In vitro-in vivo translation of lipid nanoparticles for hepatocellular siRNA delivery

Screening lipid nanoparticles using DNA barcoding and qPCR

Quantifying the biodistribution of lipid nanoparticles (LNPs) is critical for optimizing mRNA delivery systems, yet current approaches have inherent limitations. This study introduces a cost-effective method utilizing double-stranded DNA (dsDNA) barcodes and quantitative polymerase chain reaction (qPCR) for rapid analysis of a small library of mRNA-LNPs biodistribution and functional delivery in vivo. Three unique 100-bp dsDNA barcodes were designed to represent for three FDA-approved LNP formulations. Concurrently, these three formulations carrying luciferase mRNA were mixed with DNA-barcoding LNPs as a pool. Following intravenous administration of the pooled LNPs in mice, qPCR analysis revealed the highest abundance of DNA barcodes and accumulation of luciferase mRNA in spleen, with positive correlation between barcodes presence and mRNA localization across organs, validating DNA barcodes as reliable indicators of mRNA-LNPs biodistribution in vivo. Bioluminescence imaging further confirmed successful delivery and protein translation of luciferase mRNA facilitated by the LNPs in vivo. Integrating DNA barcodes for biodistribution analysis and luciferase mRNA for assessing functional delivery enabled comprehensive evaluation of LNP performance. This robust methodology provides valuable insights into the localization patterns and mRNA delivery capabilities of different LNP formulations, paving the way for the development of more effective and targeted mRNA-based therapeutics.

Asialofetuin-Coupled Lipid-Based nanosystems to target the Asialoglycoprotein receptor: Delivering genes to hepatocytes for the treatment of Fabry disease

Exploiting the protein production capacity of hepatocytes for de novo expression of α-Galactosidase A (α-Gal A) by gene supplementation therapy represents one of the most promising strategies for the treatment of Fabry disease (FD). The asialoglycoprotein receptor (ASGPr) has proven to be one of the target receptors of choice for hepatocyte-directed nanomedicines, and natural glycoproteins such as asialofetuin (AF) can be used as specific ligands. Herein, we have developed AF-decorated solid lipid nanoparticles (SLNs), prepared by different techniques and cationic lipid compositions, for restoring the enzyme deficiency in FD by gene supplementation targeted to hepatocytes. After the physicochemical characterization of the vectors, cell association and transfection efficacy were evaluated in vitro in human hepatocytes (Hep G2), and the capacity to increase α-Gal A activity was evaluated in vivo after intravenous administration to α-Gal A knockout mice. The efficacy and targeting effect were conditioned by the type of SLN. In general, vectors containing a mixture of the cationic lipids DOTAP and DODAP showed enhanced transfection efficacy compared to their counterparts without DODAP. The incorporation of AF in the vectors formulated with SLNs prepared with DOTAP and DODAP by hot-melt emulsification significantly improved the efficacy to induce the expression of α-Gal A in hepatocytes in vitro compared to the control without AF. However, the administration to Fabry mice did not result in a significant increase in enzyme activity. The lack of in vitro-in vivo correlation corroborates the need to understand key factors influencing the behavior of non-viral vectors in biological media for nucleic acid therapies, as well as the desirability of in vivo studies in the early stages of pharmaceutical development of nucleic acid delivery systems.

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

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

Cyclen-based lipidoids for mRNA delivery and immunotherapy

As mRNA vaccines continue to gain widespread attention, the development of lipid nanoparticles (LNPs), as the preferred platform for mRNA delivery, has become a key focus of research. 1,4,7,10-Tetraazacyclododecane (cyclen), with its excellent protonation capability and ease of modification, has emerged as a promising candidate for the ionizable head group of lipid materials. In this study, a series of cyclen-based lipidoids with different linkages and hydrophobic tails was designed and conveniently synthesized. Structure-activity relationship studies were performed to screen out the carriers capable of efficient mRNA delivery and with potential for tumor therapeutic applications. In vivo biodistribution experiments in mice revealed that the lipidoid OEs-K, containing both hydroxyl and ester groups in its linkage, exhibited high mRNA delivery efficiency and lymph node-targeting properties. Using a subcutaneous EG.7-OVA tumor model in mice, the delivery of tumor antigen OVA mRNA using the lipidoid material was evaluated for its antitumor immunotherapeutic potential. Results demonstrated that LNPs formulated with OEs-K promoted dendritic cell uptake in lymph nodes, effectively activated immune responses, and inhibited tumor growth. Hematological and histopathological evaluations indicated no significant toxicity to the body. This study provides insights into the design and development of carrier materials for mRNA vaccines.

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

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

Exploring the Challenges of Lipid Nanoparticle Development: The In Vitro-In Vivo Correlation Gap

BACKGROUND/OBJECTIVES

The development of lipid nanoparticles (LNPs) as delivery platforms for nucleic acids has revolutionised possibilities for both therapeutic and vaccine applications. However, emerging studies highlight challenges in achieving reliable in vitro-in vivo correlation (IVIVC), which delays the translation of experimental findings into clinical applications. This study investigates these potential discrepancies by evaluating the physicochemical properties, in vitro efficacy (across three commonly used cell lines), and in vivo performance (mRNA expression and vaccine efficacy) of four LNP formulations.

METHODS

LNPs composed of DSPC, cholesterol, a PEGylated lipid, and one of four ionizable lipids (SM-102, ALC-0315, MC3, or C12-200) were manufactured using microfluidics.

RESULTS

All formulations exhibited comparable physicochemical properties, as expected (size 70-100 nm, low PDI, near-neutral zeta potential, and high mRNA encapsulation). In vitro studies demonstrated variable LNP-mediated mRNA expression in both immortalised and immune cells, with SM-102 inducing significantly higher protein expression (p < 0.05) than the other formulations in immortalised and immune cells. However, in vivo results revealed that ALC-0315 and SM-102-based LNPs achieved significantly (p < 0.05) higher protein expression without a significant difference between them, while MC3- and C12-200-based LNPs exhibited lower expression levels. As vaccine formulations, all LNPs elicited strong immune responses with no significant differences among them.

CONCLUSIONS

These findings highlight the complexities of correlating in vitro and in vivo outcomes in LNP development and demonstrate the importance of holistic evaluation strategies to optimise their clinical translation.

