibodies can be detected quite commonly within the human population raise concerns that PEG content in commercial LNP products could further stimulate immune responses to PEG. The presence of anti-PEG antibodies has been linked to accelerated clearance of LNPs, potentially a source of variability in the biological response to mRNA-LNP products. This motivated us to explore potential PEG alternatives. Herein, we report physicochemical and biological properties of mRNA-LNPs assembled using poly(2-oxazoline) (POx)- and poly(2-oxazine) (POz)-based polymer-lipid conjugates. Notably, we investigated monoacyl lipids as alternatives to diacyl lipids. mRNA-LNPs produced using monoacyl POx/POz-lipids displayed comparable biophysical characteristics and cytocompatibility. Delivery of reporter mRNA resulted in similar transfection efficiencies, in both adherent and suspension cells, and in mice, compared to PEG-lipid equivalents. Our results suggest that monoacyl POx/POz-lipid-containing LNPs are promising candidates for the development of PEG-free LNP-based therapeutic products.

Lipid Nanocarrier-Based mRNA Therapy: Challenges and Promise for Clinical Transformation

Due to the outbreak of novel coronavirus pneumonia, messenger RNA (mRNA) technology has attracted heated attention. A specific, safe, and efficient mRNA delivery system is needed. Lipid nanocarriers have become attractive carriers for mRNA delivery due to their high delivery efficiency, few side effects, and easy modification to change their structures and functions. To achieve the desired biological effect, lipid nanocarriers must reach the designated location for effective drug delivery. Therefore, the effects of the composition of lipid nanocarriers on their key properties are briefly reviewed. In addition, the progress of smart drug delivery by changing the composition of lipid nanocarriers is summarized, and the importance of component design and structure is emphasized. Subsequently, this review summarizes the latest progress in lipid nanocarrier-based mRNA technology and provides corresponding strategies for its current challenges, putting forward valuable information for the future design of lipid nanocarriers and mRNA.

Steering the course of CAR T cell therapy with lipid nanoparticles

Lipid nanoparticles (LNPs) have proven themselves as transformative actors in chimeric antigen receptor (CAR) T cell therapy, surpassing traditional methods and addressing challenges like immunogenicity, reduced toxicity, and improved safety. Promising preclinical results signal a shift toward safer and more effective CAR T cell treatments. Ongoing research aims to validate these findings in clinical trials, marking a new era guided by LNPs utility in CAR therapy. Herein, we explore the preference for LNPs over traditional methods, highlighting the versatility of LNPs and their effective delivery of nucleic acids. Additionally, we address key challenges in clinical considerations, heralding a new era in CAR T cell therapy.

CO-DELIVERY of glutamic acid-extended peptide antigen and imidazoquinoline TLR7/8 agonist via ionizable lipid nanoparticles induces protective anti-tumor immunity

Cancer vaccines aim at generating cytotoxic CD8+ T cells that kill cancer cells and confer durable tumor regression. Hereto, CD8+ peptide epitopes should be presented by antigen presenting cells to CD8+ T cells in lymphoid tissue. Unfortunately, in unformulated soluble form, peptide antigens are poorly taken up by antigen presenting cells and do not efficiently reach lymph nodes. Hence, the lack of efficient delivery remains a major limitation for successful clinical translation of cancer vaccination using peptide antigens. Here we propose a generic peptide nanoformulation strategy by extending the amino acid sequence of the peptide antigen epitope with 10 glutamic acid residues. The resulting overall anionic charge of the peptide allows encapsulation into lipid nanoparticles (peptide-LNP) by electrostatic interaction with an ionizable cationic lipid. We demonstrate that intravenous injection of peptide-LNP efficiently delivers the peptide to immune cells in the spleen. Peptide-LNP that co-encapsulate an imidazoquinoline TLR7/8 agonist (IMDQ) induce robust innate immune activation in a broad range of immune cell subsets in the spleen. Peptide-LNP containing the minimal CD8+ T cell epitope of the HPV type 16 E7 oncoprotein and IMDQ induces high levels of antigen-specific CD8+ T cells in the blood, and can confer protective immunity against E7-expressing tumors in both prophylactic and therapeutic settings.

Distinct dynamics of mRNA LNPs in mice and nonhuman primates revealed by in vivo imaging

The characterization of vaccine distribution to relevant tissues after in vivo administration is critical to understanding their mechanisms of action. Vaccines based on mRNA lipid nanoparticles (LNPs) are now being widely considered against infectious diseases and cancer. Here, we used in vivo imaging approaches to compare the trafficking of two LNP formulations encapsulating mRNA following intramuscular administration: DLin-MC3-DMA (MC3) and the recently developed DOG-IM4. The mRNA formulated in DOG-IM4 LNPs persisted at the injection site, whereas mRNA formulated in MC3 LNPs rapidly migrated to the draining lymph nodes. Furthermore, MC3 LNPs induced the fastest increase in blood neutrophil counts after injection and greater inflammation, as shown by IL-1RA, IL-15, CCL-1, and IL-6 concentrations in nonhuman primate sera. These observations highlight the influence of the nature of the LNP on mRNA vaccine distribution and early immune responses.

Single-Particle Spectroscopic Chromatography Reveals Heterogeneous RNA Loading and Size Correlations in Lipid Nanoparticles

Lipid nanoparticles (LNP) have emerged as pivotal delivery vehicles for RNA therapeutics. Previous research and development usually assumed that LNPs are homogeneous in population, loading density, and composition. Such perspectives are difficult to examine due to the lack of suitable tools to characterize these physicochemical properties at the single-nanoparticle level. Here, we report an integrated spectroscopy-chromatography approach as a generalizable strategy to dissect the complexities of multicomponent LNP assembly. Our platform couples cylindrical illumination confocal spectroscopy (CICS) with single-nanoparticle free solution hydrodynamic separation (SN-FSHS) to simultaneously profile population identity, hydrodynamic size, RNA loading levels, and distributions of helper lipid and PEGylated lipid of LNPs at the single-particle level and in a high-throughput manner. Using a benchmark siRNA LNP formulation, we demonstrate the capability of this platform by distinguishing seven distinct LNP populations, quantitatively characterizing size distribution and RNA loading level in wide ranges, and more importantly, resolving composition-size correlations. This SN-FSHS-CICS analysis provides critical insights into a substantial degree of heterogeneity in the packing density of RNA in LNPs and size-dependent loading-size correlations, explained by kinetics-driven assembly mechanisms of RNA LNPs.

