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

Effects of Histidine Oligomers in Lipid Nanoparticles on siRNA Delivery

In this study, histidine oligomer (oHis; 10mer)-incorporating LNPs (H10LNPs) are developed as a novel carrier for efficient siRNA delivery. Notably, the unmodified oHis (10mer) is greatly incorporated within LNPs through ionic interaction with siRNAs, which serves as an endosome escape enhancer. H10LNPs with a size of ≈65 nm demonstrate a significantly enhanced extent of endosomal escape, as evidenced by calcein assay and confocal microscopy images of intracellular fluorescence, surpassing conventional LNPs. Furthermore, the half inhibitory concentration (IC50) of the human endogenous globotriaosylceramide synthase (Gb3 synthase) gene in H10LNPs-treated cells exhibits a significant threefold decrease, compared to that in LNP-treated cells. Notably, H10LNPs maintain comparable biocompatibility and biodistribution both in vitro and in vivo. Considering that the fabricated siRNA H10LNPs exhibit excellent biocompatibility and superior gene silencing activity over conventional LNPs, these particles can be harnessed for the safe delivery of therapeutic siRNAs. Additionally, this study introduces promising, feasible, simple, and alternative formulation processes for integrating unmodified functional cationic peptides into LNPs to enhance the delivery efficiency of a wide range of nucleic acid-based drugs.

Strategies and mechanisms for endosomal escape of therapeutic nucleic acids

Despite impressive recent establishment of therapeutic nucleic acids as drugs and vaccines, their broader medical use is impaired by modest performance in intracellular delivery. Inefficient endosomal escape presents a major limitation responsible for inadequate cytosolic cargo release. Depending on the carrier, this endosomal barrier can strongly limit or even abolish nucleic acid delivery. Different recent endosomal escape strategies and their hypothesized mechanisms are reviewed.

Amifostine loaded lipid-calcium carbonate nanoparticles as an oral drug delivery system for radiation protection

Amifostine (AMF) as the first-line radiation protection drug, usually suffered from low compliance and short half-life upon clinical applications. The development of oral drug delivery system (DDS) for AMF is a promising solution. However, the inherent shortages of AMF present significant challenges in the design of suitable oral DDS. Here in this study, we utilized the ability of calcium ions to bind with AMF and prepared AMF loaded calcium carbonate (CC) core, CC/AMF, using phase transferred coprecipitation method. We further modified the CC/AMF using phospholipids to prepare AMF loaded lipid-calcium carbonate (LCC) hybrid nanoparticles (LCC/AMF) via a thin-film dispersion method. LCC/AMF combines the oral advantages of lipid nanoparticles with the drug-loading capabilities of CC, which was shown as uniform nano-sized formulation with decent stability in aqueous solution. With favorable intestinal transport and absorption effects, it effectively enhances the in vivo radiation protection efficacy of AMF through oral administration. More importantly, we further investigated the cellular accumulation profile and intracellular transport mechanism of LCC/AMF using MDCK and Caco-2 cell lines as models. This research not only alters the current administration method of AMF to enhance its convenience and compliance, but also provides insights and guidance for the development of more suitable oral DDS for AMF in the future.

Rational design of lipid nanoparticles: overcoming physiological barriers for selective intracellular mRNA delivery

This review introduces the typical delivery process of messenger RNA (mRNA) nanomedicines and concludes that the delivery involves a at least four-step SCER cascade and that high efficiency at every step is critical to guarantee high overall therapeutic outcomes. This SCER cascade process includes selective organ-targeting delivery, cellular uptake, endosomal escape, and cytosolic mRNA release. Lipid nanoparticles (LNPs) have emerged as a state-of-the-art vehicle for in vivo mRNA delivery. The review emphasizes the importance of LNPs in achieving selective, efficient, and safe mRNA delivery. The discussion then extends to the technical and clinical considerations of LNPs, detailing the roles of individual components in the SCER cascade process, especially ionizable lipids and helper phospholipids. The review aims to provide an updated overview of LNP-based mRNA delivery, outlining recent innovations and addressing challenges while exploring future developments for clinical translation over the next decade.

Atavistic strategy for the treatment of hyperuricemia via ionizable liposomal mRNA

Hyperuricemia is associated with an increased risk of gout, hypertension, diabetes, and cardiovascular diseases. Most mammals maintain normal serum uric acid (SUA) via urate oxidase (Uox), an enzyme that metabolizes poorly-soluble UA to highly-soluble allantoin. In contrast, Uox became a pseudogene in humans and apes over the long course of evolution. Here we demonstrate an atavistic strategy for treating hyperuricemia based on endogenous expression of Uox in hepatocytes mediated by mRNA (mUox) loaded with an ionizable lipid nanoparticle termed iLAND. mUox@iLAND allows effective transfection and protein expression in vitro. A single dose of mUox@iLAND lowers SUA levels for several weeks in two female murine models, including a novel long-lasting model, which is also confirmed by metabolomics analysis. Together with the excellent safety profiles observed in vivo, the proposed mRNA agent demonstrates substantial potential for hyperuricemia therapy and the prevention of associated conditions.