Protein corona formed on lipid nanoparticles compromises delivery efficiency of mRNA cargo

Lipid nanoparticles (LNPs) are the most clinically advanced nonviral RNA-delivery vehicles, though challenges remain in fully understanding how LNPs interact with biological systems. In vivo , proteins form an associated corona on LNPs that redefines their physicochemical properties and influences delivery outcomes. Despite its importance, the LNP protein corona is challenging to study owing to the technical difficulty of selectively recovering soft nanoparticles from biological samples. Herein, we developed a quantitative, label-free mass spectrometry-based proteomics approach to characterize the protein corona on LNPs. Critically, this protein corona isolation workflow avoids artifacts introduced by the presence of endogenous nanoparticles in human biofluids. We applied continuous density gradient ultracentrifugation for protein-LNP complex isolation, with mass spectrometry for protein identification normalized to protein composition in the biofluid alone. With this approach, we quantify proteins consistently enriched in the LNP corona including vitronectin, C-reactive protein, and alpha-2-macroglobulin. We explore the impact of these corona proteins on cell uptake and mRNA expression in HepG2 human liver cells, and find that, surprisingly, increased levels of cell uptake do not correlate with increased mRNA expression in part likely due to protein corona-induced lysosomal trafficking of LNPs. Our results underscore the need to consider the protein corona in the design of LNP-based therapeutics.

Abstract Figure

Transfection Potency of Lipid Nanoparticles Containing mRNA Depends on Relative Loading Levels

When formulating mRNA into lipid nanoparticles (LNP), various copy numbers of mRNA are encapsulated, leading to a distribution of mRNA loading levels within the LNPs. It is unclear whether the mRNA loading level affects the functional delivery of the message. Here we show that depending on the mRNA loading level, LNPs exhibit distinct mass densities and can be fractionated via ultracentrifugation. Upon fractionation, we investigated if mRNA loading levels influence LNP sizing, lipid composition, and morphology. We further conducted in vitro and in vivo functional delivery of mRNA and found that the LNP fraction with the highest mRNA loading levels was the least transfection competent.

In Vivo Delivery Processes and Development Strategies of Lipid Nanoparticles

Lipid nanoparticles (LNPs) represent an advanced and highly efficient delivery system for RNA molecules, demonstrating exceptional biocompatibility and remarkable delivery efficiency. This is evidenced by the clinical authorization of three LNP formulations: Patisiran, BNT162b2, and mRNA-1273. To further maximize the efficacy of RNA-based therapy, it is imperative to develop more potent LNP delivery systems that can effectively protect inherently unstable and negatively charged RNA molecules from degradation by nucleases, while facilitating their cellular uptake into target cells. Therefore, this review presents feasible strategies commonly employed for the development of efficient LNP delivery systems. The strategies encompass combinatorial chemistry for large-scale synthesis of ionizable lipids, rational design strategy of ionizable lipids, functional molecules-derived lipid molecules, the optimization of LNP formulations, and the adjustment of particle size and charge property of LNPs. Prior to introducing these developing strategies, in vivo delivery processes of LNPs, a crucial determinant influencing the clinical translation of LNP formulations, is described to better understand how to develop LNP delivery systems.

Recent advancements in small interfering RNA based therapeutic approach on breast cancer

Breast cancer (BC) is the most common and malignant tumor diagnosed in women, with 2.9 million cases in 2023 and the fifth highest cancer-causing mortality worldwide. Recent developments in targeted therapy options for BC have demonstrated the promising potential of small interfering RNA (siRNA)-based cancer therapeutic approaches. As BC continues to be a global burden, siRNA therapy emerges as a potential treatment strategy to regulate disease-related genes in other types of cancers, including BC. siRNAs are tiny RNA molecules that, by preventing their expression, can specifically silence genes linked to the development of cancer. In order to increase the stability and effectiveness of siRNA delivery to BC cells, minimize off-target effects, and improve treatment efficacy, advanced delivery technologies such as lipid nanoparticles and nanocarriers have been created. Additionally, combination therapies, such as siRNAs that target multiple pathways are used in conjunction with conventional chemotherapy agents, have shown synergistic effects in various preclinical studies, opening up new treatment options for breast cancer that are personalized and precision medicine-oriented. Targeting important genes linked to BC growth, metastasis, and chemo-resistance has been reported in BC research using siRNA-based therapies. This study reviews recent reports on therapeutic approaches to siRNA for advanced treatment of BC. Furthermore, this review evaluates the role and mechanisms of siRNA in BC and demonstrates the potential of exploiting siRNA as a novel target for BC therapy.

Intracellular delivery strategies using membrane-interacting peptides and proteins

While the cellular cytosol and organelles contain attractive targets for disease treatments, it remains a challenge to deliver therapeutic biomacromolecules to these sites. This is due to the selective permeability of the plasma and endosomal membranes, especially for large and hydrophilic therapeutic cargos such as proteins and nucleic acids. In response, many different delivery systems and molecules have been devised to help therapeutics cross these barriers to reach cytosolic targets. Among them are peptide and protein-based systems, which have several advantages over other natural and synthetic materials including their ability to interact with cell membranes. In this review, we will describe recent advances and current challenges of peptide and protein strategies that leverage cell membrane association and modulation to enable cytosolic delivery of biomacromolecule cargo. The approaches covered here include peptides and proteins derived from or inspired by natural sequences as well as those designed de novo for delivery function.

Chemical Design Strategy of Ionizable Lipids for In Vivo mRNA Delivery

Lipid nanoparticles (LNPs) are the most clinically successful drug delivery systems that have accelerated the development of mRNA drugs and vaccines. Among various structural components of LNPs, more recent attention has been paid in ionizable lipids (ILs) that was supposed as the key component in determining the effectiveness of LNPs for in vivo mRNA delivery. ILs are typically comprised of three moieties including ionizable heads, linkers, and hydrophobic tails, which suggested that the combination of different functional groups in three moieties could produce ILs with diverse chemical structures and biological identities. In this concept article, we provide a summary of chemical design strategy for high-performing IL candidates and discuss their structure-activity relationships for shifting tissue-selective mRNA delivery. We also propose an outlook for the development of next-generation ILs, enabling the broader translation of mRNA formulated with LNPs.

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.

Frameworks for transformational breakthroughs in RNA-based medicines

RNA has sparked a revolution in modern medicine, with the potential to transform the way we treat diseases. Recent regulatory approvals, hundreds of new clinical trials, the emergence of CRISPR gene editing, and the effectiveness of mRNA vaccines in dramatic response to the COVID-19 pandemic have converged to create tremendous momentum and expectation. However, challenges with this relatively new class of drugs persist and require specialized knowledge and expertise to overcome. This Review explores shared strategies for developing RNA drug platforms, including layering technologies, addressing common biases and identifying gaps in understanding. It discusses the potential of RNA-based therapeutics to transform medicine, as well as the challenges associated with improving applicability, efficacy and safety profiles. Insights gained from RNA modalities such as antisense oligonucleotides (ASOs) and small interfering RNAs are used to identify important next steps for mRNA and gene editing technologies.