Improved specificity and efficacy of base-editing therapies with hybrid guide RNAs

Phenylketonuria (PKU), hereditary tyrosinemia type 1 (HT1), and mucopolysaccharidosis type 1 (MPSI) are autosomal recessive disorders linked to the phenylalanine hydroxylase (PAH) gene, fumarylacetoacetate hydrolase (FAH) gene, and alpha-L-iduronidase (IDUA) gene, respectively. Potential therapeutic strategies to ameliorate disease include corrective editing of pathogenic variants in the PAH and IDUA genes and, as a variant-agnostic approach, inactivation of the 4-hydroxyphenylpyruvate dioxygenase (HPD) gene, a modifier of HT1, via adenine base editing. Here we evaluated the off-target editing profiles of therapeutic lead guide RNAs (gRNAs) that, when combined with adenine base editors correct the recurrent PAH P281L variant, PAH R408W variant, or IDUA W402X variant or disrupt the HPD gene in human hepatocytes. To mitigate off-target mutagenesis, we systematically screened hybrid gRNAs with DNA nucleotide substitutions. Comprehensive and variant-aware specificity profiling of these hybrid gRNAs reveal dramatically reduced off-target editing and reduced bystander editing. Lastly, in a humanized PAH P281L mouse model, we showed that when formulated in lipid nanoparticles (LNPs) with adenine base editor mRNA, selected hybrid gRNAs revert the PKU phenotype, substantially enhance on-target editing, and reduce bystander editing in vivo. These studies highlight the utility of hybrid gRNAs to improve the safety and efficacy of base-editing therapies.

Temporal restriction of Cas9 expression improves CRISPR-mediated deletion efficacy and fidelity

Clinical application of CRISPR-Cas9 technology for large deletions of somatic mutations is inefficient, and methods to improve utility suffer from our inability to rapidly assess mono- vs. biallelic deletions. Here we establish a model system for investigating allelic heterogeneity at the single-cell level and identify indel scarring from non-simultaneous nuclease activity at gRNA cut sites as a major barrier to CRISPR-del efficacy both in vitro and in vivo. We show that non-simultaneous nuclease activity is partially prevented via restriction of CRISPR-Cas9 expression via inducible adeno-associated viruses (AAVs) or lipid nanoparticles (LNPs). Inducible AAV-based expression of CRISPR-del machinery significantly improved mono- and biallelic deletion frequency in vivo, supporting the use of the Xon cassette over traditional constitutively expressing AAV approaches. These data depicting improvements to deletions and insight into allelic heterogeneity after CRISPR-del will inform therapeutic approaches for phenotypes that require either large mono- or biallelic deletions, such as autosomal recessive diseases or where mutant allele-specific gRNAs are not readily available, or in situations where the targeted sequence for excision is located multiple times in a genome.

Dual Effect by Chemical Electron Transfer Enhanced siRNA Lipid Nanoparticles: Reactive Oxygen Species-Triggered Tumor Cell Killing Aggravated by Nrf2 Gene Silencing

Insufficient endosomal escape presents a major hurdle for successful nucleic acid therapy. Here, for the first time, a chemical electron transfer (CET) system was integrated into small interfering RNA (siRNA) lipid nanoparticles (LNPs). The CET acceptor can be chemically excited using the generated energy between the donor and hydrogen peroxide, which triggers the generation of reactive oxygen species (ROS), promoting endosomal lipid membrane destabilization. Tetra-oleoyl tri-lysino succinoyl tetraethylene pentamine was included as an ionizable lipopeptide with a U-shaped topology for effective siRNA encapsulation and pH-induced endosomal escape. LNPs loaded with siRNA and CET components demonstrated a more efficient endosomal escape, as evidenced by a galectin-8-mRuby reporter; ROS significantly augmented galectin-8 recruitment by at least threefold compared with the control groups, with a p value of 0.03. Moreover, CET-enhanced LNPs achieved a 24% improvement in apoptosis level by knocking down the tumor-protective gene nuclear factor erythroid 2-related factor 2, boosting the CET-mediated ROS cell killing.

The mechanical properties of lipid nanoparticles depend on the type of biomacromolecule they are loaded with

For drug delivery systems, the mechanical properties of drug carriers are suspected to play a crucial role in the delivery process. However, there is a lack of reliable methods available to measure the mechanical properties of drug carriers, which hampers the establishment of a link between delivery efficiency and the mechanical properties of carriers. Lipid nanoparticles (LNPs) are advanced systems for delivering nucleic acids to target cell populations for vaccination purposes (mRNA) or the development of new drugs. Hence, it is crucial to develop reliable techniques to measure the mechanical properties of LNPs. In this article, we used AFM to image and probe the mechanical properties of LNPs which are loaded with two different biopolymers either pDNA or mRNA. Imaging the LNPs before and after indentation, as well as recording the retraction curve, enables us to obtain more insight into how the AFM tip penetrates into the particle and to determine whether the deformation of the LNPs is reversible. For pDNA, the indentation by the tip leads to irreversible rupture of the LNPs, while the deformation is reversible for the mRNA-loaded LNPs. Moreover, the forces reached for pDNA are higher than for mRNA. These results pave the way toward the establishment of the link between the LNP formulation and the delivery efficiency.

Electrophoretic Microfluidic Characterization of mRNA- and pDNA-Loaded Lipid Nanoparticles

Lipid nanoparticles (LNPs) are clinically advanced nonviral gene delivery vehicles with a demonstrated ability to address viral, oncological, and genetic diseases. However, the further development of LNP therapies requires rapid analytical techniques to support their development and manufacturing. The method developed and described in this paper presents an approach to rapidly and accurately analyze LNPs for optimized therapeutic loading by utilizing an electrophoresis microfluidic platform to analyze the composition of LNPs with different clinical lipid compositions (Onpattro, Comirnaty, and Spikevax) and nucleic acid (plasmid DNA (pDNA) and messenger RNA (mRNA)) formulations. This method enables the high-throughput screening of LNPs using a 96- or 384-well plate with approximate times of 2-4 min per sample using a total volume of 11 μL. The lipid analysis requires concentrations approximately between 109 and 1010 particles/mL and has an average precision error of 10.4% and a prediction error of 19.1% when compared to using a NanoSight, while the nucleic acid analysis requires low concentrations of 1.17 ng/μL for pDNA and 0.17 ng/μL for mRNA and has an average precision error of 4.8% and a prediction error of 9.4% when compared to using a PicoGreen and RiboGreen assay. In addition, our method quantifies the relative concentration of nucleic acid per LNP. Utilizing this approach, we observed an average of 263 ± 62.2 mRNA per LNP and 126.3 ± 21.2 pDNA per LNP for the LNP formulations used in this study, where the accuracy of these estimations is dependent on reference standards. We foresee the utility of this technique in the high-throughput characterization of LNPs during manufacturing and formulation research and development.

