Cholesterol Sequestration from Caveolae/Lipid Rafts Enhances Cationic Liposome-Mediated Nucleic Acid Delivery into Endothelial Cells

SMART-lipid nanoparticles enabled mRNA vaccine elicits cross-reactive humoral responses against the omicron sub-variants

The continual emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has necessitated the development of broad cross-reactive vaccines. Recent findings suggest that enhanced antigen presentation could lead to cross-reactive humoral responses against the emerging variants. Toward enhancing the antigen presentation to dendritic cells (DCs), we developed a novel shikimoylated mannose receptor targeting lipid nanoparticle (SMART-LNP) system that could effectively deliver mRNAs into DCs. To improve the translation of mRNA, we developed spike domain-based trimeric S1 (TS1) mRNA with optimized codon sequence, base modification, and engineered 5' and 3' UTRs. In a mouse model, SMART-LNP-TS1 vaccine could elicit robust broad cross-reactive IgGs against Omicron sub-variants, and induced interferon-γ-producing T cells against SARS-CoV-2 virus compared with non-targeted LNP-TS1 vaccine. Further, T cells analysis revealed that SMART-LNP-TS1 vaccine induced long-lived memory T cell subsets, T helper 1 (Th1)-dominant and cytotoxic T cells immune responses against the SARS-CoV-2 virus. Importantly, SMART-LNP-TS1 vaccine produced strong Th1-predominant humoral and cellular immune responses. Overall, SMART-LNPs can be explored for precise antigenic mRNA delivery and robust immune responses. This platform technology can be explored further as a next-generation delivery system for mRNA-based immune therapies.

Zwitterionic materials for nucleic acid delivery and therapeutic applications

Nucleic acid therapeutics have demonstrated substantial potential in combating various diseases. However, challenges persist, particularly in the delivery of multifunctional nucleic acids. To address this issue, numerous gene delivery vectors have been developed to fully unlock the potential of gene therapy. The advancement of innovative materials with exceptional delivery properties is critical to propel the clinical translation of nucleic acid drugs. Cationic vector materials have received extensive attention, while zwitterionic materials remain relatively underappreciated in delivery. In this review, we outline a diverse range of zwitterionic material nucleic acid carriers, predominantly encompassing zwitterionic lipids, polymers and peptides. Their respective chemical structures, synthesis approaches, properties, advantages, and therapeutic applications are summarized and discussed. Furthermore, we highlight the challenges and future opportunities associated with the development of zwitterionic vector materials. This review will aid to understand the zwitterionic materials in aiding gene delivery, contributing to the continual progress of nucleic acid therapeutics.

A Comparison of Cellular Uptake Mechanisms, Delivery Efficacy, and Intracellular Fate between Liposomes and Extracellular Vesicles

A key aspect for successful drug delivery via lipid-based nanoparticles is their internalization in target cells. Two prominent examples of such drug delivery systems are artificial phospholipid-based carriers, such as liposomes, and their biological counterparts, the extracellular vesicles (EVs). Despite a wealth of literature, it remains unclear which mechanisms precisely orchestrate nanoparticle-mediated cargo delivery to recipient cells and the subsequent intracellular fate of therapeutic cargo. In this review, internalization mechanisms involved in the uptake of liposomes and EVs by recipient cells are evaluated, also exploring their intracellular fate after intracellular trafficking. Opportunities are highlighted to tweak these internalization mechanisms and intracellular fates to enhance the therapeutic efficacy of these drug delivery systems. Overall, literature to date shows that both liposomes and EVs are predominantly internalized through classical endocytosis mechanisms, sharing a common fate: accumulation inside lysosomes. Studies tackling the differences between liposomes and EVs, with respect to cellular uptake, intracellular delivery and therapy efficacy, remain scarce, despite its importance for the selection of an appropriate drug delivery system. In addition, further exploration of functionalization strategies of both liposomes and EVs represents an important avenue to pursue in order to control internalization and fate, thereby improving therapeutic efficacy.

Enterovirus 71 enters human brain microvascular endothelial cells through an ARF6-mediated endocytic pathway

Infection of the central nervous system caused by enterovirus 71 (EV71) remains the main cause of death in hand-foot-and-mouth disease. However, the mechanism responsible for how EV71 breaks through the blood-brain barrier to infect brain cells has yet to be elucidated. By performing a high-throughput small interfering RNA (siRNA) screening and validation, we found that the infection of human brain microvascular endothelial cells (HBMECs) by EV71 was independent of the endocytosis pathways mediated by caveolin, clathrin, and macropinocytosis but dependent on ADP-ribosylation factor 6 (ARF6), a small guanosinetriphosphate (GTP)-binding protein of the Ras superfamily. The specific siRNA targeting ARF6 markedly inhibited HBMECs susceptibility to EV71. EV71 infectivity was inhibited by NAV-2729, a specific inhibitor of ARF6, in a dose-dependent manner. The subcellular analysis demonstrated the co-localization of the endocytosed EV71 and ARF6, while knockdown of ARF6 with siRNA remarkably influenced EV71 endocytosis. By immunoprecipitation assays, we found a direct interaction of ARF6 with EV71 viral protein. Furthermore, ARF1, another small GTP-binding protein, was also found to participate in ARF6-mediated EV71 endocytosis. Murine experiments demonstrated that NAV-2729 significantly alleviated mortality caused by EV71 infection. Our study revealed a new pathway by which EV71 enters the HBMECs and provides new targets for drug development.