Development of an extended action fostemsavir lipid nanoparticle

An extended action fostemsavir (FTR) lipid nanoparticle (LNP) formulation prevents human immunodeficiency virus type one (HIV-1) infection. This FTR formulation establishes a drug depot in monocyte-derived macrophages that extend the drug's plasma residence time. The LNP's physicochemical properties improve FTR's antiretroviral activities, which are linked to the drug's ability to withstand fluid flow forces and levels of drug cellular internalization. Each is, in measure, dependent on PEGylated lipid composition and flow rate ratios affecting the size, polydispersity, shape, zeta potential, stability, biodistribution, and antiretroviral efficacy. The FTR LNP physicochemical properties enable the drug-particle's extended actions.

Quantitative Visualization of Lipid Nanoparticle Fusion as a Function of Formulation and Process Parameters

Lipid nanoparticles (LNPs) have proven to be promising delivery vehicles for RNA-based vaccines and therapeutics, particularly in LNP formulations containing ionizable cationic lipids that undergo protonation/deprotonation in response to buffer pH changes. These nanoparticles are typically formulated using a rapid mixing technique at low pH, followed by a return to physiological pH that triggers LNP-LNP fusion. A detailed understanding of these dynamic processes is crucial to optimize the overall performance and efficiency of LNPs. However, knowledge gaps persist regarding how particle formation mechanisms impact drug loading and delivery functions. In this work, we employ single-molecule Convex Lens-induced Confinement (CLiC) microscopy in combination with Förster resonance energy transfer (FRET) measurements to study LNP fusion dynamics in relation to various formulation parameters, including lipid concentration, buffer conditions, drug loading ratio, PEG-lipid concentrations, and ionizable lipid selection. Our results reveal a strong correlation between the measured fusion dynamics and the formulation parameters used; these findings are consistent with DLS and Cryo-TEM-based assays. These measurements offer a cost-effective method for characterizing and screening potential drug candidates and can provide additional insights into their design, with opportunities for optimization.

Organ-Specific Gene Expression Control Using DNA Origami-Based Nanodevices

Nanodevices that function in specific organs or cells are one of the ultimate goals of synthetic biology. The recent progress in DNA nanotechnology such as DNA origami has allowed us to construct nanodevices to deliver a payload (e.g., drug) to the tumor. However, delivery to specific organs remains difficult due to the fragility of the DNA nanostructure and the low targeting capability of the DNA nanostructure. Here, we constructed tough DNA origami that allowed us to encapsulate the DNA origami into lipid-based nanoparticles (LNPs) under harsh conditions (low pH), harnessing organ-specific delivery of the gene of interest (GOI). We found that DNA origami-encapsulated LNPs can increase the functionality of payload GOIs (mRNA and siRNA) inside mouse organs through the contribution from different LNP structures revealed by cryogenic electron microscope (Cryo-EM). These data should be the basis for future organ-specific gene expression control using DNA origami nanodevices.

Reformulating lipid nanoparticles for organ-targeted mRNA accumulation and translation

Fully targeted mRNA therapeutics necessitate simultaneous organ-specific accumulation and effective translation. Despite some progress, delivery systems are still unable to fully achieve this. Here, we reformulate lipid nanoparticles (LNPs) through adjustments in lipid material structures and compositions to systematically achieve the pulmonary and hepatic (respectively) targeted mRNA distribution and expression. A combinatorial library of degradable-core based ionizable cationic lipids is designed, following by optimisation of LNP compositions. Contrary to current LNP paradigms, our findings demonstrate that cholesterol and phospholipid are dispensable for LNP functionality. Specifically, cholesterol-removal addresses the persistent challenge of preventing nanoparticle accumulation in hepatic tissues. By modulating and simplifying intrinsic LNP components, concurrent mRNA accumulation and translation is achieved in the lung and liver, respectively. This targeting strategy is applicable to existing LNP systems with potential to expand the progress of precise mRNA therapy for diverse diseases.