Plasmid DNA ionisable lipid nanoparticles as non-inert carriers and potent immune activators for cancer immunotherapy

Immunotherapy is currently a standard of care in the treatment of many malignancies. However, predictable side effects caused by systemic administration of highly immunostimulatory molecules have been a serious concern within this field. Intratumoural expression or silencing of immunogenic and immunoinhibitory molecules using nucleic acid-based approaches such as plasmid DNA (pDNA) and small interfering RNA (siRNA), respectively, could represent a next generation of cancer immunotherapy. Here, we employed lipid nanoparticles (LNPs) to deliver either non-specific pDNA and siRNA, or constructs targeting two prominent immunotherapeutic targets OX40L and indoleamine 2,3-dioxygenase-1 (IDO), to tumours in vivo. In the B16F10 mouse model, intratumoural delivery of LNP-formulated non-specific pDNA and siRNA led to strong local immune activation and tumour growth inhibition even at low doses due to the pDNA immunogenic nature. Replacement of these non-specific constructs by pOX40L and siIDO resulted in more prominent immune activation as evidenced by increased immune cell infiltration in tumours and tumour-draining lymph nodes. Consistently, pOX40L alone or in combination with siIDO could prolong overall survival, resulting in complete tumour regression and the formation of immunological memory in tumour rechallenge models. Our results suggest that intratumoural administration of LNP-formulated pDNA and siRNA offers a promising approach for cancer immunotherapy.

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

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

Digital Barcodes for High-Throughput Screening

High-throughput screening is an indispensable technology in drug discovery, cancer therapy, and disease diagnosis, and it could greatly reduce time cost, reagent consumption, and labor expense. Here, four high-throughput screening methods with high sensitivity and accessibility are discussed in detail. Fluorescence, DNA, heavy metal, and nonmetal isotope barcodes, which generally label antibodies, proteins, and saccharides to identify cells, are detected by flow cytometry, second-generation DNA sequencing, mass cytometry, and second-ion mass spectrometry, respectively. Encoding binary information in barcodes, labeling individual cells by barcodes, performing the characterization of cells together, and identifying the result belonging to individual cells via barcodes are the main steps for high-throughput screening. Applications of the four digital barcodes in high-throughput screening for both in vitro and in vivo tests are described in detail, and their advantages and disadvantages are also summarized. High-throughput screening has provided a powerful platform widely accessible for multidisciplinary studies and has greatly sped up the progress of drug discovery, disease diagnosis, and cancer therapy.

Construction of Peptide-Lipoic Acid Cationic Polymers with Redox Responsiveness and Low Toxicity for Gene Delivery

As gene therapy continues to evolve, the development of safe and effective cationic polymer carriers is critical. In this work, three polymers have been prepared by ring-opening polymerization on the basis of peptide-lipoic acid monomers. By adjusting the sequence of the peptides, redox-responsive cationic polymers with different positive charge numbers were obtained, as well as investigating their performance as gene carriers. The results showed that the polymers complexed with negatively charged genes by electrostatic interaction and successfully transported the genes into the cells, additionally degrading and releasing the genes under glutathione (GSH) conditions. Furthermore, the polymers as gene carriers in different cell lines demonstrated lower cytotoxicity, with an excellent cell survival rate of 8 times higher than the "gold standard" polyethylenimine (PEI) at the same concentration. In vitro transfection experiments showed that the polymers successfully released and transfected genes into cells, demonstrating their immense potential in gene therapy.

The mixing method used to formulate lipid nanoparticles affects mRNA delivery efficacy and organ tropism

mRNA is a versatile drug molecule with therapeutic applications ranging from protein replacement therapies to in vivo gene engineering. mRNA delivery is often accomplished using lipid nanoparticles, which are formulated via mixing of aqueous and organic solutions. Although this has historically been accomplished by manual mixing for bench scale science, microfluidic mixing is required for scalable continuous manufacturing and batch to batch control. Currently, there is limited understanding on how the mixing process affects mRNA delivery efficacy, particularly in regard to tropism. To address this knowledge gap, we examined the influence of the type of mixing and microfluidic mixing parameters on the performance of lipid nanoparticles in mice. This was accomplished with a Design of Experiment approach using four nanoparticle formulations with varied ionizable lipid chemistry. We found that each formulation required unique optimization of mixing parameters, with the total delivery efficacy of each lipid nanoparticle generated with microfluidics ranging from 100-fold less to 4-fold more than manually mixed LNPs. Further, mixing parameters influenced organ tropism, with the most efficacious formulations disproportionately increasing liver delivery compared to other organs. These data suggest that mixing parameters for lipid nanoparticle production may require optimization for each unique chemical formulation, complicating translational efforts. Further, microfluidic parameters must be chosen carefully to balance overall mRNA delivery efficacy with application-specific tropism requirements.

The Expression Kinetics and Immunogenicity of Lipid Nanoparticles Delivering Plasmid DNA and mRNA in Mice

In recent years, lipid nanoparticles (LNPs) have emerged as a revolutionary technology for vaccine delivery. LNPs serve as an integral component of mRNA vaccines by protecting and transporting the mRNA payload into host cells. Despite their prominence in mRNA vaccines, there remains a notable gap in our understanding of the potential application of LNPs for the delivery of DNA vaccines. In this study, we sought to investigate the suitability of leading LNP formulations for the delivery of plasmid DNA (pDNA). In addition, we aimed to explore key differences in the properties of popular LNP formulations when delivering either mRNA or DNA. To address these questions, we compared three leading LNP formulations encapsulating mRNA- or pDNA-encoding firefly luciferase based on potency, expression kinetics, biodistribution, and immunogenicity. Following intramuscular injection in mice, we determined that RNA-LNPs formulated with either SM-102 or ALC-0315 lipids were the most potent (all p-values < 0.01) and immunogenic (all p-values < 0.05), while DNA-LNPs formulated with SM-102 or ALC-0315 demonstrated the longest duration of signal. Additionally, all LNP formulations were found to induce expression in the liver that was proportional to the signal at the injection site (SM102: r = 0.8787, p < 0.0001; ALC0315: r = 0.9012, p < 0.0001; KC2: r = 0.9343, p < 0.0001). Overall, this study provides important insights into the differences between leading LNP formulations and their applicability to DNA- and RNA-based vaccinations.

