Lipid nanoparticle topology regulates endosomal escape and delivery of RNA to the cytoplasm

Innovative gene delivery systems for retinal disease therapy

The human retina, a complex and highly specialized structure, includes multiple cell types that work synergistically to generate and transmit visual signals. However, genetic predisposition or age-related degeneration can lead to retinal damage that severely impairs vision or causes blindness. Treatment options for retinal diseases are limited, and there is an urgent need for innovative therapeutic strategies. Cell and gene therapies are promising because of the efficacy of delivery systems that transport therapeutic genes to targeted retinal cells. Gene delivery systems hold great promise for treating retinal diseases by enabling the targeted delivery of therapeutic genes to affected cells or by converting endogenous cells into functional ones to facilitate nerve regeneration, potentially restoring vision. This review focuses on two principal categories of gene delivery vectors used in the treatment of retinal diseases: viral and non-viral systems. Viral vectors, including lentiviruses and adeno-associated viruses, exploit the innate ability of viruses to infiltrate cells, which is followed by the introduction of therapeutic genetic material into target cells for gene correction. Lentiviruses can accommodate exogenous genes up to 8 kb in length, but their mechanism of integration into the host genome presents insertion mutation risks. Conversely, adeno-associated viruses are safer, as they exist as episomes in the nucleus, yet their limited packaging capacity constrains their application to a narrower spectrum of diseases, which necessitates the exploration of alternative delivery methods. In parallel, progress has also occurred in the development of novel non-viral delivery systems, particularly those based on liposomal technology. Manipulation of the ratios of hydrophilic and hydrophobic molecules within liposomes and the development of new lipid formulations have led to the creation of advanced non-viral vectors. These innovative systems include solid lipid nanoparticles, polymer nanoparticles, dendrimers, polymeric micelles, and polymeric nanoparticles. Compared with their viral counterparts, non-viral delivery systems offer markedly enhanced loading capacities that enable the direct delivery of nucleic acids, mRNA, or protein molecules into cells. This bypasses the need for DNA transcription and processing, which significantly enhances therapeutic efficiency. Nevertheless, the immunogenic potential and accumulation toxicity associated with non-viral particulate systems necessitates continued optimization to reduce adverse effects in vivo . This review explores the various delivery systems for retinal therapies and retinal nerve regeneration, and details the characteristics, advantages, limitations, and clinical applications of each vector type. By systematically outlining these factors, our goal is to guide the selection of the optimal delivery tool for a specific retinal disease, which will enhance treatment efficacy and improve patient outcomes while paving the way for more effective and targeted therapeutic interventions.

Mechanisms of receptor-mediated transcytosis at the blood-brain barrier

In receptor-mediated transcytosis (RMT) of large therapeutics across the blood-brain barrier (BBB), the construct - a macromolecule or a larger carrier with therapeutic payload - binds a protein on brain capillary endothelial cells (BCEC), with internalization and release into the brain parenchyma. The construct's internalization into, trafficking across and release from, but also possible entrapment within BCEC are affected by its engineered properties whose optimization has helped derive insights into transport mechanisms at BCEC. Furthermore, advances in multi-omics, as well as large-scale screening and directed evolution campaigns have helped identify new targets for RMT at BCEC. In this perspective, I raise and reflect on some fundamental questions one can arrive at by comparing the engineered properties of BBB-targeted constructs and the properties of different target proteins. These questions concern the underlying, transcytosis-promoting factors that the optimization of constructs' engineered properties appears to converge on, the precise role of target proteins in RMT, the different mechanisms through which these targets may mediate construct trafficking, and the tentative criteria for target selection on BCEC. Based on these considerations I propose several scenarios and strategies to interfere with the construct's trafficking for more efficient internalization, transport through the endosomal network toward the abluminal membrane, and release from BCEC, both for smaller macromolecules and for larger carriers.

Peptides: potential delivery systems for mRNA

mRNA-based therapies have broad applications in various disease treatments and have been applied in protein replacement therapy, gene editing, and vaccine development. Numerous research studies have been carried out aiming to increase the stability of mRNA, improve its translational efficiency, and reduce its immunogenicity. However, given mRNA's large molecular size and strong electronegativity, the safety and efficient delivery of mRNA into the target cells remains the critical rate-limiting step in current mRNA drug development. Various nanocarriers, such as liposomes, lipid nanoparticles, polyetherimide, and mesoporous silica nanoparticles, have been employed for mRNA delivery in the past few decades. Among them, peptides have demonstrated great potential as promising carrier candidates for mRNA delivery due to their high cell membrane permeability, good biocompatibility, definite chemical structure, and ease of preparation. Here, peptide-based mRNA delivery systems are systematically analyzed, including their construction strategies, mechanisms of action in mRNA delivery, and the application limitations or challenges. It is hoped that this review will guide the design, optimization, and applications of peptide carriers in mRNA-based drug development.

Structure-guided design of endosomolytic chloroquine-like lipid nanoparticles for mRNA delivery and genome editing

Despite remarkable progress in designing RNA delivery systems, endosomal escape remains a recognized challenge for efficient RNA delivery. In this study, we develop a robust mRNA delivery platform termed endosomolytic chloroquine-like optimized lipid nanoparticles (ecoLNPs) for versatile mRNA delivery in vitro and in vivo via integrating the signature scaffold extracted from endosomolytic chloroquine into ionizable lipids. RNase-resistant ecoLNPs are capable of delivering a broad variety of mRNA payloads to diverse cell types, even hard-to-transfect 3D cells, with an efficiency of up to 18.9-fold higher than that of commercial transfection reagents. The pH-responsive endosomolytic activity of ecoLNPs can be largely attributed to the proton sponge effect and saposin B-promoted membrane disruption. In vivo, ecoLNPs enable potent local and systemic mRNA delivery and exhibit comparable potency to the clinically approved mRNA vaccine carrier, but strong tropism for lymph nodes following intramuscular injection. Furthermore, ecoLNPs are able to retain in vivo delivery potency for at least one week under non-frozen conditions and induce efficient genome editing in transgenic mice. Overall, the structure-guided integration strategy provides a pathway for de novo design of endosomolytic mRNA delivery systems.

Transition Temperature-Guided Design of Lipid Nanoparticles for Effective mRNA Delivery

Lipid nanoparticles (LNPs) are promising mRNA delivery vehicles due to their biocompatibility and tunable characteristics. While current rational design approaches focus on ionizable lipids' pKa and zeta potential to optimize mRNA encapsulation and endosomal escape, the selection of helper lipids remains largely empirical. We propose that the lipid transition temperature (Tm), marking the shift from the gel to the liquid crystalline phase, can guide rational helper lipid selection. Through screening 54 ionizable lipids, we identified H7T4, which displayed favorable physicochemical properties when combined with its tail variants but exhibited poor transfection efficiency. Using nano differential scanning calorimetry (nDSC) and biological small-angle X-ray scattering (BioSAXS), we found that lowering the system's Tm by combining H7T4 (high transition temperature) with a low-transition-temperature helper lipid such as 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) significantly enhanced mRNA cellular uptake both in vitro and in vivo. These findings establish Tm as a crucial parameter for a rational LNP design.