Unravelling the interactions of biodegradable dendritic nucleic acid carriers and neural cells

Nanomedicines based on nanoparticles as carriers of therapeutics are expected to drastically influence the future of healthcare. However, clinical translation of these technologies can be very challenging. The development process of nanoparticles for biological applications encompasses the analysis and understanding of several steps in vitro, before in vivo, and subsequent clinical applications, namely, the in-depth study of biosafety, cellular interaction, and intracellular trafficking. Recently, we proposed a new family of fully biodegradable PEG-GATGE (Poly(Ethylene Glycol)-Gallic Acid-Triethylene Glycol Ester) dendritic block copolymers to act as versatile delivery vectors in nanomedicine. These nanosystems showed great promise in complexing, protecting, and delivering nucleic acids to cells, forming nanoscaled complexes called dendriplexes. Due to these favourable features, in the present study, the dendriplexes' characterization was expanded and, in addition, their biocompatibility, cellular uptake, and cellular path in neuronal cells from the peripheral and central nervous systems were assessed. Our fully biodegradable dendritic nanosystem was found to be biocompatible in all the studied neuronal cells and mediates fast cellular interaction and endocytosis in both cell line tested and primary mouse cortical neurons. Nevertheless, the mechanism of dendriplex cell entry and intracellular fate was found to be different in cell lines and primary cultures. Dendriplexes' internalization was observed to be mediated by clathrin in ND7/23 and HT22 cells, while caveolin-mediated endocytosis occurred in primary mouse cortical neurons, in which, after internalization, dendriplexes were not colocalized with lysosomes or autophagosomes. Taken together, these results further point to PEG-GATGE dendrimers as biosafe delivery vectors of nucleic acids to neuronal cells in vitro, suggesting their feasibility as carriers in the context of nervous system applications. Furthermore, our data reinforce the importance of testing the performance of new vectors in different models to verify their potential applicability in vitro and/or in vivo.

Diosgenin enhances liposome-enabled nucleic acid delivery and CRISPR/Cas9-mediated gene editing by modulating endocytic pathways

The CRISPR/Cas9 system holds great promise in treating genetic diseases, owing to its safe and precise genome editing. However, the major challenges to implementing the technology in clinics lie in transiently limiting the expression of genome editing factors and achieving therapeutically relevant frequencies with fidelity. Recent findings revealed that non-viral vectors could be a potential alternative delivery system to overcome these limitations. In our previous research, we demonstrated that liposomal formulations with amide linker-based cationic lipids and cholesterol were found to be effective in delivering a variety of nucleic acids. In the current study, we screened steroidal sapogenins as an alternative co-lipid to cholesterol in cationic liposomal formulations and found that liposomes with diosgenin (AD, Amide lipid: Diosgenin) further improved nucleic acid delivery efficacy, in particular, delivering Cas9 pDNA and mRNA for efficient genome editing at multiple loci, including AAVS1 and HBB, when compared to amide cholesterol. Mechanistic insights into the endocytosis of lipoplexes revealed that diosgenin facilitated the lipoplexes' cholesterol-independent and clathrin-mediated endocytosis, which in turn leads to increased intracellular delivery. Our study identifies diosgenin-doped liposomes as an efficient tool to deliver CRISPR/Cas9 system.

A Microfluidic System of Gene Transfer by Ultrasound

Ultrasonic gene transfer has advantages beyond other cell transfer techniques because ultrasound does not directly act on cells, but rather pushes the gene fragments around the cells into cells through an acoustic hole effect. Most examples reported were carried out in macro volumes with conventional ultrasonic equipment. In the present study, a MEMS focused ultrasonic transducer based on piezoelectric thin film with flexible substrate was integrated with microchannels to form a microfluidic system of gene transfer. The core part of the system is a bowl-shaped curved piezoelectric film structure that functions to focus ultrasonic waves automatically. Therefore, the low input voltage and power can obtain the sound pressure exceeding the cavitation threshold in the local area of the microchannel in order to reduce the damage to cells. The feasibility of the system is demonstrated by finite element simulation and an integrated system of MEMS ultrasonic devices and microchannels are developed to successfully carry out the ultrasonic gene transfection experiments for HeLa cells. The results show that having more ultrasonic transducers leads a higher transfection rate. The system is of great significance to the development of single-cell biochip platforms for early cancer diagnosis and assessment of cancer treatment.