Evaluation of a DoE based approach for comprehensive modelling of the effect of lipid nanoparticle composition on nucleic acid delivery

Therapeutic nucleic acids (TNAs) comprise an alternative to conventional drugs for cancer therapy. Recently, stable nucleic acid lipid particles (SNALPs) have been explored to deliver TNA efficiently and safely both in vitro and in vivo. Small interfering RNA (siRNA) and messenger RNA (mRNA) based drugs have been suggested for a wide range of pathologies, and their respective lipid nanoparticle (LNP) formulations have been optimised using a Design of Experiments (DoE) approach. However, it is uncertain as to whether data obtained from DoE using simple experimental outputs can be used to generate a general heuristic for delivery of diverse TNA both in vitro and in vivo. Using plasmid DNA (pDNA), for which limited DoE optimisation has been performed, and siRNA to represent the two extremities of the TNA spectrum in terms of size and biological requirements, we performed a comparative DoE for both molecules and assessed the predictive qualities of the model both in vitro and in vivo. By producing a minimum run of 24 SNALP formulations with different lipid compositions incorporating either pDNA or siRNA, DoE models were successfully established for predicting the effect of individual lipid composition on particle size, TNA encapsulation and transfection both in vitro and in vivo. The results showed that the particle size, and in vitro and in vivo transfection efficiency of both pDNA and siRNA SNALP formulations were affected by lipid compositions. The encapsulation efficiency of pDNA SNALPs but not siRNA SNALPs was affected by the lipid composition. Notably, the optimal lipid compositions of SNALPs for pDNA/siRNA delivery were not identical. Furthermore, in vitro transfection efficiency could not be used to predict promising LNP candidates in vivo. The DoE approach described in this study may provide a method for comprehensive optimisation of LNPs for various applications. The model and optimal formulation described in this study can serve as a foundation from which to develop other novel NA containing LNPs for multiple applications such as NA based vaccines, cancer immunotherapies and other TNA therapies.

Peptide-encoding mRNA barcodes for the high-throughput in vivo screening of libraries of lipid nanoparticles for mRNA delivery

Developing safe and effective nanoparticles for the delivery of messenger RNA (mRNA) is slow and expensive, partly due to the lack of predictive power of in vitro screening methods and the low-throughput nature of in vivo screening. While DNA barcoding and batch analysis present methods for increasing in vivo screening throughput, they can also result in incomplete or misleading measures of efficacy. Here, we describe a high-throughput and accurate method for the screening of pooled nanoparticle formulations within the same animal. The method uses liquid chromatography with tandem mass spectrometry to detect peptide barcodes translated from mRNAs in nanoparticle-transfected cells. We show the method's applicability by evaluating a library of over 400 nanoparticle formulations with 384 unique ionizable lipids using only nine mice to optimize the formulation of a biodegradable lipid nanoparticle for mRNA delivery to the liver. Barcoding lipid nanoparticles with peptide-encoding mRNAs may facilitate the rapid development of nanoparticles for mRNA delivery to specific cells and tissues.

Immune-Modulating Lipid Nanomaterials for the Delivery of Biopharmaceuticals

In recent years, with the approval of preventative vaccines for pandemics, lipid nanoparticles have become a prominent RNA delivery vehicle. The lack of long-lasting effects of non-viral vectors is an advantage for infectious disease vaccines. With the introduction of microfluidic processes that facilitate the encapsulation of nucleic acid cargo, lipid nanoparticles are being studied as delivery vehicles for various RNA-based biopharmaceuticals. In particular, using microfluidic chip-based fabrication processes, nucleic acids such as RNA and proteins can be effectively incorporated into lipid nanoparticles and utilized as delivery vehicles for various biopharmaceuticals. Due to the successful development of mRNA therapies, lipid nanoparticles have emerged as a promising approach for the delivery of biopharmaceuticals. Biopharmaceuticals of various types (DNA, mRNA, short RNA, proteins) possess expression mechanisms that are suitable for manufacturing personalized cancer vaccines, while also requiring formulation with lipid nanoparticles. In this review, we describe the basic design of lipid nanoparticles, the types of biopharmaceuticals used as carriers, and the microfluidic processes involved. We then present research cases focusing on lipid-nanoparticle-based immune modulation and discuss the current status of commercially available lipid nanoparticles, as well as future prospects for the development of lipid nanoparticles for immune regulation purposes.

Engineered Design of a Mesoporous Silica Nanoparticle-Based Nanocarrier for Efficient mRNA Delivery in Vivo

We have developed tailor-designed mesoporous silica nanoparticles (MSNPs) specifically for delivering mRNA. Our unique assembly protocol involves premixing mRNA with a cationic polymer and then electrostatically binding it to the MSNP surface. Since the key physicochemical parameters of MSNPs could influence the biological outcome, we also investigated the roles of size, porosity, surface topology, and aspect ratio on the mRNA delivery. These efforts allow us to identify the best-performing carrier, which was able to achieve efficient cellular uptake and intracellular escape while delivering a luciferase mRNA in mice. The optimized carrier remained stable and active for at least 7 days after being stored at 4 °C and was able to enable tissue-specific mRNA expression, particularly in the pancreas and mesentery after intraperitoneal injection. The optimized carrier was further manufactured in a larger batch size and found to be equally efficient in delivering mRNA in mice and rats, without any obvious toxicity.

Therapeutic siRNA: State-of-the-Art and Future Perspectives

The highly specific induction of RNA interference-mediated gene knockdown, based on the direct application of small interfering RNAs (siRNAs), opens novel avenues towards innovative therapies. Two decades after the discovery of the RNA interference mechanism, the first siRNA drugs received approval for clinical use by the US Food and Drug Administration and the European Medicines Agency between 2018 and 2022. These are mainly based on an siRNA conjugation with a targeting moiety for liver hepatocytes, N-acetylgalactosamine, and cover the treatment of acute hepatic porphyria, transthyretin-mediated amyloidosis, hypercholesterolemia, and primary hyperoxaluria type 1. Still, the development of siRNA therapeutics faces several challenges and issues, including the definition of optimal siRNAs in terms of target, sequence, and chemical modifications, siRNA delivery to its intended site of action, and the absence of unspecific off-target effects. Further siRNA drugs are in clinical studies, based on different delivery systems and covering a wide range of different pathologies including metabolic diseases, hematology, infectious diseases, oncology, ocular diseases, and others. This article reviews the knowledge on siRNA design and chemical modification, as well as issues related to siRNA delivery that may be addressed using different delivery systems. Details on the mode of action and clinical status of the various siRNA therapeutics are provided, before giving an outlook on issues regarding the future of siRNA drugs and on their potential as one emerging standard modality in pharmacotherapy. Notably, this may also cover otherwise un-druggable diseases, the definition of non-coding RNAs as targets, and novel concepts of personalized and combination treatment regimens.