Oxidized mRNA Lipid Nanoparticles for In Situ Chimeric Antigen Receptor Monocyte Engineering

Chimeric antigen receptor (CAR) monocyte and macrophage therapies are promising solid tumor immunotherapies that can overcome the challenges facing conventional CAR T cell therapy. mRNA lipid nanoparticles (mRNA-LNPs) offer a viable platform for in situ engineering of CAR monocytes with transient and tunable CAR expression to reduce off-tumor toxicity and streamline cell manufacturing. However, identifying LNPs with monocyte tropism and intracellular delivery potency is difficult using traditional screening techniques. Here, ionizable lipid design and high-throughput in vivo screening are utilized to identify a new class of oxidized LNPs with innate tropism and mRNA delivery to monocytes. A library of oxidized (oLNPs) and unoxidized LNPs (uLNPs) is synthesized to evaluate mRNA delivery to immune cells. oLNPs demonstrate notable differences in morphology, ionization energy, and pKa, therefore enhancing delivery to human macrophages, but not T cells. Subsequently, in vivo library screening with DNA barcodes identifies an oLNP formulation, C14-O2, with innate tropism to monocytes. In a proof-of-concept study, the C14-O2 LNP is used to engineer functional CD19-CAR monocytes in situ for robust B cell aplasia (45%) in healthy mice. This work highlights the utility of oxidized LNPs as a promising platform for engineering CAR macrophages/monocytes for solid tumor CAR monocyte therapy.

Permanently Charged Cationic Lipids-Evolution from Excipients to Therapeutic Lipids

Cationic lipids are crucial in medical and biotechnological applications including cellular transfection and gene delivery. Ionizable cationic lipids are critical components of the mRNA-based COVID vaccines while permanently charged cationic lipids have shown promise in cancer treatment. Despite significant research progress over the past few decades in designing improved, biocompatible cationic lipids, their transfection efficiency remains lower than that of viral vectors. Cationic lipids with additional functionalities like fusogenicity, stimuli-responsiveness, targeting capabilities, and therapeutic activity have been engineered to improve their performance. This review highlights the importance of molecular hybridization toward the design of biocompatible cationic lipids having fusogenic, stimuli-responsive, targeting, or therapeutic properties. This review mainly focuses on cationic lipids, having a permanent positive charge in the headgroup region, as these are typically employed to both increase cellular interactions and for improved loading, particularly for anionic nucleic acid-based therapeutics and vaccines. Structure-activity relationships between the lipid chemical structure (headgroup, spacer, hydrocarbon chain) and, to a lesser extent, the self-assembled nanostructure and the intrinsic biological activity of the multi-functional cationic lipids are described. Finally, the challenges involved in developing smart lipids without affecting their inherent capacity to self-assemble into structured nano-carriers are discussed.

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.

Development of Focused Ultrasound-Assisted Nanoplexes for RNA Delivery

RNA-based therapeutics, including siRNA, have obtained recognition in recent years due to their potential to treat various chronic and rare diseases. However, there are still limitations to lipid-based drug delivery systems in the clinical use of RNA therapeutics due to the need for optimization in the design and the preparation process. In this study, we propose adaptive focused ultrasound (AFU) as a drug loading technique to protect RNA from degradation by encapsulating small RNA in nanoliposomes, which we term nanoplexes. The AFU method is non-invasive and isothermal, as nanoplexes are produced without direct contact with any external materials while maintaining precise temperature control according to the desired settings. The controllability of sample treatments can be effectively modulated, allowing for a wide range of ultrasound intensities to be applied. Importantly, the absence of co-solvents in the process eliminates the need for additional substances, thereby minimizing the potential for cross-contaminations. Since AFU is a non-invasive method, the entire process can be conducted under sterile conditions. A minimal volume (300 μL) is required for this process, and the treatment is speedy (10 min in this study). Our in vitro experiments with silencer CD44 siRNA, which performs as a model therapeutic drug in different mammalian cell lines, showed encouraging results (knockdown > 80%). To quantify gene silencing efficacy, we employed quantitative polymerase chain reaction (qPCR). Additionally, cryo-electron microscopy (cryo-EM) and atomic force microscopy (AFM) techniques were employed to capture images of nanoplexes. These images revealed the presence of individual nanoparticles measuring approximately 100-200 nm in contrast with the random distribution of clustered complexes observed in ultrasound-untreated samples of liposome nanoparticles and siRNA. AFU holds great potential as a standardized liposome processing and loading method because its process is fast, sterile, and does not require additional solvents.

Strategies for enhanced gene delivery to the central nervous system

The delivery of genes to the central nervous system (CNS) has been a persistent challenge due to various biological barriers. The blood-brain barrier (BBB), in particular, hampers the access of systemically injected drugs to parenchymal cells, allowing only a minimal percentage (<1%) to pass through. Recent scientific insights highlight the crucial role of the extracellular space (ECS) in governing drug diffusion. Taking into account advancements in vectors, techniques, and knowledge, the discussion will center on the most notable vectors utilized for gene delivery to the CNS. This review will explore the influence of the ECS - a dynamically regulated barrier-on drug diffusion. Furthermore, we will underscore the significance of employing remote-control technologies to facilitate BBB traversal and modulate the ECS. Given the rapid progress in gene editing, our discussion will also encompass the latest advances focused on delivering therapeutic editing in vivo to the CNS tissue. In the end, a brief summary on the impact of Artificial Intelligence (AI)/Machine Learning (ML), ultrasmall, soft endovascular robots, and high-resolution endovascular cameras on improving the gene delivery to the CNS will be provided.