Cubic Phase-Inducible Zwitterionic Phospholipids Improve the Functional Delivery of mRNA

Lipid nanoparticles (LNPs) are clinically advanced delivery systems for RNA. The extensively developed structure of ionizable lipids greatly contributes to the functional delivery of mRNA. However, endosomal escape is one of the severe biological barriers that continue to render this process inefficient (e.g., less than 10%). Although LNPs contain phospholipids, their role is poorly understood, and there have been few attempts to perform the chemical engineering required to improve their functionality. Herein, a cubic phase-inducible fusogenic zwitterionic phospholipid derived from 1,2-dioleoyl-3-sn-glycero-phosphoethanolamine (DOPE), DOPE-Cx is described, that is designed to correct this problem. The orientation of a zwitterionic head group of DOPE is engineered by attaching a series of hydrophobic moieties for zwitterionic intermolecular interaction with the head structure of phosphatidylcholine (PC), and this is followed by a lipid-phase transition into non-lamellar phases to facilitate membrane fusion-mediated endosomal escape. A structure-activity relationship study reveals that DOPE-Cx lipids with small hydrophobic chains induce cubic phases instead of a hexagonal phase when mixed with PC, which enhances the functional delivery of mRNA in the liver as opposed to the action of the typically utilized and naturally occurring phospholipids. Engineered functionalized phospholipids will be of great value for the therapeutic applications of mRNAs.

Recent strategies for enhanced delivery of mRNA to the lungs

mRNA-based therapies have emerged as a transformative tool in modern medicine, gaining significant attention following their successful use in COVID-19 vaccines. Delivery to the lungs offers several compelling advantages for mRNA delivery. The lungs are one of the most vascularized organs in the body, which provides an extensive surface area that can facilitate efficient drug transport. Local delivery to the lungs bypasses gastrointestinal degradation, potentially enhancing therapeutic efficacy. In addition, the extensive capillary network of the lungs provides an ideal target for systemic delivery. However, developing effective mRNA therapies for the lungs presents significant challenges. The complex anatomy of the lungs and the body's immune response to foreign particles create barriers to delivery. This review discusses key approaches for overcoming these challenges and improving mRNA delivery to the lungs. It examines both local and systemic delivery strategies aimed at improving lung delivery while mitigating off-target effects. Although substantial progress has been made in lung-targeted mRNA therapies, challenges remain in optimizing cellular uptake and achieving therapeutic efficacy within pulmonary tissues. The continued refinement of delivery strategies that enhance lung-specific targeting while minimizing degradation is critical for the clinical success of mRNA-based pulmonary therapies.

More than a delivery system: the evolving role of lipid-based nanoparticles

Lipid-based nanoparticles, including liposomes and lipid nanoparticles (LNPs), make up an important class of drug delivery systems. Their modularity enables encapsulation of a wide range of therapeutic cargoes, their ease of functionalization allows for incorporation of targeting motifs and anti-fouling coatings, and their scalability facilitates rapid translation to the clinic. While the discovery and early understanding of lipid-based nanoparticles is heavily rooted in biology, formulation development has largely focused on materials properties, such as how liposome and lipid nanoparticle composition can be altered to maximize drug loading, stability and circulation. To achieve targeted delivery and enable improved accumulation of therapeutics at target tissues or disease sites, emphasis is typically placed on the use of external modifications, such as peptide, protein, and polymer motifs. However, these approaches can increase the complexity of the nanocarrier and complicate scale up. In this review, we focus on how our understanding of lipid structure and function in biological contexts can be used to design intrinsically functional and targeted nanocarriers. We highlight formulation-based strategies, such as the incorporation of bioactive lipids, that have been used to modulate liposome and lipid nanoparticle properties and improve their functionality while retaining simple nanocarrier designs. We also highlight classes of naturally occurring lipids, their functions, and how they have been incorporated into lipid-based nanoparticles. We will additionally position these approaches into the historical context of both liposome and LNP development.

Machine-Learning Framework to Predict the Performance of Lipid Nanoparticles for Nucleic Acid Delivery

Lipid nanoparticles (LNPs) are highly effective carriers for gene therapies, including mRNA and siRNA delivery, due to their ability to transport nucleic acids across biological membranes, low cytotoxicity, improved pharmacokinetics, and scalability. A typical approach to formulate LNPs is to establish a quantitative structure-activity relationship (QSAR) between their compositions and in vitro/in vivo activities, which allows for the prediction of activity based on molecular structure. However, developing QSAR for LNPs can be challenging due to the complexity of multicomponent formulations, interactions with biological membranes, stability in physiological environments, and diverse physicochemical properties. To address these challenges, we developed a machine-learning (ML) framework to predict the activity and cell viability of LNPs for nucleic acid delivery. We curated data from 6454 LNP formulations reported across 21 independent studies and implemented 11 different molecular featurization techniques, ranging from descriptors and fingerprints to graph-based representations, alongside six ML algorithms for binary and multiclass classification. Using scaffold-based 5-fold cross-validation, our models achieved classification accuracies exceeding 90% for both activity and cell viability prediction tasks. Among all model-feature combinations, descriptor-based features combined with ensemble models such as balanced random forest and extra trees yielded the highest performance. Through SHAP-based feature attribution and interaction analysis, we identified key physicochemical properties and compositional features driving the LNP performance, highlighting the importance of synergistic effects among multiple molecular features. Furthermore, we developed a transfer-learning strategy to bridge in vitro-to-in vivo prediction gaps by incorporating base model predictions along with additional biological attributes, such as the particle size, polydispersity index, and ζ potential. Despite the smaller size and inherent class imbalance of the in vivo data set, the transfer-learning models demonstrated a promising predictive performance, with accuracies exceeding 82%. Our findings underscore the potential of interpretable ML frameworks to guide rational LNP design and provide a scalable approach to QSAR modeling in complex nanomedicine systems.

A Versatile Strategy to Transform Cationic Polymers for Efficient and Organ-Selective mRNA Delivery

The progress of mRNA therapeutics underscores the imperative demand for the development of targeted delivery systems. While cationic polymers hold promise as genetic vectors, their poor in vivo efficacy and numerous variants highlight the urgent need for a universal functionalization strategy to bolster their delivery capabilities. Here, we present a versatile strategy to transform low-cost commercial cationic polymers into phospholipidated and alkylated polymers (PAPs), enabling efficient and organ-selective mRNA delivery in vivo. This straightforward post-functionalization method can be readily broadened to a diverse array of existing cationic polymers, enhancing their cellular uptake, endosomal escape, and mRNA release functionalities. Consequently, PAPs facilitate up to 30,500-fold higher mRNA expression compared to their unmodified counterparts in vivo. Notably, the one-component PAPs enable spleen-specific mRNA delivery, with their vaccine application validated in a mouse melanoma model following intravenous administration. Better still, PAPs can synergize with different helper lipids to formulate four-component lipid nanoparticles (LNPs), achieving respective lung- and liver-specific mRNA delivery. Noteworthy is that these organ-selective mRNA delivery systems significantly outperform previous polymer and LNP benchmarks. This transformation strategy for cationic polymers represents a generalized methodology to give highly effective mRNA carriers, highlighting substantial potential for clinical translation of mRNA therapies with organ-targeting requirements.

Multicomponent thiolactone-based ionizable lipid screening platform for efficient and tunable mRNA delivery to the lungs

Ionizable lipids are essential components of lipid nanoparticles (LNPs) for efficient mRNA delivery. However, designing them for high protein expression, endosomal escape, and organ targeting is challenging due to complex structure-activity relationships. Here, we present a high-throughput platform for screening ionizable lipids using a two-step, scalable, one-pot reaction. This enabled the synthesis and vivo screening of 91 new lipids, followed by a structure-activity study, leading to the development of CP-LC-0729, which significantly surpasses the MC3 benchmark in protein expression with preliminary studies showing no in vivo toxicity. Additionally, a one-step strategy helped to yield a permanently cationic lipid which was tested in a fifth-lipid formulation, showing a highly selective lung delivery with a 32-fold increase in protein expression in vivo, outperforming current endogenous targeting strategies. All these findings underscore the potential of lipid CP-LC-0729 and our lipid platform in advancing the efficiency and specificity of mRNA delivery systems.