Nucleic Acid-Loaded Lipid Nanoparticle Interactions with Model Endosomal Membranes

Lipid nanoparticles (LNPs) are important delivery systems for RNA-based therapeutics, yet the mechanism of their interaction with endosomal membranes remains unclear. Here, the interactions of nucleic acid-loaded LNPs that contain an ionizable lipid with models of the early and late endosomal membranes are studied, for the first time, using different reflectometry techniques. Novel insight is provided with respect to the subphase pH, the stage of the endosome, and the nature of the nucleic acid cargo. It is found that the insertion of lipids from the LNPs into the model membrane is greatest at pH 6.5 and 5.5, whereas at higher pH, lipid insertion is suppressed with evidence instead for the binding of intact LNPs, demonstrating the importance of the pH in the fusion of LNPs undergoing the endosomal pathway. Furthermore, and independently of the pH, the effect of the early- versus late-stage endosomal models is minimal, suggesting that the increased fluidity and anionic nature of the late endosome has little effect on the extent of LNP interaction. Last, there is greater nucleic acid delivery from LNPs containing mRNA than Poly(A), indicating that the extent of interaction can be tuned according to the nature of the nucleic acid cargo. Such new information on the relative impact of factors influencing nucleic acid delivery by LNP interactions with endosomal membranes is important in the design and tuning of vehicles with improved nucleic acid delivery capacities.

Doxorubicin-conjugated siRNA lipid nanoparticles for combination cancer therapy

Evasion of apoptosis is a hallmark of cancer, attributed in part to overexpression of the anti-apoptotic protein B-cell lymphoma 2 (Bcl-2). In a variety of cancer types, including lymphoma, Bcl-2 is overexpressed. Therapeutic targeting of Bcl-2 has demonstrated efficacy in the clinic and is the subject of extensive clinical testing in combination with chemotherapy. Therefore, the development of co-delivery systems for Bcl-2 targeting agents, such as small interfering RNA (siRNA), and chemotherapeutics, such as doxorubicin (DOX), holds promise for enabling combination cancer therapies. Lipid nanoparticles (LNPs) are a clinically advanced nucleic acid delivery system with a compact structure suitable for siRNA encapsulation and delivery. Inspired by ongoing clinical trials of albumin-hitchhiking doxorubicin prodrugs, here we developed a DOX-siRNA co-delivery strategy via conjugation of doxorubicin to the surface of siRNA-loaded LNPs. Our optimized LNPs enabled potent knockdown of Bcl-2 and efficient delivery of DOX into the nucleus of Burkitts' lymphoma (Raji) cells, leading to effective inhibition of tumor growth in a mouse model of lymphoma. Based on these results, our LNPs may provide a platform for the co-delivery of various nucleic acids and DOX for the development of new combination cancer therapies.

Optimization of Lipid Nanoparticles for saRNA Expression and Cellular Activation Using a Design-of-Experiment Approach

Lipid nanoparticles (LNPs) are the leading technology for RNA delivery, given the success of the Pfizer/BioNTech and Moderna COVID-19 mRNA (mRNA) vaccines, and small interfering RNA (siRNA) therapies (patisiran). However, optimization of LNP process parameters and compositions for larger RNA payloads such as self-amplifying RNA (saRNA), which can have complex secondary structures, have not been carried out. Furthermore, the interactions between process parameters, critical quality attributes (CQAs), and function, such as protein expression and cellular activation, are not well understood. Here, we used two iterations of design of experiments (DoE) (definitive screening design and Box-Behnken design) to optimize saRNA formulations using the leading, FDA-approved ionizable lipids (MC3, ALC-0315, and SM-102). We observed that PEG is required to preserve the CQAs and that saRNA is more challenging to encapsulate and preserve than mRNA. We identified three formulations to minimize cellular activation, maximize cellular activation, or meet a CQA profile while maximizing protein expression. The significant parameters and design of the response surface modeling and multiple response optimization may be useful for designing formulations for a range of applications, such as vaccines or protein replacement therapies, for larger RNA cargoes.

Performance of nanoparticles for biomedical applications: The in vitro/in vivo discrepancy

Nanomedicine has a great potential to revolutionize the therapeutic landscape. However, up-to-date results obtained from in vitro experiments predict the in vivo performance of nanoparticles weakly or not at all. There is a need for in vitro experiments that better resemble the in vivo reality. As a result, animal experiments can be reduced, and potent in vivo candidates will not be missed. It is important to gain a deeper knowledge about nanoparticle characteristics in physiological environment. In this context, the protein corona plays a crucial role. Its formation process including driving forces, kinetics, and influencing factors has to be explored in more detail. There exist different methods for the investigation of the protein corona and its impact on physico-chemical and biological properties of nanoparticles, which are compiled and critically reflected in this review article. The obtained information about the protein corona can be exploited to optimize nanoparticles for in vivo application. Still the translation from in vitro to in vivo remains challenging. Functional in vitro screening under physiological conditions such as in full serum, in 3D multicellular spheroids/organoids, or under flow conditions is recommended. Innovative in vivo screening using barcoded nanoparticles can simultaneously test more than hundred samples regarding biodistribution and functional delivery within a single mouse.

Modulating intracellular pathways to improve non-viral delivery of RNA therapeutics

RNA therapeutics (e.g. siRNA, oligonucleotides, mRNA, etc.) show great potential for the treatment of a myriad of diseases. However, to reach their site of action in the cytosol or nucleus of target cells, multiple intra- and extracellular barriers have to be surmounted. Several non-viral delivery systems, such as nanoparticles and conjugates, have been successfully developed to meet this requirement. Unfortunately, despite these clear advances, state-of-the-art delivery agents still suffer from relatively low intracellular delivery efficiencies. Notably, our current understanding of the intracellular delivery process is largely oversimplified. Gaining mechanistic insight into how RNA formulations are processed by cells will fuel rational design of the next generation of delivery carriers. In addition, identifying which intracellular pathways contribute to productive RNA delivery could provide opportunities to boost the delivery performance of existing nanoformulations. In this review, we discuss both established as well as emerging techniques that can be used to assess the impact of different intracellular barriers on RNA transfection performance. Next, we highlight how several modulators, including small molecules but also genetic perturbation technologies, can boost RNA delivery by intervening at differing stages of the intracellular delivery process, such as cellular uptake, intracellular trafficking, endosomal escape, autophagy and exocytosis.

