A perspective of lipid nanoparticles for RNA delivery

Pia Mater-Penetrable Lipopolymer Nanoparticles for Gliocyte-Targeted IL-10 mRNA Therapy Alleviate Paclitaxel-Induced Peripheral Neuropathy

Paclitaxel (PTX) is a commonly used chemotherapeutic agent for treating various solid tumors; however, it often leads to a severe side effect known as paclitaxel-induced peripheral neuropathy (PIPN), for which effective treatments are limited. Although mRNA therapies have shown promise in addressing central nervous system (CNS) disorders, the successful delivery of mRNA therapeutics to the nervous system is still hindered by many biological barriers. In this study, it is demonstrated that, compared with commercial MC3 lipid nanoparticles (MC3 LNPs), mRNA-loaded P6CIT-derived lipopolymer nanoparticles (P6CIT LPNPs), which are delivered via intrathecal injection, achieve effective penetration through the pia mater. More importantly, this P6CIT LPNP demonstrates the ability to achieve highly targeted mRNA transfection in gliocytes within the spinal cord and dorsal root ganglia (DRG), which is essential for the regulation of neuroinflammation. Furthermore, two intrathecal injections of P6CIT LPNPs encapsulating mIL-10 (P6CIT/mIL-10) significantly alleviate PIPN by reducing proinflammatory cytokine production, gliocyte activation, and presynaptic NMDA receptor hyperactivity in both male and female mice. This study presents a promising and clinically translatable platform for using mRNA-loaded LPNPs to treat PIPN.

Significance of gene therapy in neurodegenerative diseases

Gene therapy is an approach that employs vectors to deliver genetic material to target cells, aiming to correct genes with pathogenic mutations and modulate one or more genes responsible for disease progression. It holds significant value for clinical applications and offers broad market potential due to the large patient population affected by various conditions. For instance, in 2023, the Food and Drug Administration (FDA) approved 55 new drugs, including five specifically for gene therapy targeting hematologic and rare diseases. Recently, with advancements in understanding the pathogenesis and development of neurodegenerative diseases (NDDs), gene therapy has emerged as a promising avenue for treating Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), and spinal muscular atrophy (SMA), particularly in personalized medicine. Notably, the FDA has approved three clinical applications for combating SMA, utilizing viral vectors delivered via intravenous and intrathecal injections. However, gene therapy for other NDDs remains in clinical trials, necessitating improvements in viral vectors, exploration of new vectors, optimization of delivery routes, and further investigation into pathogenesis to identify novel targets. This review discusses recent advancements in gene therapy for NDDs, offering insights into developing new therapeutic strategies.

A Metabolite Co-Delivery Strategy to Improve mRNA Lipid Nanoparticle Delivery

Lipid nanoparticles (LNPs) effectively protect mRNA and facilitate its entry into target cells for protein synthesis. Despite these successes, cellular entry alone may not be enough for optimal protein expression, as mRNA translation also depends on the availability of essential metabolites, including metabolic energy sources, coenzymes, and amino acids. Without adequate metabolites, mRNA translation may be less efficient, potentially leading to higher dosing requirements or poorer therapeutic outcomes for LNP therapies. To address this, we develop a metabolite co-delivery strategy by encapsulating essential metabolites within mRNA LNPs, hypothesizing that our approach can uniformly improve mRNA delivery. Instead of adding a fifth component to the organic phase, our strategy involves mixing the metabolite with the mRNA payload in the aqueous phase, while maintaining the molar ratio of the components in the organic phase during LNP formulation. We verify our approach in vitro and in vivo, highlighting the broad applicability of our strategy through mechanism and efficacy studies across multiple cell lines, and physiological conditions, such as normoxia (i.e., 21% oxygen), hypoxia (i.e., 1% oxygen), and in mice. Taken collectively, we anticipate that our metabolite co-delivery strategy may serve as a generalizable strategy to enhance in vitro and in vivo protein expression using mRNA LNPs, potentially offering broad applicability for the study and treatment of disease.