Click Lipid Nanoparticles for the Delivery of mRNA to Metabolically Labeled Cancer Cells

Lipid nanoparticle (LNP)-based mRNA delivery has a lot of potential in combating a wide range of diseases, but delivering mRNA to specific cell types continues to be challenging. Despite recent advances in organ and cell specificity, the majority of clinical LNP systems cannot fully release their payload to a targeted site. Incorporating active targeting moieties into LNPs is highly desired to expand nanomedicine applications. In this Letter, we developed LNPs that harness the power of bioorthogonal "click" azide-alkyne chemical reactions. We show that the plasma membranes of cancer cells can be labeled with azide groups by metabolic sugar labeling, and these azide groups can react with dibenzocyclooctyne (DBCO) on LNPs to achieve specific binding. To achieve this, we synthesized new and versatile lipids by functionalizing DBCO groups to phospholipids with or without a poly(ethylene glycol) (PEG) linker. The DBCO lipids were successfully formulated into DBCO-LNPs comprising other standard lipid compounds. When using these DBCO-LNPs to deliver mRNA to metabolically labeled cells, DBCO-LNPs showed a remarkable ability to preferentially deliver mRNA to azide-labeled cells. Removing PEG linkers from DBCO lipids enables better integration and retention in the LNP, and the higher the amount of DBCO lipid, the stronger the targeting effect. This work demonstrates that cell-specific targeting can be achieved utilizing azide-alkyne ″click″ chemistry and could inspire the development of the next generation of LNPs for active cyto-tropic nanomedicines.

Receptor-ligand interactions for optimized endocytosis in targeted therapies

Receptor-mediated endocytosis plays a crucial role in the success of numerous therapies and remains central to advancing drug development. This process begins with ligand binding to specific receptors, triggering the internalization and intracellular trafficking of receptor-ligand complexes. These complexes are subsequently directed into distinct routes, either toward lysosomal degradation or recycling to the cell surface, with implications for therapeutic outcomes. This review examines receptor-ligand interactions as key modulators of endocytosis, emphasizing their role in shaping therapeutic design and efficacy. Advances in selecting receptor-ligand pairs and engineering ligands with optimized properties have enabled precise control over internalization, endosomal sorting, and trafficking, providing tailored solutions for diverse therapeutic applications. Leveraging these insights, strategies such as RNA-based therapies, antibody-drug conjugates (ADCs), and targeted protein degradation (TPD) platforms have been refined to selectively avoid or promote lysosomal degradation, thereby enhancing therapeutic efficacy. By bridging fundamental mechanisms of receptor-mediated endocytosis with innovative therapeutic approaches, this review offers a framework for advancing precision medicine.

Predictive Lung- and Spleen-Targeted mRNA Delivery with Biodegradable Ionizable Lipids in Four-Component LNPs

Background/Objectives: Lipid nanoparticles (LNPs) are leading mRNA delivery vehicles, with ionizable lipids (ILs) as their key component. However, the relationship between the IL structure and LNP endogenous organ-targeting is not well understood. In this study, we developed a novel library of biodegradable ILs featuring beta-propionate linkers, which, when incorporated into a four-component LNP formulation, show excellent extrahepatic selectivity and high protein expression. Methods: We explored the impact of structural modifications in the hydrophobic chains and polar-head groups in the ILs while keeping the linkers unchanged. In vivo results were evaluated to examine how structural changes influence the biodistribution to spleen or lungs. LNP formulations were assessed for their protein expression levels and organ-specific targeting. Additionally, protein corona formation by the best-performing LNPs was examined to provide further mechanistic insights. Results: Organ targeting was significantly influenced by structural changes in the ILs, allowing for precise control of the biodistribution between the spleen and lungs. Branched hydrophobic chains demonstrated a higher propensity for spleen targeting, while modifications in the polar-head group could drastically shift biodistribution from the lung to the spleen. This led to the identification of LNPs' zeta potential as a key determinant of their extrahepatic targeting properties. Notably, ionizable lipid A3T2C7, also known as CP-LC-1495, displayed strong lung selectivity (97%) and high protein expression in lung tissue (1.21 × 108 p/s). Similarly, several promising candidates for spleen-targeting LNPs displayed protein expression levels exceeding 1 × 107 p/s (selectivity >80%). Conclusions: This study elucidates the structure-function relationships of ILs in passive organ-specific mRNA delivery, highlighting how the fine-tuning of hydrophobic chains, polar-head groups, and surface charge (zeta potential) allows for the precise control of LNP endogenous biodistribution, a mechanism influenced by protein corona formation. These findings enable the rational design of targeted LNP systems, enhancing their therapeutic potential for specific organs, such as the spleen and lungs.

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.

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.

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.

Direct Cytosolic Delivery of siRNA Conjugates: A Paradigm in Antiangiogenic Therapy for Choroidal Neovascularization

Small interfering RNA (siRNA) has garnered tremendous interest as a potential therapeutic tool because of its intriguing gene-silencing ability. Toward the success in the manufacture of siRNA therapeutics for the potential treatment of choroidal neovascularization (CNV), siRNA conjugated with dual functional units of membrane-penetrating heptafluoropropyl and age-related macular degeneration-targeting cyclic Arg-Gly-Asp (RGD) peptide was attempted for transcellular transportation into the cell interiors. Of note, cyclic RGD allowed selective affinities toward the angiogenic endothelial cells in the pathological CNV. Noteworthy is the functional heptafluoropropyl group, due to its tempting lipophobic and hydrophobic properties, stimulating energy-independent transcellular trafficking behaviors to the cytoplasm directly from the extracellular compartments, namely, the nonendocytotic pathway. The behaviors manage to avoid the well-acknowledged drawback of endolysosomal entrapment, which is deemed to be the critical threat to the biovulnerable genomic therapeutics, thereby contributing to potent gene knockdown at the affected cells. Aiming for treatment of CNV, the siRNA duo was schemed with appropriate chemistry-based modifications for the targeted knockdown of both angiogenic VEGF-A and VEGF-R2. Subsequent investigations verified the potent reduction of vascular leakage, and our proposed siRNA duo accomplished a significant reduction of 67.3% in the mean area of the CNV lesion. Bioinformatic analysis has unveiled a multitude of therapeutic benefits conferred by anti-VEGF therapy, extending beyond the mere inhibition of angiogenesis, including the regulated leukocyte transendothelial migration, retinol metabolism, and estrogen signaling pathways. Hence, our proposed chemistry represents an interesting siRNA conjugate strategy accomplishing direct intracellular transportation of macromolecular biological payloads to the cytosol. Hence, this proposed fluorination strategy should be highlighted to encourage the development of appropriate prodrug chemistry in pursuit of transcellular trafficking of membrane-impermissible and biovulnerable biotherapeutics.

Advancing Natural Killer Cell Therapy: Genetic Engineering Strategies for Enhanced Cancer Immunotherapy

Natural killer (NK) cells are pivotal innate immune system components that exhibit spontaneous cytolytic activity against abnormal cells, such as infected and tumor cells. NK cells have shown significant promise in adoptive cell therapy because of their favorable safety profiles and minimal toxicity in clinical settings. Despite their advantages, the therapeutic application of unmodified NK cells faces challenges, including limited in vivo persistence, particularly in the immunosuppressive tumor microenvironment. Recent advances in genetic engineering have enhanced the therapeutic potential of NK cells by addressing these limitations and improving their therapeutic efficacy. In this review, we have described various methodologies for the genetic modification of NK cells, including viral vectors, electroporation, and nanoparticle-based approaches. The ongoing research on nanomaterialbased approaches highlights their potential to overcome current limitations in NK cell therapy, paving the way for advanced cancer therapy and improved clinical outcomes. In this review, we also emphasize the potential of engineered NK cells in cancer immunotherapy and other clinical applications, highlighting the expanding scope of NK cell-based treatments and the critical role of innovative genetic engineering techniques.