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.

Localization of Intramuscular mRNA Delivery Using Deep Eutectic-Lipid Nanocomposites

Messenger ribonucleic acid (mRNA) has long been touted as a next-generation therapeutic modality for infectious disease, cancer, and genetic disorders. Lipid nanoparticles (LNPs) provide an elegant delivery strategy for mRNA cargo to help realize this potential for vaccination. However, systemic exposure seen with traditional LNP formulations can have significant implications on efficacy and safety. Efforts to mitigate this have largely been focused on laborious lipid or LNP redesign. Here, the use of a deep eutectic-lipid nanocomposite delivery system for the tuning of mRNA expression for intramuscular injections in vivo is reported. One deep eutectic, cholinium malonate, allows for the linear control of percent expression at the muscular injection site based solely on its concentration in the formulation. The same deep eutectic solvent (DES) can increase local muscle expression by 68% and significantly decrease off-target liver expression by 72%. Physico-chemical studies suggest that the DES incorporates into or onto the pre-formed LNPs thus impacting endosomal escape and in situ interactions. These nanocomposites provide new possibilities for previously approved LNP formulations and without the need for lipid redesign to induce localized expression.

pH-Dependent Lyotropic Liquid Crystalline Mesophase and Ionization Behavior of Phytantriol-Based Ionizable Lipid Nanoparticles

Self-assembled lipid nanoparticles (LNPs), serving as essential nanocarriers in recent COVID-19 mRNA vaccines, provide a stable and versatile platform for delivering a wide range of biological materials. Notably, LNPs with unique inverse mesostructures, such as cubosomes and hexosomes, are recognized as fusogenic nanocarriers in the drug delivery field. This study delves into the physicochemical properties, including size, lyotropic liquid crystalline mesophase, and apparent pKa of LNPs with various lipid components, consisting of two ionizable lipids (ALC-0315 and SM-102) used in commercial COVID-19 mRNA vaccines and a well-known inverse mesophase structure-forming helper lipid, phytantriol (PT). Two partial mesophase diagrams are generated for both ALC-0315/PT LNPs and SM-102/PT LNPs as a function of two factors, ionizable lipid ratio (α, 0-100 mol%) and pH condition (pH 3-11). Furthermore, the impact of different LNP stabilizers (Pluronic F127, Pluronic F108, and Tween 80) on their pH-dependent phase behavior is evaluated. The findings offer insights into the self-assembled mesostructure and ionization state of the studied LNPs with potentially enhanced endosomal escape ability. This research is relevant to developing innovative next-generation LNP systems for delivering various therapeutics.

Analytical techniques for the characterization of nanoparticles for mRNA delivery

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

Finely tuned ionizable lipid nanoparticles for CRISPR/Cas9 ribonucleoprotein delivery and gene editing

Nonviral delivery of the CRISPR/Cas9 system provides great benefits for in vivo gene therapy due to the low risk of side effects. However, in vivo gene editing by delivering the Cas9 ribonucleoprotein (RNP) is challenging due to the poor delivery into target tissues and cells. Here, we introduce an effective delivery method for the CRISPR/Cas9 RNPs by finely tuning the formulation of ionizable lipid nanoparticles. The LNPs delivering CRISPR/Cas9 RNPs (CrLNPs) are demonstrated to induce gene editing with high efficiencies in various cancer cell lines in vitro. Furthermore, we show that CrLNPs can be delivered into tumor tissues with high efficiency, as well as induce significant gene editing in vivo. The current study presents an effective platform for nonviral delivery of the CRISPR/Cas9 system that can be applied as an in vivo gene editing therapeutic for treating various diseases such as cancer and genetic disorders.

Analytical Characterization of Heterogeneities in mRNA-Lipid Nanoparticles Using Sucrose Density Gradient Ultracentrifugation

Rational design and robust formulation processes are critical for optimal delivery of mRNA by lipid nanoparticles (LNPs). Varying degrees of heterogeneity in mRNA-LNPs can affect their biophysical and functional properties. Given the profound complexity of mRNA-LNPs, it is critical to develop comprehensive and orthogonal analytical techniques for a better understanding of these formulations. To this end, we developed a robust ultracentrifugation method for density-based separation of subpopulations of mRNA-LNPs. Four LNP formulations encapsulating human erythropoietin (hEPO) with varying functionalities were synthesized using two ionizable lipids, A and B, and two helper lipids, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and 1,2-dierucoyl-sn-glycero-3-phosphoethanolamine (DEPE), along with cholesterol and DMG-PEG-2K. Upon ultracentrifugation on a sucrose gradient, a distinct pattern of "fractions" was observed across the gradient, from the less dense topmost fraction to the increasingly denser bottom fractions, which were harvested for comprehensive analyses. Parent LNPs, A-DOPE and B-DOPE, were resolved into three density-based fractions, each differing significantly in the hEPO expression following intravenous and intramuscular routes of administration. Parent B-DEPE LNPs resolved into two density-based fractions, with most of the payload and lipid content being attributed to the topmost fraction compared to the lower one, indicating some degree of heterogeneity, while parent A-DEPE LNPs showed remarkable homogeneity, as indicated by comparable in vivo potency, lipid numbers, and particle count among the three density-based fractions. This study is the first to demonstrate the application of density gradient-based ultracentrifugation (DGC) for a head-to-head comparison of heterogeneity as a function of biological performance and biophysical characteristics of parent mRNA-LNPs and their subpopulations.