Power in Numbers: Harnessing Combinatorial and Integrated Screens to Advance Nanomedicine

Nanocarriers have significant potential to advance personalized medicine through targeted drug delivery. However, to date, efforts to improve nanoparticle accumulation at target disease sites have largely failed to translate clinically, stemming from an incomplete understanding of nano-bio interactions. While progress has been made to evaluate the effects of specific physical and chemical nanoparticle properties on trafficking and uptake, there is much to be gained from controlling these properties singularly and in combination to determine their interactions with different cell types. We and others have recently begun leveraging library-based nanoparticle screens to study structure-function relationships of lipid- and polymer-based drug delivery systems to guide nanoparticle design. These combinatorial screening efforts are showing promise in leading to the successful identification of critical characteristics that yield improved and specific accumulation at target sites. However, there is a crucial need to equally consider the influence of biological complexity on nanoparticle delivery, particularly in the context of clinical translation. For example, tissue and cellular heterogeneity presents an additional dimension to nanoparticle trafficking, uptake, and accumulation; applying imaging and screening tools as well as bioinformatics may further expand our understanding of how nanoparticles engage with cells and tissues. Given recent advances in the fields of omics and machine learning, there is substantial promise to revolutionize nanocarrier development through the use of integrated screens, harnessing the combinatorial parameter space afforded both by nanoparticle libraries and clinically annotated biological data sets in combination with high throughput in vivo studies.

Optimization of phospholipid chemistry for improved lipid nanoparticle (LNP) delivery of messenger RNA (mRNA)

Lipid nanoparticles (LNPs) have been established as an essential platform for nucleic acid delivery. Efforts have led to the development of vaccines that protect against SARS-CoV-2 infection using LNPs to deliver messenger RNA (mRNA) coding for the viral spike protein. Out of the four essential components that comprise LNPs, phospholipids represent an underappreciated opportunity for fundamental and translational study. We investigated this avenue by systematically modulating the identity of the phospholipid in LNPs with the goal of identifying specific moieties that directly enhance or hinder delivery efficacy. Results indicate that phospholipid chemistry can enhance mRNA delivery by increasing membrane fusion and enhancing endosomal escape. Phospholipids containing phosphoethanolamine (PE) head groups likely increase endosomal escape due to their fusogenic properties. Additionally, it was found that zwitterionic phospholipids mainly aided liver delivery, whereas negatively charged phospholipids changed the tropism of the LNPs from liver to spleen. These results demonstrate that the choice of phospholipid plays a role intracellularly by enhancing endosomal escape, while also driving organ tropism in vivo. These findings were then applied to Selective Organ Targeting (SORT) LNPs to manipulate and control spleen-specific delivery. Overall, selection of the phospholipid in LNPs provides an important handle to design and optimize LNPs for improved mRNA delivery and more effective therapeutics.

Kinetic Modeling to Accelerate the Development of Nucleic Acid Formulations

A critical hurdle in the clinical translation of nucleic acid drugs is the inefficiency in testing formulations for therapeutic potential. Specifically, the ability to quantitatively predict gene expression is lacking when transitioning between cell culture and animal studies. We address this challenge by developing a mathematical framework that can reliably predict short-interfering RNA (siRNA)-mediated gene silencing with as few as one experimental data point as an input, evaluate the efficacies of existing formulations in an expeditious manner, and ultimately guide the design of nanocarriers with optimized performances. The model herein consisted of only essential rate-limiting steps and parameters with easily characterizable values of the RNA interference process, enabling the easy identification of which parameters play dominant roles in determining the potencies of siRNA formulations. Predictions from our framework were in close agreement with in vitro and in vivo experimental results across a retrospective analysis using multiple published data sets. Notably, our findings suggested that siRNA dilution was the primary determinant of gene-silencing kinetics. Our framework shed light on the fact that this dilution rate is governed by different parameters, i.e., cell dilution (in vitro) versus clearance from target tissue (in vivo), highlighting a key reason why in vitro experiments do not always predict in vivo outcomes. Moreover, although our current effort focuses on siRNA, we anticipate that the framework can be modified and applied to other nucleic acids, such as mRNA, that rely on similar biological processes.

Particle Integrity and Size Effect on the Journey of Polymeric Nanocarriers in Zebrafish Model and the Correlation with Mice

Polymeric nanocarriers have high biocompatibility for potential drug delivery applications. After entering bloodstream, nanocarriers will circulate, interact with proteins, dissociate, or be cleared by reticuloendothelial system. Zebrafish as a visual animal model, can serve as a tool for screening nanomedicines and monitoring nanocarrier behaviors in vivo. However, a comprehensive correlation between zebrafish and rodent models is currently deficient. Here, different-sized poly(caprolactone) nanocarriers (PCL NCs) are fabricated with or without PEGylation to investigate correlation between zebrafish and mice regarding their biofate via Förster resonance energy transfer technique. Results show that PEGylated PCL NCs have higher integrity in both zebrafish and mice. Small PEG-PCL NCs have longer circulation, while large PEG-PCL NCs have dramatically higher macrophage sequestration in zebrafish and mice spleen, leading to poor circulation. PCL NCs dissociate rapidly with less macrophage sequestration. Moreover, in 7 days postfertilization (dpf) zebrafish, polymers are eliminated via hepatobiliary pathway, which is not fully functional at earlier stages of development. The effects of nanocarrier integrity on macrophage sequestration in zebrafish and good correlation with mice spleen are pioneered to be demonstrated. The findings suggest that 7 dpf zebrafish are suitable as an in vivo screening model of nanocarriers and predict their biofate in rodents.

Macrophage reprogramming into a pro-healing phenotype by siRNA delivered with LBL assembled nanocomplexes for wound healing applications

Excessive inflammatory responses in wounds are characterized by the presence of high levels of pro-inflammatory M1 macrophages rather than pro-healing M2 macrophages, which leads to delayed wound healing. Macrophage reprogramming from the M1 to M2 phenotype through knockdown of interferon regulatory factor 5 (irf5) has emerged as a possible therapeutic strategy. While downregulation of irf5 could be achieved by siRNA, it very much depends on successful intracellular delivery by suitable siRNA carriers. Here, we report on highly stable selenium-based layer-by-layer (LBL) nanocomplexes (NCs) for siRNA delivery with polyethyleneimine (PEI-LBL-NCs) as the final polymer layer. PEI-LBL-NCs showed good protection of siRNA with only 40% siRNA release in a buffer of pH = 8.5 after 72 h or in simulated wound fluid after 4 h. PEI-LBL-NCs also proved to be able to transfect RAW 264.7 cells with irf5-siRNA, resulting in successful reprogramming to the M2 phenotype as evidenced by a 3.4 and 2.6 times decrease in NOS-2 and TNF-α mRNA expression levels, respectively. Moreover, irf5-siRNA transfected cells exhibited a 2.5 times increase of the healing mediator Arg-1 and a 64% increase in expression of the M2 cell surface marker CD206⁺. Incubation of fibroblast cells with conditioned medium isolated from irf5-siRNA transfected RAW 264.7 cells resulted in accelerated wound healing in an in vitro scratch assay. These results show that irf5-siRNA loaded PEI-LBL-NCs are a promising therapeutic approach to tune macrophage polarization for improved wound healing.