Zwitterionic lipid nanoparticles for efficient siRNA delivery and hypercholesterolemia therapy with rational charge self-transformation

Rationale: Effective delivery of small interfering RNA (siRNA) remains a significant challenge in treating hypercholesterolemia due to biocompatibility, cellular uptake, and endosomal escape issues. Rational regulation of carrier surface charge contributes to efficient siRNA delivery in vivo. Methods: This study introduces zwitterionic lipid nanoparticles (ZwiLNPs) as a novel solution to these challenges. By leveraging the unique properties of zwitterionic polymers, we achieved robust siRNA encapsulation and targeted delivery. The design of ZwiLNPs facilitates charge self-transformation in response to physiological conditions, which enhances their biocompatibility and cellular uptake efficiency. Result: In vivo studies demonstrated significant liver-targeting capabilities of ZwiLNPs, with improved endosomal escape following cellular internalization. Comparative analyses confirmed that ZwiLNPs outperform conventional lipid nanoparticles in terms of both cellular uptake and endosomal release. Conclusion: These findings position ZwiLNPs as a promising platform for RNA interference therapies, particularly for hypercholesterolemia and other lipid-related disorders.

Intracellular trafficking of lipid nanoparticles is hindered by cholesterol

The intracellular trafficking of lipid nanoparticles (LNPs) leading to endosomal escape is critical for delivery efficiency. How components of LNP affect its intracellular trafficking and delivery efficiency remains unknown. Here, we developed a highly sensitive LNP/nucleic acid tracking platform based on streptavidin-biotin-DNA complex and high throughput imaging. Naked nucleic acids were found to be retained in the endocytotic vesicles proportional to endocytosis activity. With the help of LNP, nucleic acids were transported along the endolysosomal pathway with N/P ratio as low as 2 amongst very weak nucleic acid and LNP interaction. As the N/P ratio increases (concomitant concentration increase of all lipids), the monophasic endocytosis of LNP-DNA demonstrated biphasic characteristics, as shown by accumulation of LNP-DNA trapped in early endosomes in the peripheral of cells. Through a series of specifically designed LNPs, we found increase in N/P ratio alone, i.e. increase of ionizable lipid content, had no effect on the formation of peripheral LNP-endosomes. Importantly, increase in cholesterol content, via dose or concentration increase, positively correlated with formation and aggregation of peripheral LNP-endosomes. Meanwhile, helper lipid such as DSPC alleviated the detrimental effect of cholesterol on aggregation of peripheral LNP-endosomes. The trapping of LNP-nucleic acids in peripheral early endosomes hindered their intracellular trafficking along the endolysosomal pathway, thus reducing their reach to releasing compartments and diminishing cargo delivery efficiency. Our results demonstrate that high cholesterol content hinders LNP intracellular trafficking, which is detrimental for intracellular delivery of cargo.

Translational nanorobotics breaking through biological membranes

In the dynamic realm of translational nanorobotics, the endeavor to develop nanorobots carrying therapeutics in rational in vivo applications necessitates a profound understanding of the biological landscape of the human body and its complexity. Within this landscape, biological membranes stand as critical barriers to the successful delivery of therapeutic cargo to the target site. Their crossing is not only a challenge for nanorobotics but also a pivotal criterion for the clinical success of therapeutic-carrying nanorobots. Nevertheless, despite their urgency, strategies for membrane crossing in translational nanorobotics remain relatively underrepresented in the scientific literature, signaling an opportunity for further research and innovation. This review focuses on nanorobots with various propulsion mechanisms from chemical and physical to hybrid mechanisms, and it identifies and describes four essential biological membranes that represent the barriers needed to be crossed in the therapeutic journey of nanorobots in in vivo applications. First is the entry point into the blood stream, which is the skin or mucosa or intravenous injection; next is the exit from the bloodstream across the endothelium to the target site; further is the entry to the cell through the plasma membrane and, finally, the escape from the lysosome, which otherwise destroys the cargo. The review also discusses design challenges inherent in translating nanorobot technologies to real-world applications and provides a critical overview of documented membrane crossings. The aim is to underscore the need for further interdisciplinary collaborations between chemists, materials scientists and chemical biologists in this vital domain of translational nanorobotics that has the potential to revolutionize the field of precision medicine.

Multi-stage-mixing to control the supramolecular structure of lipid nanoparticles, thereby creating a core-then-shell arrangement that improves performance by orders of magnitude

As they became the dominant gene therapy platform, lipid nanoparticles (LNPs) experienced nearly all their innovation in varying the structure of individual molecules in LNPs. This ignored control of the spatial arrangement of molecules, which is suboptimal because supramolecular structure determines function in biology. To control LNPs' supramolecular structure, we introduce multi-stage-mixing (MSM) to successively add different molecules to LNPs. We first utilize MSM to create a core-then-shell (CTS) synthesis. CTS-LNPs display a clear core-shell structure, vastly lower frequency of LNPs containing no detectable mRNA, and improved mRNA-LNP expression. With DNA-loaded LNPs, which for decades lagged behind mRNA-LNPs due to low expression, CTS improved DNA-LNPs' protein expression by 2-3 orders of magnitude, bringing it within range of mRNA-LNPs. These results show that supramolecular arrangement is critical to LNP performance and can be controlled by mixing methodology. Further, MSM/CTS have finally made DNA-LNPs into a practical platform for long-term gene expression.

The use of nanocarriers in treating Batten disease: A systematic review

The neuronal ceroid lipofuscinoses, commonly known as Batten disease, are a group of lysosomal storage disorders affecting children. There is extensive central nervous system and retinal degeneration, resulting in seizures, vision loss and a progressive cognitive and motor decline. Enzyme replacement and gene therapies are being developed, and mRNA and oligonucleotide therapies are more recently being considered. Overcoming the challenges of the blood-brain barrier and blood-ocular barrier is crucial for effectively targeting the brain and eye, whatever the therapeutic approach. Nanoparticles and extracellular vesicles are small carriers that can encapsulate a cargo and pass through these cell barriers. They have been investigated as drug carriers for other pathologies and could be a promising treatment strategy for Batten disease. Their use in gene, enzyme, or mRNA replacement therapy of all lysosomal storage disorders, including Mucopolysaccharidoses, Niemann-Pick diseases, and Fabry disease, is investigated in this systematic review. Different nanocarriers can efficiently target the lysosome and cross the barriers into the brain and eyes. This supports continued exploration of nanocarriers as potential future treatment options for Batten disease.

Non-Invasive Delivery of CRISPR/Cas9 Ribonucleoproteins (Cas9 RNPs) into Cells via Nanoparticles for Membrane Transport

The clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system is a promising biotechnology tool for genome editing. However, in living organisms, several pharmacokinetic challenges arise, including off-target side effects due to incorrect distribution, low bioavailability caused by membrane impermeability, and instability resulting from enzymatic degradation. Therefore, innovative delivery strategies must be developed to address these issues. Modified nanoparticles offer a potential solution for the non-invasive delivery of CRISPR/Cas9 ribonucleoproteins (Cas9 RNPs). Cas9 RNPs encapsulated in nanoparticles are protected from enzymatic degradation, similar to how microRNAs are shielded within exosomes. It is well-established that certain materials, including proteins, are expressed selectively in specific cell types. For example, the α-7 nicotinic receptor is expressed in endothelial and neuronal cells, while the αvβ3 integrin is expressed in cancer cells. These endogenous materials can facilitate receptor-mediated endocytosis or transcytosis. Nanoparticles encapsulating Cas9 RNPs and coated with ligands targeting such receptors may be internalized through receptor-mediated mechanisms. Once internalized, Cas9 RNPs could perform the desired gene editing in the nucleus after escaping the endosome through mechanisms such as the proton sponge effect or membrane fusion. In this review, I discuss the potential and advantages of delivering Cas9 RNP-encapsulated nanoparticles coated with ligands through receptor-mediated endocytosis or transcytosis.