Rational Design of Lipid-Based Vectors for Advanced Therapeutic Vaccines

Recent advancements in vaccine delivery systems have seen the utilization of various materials, including lipids, polymers, peptides, metals, and inorganic substances, for constructing non-viral vectors. Among these, lipid-based nanoparticles, composed of natural, synthetic, or physiological lipid/phospholipid materials, offer significant advantages such as biocompatibility, biodegradability, and safety, making them ideal for vaccine delivery. These lipid-based vectors can protect encapsulated antigens and/or mRNA from degradation, precisely tune chemical and physical properties to mimic viruses, facilitate targeted delivery to specific immune cells, and enable efficient endosomal escape for robust immune activation. Notably, lipid-based vaccines, exemplified by those developed by BioNTech/Pfizer and Moderna against COVID-19, have gained approval for human use. This review highlights rational design strategies for vaccine delivery, emphasizing lymphoid organ targeting and effective endosomal escape. It also discusses the importance of rational formulation design and structure-activity relationships, along with reviewing components and potential applications of lipid-based vectors. Additionally, it addresses current challenges and future prospects in translating lipid-based vaccine therapies for cancer and infectious diseases into clinical practice.

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.

Small-angle X-ray and neutron scattering applied to lipid-based nanoparticles: Recent advancements across different length scales

Lipid-based nanoparticles (LNPs), ranging from nanovesicles to non-lamellar assemblies, have gained significant attention in recent years, as versatile carriers for delivering drugs, vaccines, and nutrients. Small-angle scattering methods, employing X-rays (SAXS) or neutrons (SANS), represent unique tools to unveil structure, dynamics, and interactions of such particles on different length scales, spanning from the nano to the molecular scale. This review explores the state-of-the-art on scattering methods applied to unveil the structure of lipid-based nanoparticles and their interactions with drugs and bioactive molecules, to inform their rational design and formulation for medical applications. We will focus on complementary information accessible with X-rays or neutrons, ranging from insights on the structure and colloidal processes at a nanoscale level (SAXS) to details on the lipid organization and molecular interactions of LNPs (SANS). In addition, we will review new opportunities offered by Time-resolved (TR)-SAXS and -SANS for the investigation of dynamic processes involving LNPs. These span from real-time monitoring of LNPs structural evolution in response to endogenous or external stimuli (TR-SANS), to the investigation of the kinetics of lipid diffusion and exchange upon interaction with biomolecules (TR-SANS). Finally, we will spotlight novel combinations of SAXS and SANS with complementary on-line techniques, recently enabled at Large Scale Facilities for X-rays and neutrons. This emerging technology enables synchronized multi-method investigation, offering exciting opportunities for the simultaneous characterization of the structure and chemical or mechanical properties of LNPs.

Determination of the interior pH of lipid nanoparticles using a pH-sensitive fluorescent dye-based DNA probe

Lipid nanoparticles (LNPs) containing ionizable cationic lipids are proven delivery systems for therapeutic nucleic acids, such as small interfering RNA (siRNA). It is important to understand the relationship between the interior pH of LNPs and the pH of the external environment to understand LNP formulation and function. Here, we developed a simple and rapid approach for determining the pH of the LNP core using a pH-sensitive fluorescent dye-based DNA probe. LNP siRNA systems containing pH-responsive DNA probes (LNP-siRNA&DNA) were generated by rapid mixing of lipids in ethanol and pH 4 aqueous buffer containing siRNA and DNA probes. We demonstrated that DNA probes were readily encapsulated in LNP systems and were sequestered into an environment at a high concentration as evidenced by an inter-probe FRET signal. It was shown that the pH of LNP encapsulated probes closely follows the pH increase or decrease of the external environment. This indicates that the clinically approved LNP RNA systems with similar lipid compositions (e.g., Onpattro and Comirnaty) are highly permeable to protons and that the pH of the interior environment closely mirrors the external environment. The pH-dependent response of the probe in LNPs was also confirmed under buffer conditions at various pHs. Furthermore, we showed that the pH-sensitive DNA probe can be incorporated into LNP systems at levels that allow the pH response to be monitored at a single LNP level using convex lens-induced confinement (CLiC) confocal microscopy. Direct visualization of the internal pH of single particles with the fluorescent DNA probe was achieved by CLiC for LNP-siRNA&DNA systems formulated under both high and normal ionic strength conditions.