Design, synthesis, and in vitro gene transfer efficacy of novel ionizable cholesterol derivatives

ABSTACTThe medicinal properties of genetic drugs are highly dependent on the design of delivery systems. Ionizable cationic lipids are considered core materials in delivery systems. However, there has not yet been a widespread consensus on the relationship between the wide diversity of lipid structure design and gene delivery efficiency. The aims of the research work were to synthesize ionizable cholesterol derivatives (iChol-lipids) and to evaluate their potential applications as gene delivery vector. A series of iChol-lipids with different head groups were synthesized with carbamate bond spacer. The chemical structures were characterized by 1H NMR, MS, melting range, and pKa. The interactions between iChol-lipids and MALAT1-siRNA were studied by molecular dynamics simulations and compared with market available DC-Chol, which revealed that hydrogen bonds, salt-bridge, and electrostatic interaction were probably involved. The self-assemble behaviors of these lipids were intensively investigated and evaluated by dynamic laser scattering in the presence of different helper lipids and PEGylated lipids. Their plasmid binding ability, transfection efficiency, hemolytic toxicity, and cytotoxicity were fully studied. IZ-Chol-LNPs was proved to be highly potential to effectively complex with DNA, and endosome escape mechanisms mediated by proton sponge effect was verified by pH-sensitive fluorescence probe BCFL.

Optimizing long-term stability of siRNA using thermoassemble ionizable reverse pluronic-Bcl2 micelleplexes

Thermosassemble Ionizable Reverse Pluronic (TIRP) platform stands out for its distinctive combination of thermoassemble and ionizable features, effectively overcoming challenges in previous siRNA delivery systems. This study opens up a formation for long-term stabilization, and high loading of siRNA, specifically crafted for targeting oncogenic pathways. TIRP-Bcl2 self-assembles into a unique micelle structure with a nanodiameter of 75.8 ± 5.7 nm, efficiently encapsulating Bcl2 siRNA while maintaining exceptional colloidal stability at 4 °C for 8 months, along with controlled release profiles lasting 180 h. The dual ionizable headgroup enhance the siRNA loading and the revers pluronic unique structural orientation enhance the stability of the siRNA. The thermoassemble of TIRP-Bcl2 facilitates flexi-rigid response to mild hyperthermia, enhancing deep tissue penetration and siRNA release in the tumor microenvironment. This responsive behavior improves intracellular uptake and gene silencing efficacy in cancer cells. TIRP, with its smaller particle size and reverse pluronic nature, efficiently transports siRNA across the blood-brain barrier, holding promise for revolutionizing glioblastoma (GBM) treatment. TIRP-Bcl2 shows significant potential for precise, personalized therapies, promising prolonged siRNA delivery and in vitro/in vivo stability. This research opens avenues for further exploration and clinical translation of this innovative nanocarrier system across different cancers.

Recent Advances in Engineering Carriers for siRNA Delivery

RNA interference (RNAi) technology has been a promising treatment strategy for combating intractable diseases. However, the applications of RNAi in clinical are hampered by extracellular and intracellular barriers. To overcome these barriers, various siRNA delivery systems have been developed in the past two decades. The first approved RNAi therapeutic, Patisiran (ONPATTRO) using lipids as the carrier, for the treatment of amyloidosis is one of the most important milestones. This has greatly encouraged researchers to work on creating new functional siRNA carriers. In this review, the recent advances in siRNA carriers consisting of lipids, polymers, and polymer-modified inorganic particles for cancer therapy are summarized. Representative examples are presented to show the structural design of the carriers in order to overcome the delivery hurdles associated with RNAi therapies. Finally, the existing challenges and future perspective for developing RNAi as a clinical modality will be discussed and proposed. It is believed that the addressed contributions in this review will promote the development of siRNA delivery systems for future clinical applications.

Lipid nanoparticles containing labile PEG-lipids transfect primary human skin cells more efficiently in the presence of apoE

Nucleic acid-based therapeutics encapsulated into lipid nanoparticles (LNPs) can potentially target the root cause of genetic skin diseases. Although nanoparticles are considered impermeable to skin, research and clinical studies have shown that nanoparticles can penetrate into skin with reduced skin barrier function when administered topically. Studies have shown that epidermal keratinocytes express the low-density lipoprotein receptor (LDLR) that mediates endocytosis of apolipoprotein E (apoE)-associated nanoparticles and that dermal fibroblasts express mannose receptors. Here we prepared LNPs designed to exploit these different endocytic pathways for intracellular mRNA delivery to the two most abundant skin cell types, containing: (i) labile PEG-lipids (DMG-PEG2000) prone to dissociate and facilitate apoE-binding to LNPs, enabling apoE-LDLR mediated uptake in keratinocytes, (ii) non-labile PEG-lipids (DSPE-PEG2000) to impose stealth-like properties to LNPs to enable targeting of distant cells, and (iii) mannose-conjugated PEG-lipids (DSPE-PEG2000-Mannose) to target fibroblasts or potentially immune cells containing mannose receptors. All types of LNPs were prepared by vortex mixing and formed monodisperse (PDI ∼ 0.1) LNP samples with sizes of 130 nm (±25%) and high mRNA encapsulation efficiencies (≥90%). The LNP-mediated transfection potency in keratinocytes and fibroblasts was highest for LNPs containing labile PEG-lipids, with the addition of apoE greatly enhancing transfection via LDLR. Coating LNPs with mannose did not improve transfection, and stealth-like LNPs show limited to no transfection. Taken together, our studies suggest using labile PEG-lipids and co-administration of apoE when exploring LNPs for skin delivery.

Systematic development of ionizable lipid nanoparticles for placental mRNA delivery using a design of experiments approach

Ionizable lipid nanoparticles (LNPs) have gained attention as mRNA delivery platforms for vaccination against COVID-19 and for protein replacement therapies. LNPs enhance mRNA stability, circulation time, cellular uptake, and preferential delivery to specific tissues compared to mRNA with no carrier platform. However, LNPs are only in the beginning stages of development for safe and effective mRNA delivery to the placenta to treat placental dysfunction. Here, we develop LNPs that enable high levels of mRNA delivery to trophoblasts in vitro and to the placenta in vivo with no toxicity. We conducted a Design of Experiments to explore how LNP composition, including the type and molar ratio of each lipid component, drives trophoblast and placental delivery. Our data revealed that utilizing C12-200 as the ionizable lipid and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) as the phospholipid in the LNP design yields high transfection efficiency in vitro. Analysis of lipid molar composition as a design parameter in LNPs displayed a strong correlation between apparent pKa and poly (ethylene) glycol (PEG) content, as a reduction in PEG molar amount increases apparent pKa. Further, we present one LNP platform that exhibits the highest delivery of placental growth factor mRNA to the placenta in pregnant mice, resulting in synthesis and secretion of a potentially therapeutic protein. Lastly, our high-performing LNPs have no toxicity to both the pregnant mice and fetuses. Our results demonstrate the feasibility of LNPs as a platform for mRNA delivery to the placenta, and our top LNP formulations may provide a therapeutic platform to treat diseases that originate from placental dysfunction during pregnancy.