Loading of Extracellular Vesicles with Nucleic Acids via Hybridization with Non-Lamellar Liquid Crystalline Lipid Nanoparticles

The translation of cell-derived extracellular vesicles (EVs) into biogenic gene delivery systems is limited by relatively inefficient loading strategies. In this work, the loading of various nucleic acids into small EVs via their spontaneous hybridization with preloaded non-lamellar liquid crystalline lipid nanoparticles (LCNPs), forming hybrid EVs (HEVs) is described. It is demonstrated that LCNPs undergo pH-dependent structural transitions from inverse hexagonal (HII) phases at pH 5 to more disordered non-lamellar phases, possibly inverse micellar (L2) or sponge (L3) phases, at pH 7.4, which are particularly suitable for inducing a controlled hybridization process with EVs. State-of-the-art single-particle analysis techniques reveal that LCNPs interact with various EV subpopulations at physiological conditions and that ≈40% of HEVs are loaded with the genetic cargo. Importantly, this study demonstrates that EV membrane proteins remain accessible on HEV surfaces, with their intrinsic enzymatic activity unaffected after the hybridization process. Finally, HEVs show in vitro improved transfection efficiencies compared to unhybridized LCNPs. In summary, this versatile platform holds potential for loading various nucleic acid molecules into native EVs and may help developing EV-based therapeutics.

Topological and Morphological Membrane Dynamics in Giant Lipid Vesicles Driven by Monoolein Cubosomes

Lipid nanoparticles have important applications as biomedical delivery platforms and broader engineering biology applications in artificial cell technologies. These emerging technologies often require changes in the shape and topology of biological or biomimetic membranes. Here we show that topologically-active lyotropic liquid crystal nanoparticles (LCNPs) can trigger such transformations in the membranes of giant unilamellar vesicles (GUVs). Monoolein (MO) LCNPs, cubosomes with an internal nanostructure of space groupI m 3 m ${Im3m}$ incorporate into 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) GUVs creating excess membrane area with stored curvature stress. Using time-resolved fluorescence confocal and lattice light sheet microscopy, we observe and characterise various life-like dynamic events in these GUVs, including growth, division, tubulation, membrane budding and fusion. Our results shed new light on the interactions of LCNPs with bilayer lipid membranes, providing insights relevant to how these nanoparticles might interact with cellular membranes during drug delivery and highlighting their potential as minimal triggers of topological transitions in artificial cells.

Solution biophysics identifies lipid nanoparticle non-sphericity, polydispersity, and dependence on internal ordering for efficacious mRNA delivery

Lipid nanoparticles (LNPs) are the most advanced delivery system currently available for RNA therapeutics. Their development has accelerated since the success of Patisiran, the first siRNA-LNP therapeutic, and the mRNA vaccines that emerged during the COVID-19 pandemic. Designing LNPs with specific targeting, high potency, and minimal side effects is crucial for their successful clinical use. However, our understanding of how the composition and mixing method influences the structural, biophysical, and biological properties of the resulting LNPs remains limited, hindering the development of LNPs. Our lack of structural understanding extends from the physical and compositional polydispersity of LNPs, which render traditional characterization methods, such as dynamic light scattering (DLS), unable to accurately quantitate the physicochemical characteristics of LNPs. In this study, we address the challenge of structurally characterizing polydisperse LNP formulations using emerging solution-based biophysical methods that have higher resolution and provide biophysical data beyond size and polydispersity. These techniques include sedimentation velocity analytical ultracentrifugation (SV-AUC), field-flow fractionation followed by multi-angle light scattering (FFF-MALS), and size-exclusion chromatography in-line with synchrotron small-angle X-ray scattering (SEC-SAXS). Here, we show that the LNPs have intrinsic polydispersity in size, RNA loading, and shape, and that these parameters are dependent on both the formulation technique and lipid composition. Lastly, we demonstrate that these biophysical methods can be employed to predict transfection in human primary T cells, intravenous administration, and intramuscular administration by examining the relationship between mRNA translation and physicochemical characteristics. We envision that employing solution-based biophysical methods will be essential for determining LNP structure-function relationships, facilitating the creation of new design rules for LNPs.

Cell Membrane Fatty Acids and PIPs Modulate the Etiology of Pancreatic Cancer by Regulating AKT

Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the worst solid malignancies in regard to outcomes and metabolic dysfunction leading to cachexia. It is alarming that PDAC incidence rates continue to increase and warrant the need for innovative approaches to combat this disease. Due to its relatively slow progression (10-20 years), prevention strategies represent an effective means to improve outcomes. One of the risk factors for many cancers and for pancreatic cancer in particular is diet. Hence, our objective is to understand how a diet rich in ω3 and ω6 polyunsaturated fatty acids affects the progression of this disease. Methods: We investigated polyunsaturated fatty acid (PUFA) effects on disease progression employing both in vitro (PDAC cell lines) and in vivo (EL-Kras and KC mice) approaches. Also, we gathered data from the National Health and Nutrition Examination Survey (NHANES) and the National Cancer Institute (NCI) from 1999 to 2017 for a retrospective observational study. Results: The consumption of PUFAs in a patient population correlates with increased PDAC incidence, particularly when the ω3 intake increases to a lesser extent than ω6. Our data demonstrate dietary PUFAs can be incorporated into plasma membrane lipids affecting PI3K/AKT signaling and support the emergence of membrane-targeted therapies. Moreover, we show that the phospholipid composition of a lipid nanoparticle (LNP) can impact the cell membrane integrity and, ultimately, cell viability after administration of these LNPs. Conclusions: Cancer prevention is impactful particularly for those with very poor prognosis, including pancreatic cancer. Our results point to the importance of dietary intervention in this disease when detected early and the potential to improve the antiproliferative effect of drug efficacy when combined with these regimens in later stages of pancreatic cancer.

Development of a Cationic Polymeric Micellar Structure with Endosomal Escape Capability Enables Enhanced Intramuscular Transfection of mRNA-LNPs

Background/Objectives: The endosomal escape of lipid nanoparticles (LNPs) is crucial for efficient mRNA-based therapeutics. Here, we present a cationic polymeric micelle (cPM) as a safe and potent co-delivery system with enhanced endosomal escape capabilities. Methods: We synthesized a cationic and ampholytic di-block copolymer, poly (poly (ethylene glycol)4-5 methacrylatea-co-hexyl methacrylateb)X-b-poly(butyl methacrylatec-co-dimethylaminoethyl methacrylated-co-propyl acrylatee)Y (p(PEG4-5MAa-co-HMAb)X-b-p(BMAc-co-DMAEMAd-co-PAAe)Y), via reversible addition-fragmentation chain transfer polymerization. The cPMs were then formulated using the synthesized polymer by the dispersion-diffusion method and characterized by dynamic light scattering (DLS) and cryo-transmission electron microscopy (CryoTEM). The membrane-destabilization activity of the cPMs was evaluated by a hemolysis assay. We performed an in vivo functional assay of firefly luciferase (Fluc) mRNA using two of the most commonly studied LNPs, SM102 LNP and Dlin-MC3-DMA LNPs. Results: With a particle size of 61.31 ± 0.68 nm and a zeta potential of 37.76 ± 2.18 mV, the cPMs exhibited a 2-3 times higher firefly luciferase signal at the injection site compared to the control groups without cPMs following intramuscular injection in mice, indicating the high potential of cPMs to enhance the endosomal escape efficiency of mRNA-LNPs. Conclusions: The developed cPM, with enhanced endosomal escape capabilities, presents a promising strategy to improve the expression efficiency of delivered mRNAs. This approach offers a novel alternative strategy with no modifications to the inherent properties of mRNA-LNPs, preventing any unforeseeable changes in formulation characteristics. Consequently, this polymer-based nanomaterial holds immense potential for clinical applications in mRNA-based vaccines.