Physiological Barriers and Strategies of Lipid-Based Nanoparticles for Nucleic Acid Drug Delivery

Lipid-based nanoparticles (LBNPs) are currently the most promising vehicles for nucleic acid drug (NAD) delivery. Although their clinical applications have achieved success, the NAD delivery efficiency and safety are still unsatisfactory, which are, to a large extent, due to the existence of multi-level physiological barriers in vivo. It is important to elucidate the interactions between these barriers and LBNPs, which will guide more rational design of efficient NAD vehicles with low adverse effects and facilitate broader applications of nucleic acid therapeutics. This review describes the obstacles and challenges of biological barriers to NAD delivery at systemic, organ, sub-organ, cellular, and subcellular levels. The strategies to overcome these barriers are comprehensively reviewed, mainly including physically/chemically engineering LBNPs and directly modifying physiological barriers by auxiliary treatments. Then the potentials and challenges for successful translation of these preclinical studies into the clinic are discussed. In the end, a forward look at the strategies on manipulating protein corona (PC) is addressed, which may pull off the trick of overcoming those physiological barriers and significantly improve the efficacy and safety of LBNP-based NADs delivery.

Elucidating Structural Configuration of Lipid Assemblies for mRNA Delivery Systems

The development of mRNA delivery systems utilizing lipid-based assemblies holds immense potential for precise control of gene expression and targeted therapeutic interventions. Despite advancements in lipid-based gene delivery systems, a critical knowledge gap remains in understanding how the biophysical characteristics of lipid assemblies and mRNA complexes influence these systems. Herein, we investigate the biophysical properties of cationic liposomes and their role in shaping mRNA lipoplexes by comparing various fabrication methods. Notably, an innovative fabrication technique called the liposome under cryo-assembly (LUCA) cycle, involving a precisely controlled freeze-thaw-vortex process, produces distinctive onion-like concentric multilamellar structures in cationic DOTAP/DOPE liposomes, in contrast to a conventional extrusion method that yields unilamellar liposomes. The inclusion of short-chain DHPC lipids further modulates the structure of cationic liposomes, transforming them from multilamellar to unilamellar structures during the LUCA cycle. Furthermore, the biophysical and biological evaluations of mRNA lipoplexes unveil that the optimal N/P charge ratio in the lipoplex can vary depending on the structure of initial cationic liposomes. Cryo-EM structural analysis demonstrates that multilamellar cationic liposomes induce two distinct interlamellar spacings in cationic lipoplexes, emphasizing the significant impact of the liposome structures on the final structure of mRNA lipoplexes. Taken together, our results provide an intriguing insight into the relationship between lipid assembly structures and the biophysical characteristics of the resulting lipoplexes. These relationships may open the door for advancing lipid-based mRNA delivery systems through more streamlined manufacturing processes.

Advances in co-pathogenesis of the united airway diseases

According to the concept of "united airway diseases", the airway is a single organ in which upper and lower airway diseases are commonly comorbid. A range of inflammatory factors have been found to play an important role in the chain reaction of upper and lower airway diseases. However, the amount of research on this concept remains limited. The underlying mechanism of the relationship between typical diseases of the united airway, such as asthma, allergic rhinitis, and chronic sinusitis, also needs to be further explored. This review highlights the interaction between upper and lower respiratory diseases gathered from epidemiological, histoembryology, neural mechanistic, microbiological, and clinical studies, revealing the relationship between the upper and lower respiratory tracts.

Tumor-activated IL-2 mRNA delivered by lipid nanoparticles for cancer immunotherapy

Interleukin-2 (IL-2) exhibits the unique capacity to modulate immune functions, potentially exerting antitumor effects by stimulating immune responses, making it highly promising for immunotherapy. However, the clinical use of recombinant IL-2 protein faces significant limitations due to its short half-life and systemic toxicity. To overcome these challenges and fully exploit IL-2's potential in tumor immunotherapy, this study reports the development of a tumor-activated IL-2 mRNA, delivered via lipid nanoparticles (LNPs). Initially, ionizable lipid U-101 derived nanoparticles (U-101-LNP) were prepared using microfluidic technology. Subsequent in vitro and in vivo delivery tests demonstrated that U-101-LNP achieved more effective transfection than the approved ALC-0315-LNP. Following this, IL-2F mRNAs, encoding fusion proteins comprising IL-2, a linker, and CD25 (IL-2Rα), were designed and synthesized through in vitro transcription. A cleavable linker, consisting of the peptide sequence SGRSEN↓IRTA, was selected for cleavage by matrix metalloproteinase-14 (MMP-14). IL-2F mRNA was then encapsulated in U-101-LNP to create U-101-LNP/IL-2F mRNA complexes. After optimization, assessments of expression efficiency, masking, and release characteristics revealed that IL-2F with linker C4 demonstrated superior performance. Finally, the antitumor activity of IL-2F mRNA was evaluated. The results indicated that U-101-LNP/IL-2F mRNA achieved the strongest antitumor effect, with an inhibition rate of 70.3%. Immunohistochemistry observations revealed significant expressions of IL-2, IFN-γ, and CD8, suggesting an up-regulation of immunomodulation in tumor tissues. This effect could be ascribed to the expression of IL-2F, followed by the cleavage of the linker under the action of MMP-14 in tumor tissue, which sustainably releases IL-2. H&E staining of tissues treated with U-101-LNP/IL-2F mRNA showed no abnormalities. Further evaluations indicated that the U-101-LNP/IL-2F mRNA group maintained proper levels of inflammatory factors without obvious alterations in liver and renal functions. Taken together, the U-101-LNP/IL-2F mRNA formulation demonstrated effective antitumor activity and safety, which suggests potential applicability in clinical immunotherapy.