Simple Scattering: Lipid nanoparticle structural data repository

Lipid nanoparticles (LNPs) are being intensively researched and developed to leverage their ability to safely and effectively deliver therapeutics. To achieve optimal therapeutic delivery, a comprehensive understanding of the relationship between formulation, structure, and efficacy is critical. However, the vast chemical space involved in the production of LNPs and the resulting structural complexity make the structure to function relationship challenging to assess and predict. New components and formulation procedures, which provide new opportunities for the use of LNPs, would be best identified and optimized using high-throughput characterization methods. Recently, a high-throughput workflow, consisting of automated mixing, small-angle X-ray scattering (SAXS), and cellular assays, demonstrated a link between formulation, internal structure, and efficacy for a library of LNPs. As SAXS data can be rapidly collected, the stage is set for the collection of thousands of SAXS profiles from a myriad of LNP formulations. In addition, correlated LNP small-angle neutron scattering (SANS) datasets, where components are systematically deuterated for additional contrast inside, provide complementary structural information. The centralization of SAXS and SANS datasets from LNPs, with appropriate, standardized metadata describing formulation parameters, into a data repository will provide valuable guidance for the formulation of LNPs with desired properties. To this end, we introduce Simple Scattering, an easy-to-use, open data repository for storing and sharing groups of correlated scattering profiles obtained from LNP screening experiments. Here, we discuss the current state of the repository, including limitations and upcoming changes, and our vision towards future usage in developing our collective knowledge base of LNPs.

Which Lipid Nanoparticle (LNP) Designs Work? A Simple Kinetic Model Linking LNP Chemical Structure to In Vivo Delivery Performance

Although lipid nanoparticles (LNPs) are the predominant nanocarriers for short-interfering RNA (siRNA) delivery, most therapies use nearly identical formulations that have taken 30 years to design but lack the diverse property ranges necessary for versatile application. This dearth in variety and the extended timeline for implementation are attributed to a limited understanding of how LNP properties facilitate overcoming biological barriers. Herein, a simple kinetic model was developed by using major rate-limiting steps for siRNA delivery, and this model enabled the identification of a critical parameter to predict LNP efficacy without extensive experimental testing. A volume-averaged log D, the "solubility" of charged molecules as a function of pH weighted by component volume fractions, resulted in a good correlation between LNP composition and siRNA delivery. Both the effects of modifying the structures of ionizable lipids and LNP composition on gene silencing were easily captured in the model predictions. Thus, this approach provides a robust LNP structure-activity relationship to dramatically accelerate the realization of effective LNP formulations.

Electrostatic adsorption of polyanions onto lipid nanoparticles controls uptake, trafficking, and transfection of RNA and DNA therapies

Rapid advances in nucleic acid therapies highlight the immense therapeutic potential of genetic therapeutics. Lipid nanoparticles (LNPs) are highly potent nonviral transfection agents that can encapsulate and deliver various nucleic acid therapeutics, including but not limited to messenger RNA (mRNA), silencing RNA (siRNA), and plasmid DNA (pDNA). However, a major challenge of targeted LNP-mediated systemic delivery is the nanoparticles' nonspecific uptake by the liver and the mononuclear phagocytic system, due partly to the adsorption of endogenous serum proteins onto LNP surfaces. Tunable LNP surface chemistries may enable efficacious delivery across a range of organs and cell types. Here, we describe a method to electrostatically adsorb bioactive polyelectrolytes onto LNPs to create layered LNPs (LLNPs). LNP cores varying in nucleic acid cargo and component lipids were stably layered with four biologically relevant polyanions: hyaluronate (HA), poly-L-aspartate (PLD), poly-L-glutamate (PLE), and polyacrylate (PAA). We further investigated the impact of the four surface polyanions on the transfection and uptake of mRNA- and pDNA-loaded LNPs in cell cultures. PLD- and PLE-LLNPs increased mRNA transfection twofold over unlayered LNPs in immune cells. HA-LLNPs increased pDNA transfection rates by more than twofold in epithelial and immune cells. In a healthy C57BL/6 murine model, PLE- and HA-LLNPs increased transfection by 1.8-fold to 2.5-fold over unlayered LNPs in the liver and spleen. These results suggest that LbL assembly is a generalizable, highly tunable platform to modify the targeting specificity, stability, and transfection efficacy of LNPs, as well as incorporate other charged targeting and therapeutic molecules into these systems.

Recent advances in nanoparticulate RNA delivery systems

Nanoparticle-based RNA delivery has shown great progress in recent years with the approval of two mRNA vaccines for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and a liver-targeted siRNA therapy. Here, we discuss the preclinical and clinical advancement of new generations of RNA delivery therapies along multiple axes. Improvements in cargo design such as RNA circularization and data-driven untranslated region optimization can drive better mRNA expression. New materials discovery research has driven improved delivery to extrahepatic targets such as the lung and splenic immune cells, which could lead to pulmonary gene therapy and better cancer vaccines, respectively. Other organs and even specific cell types can be targeted for delivery via conjugation of small molecule ligands, antibodies, or peptides to RNA delivery nanoparticles. Moreover, the immune response to any RNA delivery nanoparticle plays a crucial role in determining efficacy. Targeting increased immunogenicity without induction of reactogenic side effects is crucial for vaccines, while minimization of immune response is important for gene therapies. New developments have addressed each of these priorities. Last, we discuss the range of RNA delivery clinical trials targeting diverse organs, cell types, and diseases and suggest some key advances that may play a role in the next wave of therapies.

Endosomal escape: A bottleneck for LNP-mediated therapeutics

Lipid nanoparticles (LNPs) have recently emerged as a powerful and versatile clinically approved platform for nucleic acid delivery, specifically for mRNA vaccines. A major bottleneck in the field is the release of mRNA-LNPs from the endosomal pathways into the cytosol of cells where they can execute their encoded functions. The data regarding the mechanism of these endosomal escape processes are limited and contradicting. Despite extensive research, there is no consensus regarding the compartment of escape, the cause of the inefficient escape and are currently lacking a robust method to detect the escape. Here, we review the currently known mechanisms of endosomal escape and the available methods to study this process. We critically discuss the limitations and challenges of these methods and the possibilities to overcome these challenges. We propose that the development of currently lacking robust, quantitative high-throughput techniques to study endosomal escape is timely and essential. A better understanding of this process will enable better RNA-LNP designs with improved efficiency to unlock new therapeutic modalities.