High-throughput evaluation of polymeric nanoparticles for tissue-targeted gene expression using barcoded plasmid DNA

Successful systemic gene delivery requires specific tissue targeting as well as efficient intracellular transfection. Increasingly, research laboratories are fabricating libraries of novel nanoparticles, engineering both new biomaterial structures and composition ratios of multicomponent systems. Yet, methods for screening gene delivery vehicles directly in vivo are often low-throughout, limiting the number of candidate nanoparticles that can be investigated. Here, we report a comprehensive, high-throughput method to evaluate a library of polymeric nanoparticles in vivo for tissue-specific gene delivery. The method involves pairing each nanoparticle formulation with a plasmid DNA (pDNA) that harbors a unique nucleotide sequence serving as the identifying "barcode". Using real time quantitative PCR (qPCR) for detection of the barcoded pDNA and quantitative reverse transcription PCR (RT-qPCR) for transcribed barcoded mRNA, we can quantify accumulation and transfection in tissues of interest. The barcode pDNA and primers were designed with sufficient sensitivity and specificity to evaluate multiple nanoparticle formulations per mouse, improving screening efficiency. Using this platform, we evaluated the biodistribution and transfection of 8 intravenously administered poly(beta-amino ester; PBAE) nanoparticle formulations, each with a PBAE polymer of differential structure. Significant levels of nanoparticle accumulation and gene transfection were observed mainly in organs involved in clearance, including spleen, liver, and kidneys. Interestingly, higher levels of transfection of select organs did not necessarily correlate with higher levels of tissue accumulation, highlighting the importance of directly measuring in vivo transfection efficiency as the key barcoded parameter in gene delivery vector optimization. To validate this method, nanoparticle formulations were used individually for luciferase pDNA delivery in vivo. The distribution of luciferase expression in tissues matched the transfection analysis by the barcode qPCR method, confirming that this platform can be used to accurately evaluate systemic gene delivery.

Osteogenic effects of microRNA-335-5p/lipidoid nanoparticles coated on titanium surface

OBJECTIVE

In this study, we aimed to investigate the therapeutic potential of miR-335-5p lipidoid nanocomplexes coated on Titanium (Ti) SLActive surface by lyophilization.

DESIGN

In our model, we coated miR-335-5p/Lipidoid nanoparticles on titanium implant, seeded GFP-labelled mouse bone marrow stromal cells (BMSCs) onto the functionalized Ti implant surface, and analyzed the transfection efficiency, cell adhesion, proliferation, and osteogenic activity of the bone-implant interface.

RESULTS

The Ti SLActive surface displayed a suitable hydrophilicity ability and provided a large surface area for miRNA loading, enabling spatial retention of the miRNAs within the nanopores until cellular delivery. We demonstrated a high transfection efficiency of miR-335-5p lipidoid nanoparticles in BMSCs seeded onto the Ti SLActive surface, even after 14 days. Alkaline phosphatase (ALP) activity and cell vitality were significantly increased in BMSCs transfected with miR-335-5p at 7 and 14 days as opposed to cells transfected with negative controls. When miR-335-5p transfected BMSCs were induced to undergo osteogenic differentiation, we detected increased mRNA expression of osteogenic markers including Alkaline phosphatase (ALP), collagen I (COL1), osteocalcin (OCN) and bone sialoprotein (BSP) at 7 and 14 days as compared with negative controls.

CONCLUSION

MiR-335-5p lipidoid nanoparticles could be used as a new cost-effective methodology to increase the osteogenic capacity of biomedical Ti implants.

Systemic delivery of mRNA and DNA to the lung using polymer-lipid nanoparticles

Non-viral vectors offer the potential to deliver nucleic acids including mRNA and DNA into cells in vivo. However, designing materials that effectively deliver to target organs and then to desired compartments within the cell remains a challenge. Here we develop polymeric materials that can be optimized for either DNA transcription in the nucleus or mRNA translation in the cytosol. We synthesized poly(beta amino ester) terpolymers (PBAEs) with modular changes to monomer chemistry to investigate influence on nucleic acid delivery. We identified two PBAEs with a single monomer change as being effective for either DNA (D-90-C12-103) or mRNA (DD-90-C12-103) delivery to lung endothelium following intravenous injection in mice. Physical properties such as particle size or charge did not account for the difference in transfection efficacy. However, endosome co-localization studies revealed that D-90-C12-103 nanoparticles resided in late endosomes to a greater extent than DD-90-C12-103. We compared luciferase expression in vivo and observed that, even with nucleic acid optimized vectors, peak luminescence using mRNA was two orders of magnitude greater than pDNA in the lungs of mice following systemic delivery. This study indicates that different nucleic acids require tailored delivery vectors, and further support the potential of PBAEs as intracellular delivery materials.

Computational and Experimental Approaches to Investigate Lipid Nanoparticles as Drug and Gene Delivery Systems

Lipid nanoparticles (LNPs) have been widely applied in drug and gene delivery. More than twenty years ago, DoxilTM was the first LNPs-based drug approved by the US Food and Drug Administration (FDA). Since then, with decades of research and development, more and more LNP-based therapeutics have been used to treat diverse diseases, which often offer the benefits of reduced toxicity and/or enhanced efficacy compared to the active ingredients alone. Here, we provide a review of recent advances in the development of efficient and robust LNPs for drug/gene delivery. We emphasize the importance of rationally combining experimental and computational approaches, especially those providing multiscale structural and functional information of LNPs, to the design of novel and powerful LNP-based delivery systems.

Biodegradable cationic nanogels with tunable size, swelling and pKa for drug delivery

Cationic polymers have garnered significant interest for their utility in intracellular drug delivery and gene therapy. However, due to their associated toxicities, novel synthesis approaches must be explored to develop materials that are biocompatible. The novel library of nanoparticles synthesized in this study exhibit tunable hydrodynamic diameters, composition and pH-responsive properties as a function of synthesis parameters. In addition, differences in the responsiveness of these nanoparticles under different pH conditions affords greater control over intracellular drug release.