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

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

NIR-triggered and glucose-powered hollow mesoporous Mo-based single-atom nanozymes for cascade chemodynamic diabetic infection therapy

Diabetic infections/wounds remain to be a threatening challenge as it seriously leads to lower limb amputation with endless pains and subsequent high economic/psychosocial costs. The exceptional peroxidase-like activity of single-atom nanozymes (SAzymes) holds great promise for chemodynamic therapy (CDT) of diabetic infection, but is extremely restricted by the near-neutral pH and insufficient H2O2 levels in physiological conditions. Herein, we innovated a hollow mesoporous molybdenum single-atom nanozyme (HMMo-zyme) featured with catalytic activity, photothermal performance and drug delivery properties for more effective antibacterial therapeutic in diabetic conditions. The glucose oxidase (GOx) was encapsulated into HMMo-zyme with phase-change material (PCM) to form HMMo/GOx@P system, which could be controllably disassembled by near-infrared ray (NIR) to trigger cascade CDT toward bacterial infections. The results revealed that the release of GOx accelerated by NIR could facilitate the continuous conversion of glucose (Glu) into gluconic acid, accompanied by a sharply decrease in pH to establish a low-pH environment that notably enhanced the catalytic activity of HMMo-zyme, which subsequently drives the conversion of generated H2O2 into toxic hydroxyl radicals (·OH) for amplified anti-bacterial treatment. As a proof of the concept, this NIR-assisted HMMo/GOx@P strategy could efficiently inhibit/kill bacteria and suppress tissue inflammations, thereby accelerating the wound healing processes both in in vitro and in vivo diabetic infection models. This study provides a novel strategy that may serve as a promising alternative for antibiotic therapeutics against diabetic infection, thus holding promise for more effective diabetic infection treatment manipulating Mo-based SAzymes.

Landscape of small nucleic acid therapeutics: moving from the bench to the clinic as next-generation medicines

The ability of small nucleic acids to modulate gene expression via a range of processes has been widely explored. Compared with conventional treatments, small nucleic acid therapeutics have the potential to achieve long-lasting or even curative effects via gene editing. As a result of recent technological advances, efficient small nucleic acid delivery for therapeutic and biomedical applications has been achieved, accelerating their clinical translation. Here, we review the increasing number of small nucleic acid therapeutic classes and the most common chemical modifications and delivery platforms. We also discuss the key advances in the design, development and therapeutic application of each delivery platform. Furthermore, this review presents comprehensive profiles of currently approved small nucleic acid drugs, including 11 antisense oligonucleotides (ASOs), 2 aptamers and 6 siRNA drugs, summarizing their modifications, disease-specific mechanisms of action and delivery strategies. Other candidates whose clinical trial status has been recorded and updated are also discussed. We also consider strategic issues such as important safety considerations, novel vectors and hurdles for translating academic breakthroughs to the clinic. Small nucleic acid therapeutics have produced favorable results in clinical trials and have the potential to address previously "undruggable" targets, suggesting that they could be useful for guiding the development of additional clinical candidates.

A review of RNA nanoparticles for drug/gene/protein delivery in advanced therapies: Current state and future prospects

Nanotechnology involves the utilization of materials with exceptional properties at the nanoscale. Over the past few years, nanotechnologies have demonstrated significant potential in improving human health, particularly in medical treatments. The self-assembly characteristic of RNA is a highly effective method for designing and constructing nanostructures using a combination of biological, chemical, and physical techniques from different fields. There is great potential for the application of RNA nanotechnology in therapeutics. This review explores various nano-based drug delivery systems and their unique features through the impressive progress of the RNA field and their significant therapeutic promises due to their unique performance in the COVID-19 pandemic. However, a significant hurdle in fully harnessing the power of RNA drugs lies in effectively delivering RNA to precise organs and tissues, a critical factor for achieving therapeutic effectiveness, minimizing side effects, and optimizing treatment outcomes. There have been many efforts to pursue targeting, but the clinical translation of RNA drugs has been hindered by the lack of clear guidelines and shared understanding. A comprehensive understanding of various principles is essential to develop vaccines using nucleic acids and nanomedicine successfully. These include mechanisms of immune responses, functions of nucleic acids, nanotechnology, and vaccinations. Regarding this matter, the aim of this review is to revisit the fundamental principles of the immune system's function, vaccination, nanotechnology, and drug delivery in relation to the creation and manufacturing of vaccines utilizing nanotechnology and nucleic acids. RNA drugs have demonstrated significant potential in treating a wide range of diseases in both clinical and preclinical research. One of the reasons is their capacity to regulate gene expression and manage protein production efficiently. Different methods, like modifying chemicals, connecting ligands, and utilizing nanotechnology, have been essential in enabling the effective use of RNA-based treatments in medical environments. The article reviews stimuli-responsive nanotechnologies for RNA delivery and their potential in RNA medicines. It emphasizes the notable benefits of these technologies in improving the effectiveness of RNA and targeting specific cells and organs. This review offers a comprehensive analysis of different RNA drugs and how they work to produce therapeutic benefits. Recent progress in using RNA-based drugs, especially mRNA treatments, has shown that targeted delivery methods work well in medical treatments.