Kinetics of RNA-LNP delivery and protein expression

Lipid nanoparticles (LNPs) employing ionizable lipids are the most advanced technology for delivery of RNA, most notably mRNA, to cells. LNPs represent well-defined core-shell particles with efficient nucleic acid encapsulation, low immunogenicity and enhanced efficacy. While much is known about the structure and activity of LNPs, less attention is given to the timing of LNP uptake, cytosolic transfer and protein expression. However, LNP kinetics is a key factor determining delivery efficiency. Hence quantitative insight into the multi-cascaded pathway of LNPs is of interest to elucidate the mechanism of delivery. Here, we review experiments as well as theoretical modeling of the timing of LNP uptake, mRNA-release and protein expression. We describe LNP delivery as a sequence of stochastic transfer processes and review a mathematical model of subsequent protein translation from mRNA. We compile probabilities and numbers obtained from time resolved microscopy. Specifically, live-cell imaging on single cell arrays (LISCA) allows for high-throughput acquisition of thousands of individual GFP reporter expression time courses. The traces yield the distribution of mRNA life-times, expression rates and expression onset. Correlation analysis reveals an inverse dependence of gene expression efficiency and transfection onset-times. Finally, we discuss why timing of mRNA release is critical in the context of codelivery of multiple nucleic acid species as in the case of mRNA co-expression or CRISPR/Cas gene editing.

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.

Dynamic carriers for therapeutic RNA delivery

Carriers for RNA delivery must be dynamic, first stabilizing and protecting therapeutic RNA during delivery to the target tissue and across cellular membrane barriers and then releasing the cargo in bioactive form. The chemical space of carriers ranges from small cationic lipids applied in lipoplexes and lipid nanoparticles, over medium-sized sequence-defined xenopeptides, to macromolecular polycations applied in polyplexes and polymer micelles. This perspective highlights the discovery of distinct virus-inspired dynamic processes that capitalize on mutual nanoparticle-host interactions to achieve potent RNA delivery. From the host side, subtle alterations of pH, ion concentration, redox potential, presence of specific proteins, receptors, or enzymes are cues, which must be recognized by the RNA nanocarrier via dynamic chemical designs including cleavable bonds, alterable physicochemical properties, and supramolecular assembly-disassembly processes to respond to changing biological microenvironment during delivery.

Liquid crystalline inverted lipid phases encapsulating siRNA enhance lipid nanoparticle mediated transfection

Efficient cytosolic delivery of RNA molecules remains a formidable barrier for RNA therapeutic strategies. Lipid nanoparticles (LNPs) serve as state-of-the-art carriers that can deliver RNA molecules intracellularly, as exemplified by the recent implementation of several vaccines against SARS-CoV-2. Using a bottom-up rational design approach, we assemble LNPs that contain programmable lipid phases encapsulating small interfering RNA (siRNA). A combination of cryogenic transmission electron microscopy, cryogenic electron tomography and small-angle X-ray scattering reveals that we can form inverse hexagonal structures, which are present in a liquid crystalline nature within the LNP core. Comparison with lamellar LNPs reveals that the presence of inverse hexagonal phases enhances the intracellular silencing efficiency over lamellar structures. We then demonstrate that lamellar LNPs exhibit an in situ transition from a lamellar to inverse hexagonal phase upon interaction with anionic membranes, whereas LNPs containing pre-programmed liquid crystalline hexagonal phases bypass this transition for a more efficient one-step delivery mechanism, explaining the increased silencing effect. This rational design of LNPs with defined lipid structures aids in the understanding of the nano-bio interface and adds substantial value for LNP design, optimization and use.

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.