Isosteric 3D Bicyclo[1.1.1]Pentane (BCP) Core-Based Lipids for mRNA Delivery and CRISPR/Cas Gene Editing

Lipid nanoparticles (LNPs) are an essential component of messenger RNA (mRNA) vaccines and genome editing therapeutics. Ionizable amino lipids, which play the most crucial role in enabling mRNA to overcome delivery barriers, have, to date, been restricted to two-dimensional (2D) architectures. Inspired by improved physicochemical properties resulting from the incorporation of three-dimensionality (3D) into small-molecule drugs, we report the creation of 3D ionizable lipid designs through the introduction of bicyclo[1.1.1]pentane (BCP) core motifs. BCP-based lipids enabled efficient in vivo mRNA delivery to the liver and spleen with significantly greater performance over 2D benzene- and cyclohexane-based analogues. Notably, lead BCP-NC2-C12 LNPs mediated ∼90% reduction in the PCSK9 serum protein level via CRISPR/Cas9 gene knockout, outperforming 2D controls and clinically used DLin-MC3-DMA LNPs at the same dose. Here, we introduce BCP-based designs with superior in vivo activity, thereby expanding the chemical scope of ionizable amino lipids from 2D to 3D and offering a promising avenue to improve mRNA and gene editing efficiency for the continued development of genetic medicines.

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.

A perspective of lipid nanoparticles for RNA delivery

Over the last two decades, lipid nanoparticles (LNPs) have evolved as an effective biocompatible and biodegradable RNA delivery platform in the fields of nanomedicine, biotechnology, and drug delivery. They are novel bionanomaterials that can be used to encapsulate a wide range of biomolecules, such as mRNA, as demonstrated by the current successes of COVID-19 mRNA vaccines. Therefore, it is important to provide a perspective on LNPs for RNA delivery, which further offers useful guidance for researchers who want to work in the RNA-based LNP field. This perspective first summarizes the approaches for the preparation of LNPs, followed by the introduction of the key characterization parameters. Then, the in vitro cell experiments to study LNP performance, including cell selection, cell viability, cellular association/uptake, endosomal escape, and their efficacy, were summarized. Finally, the in vivo animal experiments in the aspects of animal selection, administration, dosing and safety, and their therapeutic efficacy were discussed. The authors hope this perspective can offer valuable guidance to researchers who enter the field of RNA-based LNPs and help them understand the crucial parameters that RNA-based LNPs demand.

Latest developments in biomaterial interfaces and drug delivery: challenges, innovations, and future outlook

An ideal drug carrier system should demonstrate optimal payload and release characteristics, thereby ensuring prolonged therapeutic index while minimizing adverse effects. The field of drug delivery has undergone significant advancements, particularly within the last two decades, owing to the revolutionary impact of biomaterials. The use of biomaterials presents significant due to their biocompatibility and biodegradability, which must be addressed in order to achieve effective drug delivery. The properties of the biomaterial and its interface are primarily influenced by their physicochemical attributes, physiological barriers, cellular trafficking, and immunomodulatory effects. By attuning these barriers, regulating the physicochemical properties, and masking the immune system's response, the bio interface can be effectively modulated, leading to the development of innovative supramolecular structures with enhanced effectiveness. With a comprehensive understanding of these technologies, there is a growing demand for repurposing existing drugs for new therapeutic indications within this space. This review aims to provide a substantial body of evidence showcasing the productiveness of biomaterials and their interface in drug delivery, as well as methods for mitigating and modulating barriers and physicochemical properties along with an examination of future prospects in this field.

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.

Stable and inhalable powder formulation of mRNA-LNPs using pH-modified spray-freeze drying

A powder formulation for mucosal administration of mRNA-encapsulated lipid nanoparticles (mRNA-LNPs) is expected to be useful for respiratory diseases. Although freeze-drying is widely used to obtain solid formulations of mRNA-LNPs, highly hydrosoluble cryoprotectants, such as sucrose are necessary. However, sucrose is not a suitable excipient for inhalation powders because of its hygroscopic and deliquescence properties. Spray freeze-drying (SFD) is a method to produce inhalable powder formulation. In this study, we prepared inhalable powder formulations of mRNA-LNPs without deliquescence excipients using pH-modified SFD, which strengthens the interaction between mRNA and ionizable lipids of LNPs by acidic pH modifier, leading to retention of the encapsulated structure of mRNA-LNPs even after SFD. Powdered mRNA-LNPs were suitable for inhalation, and mRNA was encapsulated in LNPs after SFD. The mRNA encapsulation efficiency and mRNA transfection efficiency of pH-modified SFD-mediated powdered mRNA-LNPs were higher than those of conventional SFD, although they were significantly lower than those of liquid intact mRNA-LNPs. However, after long-term storage, the powdered formulation of the mRNA-LNPs exhibited higher mRNA transfection efficiency than liquid mRNA-LNP. Powdered mRNA-LNPs also exerted their function in air-liquid interface cultivation and in vivo intratracheal administration. Collectively, the powder formulation of mRNA-LNPs especially prepared by SFD is expected to be applied for dry powder inhalers.

The interaction of a self-assembled nanoparticle and a lipid membrane: Binding, disassembly and re-distribution

Here we report a detailed study of the interactions of nanoparticles, formed by the self-assembly of cholesterol-containing porphyrins, with lipid membranes. We show that the interaction is a two-step process: first, the docking and fusion, then, the redistribution of the building blocks of the self-assembled nanoparticles (SANs henceforth). Analysis of the binding and structural data is consistent with the docking step being driven by a multivalence cooperative effect and with the formation of SAN aggregates on the membrane, whilst the solubility of the cholesterol anchor in the membrane is key to both the fusion and redistribution of the SANs building blocks. The tendency of the SAN to aggregate in the membrane helps explain the photosensitizer properties of the SANs, essential to their anti-microbial activity. The solubility of the cholesteryl anchors drives fusion to the membrane and de-assembly of the SAN, explaining the capability of the SANs to deliver therapeutic cargos at the lipid interface. The subsequent redistribution of the SANs building blocks offer a plausible pathway to body clearance that is not immediately available to hard nanoparticles. These properties, and the modularity of the synthesis, point to the SANs being an excellent platform for the development of nanomedicines. An unexpected consequence of unraveling the mechanism of membrane interaction of these SANs is that it allows us to derive a value of the free energy of binding of cholesterol (the membrane anchor of the SAN building blocks) to a lipid membrane, that is consistent with the literature values. This is an additional property that can be exploited to determine the affinity of a variety of membrane anchors to membranes of various compositions.

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.

Enhanced Cellular Immunity for Hepatitis B Virus Vaccine: A Novel Polyinosinic-Polycytidylic Acid-Incorporated Adjuvant Leveraging Cytoplasmic Retinoic Acid-Inducible Gene-Like Receptor Activation and Increased Antigen Uptake

Conventional aluminum adjuvants exhibit limited cellular immunity. Polyinosinic-polycytidylic acid (poly I:C) activates cytoplasmic retinoic acid-inducible gene-like receptor (RLR), triggering strong T cell activation and cellular responses. However, when applied as an adjuvant, its limited endocytosis and restricted cytoplasmic delivery diminish its effectiveness and increase its toxicity. Hybrid polymer-lipid nanoparticle (PLNP) possesses numerous benefits such as good stability, reduced drug leakage, simple fabrication, easy property modulation, and excellent reproducibility compared to the lipid nanoparticle or the polymeric vector. Here, we developed a novel cationic polymer-lipid hybrid adjuvant capable of incorporating poly I:C to enhance cellular immunity. The hepatitis B surface antigen (HBsAg) was immobilized onto poly I:C-incorprated PLNP (PPLNP) via electrostatic interactions, forming the HBsAg/PPLNP vaccine formulation. The PPLNP adjuvant largely enhanced the cellular endocytosis and cytoplasmic transport of poly I:C, activating RLR followed by promoting type I interferon (IFN) secretion. Meanwhile, PPLNP obviously enhanced the antigen uptake, prolonged antigen retention at the site of administration, and facilitated enhanced transport of antigens to lymph nodes. The HBsAg/PPLNP nanovaccine led to amplified concentrations of antigen-specific immunoglobulin G (IgG), IFN-γ, granzyme B, and an enhanced IgG2a/IgG1 ratio, alongside the FasL+/CD8+ T cell activation, favoring a T helper 1 (TH1)-driven immune response. PPLNP, distinguished by its biocompatibility, ease of fabrication, and effectiveness in augmenting cellular immunity, holds significant promise as a new adjuvant.