Modular Design of Lipopeptide-Based Organ-Specific Targeting (POST) Lipid Nanoparticles for Highly Efficient RNA Delivery

Lipid nanoparticles (LNPs) with highly efficient and specific extrahepatic targeting abilities are promising in gene delivery, and the lipopeptides (LPs) with excellent designability and functionality are expected to empower the construction of functional LNPs. This study aims to develop highly efficient ionizable components that accurately match different targeting lipid systems through the modular design of LPs. Based on this, a lipopeptide-based organ-specific targeting (POST) LNP screening strategy is constructed, in which lysine-histidine-based lipopeptides (KH-LPs) are designed as highly efficient ionizable components. The optimal KH-LP LNP screened in vitro shows excellent siRNA/mRNA transfecting ability in various hard-to-transfect cell lines. Compared to the classic LNPs, the POST LNPs screened in vivo achieve even higher (or at least comparable) efficiency and specificity in delivering mRNA and siRNA to the lung, liver, and spleen, respectively. The structure-activity relationship (SAR) proves that the modular regulation of LP structures can accurately provide the optimal ionizable components for different targeting lipid systems, demonstrating the potential of this strategy in developing efficient and selective targeting systems, which is expected to open up more possibilities for gene therapy.

Interaction design in mRNA delivery systems

Following the coronavirus disease 2019 (COVID-19) pandemic, mRNA technology has made significant breakthroughs, emerging as a potential universal platform for combating various diseases. To address the challenges associated with mRNA delivery, such as instability and limited delivery efficacy, continuous advancements in genetic engineering and nanotechnology have led to the exploration and refinement of various mRNA structural modifications and delivery platforms. These achievements have significantly broadened the clinical applications of mRNA therapies. Despite the progress, the understanding of the interactions in mRNA delivery systems remains limited. These interactions are complex and multi-dimensional, occurring between mRNA and vehicles as well as delivery materials and helper ingredients. Resultantly, stability of the mRNA delivery systems and their delivery efficiency can be both significantly affected. This review outlines the current state of mRNA delivery strategies and summarizes the interactions in mRNA delivery systems. The interactions include the electrostatic interactions, hydrophobic interactions, hydrogen bonding, π-π stacking, coordination interactions, and so on. This interaction understanding provides guideline for future design of next-generation mRNA delivery systems, thereby offering new perspectives and strategies for developing diverse mRNA therapeutics.

RNA Structure: Past, Future, and Gene Therapy Applications

First believed to be a simple intermediary between the information encoded in deoxyribonucleic acid and that functionally displayed in proteins, ribonucleic acid (RNA) is now known to have many functions through its abundance and intricate, ubiquitous, diverse, and dynamic structure. About 70-90% of the human genome is transcribed into protein-coding and noncoding RNAs as main determinants along with regulatory sequences of cellular to populational biological diversity. From the nucleotide sequence or primary structure, through Watson-Crick pairing self-folding or secondary structure, to compaction via longer distance Watson-Crick and non-Watson-Crick interactions or tertiary structure, and interactions with RNA or other biopolymers or quaternary structure, or with metabolites and biomolecules or quinary structure, RNA structure plays a critical role in RNA's lifecycle from transcription to decay and many cellular processes. In contrast to the success of 3-dimensional protein structure prediction using AlphaFold, RNA tertiary and beyond structures prediction remains challenging. However, approaches involving machine learning and artificial intelligence, sequencing of RNA and its modifications, and structural analyses at the single-cell and intact tissue levels, among others, provide an optimistic outlook for the continued development and refinement of RNA-based applications. Here, we highlight those in gene therapy.