Pharmacokinetic Analyses of a Lipid Nanoparticle-Encapsulated mRNA-Encoded Antibody against Rift Valley Fever Virus

Rift Valley fever virus (RVFV) could cause an emergency illness characterized by fever, muscle pain, and even death in humans or ruminants. However, there are no approved antiviral drugs that prevent or treat RVFV infection. While therapeutic antibodies have shown promising potential for prevention or treatment in several studies, many studies are ongoing, especially in the field of infectious diseases. Among these studies, the mRNA-LNP platform shows great potential for application, following the COVID-19 pandemic. Previously, we have obtained a neutralizing antibody against RVFV, which was named A38 protein and verified to have a high binding and neutralization ability. In this study, we aimed to identify an effectively optimized sequence and expressed the prioritized mRNA-encoded antibody in vitro. Notably, we effectively expressed mRNA-encoded protein and used the mRNA-LNP platform to generate A38-mRNA-LNP. Pharmacokinetic experiments were conducted in vivo and set up in two groups of mRNA-A38 group and A38 protein group, which were derived from mRNA-LNP and plasmid DNA-expressed proteins, respectively. A38-mRNA-LNPs were administrated by intramuscular injection, A38 proteins were administrated by intravenous administration, and their unique ability to maintain long-lasting protein concentrations by mRNA-encoded protein was demonstrated with the mRNA-encoded protein providing a longer circulating half-life compared to injection of the free A38 protein. These preclinical data on the mRNA-encoded antibody highlighted its potential to prevent infectious diseases in the future.

Nano-Bio Interactions: Exploring the Biological Behavior and the Fate of Lipid-Based Gene Delivery Systems

Gene therapy for many diseases is rapidly becoming a reality, as demonstrated by the recent approval of various nucleic acid-based therapeutics. Non-viral systems such as lipid-based carriers, lipid nanoparticles (LNPs), for delivering different payloads including small interfering RNA, plasmid DNA, and messenger RNA have been particularly extensively explored and developed for clinical uses. One of the most important issues in LNP development is delivery to extrahepatic tissues. To achieve this, various lipids and lipid-like materials are being examined and screened. Several LNP formulations that target extrahepatic tissues, such as the spleen and the lungs have been developed by adjusting the lipid compositions of LNPs. However, mechanistic details of how the characteristics of LNPs affect delivery efficiency remains unclear. The purpose of this review is to provide an overview of LNP-based nucleic acid delivery focusing on LNP components and their structures, as well as discussing biological factors, such as biomolecular corona and cellular responses related to the delivery efficiency.

Redox-Responsive Polymeric Nanoparticle for Nucleic Acid Delivery and Cancer Therapy: Progress, Opportunities, and Challenges

Cancer development and progression of cancer are closely associated with the activation of oncogenes and loss of tumor suppressor genes. Nucleic acid drugs (e.g., siRNA, mRNA, and DNA) are widely used for cancer therapy due to their specific ability to regulate the expression of any cancer-associated genes. However, nucleic acid drugs are negatively charged biomacromolecules that are susceptible to serum nucleases and cannot cross cell membrane. Therefore, specific delivery tools are required to facilitate the intracellular delivery of nucleic acid drugs. In the past few decades, a variety of nanoparticles (NPs) are designed and developed for nucleic acid delivery and cancer therapy. In particular, the polymeric NPs in response to the abnormal redox status in cancer cells have garnered much more attention as their potential in redox-triggered nanostructure dissociation and rapid intracellular release of nucleic acid drugs. In this review, the important genes or signaling pathways regulating the abnormal redox status in cancer cells are briefly introduced and the recent development of redox-responsive NPs for nucleic acid delivery and cancer therapy is systemically summarized. The future development of NPs-mediated nucleic acid delivery and their challenges in clinical translation are also discussed.

Probing Molecular Packing of Lipid Nanoparticles from 31P Solution and Solid-State NMR

Lipid nanoparticles (LNPs) are intricate multicomponent systems widely recognized for their efficient delivery of oligonucleotide cargo to host cells. Gaining insights into the molecular properties of LNPs is crucial for their effective design and characterization. However, analysis of their internal structure at the molecular level presents a significant challenge. This study introduces 31P nuclear magnetic resonance (NMR) methods to acquire structural and dynamic information about the phospholipid envelope of LNPs. Specifically, we demonstrate that the 31P chemical shift anisotropy (CSA) parameters serve as a sensitive indicator of the molecular assembly of distearoylphosphatidylcholine (DSPC) lipids within the particles. An analytical protocol for measuring 31P CSA is developed, which can be implemented using either solution NMR or solid-state NMR, offering wide accessibility and adaptability. The capability of this method is demonstrated using both model DSPC liposomes and real-world pharmaceutical LNP formulations. Furthermore, our method can be employed to investigate the impact of formulation processes and composition on the assembly of specifically LNP particles or, more generally, phospholipid-based delivery systems. This makes it an indispensable tool for evaluating critical pharmaceutical properties such as structural homogeneity, batch-to-batch reproducibility, and the stability of the particles.

Ionizable Polymeric Micelles with Phenylalanine Moieties Enhance Intracellular Delivery of Self-Replicating RNA for Long-Lasting Protein Expression In Vivo

mRNA-based therapeutics are revolutionizing the landscape of medical interventions. However, the short half-life of mRNA and transient protein expression often limits its therapeutic potential, demanding high treatment doses or repeated administrations. Self-replicating RNA (RepRNA)-based treatments could offer enhanced protein production and reduce the required dosage. Here, we developed polymeric micelles based on flexible poly(ethylene glycol)-poly(glycerol) (PEG-PG) block copolymers modified with phenylalanine (Phe) moieties via biodegradable ester bonds for the efficient delivery of RepRNA. These polymers successfully encapsulated RepRNA into sub-100 nm micelles assisted by the hydrophobicity of the Phe moieties and their ability to π-π stack with the bases in RepRNA. The micelles made from Phe-modified PEG-PG (PEG-PG(Phe)) effectively maintained the integrity of the loaded RepRNA in RNase-rich serum conditions. Once taken up by cells, the micelles triggered a pH-responsive membrane disruption, promoted by the strong protonation of the amino groups at endosomal pH, thereby delivering the RepRNA to the cytosol. The system induced strong protein expression in vitro and outperformed commercial transfecting reagents in vivo, where it resulted in enhanced and long-lasting protein expression.