Paracyclophane-based ionizable lipids for efficient mRNA delivery in vivo

mRNA therapeutics utilizing lipid nanoparticle (LNP) delivery technology represent a medical innovation for the treatment of various diseases. Amine-derived ionizable cationic lipids have been regarded as the pivotal component of LNPs, which often utilize commercially available small amine molecules as their cores. Given that even minor changes in the structure of ionizable lipids can result in significant differences in the delivery performance, there is a growing need to redesign the lipid amine-cores to optimize mRNA therapy. Here, we rationally design and synthesize a library of 198 paracyclophane-based ionizable lipids (PILs), which are then formulated into LNPs for mRNA delivery in vitro and in vivo. The resulting PIL LNPs display favorable characteristics, including appropriate particle sizes, zeta potentials, mRNA binding capability, efficacious endosomal escape, and robust mRNA delivery in vitro. Tailoring the PIL structures further enables mRNA expression specifically in the liver or simultaneously across multi-organs in vivo. Notably, the optimized PIL LNPs demonstrate superior efficacy compared to the U.S. Food and Drug Administration (FDA) approved DLin-MC3-DMA LNPs following intravenous administration. Additionally, when administered intramuscularly, our PIL LNPs exhibit higher efficacy than the SM-102 and ALC-0315 LNPs that are employed in the coronavirus disease 2019 (COVID-19) mRNA vaccines. These findings demonstrate the potential of paracyclophane-based ionizable lipids in advancing mRNA therapeutics, particularly for liver-targeted drugs and vaccines.

Engineered zwitterionic diblock copolymer-siRNA polyplexes provide highly effective treatment of triple-negative breast cancer in a 4T1 murine model

Self-assembly of siRNA with a block copolymer featuring guanidinium and zwitterion functionalized blocks generates core-shell-like nanovectors that provide cytosolic access to siRNA and efficiently evade phagocytic clearance. The guanidinium-functionalized inner block complexes siRNA in the nanovector interior and enables cytosolic delivery. The zwitterionic outer block provides a non-interacting shell on the nanovectors that reduces macrophage uptake in vitro and phagocytic clearance and enhances tumor localization in vivo. These nanovectors were used to treat a 4T1 (murine) model of triple-negative breast cancer (TNBC). The nanovectors deliver siRNA efficiently to 4T1 triple-negative breast cancer cells in vitro, with high selectivity relative to macrophages. This efficiency and selectivity translate into in vivo efficacy: diblock nanovectors evaded phagocytic clearance and efficiently localized in an aggressive murine 4T1 orthotopic model, with a ~3-fold increase of vector residing in the tumor compared to the homopolymer nanovectors. This increased localization efficiently knocked down STAT3 (~80%) and provided tumorostasis (100% growth inhibition) at a low dose of 0.14 mg/kg. The in vitro and in vivo efficacy of these nanovectors demonstrate the potential of engineered polymer architectures to generate effective self-assembled siRNA therapeutics that avoid phagocytic clearance for the treatment of diseases requiring systemic administration.

Recent Advances in Lipid Nanoparticles and Their Safety Concerns for mRNA Delivery

INTRODUCTION

The advent of lipid nanoparticles (LNPs) as a delivery platform for mRNA therapeutics has revolutionized the biomedical field, particularly in treating infectious diseases, cancer, genetic disorders, and metabolic diseases. Recent Advances in Therapeutic LNPs: LNPs, composed of ionizable lipids, phospholipids, cholesterol, and polyethylene glycol (PEG) lipids, facilitate efficient cellular uptake and cytosolic release of mRNA while mitigating degradation by nucleases. However, as synthetic entities, LNPs face challenges that alter their therapeutic efficacy and safety concerns. Toxicity/Reactogenicity/Immunogenicity: This review provides a comprehensive overview of the latest advancements in LNP research, focusing on preclinical safety assessments encompassing toxicity, reactogenicity, and immunogenicity. Summary and Outlook: Additionally, it outlines potential strategies for addressing these challenges and offers insights into future research directions for enhancing the application of LNPs in mRNA therapeutics.

Lipid nanoparticles-based RNA therapies for breast cancer treatment

Breast cancer (BC) prevails as a major burden on global healthcare, being the most prevalent form of cancer among women. BC is a complex and heterogeneous disease, and current therapies, such as chemotherapy and radiotherapy, frequently fall short in providing effective solutions. These treatments fail to mitigate the risk of cancer recurrence and cause severe side effects that, in turn, compromise therapeutic responses in patients. Over the last decade, several strategies have been proposed to overcome these limitations. Among them, RNA-based technologies have demonstrated their potential across various clinical applications, notably in cancer therapy. However, RNA therapies are still limited by a series of critical issues like off-target effect and poor stability in circulation. Thus, novel approaches have been investigated to improve the targeting and bioavailability of RNA-based formulations to achieve an appropriate therapeutic outcome. Lipid nanoparticles (LNPs) have been largely proven to be an advantageous carrier for nucleic acids and RNA. This perspective explores the most recent advances on RNA-based technology with an emphasis on LNPs' utilization as effective nanocarriers in BC therapy and most recent progresses in their clinical applications.

Advances in the design and delivery of RNA vaccines for infectious diseases

RNA medicines represent a paradigm shift in treatment and prevention of critical diseases of global significance, e.g., infectious diseases. The highly successful messenger RNA (mRNA) vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were developed at record speed during the coronavirus disease 2019 pandemic. A consequence of this is exceptionally shortened vaccine development times, which in combination with adaptability makes the RNA vaccine technology highly attractive against infectious diseases and for pandemic preparedness. Here, we review state of the art in the design and delivery of RNA vaccines for infectious diseases based on different RNA modalities, including linear mRNA, self-amplifying RNA, trans-amplifying RNA, and circular RNA. We provide an overview of the clinical pipeline of RNA vaccines for infectious diseases, and present analytical procedures, which are paramount for characterizing quality attributes and guaranteeing their quality, and we discuss future perspectives for using RNA vaccines to combat pathogens beyond SARS-CoV-2.

Fabrication of mRNA encapsulated lipid nanoparticles using state of the art SMART-MaGIC technology and transfection in vitro

The messenger ribose nucleic acid (mRNA) in the form of Corona virus of 2019 (COVID-19) vaccines were effectively delivered through lipid nanoparticles (LNP) proving its use as effective carriers in clinical applications. In the present work, mRNA (erythropoietin (EPO)) encapsulated LNPs were prepared using a next generation state-of-the-art patented, Sprayed Multi Absorbed-droplet Reposing Technology (SMART) coupled with Multi-channeled and Guided Inner-Controlling printheads (MaGIC) technologies. The LNP-mRNA were synthesized at different N/P ratios and the particles were characterized for particle size and zeta potential (Zetasizer), encapsulation or complexation (gel retardation assay) and transfection (Fluorescence microscopy and ELISA) in MG63 sarcoma cells in vitro. The results showed a narrow distribution of mRNA-lipid particles of 200 nm when fabricated with SMART alone and then the size was reduced to approximately 50 nm with the combination of SMART-MaGIC technologies. The gel retardation assay showed that the N/P > 1 exhibited strong encapsulation of mRNA with lipid. The in vitro results showed the toxicity profile of the lipids where N/P ratio of 5 was optimized with > 50% cell viability. It can be concluded that the functional LNP-mRNA prepared and analyzed with SMART-MaGIC technologies, could be a potential new fabrication method of mRNA loaded LNPs for point-of-service or distributed manufacturing.