A Novel Approach for Bladder Cancer Treatment: Nanoparticles as a Drug Delivery System

Bladder cancer represents one of the most prevalent malignant neoplasms of the urinary tract. In the Asian context, it represents the eighth most common cancer in males. In 2022, there were approximately 613,791 individuals diagnosed with bladder cancer worldwide. Despite the availability of efficacious treatments for the two principal forms of bladder cancer, namely non-invasive and invasive bladder cancer, the high incidence of recurrence following treatment and the suboptimal outcomes observed in patients with high-grade and advanced disease represent significant concerns in the management of bladder cancer at this juncture. Nanoparticles have gained attention for their excellent properties, including stable physical properties, a porous structure that can be loaded with a variety of substances, and so on. The in-depth research on nanoparticles has led to their emergence as a new class of nanoparticles for combination therapy, due to their advantageous properties. These include the extension of the drug release window, the enhancement of drug bioavailability, the improvement of drug targeting ability, the reduction of local and systemic toxicity, and the simultaneous delivery of multiple drugs for combination therapy. As a result, nanoparticles have become a novel agent of the drug delivery system. The advent of nanoparticles has provided a new impetus for the development of non-surgical treatments for bladder cancer, including chemotherapy, immunotherapy, gene therapy and phototherapy. The unique properties of nanoparticles have facilitated the combination of diverse non-surgical therapeutic modalities, enhancing their overall efficacy. This review examines the recent advancements in the use of nanoparticles in non-surgical bladder cancer treatments, encompassing aspects such as delivery, therapeutic efficacy, and the associated toxicity of nanoparticles, as well as the challenges encountered in clinical applications.

Prevent and Reverse Metabolic Dysfunction-Associated Steatohepatitis and Hepatic Fibrosis via mRNA-Mediated Liver-Specific Antibody Therapy

Chronic exposure of the liver to multiple insults culminates in the development of metabolic dysfunction-associated steatohepatitis (MASH), a complicated metabolic syndrome characterized by hepatic steatosis and inflammation, typically accompanied by progressive fibrosis. Despite extensive clinical evaluation, there remain challenges in MASH drug development, which are primarily due to unsatisfactory efficacy and limited specificity. Strategies to address the unmet medical need for MASH with fibrosis before it reaches the irreversible stage of decompensated cirrhosis are critically needed. Herein, we developed an mRNA-mediated liver-specific antibody therapy for MASH and hepatic fibrosis using a targeted lipid nanoparticle (LNP) delivery system. When encapsulated with IL-11 single-chain variable fragment (scFv)-encoded mRNA, the targeted AA3G LNP (termed mIL11-scFv@AA3G) specifically accumulated in the liver and secreted IL-11 scFv to neutralize overexpressed IL-11 in hepatic environments, thus inhibiting the IL-11 signaling pathway in hepatocytes and hepatic stellate cells. As a preventative regimen, systemic administration of mIL11-scFv@AA3G reversed MASH and prevented the progression to fibrosis in a murine model of early MASH. Notably, mIL11-scFv@AA3G exhibited superior efficacy compared to systemic administration of IL-11 scFv alone, attributed to the sustained antibody expression in the liver, which lasted 18-fold longer than that of IL-11 scFv. When tested in the MASH model with fibrosis, mIL11-scFv@AA3G effectively ameliorated steatosis and resolved fibrosis and inflammation. These findings present a versatile LNP platform targeting liver cell subtypes for the sustained expression of therapeutic antibodies to treat MASH and fibrosis. The developed mRNA-mediated liver-specific antibody therapy offers a promising approach for addressing MASH and holds the potential for expansion to various other diseases.

Biomimetic Nucleic Acid Drug Delivery Systems for Relieving Tumor Immunosuppressive Microenvironment

Immunotherapy combats tumors by enhancing the body's immune surveillance and clearance of tumor cells. Various nucleic acid drugs can be used in immunotherapy, such as DNA expressing cytokines, mRNA tumor vaccines, small interfering RNAs (siRNA) knocking down immunosuppressive molecules, and oligonucleotides that can be used as immune adjuvants. Nucleic acid drugs, which are prone to nuclease degradation in the circulation and find it difficult to enter the target cells, typically necessitate developing appropriate vectors for effective in vivo delivery. Biomimetic drug delivery systems, derived from viruses, bacteria, and cells, can protect the cargos from degradation and clearance, and deliver them to the target cells to ensure safety. Moreover, they can activate the immune system through their endogenous activities and active components, thereby improving the efficacy of antitumor immunotherapeutic nucleic acid drugs. In this review, biomimetic nucleic acid delivery systems for relieving a tumor immunosuppressive microenvironment are introduced. Their immune activation mechanisms, including upregulating the proinflammatory cytokines, serving as tumor vaccines, inhibiting immune checkpoints, and modulating intratumoral immune cells, are elaborated. The advantages and disadvantages, as well as possible directions for their clinical translation, are summarized at last.

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.