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

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

Messenger RNA Therapy for Female Reproductive Health

Female reproductive health has traditionally been an underrepresented area of research in the drug delivery sciences. This disparity is also seen in the emerging field of mRNA therapeutics, a class of medicines that promises to treat and prevent disease by upregulating protein expression in the body. Here, we review advances in mRNA therapies through the lens of improving female reproductive health. Specifically, we begin our review by discussing the fundamental structure and biochemical modifications associated with mRNA-based drugs. Then, we discuss various packaging technologies, including lipid nanoparticles, that can be utilized to protect and transport mRNA drugs to target cells in the body. Last, we conclude our review by discussing the usage of mRNA therapy for addressing pregnancy-related health and vaccination against sexually transmitted diseases in women. Of note, we also highlight relevant clinical trials using mRNA for female reproductive health while also providing their corresponding National Clinical Trial identifiers. In undertaking this review, our aim is to provide a fundamental background understanding of mRNA therapy and its usage to specifically address female health issues with an overarching goal of providing information toward addressing gender disparity in certain aspects of health research.

Cationic nanoparticles-based approaches for immune tolerance induction in vivo

The development of autoimmune diseases and the rejection of transplanted organs are primarily caused by an exaggerated immune response to autoantigens or graft antigens. Achieving immune tolerance is crucial for the effective treatment of these conditions. However, traditional therapies often have limited therapeutic efficacy and can result in systemic toxic effects. The emergence of nanomedicine offers a promising avenue for addressing immune-related diseases. Among the various nanoparticle formulations, cationic nanoparticles have demonstrated significant potential in inducing immune tolerance. In this review, we provide an overview of the underlying mechanism of autoimmune disease and organ transplantation rejection. We then highlight the recent advancements and advantages of utilizing cationic nanoparticles for inducing immune tolerance in the treatment of autoimmune diseases and the prevention of transplant rejection.

Nanoparticle-Mediated Delivery of Anti-PU.1 siRNA via Localized Intracisternal Administration Reduces Neuroinflammation

Neuroinflammation is a hallmark of neurodegenerative disorders including Alzheimer's disease (AD). Microglia, the brain's immune cells, express many of the AD-risk loci identified in genome wide association studies and present a promising target for anti-inflammatory RNA therapeutics but are difficult to transfect with current methods. Here, several lipid nanoparticle (LNP) formulations are examined, and a lead candidate that supports efficient RNA delivery in cultures of human stem cell-derived microglia-like cells (iMGLs) and animal models of neuroinflammation is identified. The lead microglia LNP (MG-LNP) formulation shows minimal toxicity and improves delivery efficiency to inflammatory iMGLs, suggesting a preference for delivery into activated microglia. Intraperitoneal injection of the MG-LNP formulation generates widespread expression of the delivered reporter construct in all organs, whereas local intracisternal injection directly into the cerebrospinal fluid leads to preferential expression in the brain. It is shown that LNP-mediated delivery of siRNA targeting the PU.1 transcription factor, a known AD-risk locus, successfully reduces PU.1 levels in iMGLs and reduces neuroinflammation in mice injected with LPS and in CK-p25 mice that mimic the chronic neuroinflammation seen in AD patients. The LNP formulation represents an effective RNA delivery vehicle when applied intrathecally and can be broadly utilized to test potential neuroinflammation-directed gene therapies.

Evaluating how cationic lipid affects mRNA-LNP physical properties and biodistribution

RNA therapeutics represents a powerful strategy for diseases where other approaches have failed, especially given the recent successes of mRNA vaccines against the coronavirus disease 2019 (COVID-19) and small interfering (siRNA) therapeutics. However, further developments are still required to reduce toxicity, improve stability and biodistribution of mRNA-LNPs (lipid nanoparticles). Here, we show a rational combinatorial approach to select the best formulation based on a new cationic lipid molecule (IM21.7c), which includes an imidazolium polar head. The study allowed us to select the optimal 5 lipids composition for in vivo mRNA delivery. IM21.7c based mRNA-LNPs measuring less than 100 nm had high encapsulation efficiency, protected mRNA from degradation, and exhibited sustained release kinetics for effective in vitro transfection. Most interestingly the biodistribution was significantly different from other clinically approved LNPs, with increased targeting to the lung. Further studies are now required to expand the possible applications of these new molecules.

Morphological Characterization of Self-Amplifying mRNA Lipid Nanoparticles

The mRNA technology has emerged as a rapid modality to develop vaccines during pandemic situations with the potential to protect against endemic diseases. The success of mRNA in producing an antigen is dependent on the ability to deliver mRNA to the cells using a vehicle, which typically consists of a lipid nanoparticle (LNP). Self-amplifying mRNA (SAM) is a synthetic mRNA platform that, besides encoding for the antigen of interest, includes the replication machinery for mRNA amplification in the cells. Thus, SAM can generate many antigen encoding mRNA copies and prolong expression of the antigen with lower doses than those required for conventional mRNA. This work describes the morphology of LNPs containing encapsulated SAM (SAM LNPs), with SAM being three to four times larger than conventional mRNA. We show evidence that SAM changes its conformational structure when encapsulated in LNPs, becoming more compact than the free SAM form. A characteristic "bleb" structure is observed in SAM LNPs, which consists of a lipid-rich core and an aqueous RNA-rich core, both surrounded by a DSPC-rich lipid shell. We used SANS and SAXS data to confirm that the prevalent morphology of the LNP consists of two-core compartments where components are heterogeneously distributed between the two cores and the shell. A capped cylinder core-shell model with two interior compartments was built to capture the overall morphology of the LNP. These findings provide evidence that bleb two-compartment structures can be a representative morphology in SAM LNPs and highlight the need for additional studies that elucidate the role of spherical and bleb morphologies, their mechanisms of formation, and the parameters that lead to a particular morphology for a rational design of LNPs for mRNA delivery.