Development of an Elastin-like Polypeptide-Based Nucleic Acid Delivery System Targeted to EGFR+ Bladder Cancer Cells Using a Layer-by-Layer Approach

Nucleic acid (NA)-based therapies are revolutionizing biomedical research through their ability to control cellular functions at the genetic level. This work demonstrates a versatile elastin-like polypeptide (ELP) carrier system using a layer-by-layer (LbL) formulation approach that delivers NA cargos ranging in size from siRNA to plasmids. The components of the system can be reconfigured to modulate the biochemical and biophysical characteristics of the carrier for engaging the unique features of the biological target. We show the physical characterization and biological performance of LbL ELP nucleic acid nanoparticles (LENNs) in murine and human bladder tumor cell lines. Targeting bladder tumors is difficult owing to the constant influx of urine into the bladder, leading to low contact times (typically <2 h) for therapeutic agents delivered via intravesical instillation. LENN complexes bind to bladder tumor cells within 30 min and become rapidly internalized to release their NA cargo within 60 min. Our data show that a readily adaptable NA-delivery system has been created that is flexible in its targeting ability, cargo size, and disassembly kinetics. This approach provides an alternative path to either lipid nanoparticle formulations that suffer from inefficiency and physicochemical instability or viral vectors that are plagued by manufacturing and immune rejection challenges. This agile ELP-based nanocarrier provides an alternative route for nucleic acid delivery using a biomanufacturable, biodegradable, biocompatible, and highly tunable vehicle capable of targeting cells via engagement with overexpressed cell surface receptors.

Inhalable mRNA Nanoparticle with Enhanced Nebulization Stability and Pulmonary Microenvironment Infiltration

The delivery of mRNA into the lungs is the key to solving infectious and intractable diseases that frequently occur in the lungs. Since inhalation using a nebulizer is the most promising method for mRNA delivery into the lungs, there have been many attempts toward adapting lipid nanoparticles for mRNA inhalation. However, conventional lipid nanoparticles, which have shown great effectiveness for systemic delivery of mRNA and intramuscular vaccination, are not effective for pulmonary delivery due to their structural instability during nebulization and their inability to adapt to the pulmonary microenvironment. To address these issues, we developed an ionizable liposome-mRNA lipocomplex (iLPX). iLPX has a highly ordered lipid bilayer structure, which increases stability during nebulization, and its poly(ethylene glycol)-free composition allows it to infiltrate the low serum environment and the pulmonary surfactant layer in the lungs. We selected an inhalation-optimized iLPX (IH-iLPX) using a multistep screening procedure that mimics the pulmonary delivery process of inhaled nanoparticles. The IH-iLPX showed a higher transfection efficiency in the lungs compared to conventional lipid nanoparticles after inhalation with no observed toxicity in vivo. Furthermore, analysis of lung distribution revealed even protein expression in the deep lungs, with effective delivery to epithelial cells. This study provides insights into the challenges and solutions related to the development of inhaled mRNA pulmonary therapeutics.

Recent Advances in RNA Interference-Based Therapy for Hepatocellular Carcinoma: Emphasis on siRNA

Even though RNA treatments were first proposed as a way to change aberrant signaling in cancer, research in this field is currently ongoing. The term "RNAi" refers to the use of several RNAi technologies, including ribozymes, riboswitches, Aptamers, small interfering RNA (siRNA), antisense oligonucleotides (ASOs), and CRISPR/Cas9 technology. The siRNA therapy has already achieved a remarkable feat by revolutionizing the treatment arena of cancers. Unlike small molecules and antibodies, which need administration every three months or even every two years, RNAi may be given every quarter to attain therapeutic results. In order to overcome complex challenges, delivering siRNAs to the targeted tissues and cells effectively and safely and improving the effectiveness of siRNAs in terms of their action, stability, specificity, and potential adverse consequences are required. In this context, the three primary techniques of siRNA therapies for hepatocellular carcinoma (HCC) are accomplished for inhibiting angiogenesis, decreasing cell proliferation, and promoting apoptosis, are discussed in this review. We also deliberate targeting issues, immunogenic reactions to siRNA therapy, and the difficulties with their intrinsic chemistry and transportation.

Preformed Vesicle Approach to LNP Manufacturing Enhances Retinal mRNA Delivery

Complete encapsulation of nucleic acids by lipid-based nanoparticles (LNPs) is often thought to be one of the main prerequisites for successful nucleic acid delivery, as the lipid environment protects mRNA from degradation by external nucleases and assists in initiating delivery processes. However, delivery of mRNA via a preformed vesicle approach (PFV-LNPs) defies this precondition. Unlike traditional LNPs, PFV-LNPs are formed via a solvent-free mixing process, leading to a superficial mRNA localization. While demonstrating low encapsulation efficiency in the RiboGreen assay, PFV-LNPs improved delivery of mRNA to the retina by up to 50% compared to the LNP analogs across several benchmark formulations, suggesting the utility of this approach regardless of the lipid composition. Successful mRNA and gene editors' delivery is observed in the retinal pigment epithelium and photoreceptors and validated in mice, non-human primates, and human retinal organoids. Deploying PFV-LNPs in gene editing experiments result in a similar extent of gene editing compared to analogous LNP (up to 3% on genomic level) in the Ai9 reporter mouse model; but, remarkably, retinal tolerability is significantly improved for PFV-LNP treatment. The study findings indicate that the LNP formulation process can greatly influence mRNA transfection and gene editing outcomes, improving LNP treatment safety without sacrificing efficacy.

Physicochemical and structural insights into lyophilized mRNA-LNP from lyoprotectant and buffer screenings

The surge in RNA therapeutics has revolutionized treatments for infectious diseases like COVID-19 and shows the potential to expand into other therapeutic areas. However, the typical requirement for ultra-cold storage of mRNA-LNP formulations poses significant logistical challenges for global distribution. Lyophilization serves as a potential strategy to extend mRNA-LNP stability while eliminating the need for ultra-cold supply chain logistics. Although recent advancements have demonstrated the promise of lyophilization, the choice of lyoprotectant is predominately focused on sucrose, and there remains a gap in comprehensive evaluation and comparison of lyoprotectants and buffers. Here, we aim to systematically investigate the impact of a diverse range of excipients including oligosaccharides, polymers, amino acids, and various buffers, on the quality and performance of lyophilized mRNA-LNPs. From the screening of 45 mRNA-LNP formulations under various lyoprotectant and buffer conditions for lyophilization, we identified previously unexplored formulation compositions, e.g., polyvinylpyrrolidone (PVP) in Tris or acetate buffers, as promising alternatives to the commonly used oligosaccharides to maintain the physicochemical stability of lyophilized mRNA-LNPs. Further, we delved into how physicochemical and structural properties influence the functionality of lyophilized mRNA-LNPs. Leveraging high-throughput small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM), we showed that there is complex interplay between mRNA-LNP structural features and cellular translation efficacy. We also assessed innate immune responses of the screened mRNA-LNPs in human peripheral blood mononuclear cells (PBMCs), and showed minimal alterations of cytokine secretion profiles induced by lyophilized formulations. Our results provide valuable insights into the structure-activity relationship of lyophilized formulations of mRNA-LNP therapeutics, paving the way for rational design of these formulations. This work creates a foundation for a comprehensive understanding of mRNA-LNP properties and in vitro performance change resulting from lyophilization.