Biomimetic Gemcitabine-Lipid Prodrug Nanoparticles for Pancreatic Cancer

Gemcitabine (Gem) is a key drug for pancreatic cancer, yet limited by high systemic toxicity, low bioavailability and poor pharmacokinetic profiles. To overcome these limitations, Gem prodrug amphiphiles were synthesised with oleyl, linoleyl and phytanyl chains. Self-assembly and lyotropic mesophase behaviour of these amphiphiles were examined using polarised optical microscopy and Synchrotron SAXS (SSAXS). Gem-phytanyl was found to form liquid crystalline inverse cubic mesophase. This prodrug was combined with phospholipids and cholesterol to create biomimetic Gem-lipid prodrug nanoparticles (Gem-LPNP), verified by SSAXS and cryo-TEM to form liposomes. In vitro testing of the Gem-LPNP in several pancreatic cancer cell lines showed lower toxicity than Gem. However, in a cell line-derived pancreatic cancer mouse model Gem-LPNP displayed greater tumour growth inhibition than Gem using a fraction (<6 %) of the clinical dose and without any systemic toxicity. The easy production, improved efficacy and low toxicity of Gem-LPNP represents a promising new nanomedicine for pancreatic cancer.

Lipid-Modified Aminoglycosides for mRNA Delivery to the Liver

Cationic lipid nanoparticles (LNPs) are widely used as carriers for delivery of nucleic acids. Most synthetic routes toward cationic lipids have derived from simple amine cores. Greater chemical diversity can be obtained through starting with natural products containing basic nitrogen atoms, which offers routes to more complex molecules. Natural building blocks are not extensively explored, such as aminoglycosides, which are both structurally and functionally interesting for developing new carriers for nucleic acid delivery. Herein, cationic lipid-modified aminoglycosides (CLAs) are explored as a family of vehicles for messenger RNA (mRNA) delivery. CLAs are synthesized from natural existing aminoglycosides coupling with alkyl epoxides and acrylates. The top hit (GT-EP10) is able to deliver Luc mRNA to C57BL/6 mice at a dose of 0.05 mg kg-1 to achieve a 107 average luminescence intensity in the liver. The Lox-Stop-Lox tdTomato mouse model is used to further demonstrate that this efficient mRNA delivery system can be potentially used for gene editing. Successful delivery of human erythropoietin mRNA shows that CLA-based LNPs have promising opportunities for delivery of therapeutic nucleic acids in the future.

Novel Tamoxifen Nanoformulations for Improving Breast Cancer Treatment: Old Wine in New Bottles

Breast cancer (BC) is one of the leading causes of death from cancer in women; second only to lung cancer. Tamoxifen (TAM) is a hydrophobic anticancer agent and a selective estrogen modulator (SERM), approved by the FDA for hormone therapy of BC. Despite having striking efficacy in BC therapy, concerns regarding the dose-dependent carcinogenicity of TAM still persist, restricting its therapeutic applications. Nanotechnology has emerged as one of the most important strategies to solve the issue of TAM toxicity, owing to the ability of nano-enabled-formulations to deliver smaller concentrations of TAM to cancer cells, over a longer period of time. Various TAM-containing-nanosystems have been successfully fabricated to selectively deliver TAM to specific molecular targets found on tumour membranes, reducing unwanted toxic effects. This review begins with an outline of breast cancer, the current treatment options and a history of how TAM has been used as a combatant of BC. A detailed discussion of various nanoformulation strategies used to deliver lower doses of TAM selectively to breast tumours will then follow. Finally, a commentary on future perspectives of TAM being employed as a targeting vector, to guide the delivery of other therapeutic and diagnostic agents selectively to breast tumours will be presented.

The role of apolipoprotein- and vitronectin-enriched protein corona on lipid nanoparticles for in vivo targeted delivery and transfection of oligonucleotides in murine tumor models

The application of lipid-based nanoparticle (LNP) delivery systems remains a popular strategy for the systemic delivery of gene therapies to specific disease targets, including solid tumors. It is now well acknowledged that upon systemic administration, biomolecules from blood will adsorb onto nanoparticles' surfaces, forming a "protein corona", affording nanoparticles a "biological identity" on top of their "synthetic identity". Detailed analysis of nanoparticle protein corona is gradually revealing the "missing link" between nanoparticle chemical properties and the biological identity. Nevertheless, the discovery of nanoparticle protein corona's impact on tumor delivery is limited. In this study, we demonstrate that protein corona can be manipulated by formulation composition and particle surface charge changes, and a single lipid switch could switch the nanoparticle protein corona profile. The protein corona composition differences had a profound impact on cell transfection, in vivo biodistribution as well as tumor-specific delivery efficiency. Nanoparticles with apolipoprotein-rich corona showed better delivery to hepatocellular carcinoma (HepG2) as compared to those with vitronectin-rich corona. In addition, we found that, the PEG conjugated lipid chain length and PEG amount in LNPs were key factors to consider in successful RNA interference therapy for solid tumors.

Delivery of mRNA vaccines with heterocyclic lipids increases anti-tumor efficacy by STING-mediated immune cell activation

Therapeutic messenger RNA vaccines enable delivery of whole antigens, which can be advantageous over peptide vaccines. However, optimal efficacy requires both intracellular delivery, to allow antigen translation, and appropriate immune activation. Here, we developed a combinatorial library of ionizable lipid-like materials to identify mRNA delivery vehicles that facilitate mRNA delivery in vivo and provide potent and specific immune activation. Using a three-dimensional multi-component reaction system, we synthesized and evaluated the vaccine potential of over 1,000 lipid formulations. The top candidate formulations induced a robust immune response, and were able to inhibit tumor growth and prolong survival in melanoma and human papillomavirus E7 in vivo tumor models. The top-performing lipids share a common structure: an unsaturated lipid tail, a dihydroimidazole linker and cyclic amine head groups. These formulations induce antigen-presenting cell maturation via the intracellular stimulator of interferon genes (STING) pathway, rather than through Toll-like receptors, and result in limited systemic cytokine expression and enhanced anti-tumor efficacy.

Let's get small (and smaller): Combining zebrafish and nanomedicine to advance neuroregenerative therapeutics

Several key attributes of zebrafish make them an ideal model system for the discovery and development of regeneration promoting therapeutics; most notably their robust capacity for self-repair which extends to the central nervous system. Further, by enabling large-scale drug discovery directly in living vertebrate disease models, zebrafish circumvent critical bottlenecks which have driven drug development costs up. This review summarizes currently available zebrafish phenotypic screening platforms, HTS-ready neurodegenerative disease modeling strategies, zebrafish small molecule screens which have succeeded in identifying regeneration promoting compounds and explores how intravital imaging in zebrafish can facilitate comprehensive analysis of nanocarrier biodistribution and pharmacokinetics. Finally, we discuss the benefits and challenges attending the combination of zebrafish and nanoparticle-based drug optimization, highlighting inspiring proof-of-concept studies and looking toward implementation across the drug development community.