Accelerated prime-and-trap vaccine regimen in mice using repRNA-based CSP malaria vaccine

Malaria, caused by Plasmodium parasites, remains one of the most devastating infectious diseases worldwide, despite control efforts to lower morbidity and mortality. Both advanced candidate vaccines, RTS,S and R21, are subunit (SU) vaccines that target a single Plasmodium falciparum (Pf) pre-erythrocytic (PE) sporozoite (spz) surface protein known as circumsporozoite (CS). These vaccines induce humoral immunity but fail to elicit CD8 + T-cell responses sufficient for long-term protection. In contrast, whole-organism (WO) vaccines, such as Radiation Attenuated Sporozoites (RAS), achieved sterile protection but require a series of intravenous doses administered in multiple clinic visits. Moreover, these WO vaccines must be produced in mosquitos, a burdensome process that severely limits their availability. To reduce reliance on WO while maintaining protection via both antibodies and Trm responses, we have developed an accelerated vaccination regimen that combines two distinct agents in a prime-and-trap strategy. The priming dose is a single dose of self-replicating RNA encoding the full-length P. yoelii CS protein, delivered via an advanced cationic nanocarrier (LIONTM). The trapping dose consists of one dose of WO RAS. Our vaccine induces a strong immune response when administered in an accelerated regimen, i.e., either 5-day or same-day immunization. Additionally, mice after same-day immunization showed a 2-day delay of blood patency with 90% sterile protection against a 3-week spz challenge. The same-day regimen also induced durable 70% sterile protection against a 2-month spz challenge. Our approach presents a clear path to late-stage preclinical and clinical testing of dose-sparing, same-day regimens that can confer sterilizing protection against malaria.

On the interactions between RNA and titrateable lipid layers: implications for RNA delivery with lipid nanoparticles

Characterising the interaction between cationic ionisable lipids (CIL) and nucleic acids (NAs) is key to understanding the process of RNA lipid nanoparticle (LNP) formation and release of NAs from LNPs. Here, we have used different surface techniques to reveal the effect of pH and NA type on the interaction with a model system of DOPC and the CIL DLin-MC3-DMA (MC3). At only 5% MC3, differences in the structure and dynamics of the lipid layer were observed. Both pH and %MC3 were shown to affect the absorption behaviour of erythropoietin mRNA, polyadenylic acid (polyA) and polyuridylic acid (polyU). The adsorbed amount of all studied NAs was found to increase with decreasing pH and increasing %MC3 but with different effects on the lipid layer, which could be linked to the NA secondary structure. For polyA at pH 6, adsorption to the surface of the layer was observed, whereas for other conditions and NAs, penetration of the NA into the layer resulted in the formation of a multilayer structure. By comparison to simulations excluding the secondary structure, differences in adsorption behaviours between polyA and polyU could be observed, indicating that the NA's secondary structure also affected the MC3-NA interactions.

Advanced optical imaging for the rational design of nanomedicines

Despite the enormous potential of nanomedicines to shape the future of medicine, their clinical translation remains suboptimal. Translational challenges are present in every step of the development pipeline, from a lack of understanding of patient heterogeneity to insufficient insights on nanoparticle properties and their impact on material-cell interactions. Here, we discuss how the adoption of advanced optical microscopy techniques, such as super-resolution optical microscopies, correlative techniques, and high-content modalities, could aid the rational design of nanocarriers, by characterizing the cell, the nanomaterial, and their interaction with unprecedented spatial and/or temporal detail. In this nanomedicine arena, we will discuss how the implementation of these techniques, with their versatility and specificity, can yield high volumes of multi-parametric data; and how machine learning can aid the rapid advances in microscopy: from image acquisition to data interpretation.

Encapsulating In Vitro Transcribed circRNA into Lipid Nanoparticles Via Microfluidic Mixing

This chapter serves as a guide for researchers embarking on circular RNA-based translational studies. It provides a foundation for the successful encapsulation of circular RNA into lipid nanoparticles (LNPs) and facilitates progress in this emerging field. Crucial scientific methods and techniques involved in the formulation process, particle characterization, and downstream processing of circ-LNPs are covered. The production of in vitro transcribed circular RNA-containing LNPs based on a commercially available lipid mix is provided, in addition to the fundamentals for successful encapsulation based on lipid mixes composed of single components. Furthermore, the transfection and validation protocols for the identification of a functional and potentially therapeutic circRNA candidate for initial in vitro verification, before subsequent LNP studies, are explained.

Fluorescent Techniques for RNA Detection in Nanoparticles

The utilization of drug delivery systems, such as lipid nanoparticles and polyplexes/micelleplexes, has shown promise in intracellularly delivering nucleic acids for addressing various diseases. Accurate quantification of the nucleic acid cargo within nanoparticles is essential for the development of safe and effective nanomedicines. Currently, the RiboGreen and SYBR Gold methods are regarded as standard techniques for the precise quantification of RNA in lipid nanoparticles and polyplexes/micelleplexes, respectively. In this chapter, we present a comprehensive protocol for the precise evaluation of the encapsulation efficiency in such formulations using these methods. Additionally, we offer detailed instructions for nanoparticle preparation, characterization, and a comparative analysis of the sensitivity of both methods in quantifying unencapsulated siRNA.

Delivery of nucleic acids using nanomaterials

The increasing number of approved nucleic acid therapeutics demonstrates the potential for the prevention and treatment of a broad spectrum of diseases. This trend underscores the significant impact and promise of nucleic acid-based treatments in the field of medicine. Nevertheless, employing nucleic acids as therapeutics is challenging due to their susceptibility to degradation by nucleases and their unfavorable physicochemical characteristics that hinder delivery into cells. Appropriate vectors play a pivotal role in improving nucleic acid stability and delivering nucleic acids into specific cells. The maturation of delivery systems has led to breakthroughs in the development of therapeutics based on nucleic acids such as DNA, siRNA, and mRNA. Non-viral vectors have gained prominence among the myriad of nanomaterials due to low immunogenicity, ease of manufacturing, and simplicity of cost-effective, large-scale production. Here, we provide an overview of the recent advancements in nanomaterials for nucleic acid delivery. Specifically, we give a detailed introduction to the characteristics of polymers, lipids, and polymer-lipid hybrids, and provide comprehensive descriptions of their applications in nucleic acid delivery. Also, biological barriers, administration routes, and strategies for organ-selective delivery of nucleic acids are discussed. In summary, this review offers insights into the rational design of next-generation delivery vectors for nucleic acid delivery.