Self-Assembly of Unusually Stable Thermotropic Network Phases by Cellobiose-Based Guerbet Glycolipids

Bicontinuous thermotropic liquid crystal (LC) materials, e.g., double gyroid (DG) phases, have garnered significant attention due to the potential utility of their 3D network structures in wide-ranging applications. However, the utility of these materials is significantly constrained by the lack of robust molecular design rules for shape-filling amphiphiles that spontaneously adopt the saddle curvatures required to access these useful supramolecular assemblies. Toward this aim, we synthesized anomerically pure Guerbet-type glycolipids bearing cellobiose head groups and branched alkyl tails and studied their thermotropic LC self-assembly. Using a combination of differential scanning calorimetry, polarized optical microscopy, and small-angle X-ray scattering, our studies demonstrate that Guerbet cellobiosides exhibit a strong propensity to self-assemble into DG morphologies over wide thermotropic phase windows. The stabilities of these assemblies sensitively depend on the branched alkyl tail structure and the anomeric configuration of the glycolipid in a previously unrecognized manner. Complementary molecular simulations furnish detailed insights into the observed self-assembly characteristics, thus unveiling molecular motifs that foster network phase self-assembly that will enable future designs and applications of network LC materials.

Biological recognition and cellular trafficking of targeted RNA-lipid nanoparticles

Lipid nanoparticles (LNPs) have unlocked the potential of ribonucleic acid (RNA) therapeutics and vaccines. Production and large-scale manufacturing methods for RNA-LNPs have been established and rapidly accelerate. Despite this, basic research on LNPs is still required, due to their high assembly complexity and fairly new development, including research on lipid organization, transfection optimization, and in vivo behavior. Understanding fundamental aspects of LNPs that is, how lipid composition and physicochemical properties affect their biodistribution, cell recognition, and transfection, could propel their clinical development and facilitate overcoming current challenges. Herein, we review recent developments in the field of LNP technology and summarize the main findings focusing on nano-bio interactions.

Lipoamino bundle LNPs for efficient mRNA transfection of dendritic cells and macrophages show high spleen selectivity

Messenger RNA (mRNA) is a powerful tool for nucleic acid-based therapies and vaccination, but efficient and specific delivery to target tissues remains a significant challenge. In this study, we demonstrate lipoamino xenopeptide carriers as components of highly efficient mRNA LNPs. These lipo-xenopeptides are defined as 2D sequences in different 3D topologies (bundles or different U-shapes). The polar artificial amino acid tetraethylene pentamino succinic acid (Stp) and various lipophilic tertiary lipoamino fatty acids (LAFs) act as ionizable amphiphilic units, connected in different ratios via bisamidated lysines as branching units. A series of more lipophilic LAF4-Stp1 carriers with bundle topology is especially well suited for efficient encapsulation of mRNA into LNPs, facilitated cellular uptake and strongly enhanced endosomal escape. These LNPs display improved, faster transfection kinetics compared to standard LNP formulations, with high potency in a variety of tumor cell lines (including N2a neuroblastoma, HepG2 and Huh7 hepatocellular, and HeLa cervical carcinoma cells), J774A.1 macrophages, and DC2.4 dendritic cells. High transfection levels were obtained even in the presence of serum at very low sub-microgram mRNA doses. Upon intravenous application of only 3 µg mRNA per mouse, in vivo mRNA expression is found with a high selectivity for dendritic cells and macrophages, resulting in a particularly high overall preferred expression in the spleen.

Biomimetic noncationic lipid nanoparticles for mRNA delivery

Although the tremendous progress has been made for mRNA delivery based on classical cationic carriers, the excess cationic charge density of lipids was necessary to compress mRNA through electrostatic interaction, and with it comes inevitably adverse events including the highly inflammatory and cytotoxic effects. How to develop the disruptive technologies to overcome cationic nature of lipids remains a major challenge for safe and efficient mRNA delivery. Here, we prepared noncationic thiourea lipids nanoparticles (NC-TNP) to compress mRNA by strong hydrogen bonds interaction between thiourea groups of NC-TNP and the phosphate groups of mRNA, abandoning the hidebound and traditional electrostatic force to construct mRNA-cationic lipids formulation. NC-TNP was a delivery system for mRNA with simple, convenient, and repeatable preparation technology and showed negligible inflammatory and cytotoxicity side effects. Furthermore, we found that NC-TNP could escape the recycling pathway to inhibit the egress of internalized nanoparticles from the intracellular compartment to the extracellular milieu which was a common fact in mRNA-LNP (lipid nanoparticles) formulation. Therefore, NC-TNP-encapsulated mRNA showed higher gene transfection efficiency in vitro and in vivo than mRNA-LNP formulation. Unexpectedly, NC-TNP showed spleen targeting delivery ability with higher accumulation ratio (spleen/liver), compared with traditional LNP. Spleen-targeting NC-TNP with mRNA exhibited high mRNA-encoded antigen expression in spleen and elicited robust immune responses. Overall, our work establishes a proof of concept for the construction of a noncationic system for mRNA delivery with good inflammatory safety profiles, high gene transfection efficiency, and spleen-targeting delivery to induce permanent and robust humoral and cell-mediated immunity for disease treatments.

pH-dependent structural transitions in cationic ionizable lipid mesophases are critical for lipid nanoparticle function

Lipid nanoparticles (LNPs) are advanced core-shell particles for messenger RNA (mRNA) based therapies that are made of polyethylene glycol (PEG) lipid, distearoylphosphatidylcholine (DSPC), cationic ionizable lipid (CIL), cholesterol (chol), and mRNA. Yet the mechanism of pH-dependent response that is believed to cause endosomal release of LNPs is not well understood. Here, we show that eGFP (enhanced green fluorescent protein) protein expression in the mouse liver mediated by the ionizable lipids DLin-MC3-DMA (MC3), DLin-KC2-DMA (KC2), and DLinDMA (DD) ranks MC3 ≥ KC2 > DD despite similar delivery of mRNA per cell in all cell fractions isolated. We hypothesize that the three CIL-LNPs react differently to pH changes and hence study the structure of CIL/chol bulk phases in water. Using synchrotron X-ray scattering a sequence of ordered CIL/chol mesophases with lowering pH values are observed. These phases show isotropic inverse micellar, cubic Fd3m inverse micellar, inverse hexagonal [Formula: see text] and bicontinuous cubic Pn3m symmetry. If polyadenylic acid, as mRNA surrogate, is added to CIL/chol, excess lipid coexists with a condensed nucleic acid lipid [Formula: see text] phase. The next-neighbor distance in the excess phase shows a discontinuity at the Fd3m inverse micellar to inverse hexagonal [Formula: see text] transition occurring at pH 6 with distinctly larger spacing and hydration for DD vs. MC3 and KC2. In mRNA LNPs, DD showed larger internal spacing, as well as retarded onset and reduced level of DD-LNP-mediated eGFP expression in vitro compared to MC3 and KC2. Our data suggest that the pH-driven Fd3m-[Formula: see text] transition in bulk phases is a hallmark of CIL-specific differences in mRNA LNP efficacy.

Lipid Nanoparticle-Mediated Hit-and-Run Approaches Yield Efficient and Safe In Situ Gene Editing in Human Skin

Despite exciting advances in gene editing, the efficient delivery of genetic tools to extrahepatic tissues remains challenging. This holds particularly true for the skin, which poses a highly restrictive delivery barrier. In this study, we ran a head-to-head comparison between Cas9 mRNA or ribonucleoprotein (RNP)-loaded lipid nanoparticles (LNPs) to deliver gene editing tools into epidermal layers of human skin, aiming for in situ gene editing. We observed distinct LNP composition and cell-specific effects such as an extended presence of RNP in slow-cycling epithelial cells for up to 72 h. While obtaining similar gene editing rates using Cas9 RNP and mRNA with MC3-based LNPs (10-16%), mRNA-loaded LNPs proved to be more cytotoxic. Interestingly, ionizable lipids with a pKa ∼ 7.1 yielded superior gene editing rates (55%-72%) in two-dimensional (2D) epithelial cells while no single guide RNA-dependent off-target effects were detectable. Unexpectedly, these high 2D editing efficacies did not translate to actual skin tissue where overall gene editing rates between 5%-12% were achieved after a single application and irrespective of the LNP composition. Finally, we successfully base-corrected a disease-causing mutation with an efficacy of ∼5% in autosomal recessive congenital ichthyosis patient cells, showcasing the potential of this strategy for the treatment of monogenic skin diseases. Taken together, this study demonstrates the feasibility of an in situ correction of disease-causing mutations in the skin that could provide effective treatment and potentially even a cure for rare, monogenic, and common skin diseases.

Cellular Trafficking of Nanotechnology-Mediated mRNA Delivery

Messenger RNA (mRNA)-based therapy has emerged as a powerful, safe, and rapidly scalable therapeutic approach that involves technologies for both mRNA itself and the delivery vehicle. Although there are some unique challenges for different applications of mRNA therapy, a common challenge for all mRNA therapeutics is the transport of mRNA into the target cell cytoplasm for sufficient protein expression. This review is focused on the behaviors at the cellular level of nanotechnology-mediated mRNA delivery systems, which have not been comprehensively reviewed yet. First, the four main therapeutic applications of mRNA are introduced, including immunotherapy, protein replacement therapy, genome editing, and cellular reprogramming. Second, common types of mRNA cargos and mRNA delivery systems are summarized. Third, strategies to enhance mRNA delivery efficiency during the cellular trafficking process are highlighted, including accumulation to the cell, internalization into the cell, endosomal escape, release of mRNA from the nanocarrier, and translation of mRNA into protein. Finally, the challenges and opportunities for the development of nanotechnology-mediated mRNA delivery systems are presented. This review can provide new insights into the future fabrication of mRNA nanocarriers with desirable cellular trafficking performance.